# BroadBand Bass Trap's Build



## cinema mad

For Any One that is interested in Building there own PRO LOOKING :bigsmile: Corner Mounted BroadBand Bass Traps take A look down A few posts for Some Ideas and What I came UP with.....


I went with Ultratel 50mm thick 1200x2400 semi rigid fiberglass for my bass traps the packs came in lots of 3 sheets per pack, it's very pricey at A retail price of over $300 per pack :yikes:, I was luckily able to get the Ultratel direct from bradfords :bigsmile:.... I made my Bass traps 8ft high X 690mm wide and 6in thick (3 layers),I put them across the corners so ended up with an air gap being 16in out from the wall corner to the front of the trap's.. Here are some pictures of the front Bass traps.....

Hope this helps.... 

Cheers.....


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## Prof.

*Re: Bass trap questions*



cinema mad said:


> I went with Ultratel 50mm thick 1200x2400 semi rigid fiberglass for my bass traps the packs came in lots of 3 sheets per pack, it's very pricey at A retail price of over $300 per pack :yikes:,


That is expensive!!..I got the 50mm. Supertel sheets for about $60.00 each..




> I made my Bass traps 8ft high X 690mm wide and 6in thick (3 layers),I put them across the corners so ended up with an air gap being 16in out from the wall corner to the front of the trap's.. Here are some pictures of the front Bass traps.....


So all three layers were 690mm. wide?..That would leave quite a gap between the panels and the corner..
I don't know if that would be beneficial or detrimental to the performance of the traps,considering that the wedge type traps are right in the corner..
Brian might be able to throw some light on that..



> Hope this helps... It appears that my 1024x768 jpeg pictures will not upload it thinks they are 1200x1000 :foottap: Works fine on AVS...


I normally load photos at 800x600 without a problem..You might have to resize them..


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## cinema mad

*Re: Bass trap questions*

Hi PROF, For A pack of 3 Ultratel 1200x2400 x50mm (2in) thick is over $300au retail but I did'nt pay that Direct from CSR Bradfords, Bradfords wont deal direct to the public only Trade or suppliers.... the Specs for 50mm Ultratel KG/m3 is [email protected] 125hz, while 50mm Supertel KG/m3 is [email protected] 125hz... So if you X that by 3 (150mm thick) Ultratel is the way to go for this type of Bass traps...

Own's Corning 2" plain 705 is 6.0pcf,96kg/m3 and [email protected] 125hz..
The Same Own's Corning plain 2" 705 with A 16" air gap is [email protected] 125hz, so as you can see with A 16" air gap from the wall 705's performance is more than 3 times better than flat on A wall....

To up the efficiency/performance of these type of corner bass traps An air gap is A must......Also noted in the fourth Edition of Master Handbook of Acoustics... Thankyou for the tip for uploading photos Prof

Here is A 750x562 picture of my front Corner Bass traps....

Cheers....


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## cinema mad

*Re: Bass trap questions*

I first made A frame 690mm wide x just under 8ft high, I covered the front with 1 large piece of Black speaker grill cloth doubled up for each Bass trap so I had no fabric joins, and for the back I used doubled up white open weave stuff like used under couches can't recall the name.. I used my air Staple gun with 80/10mm staples to attach the coverings... 

To attach the Bass traps to the wall I used A stud wall hook right in the top corner of the wall and attached 2x 4mm Gauge 40mm length eye screws to the top left and right corners of the bass trap's, then used 12 KG picture frame wire to pull and hold the bass trap tight into the corners... I also made A stand for the bass traps to sit them on for added stability and authetics.... see the attached picture....

I purchased the black speaker grill cloth and white open weave fabric from Spotlight....The Fixings I got from Bunnings....

Hope this helps.....Cheers....


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## Prof.

*Re: Bass trap questions*

Hi Jason..

Thanks for the detailed description of your bass traps..:T



cinema mad said:


> the Specs for 50mm Ultratel KG/m3 is [email protected] 125hz, while 50mm Supertel KG/m3 is [email protected] 125hz... So if you X that by 3 (150mm thick) Ultratel is the way to go for this type of Bass traps...


Yes, I did see the specs. for the two types and the Ultratel is a denser, more compacted fibreglass..which tends me to believe that it would be more reflective than the Supertel..
But hey..if it's worked for you in your environment, then that's all that matters..



> Own's Corning 2" plain 705 is 6.0pcf,96kg/m3 and [email protected] 125hz..
> The Same Own's Corning plain 2" 705 with A 16" air gap is [email protected] 125hz, so as you can see with A 16" air gap from the wall 705's performance is more than 3 times better than flat on A wall....


I'm surprised that a 16" air gap could change the performance as much as that!

I'll have to incorporate that sort of air gap in my traps, and see if there's any improvement..


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## Prof.

*Re: Bass trap questions*



cinema mad said:


> I first made A frame 690mm wide x just under 8ft high, I covered the front with 1 large piece of Black speaker grill cloth doubled up for each Bass trap so I had no fabric joins, and for the back I used doubled up white open weave stuff like used under couches can't recall the name.. I used my air Staple gun with 80/10mm staples to attach the coverings...
> 
> To attach the Bass traps to the wall I used A stud wall hook right in the top corner of the wall and attached 2x 4mm Gauge 40mm length eye screws to the top left and right corners of the bass trap's, then used 12 KG picture frame wire to pull and hold the bass trap tight into the corners... I also made A stand for the bass traps to sit them on for added stability and authetics.... see the attached picture....


Sounds like a very effective design..well done..:T



> I purchased the black speaker grill cloth and white open weave fabric from Spotlight....The Fixings I got from Bunnings....


I've bought numerous materials from Spotlight over the years, but I've never seen any grille cloth there..:scratch:
Are you sure it was grille cloth or something that looks like it?..
I recently bought a material from them that looks like grille cloth, which I'm using to cover some new acoustic panels..
It's called Black Polyester Stretch...It has the same open weave as grille cloth, but it's a fraction of the price, and comes in 1500mm. wide rolls..

BTW..I think that white material you're referring to is Dacron..

Some full shots of the finished traps would be nice to see..


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## cinema mad

*Re: Bass trap questions*

Hi Prof, Thankyou for the kind words...

The Black speaker cloth I used from spotlight sounds simmilar to yours, Scott from spotlight Geelong orderd in A few rolls its called "Loud Speaker Meterial" original name :sarcastic: spotlights part No 1283123... and the roll is around 1400mm wide.. The problem is he is not back at the Geelong store untill tomorrow to confirm I was given the correct part No... I will post A picture of the white material I used on the rear of the front corner Bass traps Because its not Dacron, full shots of front bass traps as you requested.... 

Hope this Helps, Cheers...


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## Prof.

*Re: Bass trap questions*



cinema mad said:


> I will post A picture of the white material I used on the rear of the front corner Bass traps Because its not Dacron, full shots of front bass traps as you requested....
> 
> Hope this Helps, Cheers...


Ah yes!..I see the white material is a type of netting, which is fitted to the back of the traps..
Obviously, this would allow sound waves to pass through without affecting the performance of the Ultratel, as opposed to a solid backing...Good idea..:T

I didn't have to worry about making my front traps look neat, because the're behind a screenwall..
I just stacked the raw panels in the corners, floor to ceiling and stapled black burlap across them..:bigsmile:

It looks like you've done a nice job on yours. :clap: .:T

I'll have to look up that material no. for the "speaker cloth" and see just what it is..
How much per metre did it cost?..The material I bought was only $9.95/M..


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## cinema mad

*Re: Bass trap questions*

Hi PROF,
I have A young 6 year old son and 14 year old daughter so I wanted to make sure that none of the Glass fibers from the ultratel could escape and be air born ....

I just got off the phone from Scott of spotlight Geelong He said that if your spotlight store does'nt carry the Speaker Cloth that they can post it any where in Australia for $6.95...

The loom width of the speaker cloth is 1.5mt, PartNo 1283123 and $12.95mt....

Cheers.....


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## Prof.

*Re: Bass trap questions*



cinema mad said:


> Hi PROF,
> I have A young 6 year old son and 14 year old daughter so I wanted to make sure that none of the Glass fibers from the ultratel could escape and be air born ....


Generally it's pretty safe...It's only when you're cutting it that you need to cover up, not to get any on your skin..



> I just got off the phone from Scott of spotlight Geelong He said that if your spotlight store does'nt carry the Speaker Cloth that they can post it any where in Australia for $6.95...
> 
> The loom width of the speaker cloth is 1.5mt, PartNo 1283123 and $12.95mt....


Thanks Jason...I'll see if I can find that part number online, but I'm not sure if Spotlight actually list their material numbers online..If not, I'll give my local shop a call..


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## cinema mad

*Re: Bass trap questions*

Because I Had A day off I decided to Build Broad Band Bass Trap's For My Rear corners.. I thought It might be good to share with you all How I made Them...
So I took some step buy step photos to help...

To Make my Rear Corners,1770x640 Broad Band Bass Traps the following items is what I used....
CSR BRADFORDS ULTRATEL 2" 1200x2400 semi riged fiberglass cut in half to make 600 X4" thick.. "Must weare Gloves and mask"
2 mtrsx1500mm wide Speaker Grill Cloth (spotlight)
4mtrs Muslenx900mm wide (spotlight)
Wood Pine 2x2.4mtrsx90mmx19mm
8x 40mmx3.5"OD" screws
PVC Glue
80/10mm Bostitch Staples

The Tools I used...
2.4mt Straight Edge (for cutting Fiberglass)
Sharp long bladed stanely Knife or Sharp BREAD knife (any sharp knife will work)
Tape mesure
Makita LS 10.13 Slide Compound Saw 
1/4in Trimmer (router)
1x small 1/4" roundover router bit
Air Stapler with 80/10 Staples
Compressor
Bench Drill for counter sink holes
Bosch power Drill
Dewalt 18v DrillDriver
Bosch random orbital sander with 240grit sand disk
Clamps 2x1mt and 4x 60mm

Broad Band Bass Trap Prep
First I measured and cut the 4 pieces of 90x19mm pine (per Bass Trap)
then I cut 4 small triangel corner pieces to give the frame Rigidity
marked out the 2x screw holes per side 8 total to drill with my bench drill (longest Piece)
Drill bit should be the size of the screws(3.5mm)..
lay out the pieces of frame (Dry Fit) clamp so flush and square and drill through the 8x pre drilled holes into the end pieces with A 2.5 to 3mm drill bit screw in screws as you drill each hole but not to tight...

Dissasemble and counter sink holes slightly
lay out frame reasemble one end (clamp) but leave one end out,Apply PVC Glue liberaly to this unasembled end on bothends of the join then clamp checking ends for flush/square and apply the scews tighten..
glue both surfaces liberaly and fit (clamp) 2 of the triangle peaces to the inside of the joins you just glued and screwed together..
Repeate the Same procedure at the other end..
Leave fram clamed to dry for 2 hours minumum..

Next sand the ends and triangle pieces flush as well as the sides/ends
Now route the outside edges top and bottom with A "small" round over Bit

Cut the semi rigid 605/supertel/Ultratel to the inside diamitor of the frame 1200x2400 cut in half=600mm x 4" thick using your straight edge and knife to score the semi rigid Fiberglass with 3 or 4 passes...
Next lay out the 1500wide speaker cloth in half +75mm on the floor taking care that the speaker cloth is folded well
lay the frame on top of the cloth making sure that the frame is equal distant at all sides top bottom, working along the sides strech the fabric up to the back of the frame working from the middle to the ends. The side affect of this will be that the fabric overhang at the ends will pull in A bit allowing us to get mor streach out of the fabric for the sides... 

Start from the middel of one side and strech the cloth and staple onto the back of the frame with 3 or 4 staples 2" apart, go to the exact oposite side and do the same strech staple
to back 3-4 staples 2" apart (Dont over strech the fabric)
Repeat this procedure crossing over sides until you get 1" from the end leving that unstapled for now..
Repeat the same above procedure untill ether side is completed...

For the ends start from the middel streching the fabric to the back of the frame with 3-4 staples an inch or so Apart 
Go to the corner and fold the fabric so you get A nice even fold and staple in place repeat this fo both corners of this end.. now working from the middel again Strech and staple the fabric to the back of the frame working to the corners (dont over strech fabric)...Repeat the procedure for the oposite end 

Flip over your broad Band bass trap to check the fabric has no rinkels or flaws..

Now lay it back down so the Rigid fiberglass is facing up so the Muslin can be fitted to the back..

First get the 4mtrs x 900mm Muslim and fold it long was so it is now 2mtrs x900mm (doubled up)
lay it over the back of the fiberglass so it is at equal distent all the way around besides the end with the fold in the Muslim Make this end flush no over hang 
Next Start At the "END" of the bass trap with the Muslim that has the fold make it 5mm before the end and stapel from the middel to the corner
Now fold the Mulim so that the over hang on the "LONG" sides is just covering the inner staples that were used for the Speaker Cloth, Paying attention that the long fold is straight all the way along the back edge of the frame.

Now go to the other end and pull the Muslin tight and staple from the middel out to the sides leaving the staples around 2"apart But not pulling the muslim over tight, Once this is done now start the sides working from one end to the other making sure that as you staple the Muslim fold is around 5mm from the outside edge of the frame you wont need to "STRECH the MUSLIM" for the LONG sides at all.

Your DIY "Pro" Looking Corner Broad band Bass trap is finnished to enjoy...:bigsmile: :yay:

I will Try to Attach the photos to there correct positions tomorrow (Unless "PROF" wants to do it) But hear they are for now all in one place Cheers.....


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## cinema mad

*Re: Bass trap questions*

And the finnished Bass traps in place in the back...

I hope this helps in giving people the motivation to have A go and make some...

Cheers...


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## Doctor X

*Re: Bass trap questions*

Now it's measurement time ! 

Regards,


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## Prof.

*Re: Bass trap questions*

Very good, detailed description Jason...and they turned out alright.:T
I'm sure your work will be of benefit for anyone contemplating building this type of trap..

I tried the flat panel approach with the large air space behind, for my traps the other night..
I think it did actually show some improvement, particularly in the detail of the lower register, but I only had enough Supertel to make the panels 4" thick..
I'll have to get some more, and try them at 6" thick...

I haven't had any luck in finding that grille cloth material..I'm afraid the female assistants at my local Spotlight have never heard of grille cloth...all they know are dress materials..:rolleyesno:

I'm still in the middle of re-modelling my theatre, and I'm using up the black stretch material I already had, for the acoustic panels..
I may not have enough to re-do the bass traps, so I'll take another look at it then..


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## cinema mad

*Re: Bass trap questions*

Hi Prof,
Thanks for the kind Words..

Yes I went with 6" thick on the front corners floor to ceiling and 4" thick for the rear corners from rear riser to ceiling but I also have thick theatre woolen curtains from Jands Audio on the large rear window..

The larger the air gap behined the Broad band Bass traps and the thicker 4"-6" the more coefficent (Supertel Ultratel) they will be in the lower end frequency's thus why I went 690 wide with the front Traps...The air gap has an affect much like using 4"Fiberglass thickness in place of 8" thus saving $$$$ and quadrupling the coefficence of the bass trap in the low frequency's, in that they will obsorb even lower also.... 

When you inquired about the Speaker cloth at your Spotlight store did you give them the Part No??...


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## Prof.

*Re: Bass trap questions*



cinema mad said:


> Hi Prof,
> Thanks for the kind Words..
> 
> Yes I went with 6" thick on the front corners floor to ceiling and 4" thick for the rear corners from rear riser to ceiling but I also have thick theatre woolen curtains from Jands Audio on the large rear window..
> 
> The larger the air gap behined the Broad band Bass traps and the thicker 4"-6" the more coefficent (Supertel Ultratel) they will be in the lower end frequency's thus why I went 690 wide with the front Traps...The air gap has an affect much like using 4"Fiberglass thickness in place of 8" thus saving $$$$ and quadrupling the coefficence of the bass trap in the low frequency's, in that they will obsorb even lower also....


Sorry Jason...I should have mentioned that the traps I changed were the rear ones..They were 6" thick, and right into the corners, but the're now 4" thick flat panels with an air space..
The front ones ( which are behind the screenwall ) are 6" thick, floor to ceiling and of the same type construction..flat panels.. 



> When you inquired about the Speaker cloth at your Spotlight store did you give them the Part No??...


I've since contacted another branch and at least they know of speaker cloth..
I've given them the part no., but their computers were down at the time..so I've given them my number and I'm just waiting for a call back..


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## Prof.

*Re: Bass trap questions*

Hi jason,

I've heard back from spotlight and they found the material from the part no.
Unfortunately it's only available from their Geelong store..:scratch:..I have no idea why other branches in major cities don't stock it..:dunno: :coocoo:

It looks like if I ever need to get any of that material, I'll have to get it through your contact..

At the moment I have enough material to re-do the bass traps..and I've just started re-building them..


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## cinema mad

Hi Prof,

What A pain mate, If or when you need some Speaker grill Cloth The Guy you need to talk to's name is Scott in the Dress department Spotlight Geelong Vic as I mentioned in the other post. He offered to ship it to you when I spoke with him... 
I think He got it in because of alot of requests so I don't think its A standard line that spotlight carry....

How is your Home theatre coming Along mate ??....


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## Prof.

cinema mad said:


> Hi Prof,
> 
> What A pain mate, If or when you need some Speaker grill Cloth The Guy you need to talk to's name is Scott in the Dress department Spotlight Geelong Vic as I mentioned in the other post. He offered to ship it to you when I spoke with him...
> I think He got it in because of alot of requests so I don't think its A standard line that spotlight carry...


.
Thanks jason..I'll keep that in mind..



> How is your Home theatre coming Along mate ??....


VERY slowly!!..It's taking longer than I expected..
It's not so much the construction side, but the finishing of the timber panels that's taking the time..
I'm using plain MDF for the soffit trays and columns and I'm applying a timber grained finish to them, using special artists paints..
Each panel has three different applications to get the required timber grain colour and effect..and of course there's a long drying time between each application..:whew:

The timber moulding I'm using for the external framing of the acoustic panels is prepainted with a white finish (you may know the type of moulding I'm talking about..it's used for skirting boards ) and this is proving even more difficult and time consuming to change it to a timber grain finish...But I'm slowly getting there and they're turning out quite nice..

So far I've finished two columns, two frames and two acoustic panels..and the soffit trays are up..
I have two more columns,two frames and two acoustic panels to go..and then I start on the new lighting!!..:whew:


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## cinema mad

I had some spare time on my hands to make Another Broadband trap 2" thick ultratel, to be mounted on the ceiling in the front 1/3 of my home theatre in between and in front of the main speakers ...My plan was to hang the trap with a 2"-4" gap between the trap and ceiling...

Pictures and details to come...

Cheers....


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## cinema mad

I just finnished making and mounting for now A small BroadBand Ceiling mounted Trap for the Treatment of first reflection Point's, I will be making one lage BroadBand Trap for the Ceiling the size will be 2" 2400x800 W.. And more for the Side Walls, and Screen Wall will be treated with 2" Semi rigid fiberglass as well But I need to get more 1200x2400 sheets of Semi Rigid Fiberglass (CSR BradFord UltraTel)... I have already used 5 1200x2400 sheets of Ultratel:yikes:

The BroadBand Trap for the first reflection points on the Ceiling for now is 2" thick 1200x750 Ultratel with A 3" air gap.. The BroadBand Traps to treat the First Reflection Points for side Wall's Will be 2" thick with A 2" to 3" air gap same as the one on the Ceiling....

I made the Frames with 42mm wide x 19mm thick Pine.. For Ceiling mounting the Trap I used Eye Screws 4mm OD X 40mm L screwed into each corner of the trap... Picture Hanging Wire 12Kg Strength for holding the trap 2" to 3" away from the Ceiling...
For Mounting the BroadBand Trap For the First Reflective Points I used Threaded Plastic Plaster inserts that I then Screwed more Eye Screws into...

I used The Mirror Technique to find the First reflection point of the front Main and Center Speakers to allow the correct Positioning of the Ceiling Trap's ....:T 

After I finnish treating my Theatre with absorbers I am going to build custom accoustic WideBand Diffusor's IE, RPG's Diffractal DFR73, Diffraction-Grating Diffusors or something simpler like Primitive Root Diffuser's to be placed on the rear, side walls and rear wall, to further refine the sound quality in the room and help with my pacific ROOM MODES combined with BroadBand bass traps/ BroadBand Traps will treat the lower and higher frequency room modes.... 

















































































Hope this Gives you some Ideas for your own Build Cheers....


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## Prof.

Very nice work Jason..:T..All those panels should help things considerably..

I used 70x19 pine ripped down to 55x19 for my frames, for the 2" Supertel..because mine are mounted directly onto the walls and I wanted a flat surface on the fronts of them..

What would we do without our Irwin clamps eh!! they're a great bit of gear..

I've used more "Wall-Mates" in my theatre than I can remember..I've even used them for the ceiling mounted projector..
I also found they work well for mounting the side surrounds, just using an eye screw and a right angle cup hook..
My surrounds weigh about 10Kg...and they hold very well..:T

Keep us up to date with your progress..


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## cinema mad

Hi Prof,
Yes the plaster inserts "Wall-Mates" are fantastic and provide A very strong anchor in plaster for many applications, It sounds like you have found many uses for them Prof :yes:...

I should point out The 42mm x 19mm pine used for the frame is perfectly flush at the front with the Fiberglass due to the double layer of Acoustic cloth's tension but the fiberglass is around 8mm higher than the pine frame at the rear of the BroadBand Trap But the Muslin hides this....

Cheers....


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## cinema mad

Thought I would share my DIY Tuned Bass Trap Build... Note This Bass trap is usfull if you dont want to absorb High Frequency's but reflect Thus it is not A BroadBand trap and is aimed for lower frequency's absorbtion...

Just Finnished My first reflection for side walls x4 4'x2' and 2x 8'x2' & 1x 4'x2' for ceiling
I also built another bass trap with high frequency reflection Membrane to go between the corner BroadBand Bass Traps in the back of the room , It will go where the back wall and ceiling meet for added low frequency absorbtion performence.

I chose to use A tuned Bass Trap to stop high frequency absorbtion as I didnt want the room to dead...
Next I will be adding Diffusion to the room, I am going with three types... 

1/ Advanced BroadBand QRD Based Nested Diffusing fractal 2'x4', 2x will be placed inbetween the first reflection absorbers on the side walls... 
2/ Primitive Root Diffusors 3-7" Deep for rear side walls... 
3/ Diffusing tiles placed on ceiling aimed at flutter echos, 25mm thick... 

So far it took me two hours to calculate/design then test make 1 flutter echo tile from MDF but I need to use hard wood as the well gaps are very close together and when routing the wells, the MDF would split :no:.... See close up picture of Diffusor Tile Prototype for Flutter Echo issue's

Any comments and suggestions are most welcome Cheers...


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## Prof.

Wow!! jason..you're really giving it the treatment!! :bigsmile:

I wouldn't be overly concerned about it being too dead..
I thought the same thing when I started adding treatments to my room..and even trhough you can hear the deadness ( for want of a better description :bigsmile: ) when I walk from the outside room into the theatre, it still sounds alive with sound when playing a movie..:T




cinema mad said:


> 3/ Diffusing tiles placed on ceiling aimed at flutter echos, 25mm thick...


What size are these diffusion tiles you're making, and how much of the ceiling area are you covering with them?
If they're are made from timber, wouldn't they tend to reflect rather than absorb sound?


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## cinema mad

Hi Prof Merry Xmas and happy new year...
My biggest concern is being surrounded with posinous Fiberglass :bigsmile:
As far as the Diffusion Tiles I can make them as long as I want but the well sequance is 4" wide total, so I can make them 4" /8' /12" and so on but you have to stay within the mathamatical formula..
They are Diffusors disigned to deal with fluter Echo in the higher frequency's but I can also mount with an air gap & add fiberglass behined them to absorb the lower frequencys....

So they will reflect in the lower frequencys if I dont design them to absorb the lower frequency's and they Diffuse not reflect in the higher frequencys...

The 2'x4' BroadBand nested diffusors are the most complexed ones I will be building :scratch: but also the best performance....
Retail they are over $2000AU each in Australia for simlar design performance But you should'nt be seated any closer than 6ft from them for Best performance because of the Well depth I will be using....

Cheers....


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## Prof.

Thanks Jason and all the best for the new year..



cinema mad said:


> The 2'x4' BroadBand nested diffusors are the most complexed ones I will be building :scratch: but also the best performance....
> Retail they are over $2000AU each in Australia for simlar design performance But you should'nt be seated any closer than 6ft from them for Best performance because of the Well depth I will be using....
> 
> Cheers....


I'll be very interested to hear your results on all these panels..and some pics during the build would be great..:T


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## cinema mad

I Made up some Acoustic Diffusing Tiles for the control of Flutter Echo, The design of these Tiles are Built using the quadratic residue sequence and based on A Prime 7 well 1-Dimention QRD Reflection phase grating principle....with the seventh well being formed when two tiles are placed beside each other.... 

As mentioned above I tried MDF but it kept splitting so I went with A hard wood "Tasman Oak" and had success...They are not that easy to make very very time consuming and A router bench with high quality router bits is A must for A clean precise finnish.... 
I am not sure wether to stain them to bring out the beautiful grain or paint them black :daydream:...

So far I have only made around 10 tiles as A trial run the next lot I will make will be 3ft long made from Tasman Oak hard wood....

More to come, Let me know what you think so far....

Cheers...


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## Prof.

Very nice job Jason..:T 
That looks like an awful lot of work!!..How many tiles did you say you're making?
I think they would look great stained and providing that it's fairly dark stain, you should have minimal light reflection from them..


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## cinema mad

Hi Prof, Yes your right that it is A lot of work in making these tiles But the main thing is that because the well depth is only small you are able to be seated closer to them unlike the primitive-root & nested QRD type Diffusors.... These tiles are the less complexed to make compared to the other Diffusors I will be making....

At this stage I am unsure exactly how many of the tiles I will make/need but most will be 3ft long as to cut down on the layout of each tile.... Once I do some more in room analysis with the "future" ETF acoustic mesurement software I will have more of an idea...

No work today to hot ment to be"37deg" here let alone where you are in SA "41deg", some places in SA are upto '43deg" today :yikes:.....

Cheers....


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## cinema mad

I finnished some of my flutter echo tiles today, I built some 3ft long tiles and stained them black with A gloss clear coat, these ones will be hung from the very top of the side walls but slightly angled down & placed near the side surround speaker position as A starting point....further room analysis with Acoustisoft R+D will help determine there final position...


If any one is looking for some good info on room Acoustics & Treatment the Forth Edition MASTER HANDBOOK OF ACOUSTICS is A must and where I have sourced much of my Ideas such as these Flutter Echo Diffusors.. But it should be Noted that this book does not give you the exact messurments of well depth and well width for IE: Flutter Echo Diffusors but does provide the mathamatical tools to help work it all out....

In the near future I will build some nested BroadBand Diffusors but they will have to wait untill I have finnished the rest of my Flutter Echo Diffusors :waiting:.... 

The well sequence and depth to make your own Flutter Echo Diffusors are as follows

The width of each well is 10mm with A 3-4mm wide fin...(quadratic residue sequence 0,1,4,2,2,4,1 prime number of 7)
1. The first is 0mm 
2. Then 5mm deep well..
3. Then 3-4mm fin followed by A 20mm deep well
4. Then 3-4mm fin followed by A 10mm deep well
5. Then 3-4mm fin followed by A 10mm deep well
6. Then 3-4mm fin followed by A 20mm deep well
7. Then 3-4mm fin followed by A 5mm deep well
8. Then last is 0mm...

See the Picture I have Attached for the layout Dimentions...

I should menton that you MUST route groves in the back of the hard wood to releave the tention in the hard wood coursed by routing the Wells in the Front in order to stop warping....
Also To make these Diffusers Takes wood working skill and is very labour intensive :whew:...

Cheers.....:T


----------



## Prof.

They're much smaller than I imagined..
How many of those strips do you place in each position?


----------



## cinema mad

To Diffuse horizontaly they are hung verticaly so as A starting point mine will be hung verticaly, In most case's the first row of Diffusors at the top are hung verticaly and then underneath that they are hung horizontaly..

The total width of the Flutter echo tile is 4", But if you wanted you could repeat the Quadratic Residue Sequence but this would need to inclued the seventh well that is formed when the Tile is placed together......

What do you think of the Finnish on the Tasman Oak ?, I am happy with it....
Cheers....


----------



## Prof.

Yeah..looks good..
What did you use to get that colour?


----------



## cinema mad

Thanks Prof,

To stain the Tasman Oak hard wood I used 500ml Wattyl professional stain "Black" and the clear Gloss was 1lt Wattyl Estapol Gloss, Polyurethane Based... Purchased from Bunnings

I loved the red wood stains but wouldnt go with my Black walls, I dont want the Diffusors to stand out to much...

Cheers....


----------



## cinema mad

Here is A picture of the V cut into the back of the Flutter Echo Diffusor tiles to help stop warping caused by the wells in the front of the Diffusors...

Cheers....


----------



## cinema mad

Couple of Pictures of A ROUGH setup to give you an idea of where and how they will be placed, In the Final setup The Diffusors will all be custom cut to fit the exact hight/length needed for A perfect fit...

It is important to note that The Flutter Echo tiles will be placed at Ceiling hight and one 4" wide continuous Diffusor will be hung horizontaly at the top where the ceiling and side walls meet and slightly tilted down all the way along the left and right side walls in the room, underneath them the diffusors will be hung Verticaly in carefully chosen places.....

IMO Diffusion is often overlooked by most & is just as important as Absorbtion, and can be as affective if applyed correctly....
QUOTE "Its Application converts small rooms with flat parellel sufaces into functional spaces with good SPEECH INTELLIGIBILITY, SOUND QUALITY,AND A NATURAL,COMFORTABLE AMBIANCE.... 

The down side of Diffuson is that it is much more complexed to design build and apply than Absorbtion and it costs more to manfacture....

Cheers....:T


----------



## Mike P.

Looking good, Jason! Do you notice an improvement in the sound with the tiles in place?


----------



## cinema mad

Hi Mike And thanks for your complement...

I only put them up today Roughly so I could post pictures, so I have'nt put them through there paces But I left them in place for now because I Have Eagle EYE on Blu-Ray so I will let you know what I think....

I have to make heaps more to the required length before I can install them permanetly and
so they hopefully look like they belong, unlike the above picture of the Diffusors placed around the surround speakers ... I got another 20mt of Tasman oak today and have already used around 15mt :thud: I would say I will end up using 40-50mt of the stuff ....

Cheers....


----------



## robbo266317

I bought some Tassie Oak before Christmas, it's not cheap...

Did you keep the shavings to do some home smoking? My local sawmill used to put a 20kg bag of sawdust aside for me in return for a couple of smoked trout!


----------



## Prof.

cinema mad said:


> Couple of Pictures of A ROUGH setup to give you an idea of where and how they will be placed, In the Final setup The Diffusors will all be custom cut to fit the exact hight/length needed for A perfect fit...
> 
> It is important to note that The Flutter Echo tiles will be placed at Ceiling hight and one 4" wide continuous Diffusor will be hung horizontaly at the top where the ceiling and side walls meet and slightly tilted down all the way along the left and right side walls in the room, underneath them the diffusors will be hung Verticaly in carefully chosen places.....
> 
> IMO Diffusion is often overlooked by most & is just as important as Absorbtion, and can be as affective if applyed correctly....
> QUOTE "Its Application converts small rooms with flat parellel sufaces into functional spaces with good SPEECH INTELLIGIBILITY, SOUND QUALITY,AND A NATURAL,COMFORTABLE AMBIANCE....
> 
> The down side of Diffuson is that it is much more complexed to design build and apply than Absorbtion and it costs more to manfacture....
> 
> Cheers....:T


Very interesting Jason..
So these tiles are placed beyond the first reflection point..somewhere near the second reflection point?

Any particular reason for coating them with *gloss* Estapol?..I think they will look distractingly shiney when you're projecting..


----------



## Prof.

robbo266317 said:


> I bought some Tassie Oak before Christmas, it's not cheap...
> 
> Did you keep the shavings to do some home smoking? My local sawmill used to put a 20kg bag of sawdust aside for me in return for a couple of smoked trout!


Good point about the shavings..:T I could do with some myself for smoking Carp:yes:..


----------



## cinema mad

Hi Prof, & thanks for your post...

I have A two stage riser with two rows of seating, so I set up first reflection absorbtion for both... The idea is that between the 2 reflection points you can have Diffusion this is one place where my Advanced BroadBand QRD nested Diffusors will be placed for the higher performance once built...With this type of Diffusor the seating position should not be any closer than around 6ft Due to Well depth....

For the picture I put the flutter Echo diffusors in this position to show where they can be placed But as pictured above they will be placed mainly around the surround speakers with A small amount of absorbtion and where the side wall and ceiling meet. So that is why I whent gloss but I totaly agree with you Prof that if they were permanatly placed between the first reflection points that flat black is more appropriate...

Cheers....


----------



## cinema mad

robbo266317 said:


> I bought some Tassie Oak before Christmas, it's not cheap...
> 
> Did you keep the shavings to do some home smoking? My local sawmill used to put a 20kg bag of sawdust aside for me in return for a couple of smoked trout!


Hi Robbo,Thanks for your post..

Yes I have heaps of the Tasman oak sawdust, so far from all the routing I would have around A 80lt bin full.
Did'nt know they use that to smoke trout, I was going to use it for the kids Guinea pig beding ....

FWIW I am paying around $5.80au per meter for 140mm x 35mm F17 tasman oak hardwood... One I run it through my thicknesser to dress it it comes up nice...

Cheers....


----------



## robbo266317

I've smoked quite a few over the years with Tassie Oak and the only complaint was from the old bloke at the sawmill who saved me the sawdust missed out one time as the others had an early lunch and found them in the fridge first.


----------



## raZorTT

Jason,

Which facing did you get the ultratel with? Would they make much difference?

Cheers,
Simon


----------



## cinema mad

You need the ultratel with no facing for BroadBand Bass traps, If you want to block out high frequencies you can just use A Brown paper membrain like the Tuned bass trap on the first page check it out .....


----------



## raZorTT

Thanks Jason


----------



## cinema mad

Once I Dress the 140x35 f17 Tassie oak through my Surface Planer down to 25mm thick it comes out like the more Expensive pre Dressed 32mm Tasman Oak :T......

Where would we be without power tools.....

Cheers.....


----------



## Prof.

Very nice bit of gear...Man would I love to have one of those in my workshop..:daydream:


----------



## cinema mad

Yes A very handy piece of gear but very messy :thumbsdown: and very very Dangerous like all planers.....

FWIW That Ryobi Surface planer was made in 1995 when Ryobi was OK but all the new Ryobi stuff is mostly rubbish now IMO, Disposable power tools ......

Cheers....


----------



## Prof.

"They don't make 'em like they used to"..:bigsmile:


----------



## robbo266317

Unfortunately it's not just Ryobi.
I have a mate who repairs power tools and he recommends buying old tools >10yo and repairing them.
You name the brand & there is a 90% chance it isn't made to last more than its warranty plus 1 day.
There are still a few good ones out there if you look hard enough! and are willing to pay.

Personally I hate the fact that the rest are just going to end up as toxic landfill.......... 
my 2c


----------



## cinema mad

Yes I agree with your mate as far as the older Ryobi stuff being good quality, But The problem being that A lot of the parts for 10y + Ryobi power tools are No Longer Available Thus can't be repaired unless you custom make the parts needed... 

FWIW I to used to Repair all heavy industrial and power Tools inc Electrical rewinds IE: Remanufacturing/ Rewinding Armatures, Stators and more in house for over 10 years....

Unfortunatly these cheap Chinese manufactured power tools are now disposable items, It costs more to repair these tools than replace which is what Ryobi/ Black&Decker (dewalt), to name A few do for warranty claims :yikes:....

Cheers....


----------



## cinema mad

I have finnished making my larger 4ft flutter Echo Diffusors 8 in total 4 per side, Just need to stain the frames and put the gloss coat on the Diffusors and frame.....
More to come....

Cheers...


----------



## Prof.

They're going to look pretty cool when their set up in you room!! :yes:


----------



## cinema mad

Yes Prof I am hopping they will look good, But as noted they are A nightmare to make...

FWIW I have been talking to Doug Plumb of Acoustisoft.com about the Excellent RplusD Room Acoustic measurement software (Ethan of real traps uses it) so I can optimize my room Acoustics, this includes speaker placement, EQ Subwoofers and "Room treatment placement" & much more....

I am going to "cheat" and use his 1 on 1 Consultation package, I figure that it would be better to use his knowledge & Expertise for the best result rather than me having to learn how to analyze & interpret what the Data is telling me + I am A very impatient :hissyfit: person when it comes to this stuff so that works against me also...


Has any one here used this High End room Acoustic software ?....

Cheers....


----------



## fredk

This is an interesting thread. I have read it several times now.

What frequency range are you diffusing with these?


----------



## cinema mad

Hi Fred & thanks for your post :T, 

This type of QRD Diffusor's coefficient range is usefull between - 3500hz --- + 20000hz.. 
If you mount these Diffusors with A space and air cavity combined with Semi riged fiberglass, absorbtion below the Diffraction limit can be achieved.....

:T Because the Well depth is only small they can be placed closer to the listner which is the biggest plus as compared to QRD Diffusors with 6" deep or deeper wells....

:thumbsdown: The Down side to this Diffusor is its smaller Diffusive frequency range as compared to A BroadBand Diffusor such as the type I will build later down the track.... 

Cheers....


----------



## fredk

Thanks Jason. I suspected that it would be higher in frequency. I would like to try some diffusion at the first reflection points on the side walls and this looked like a possible candidate. I think that with the smaller wells, they could look quite elegant.

I need to go back and re-read that section of the Master Handbook.


----------



## thewire

I have textured walls if that counts. :bigsmile:


----------



## cinema mad

Finnished 4 diffusors & frames 2x4ft & 2x3ft with 4 Flutter Echo tiles per frame...
They will be hung slightly angled down.. They are mounted from A peace of 25mm x 32mm hard wood screwed into the stud of the wall then the mount on the back of each frame is simply hung off it....But the Diffusor mount is not fixed in place on the back of frame untill I check were the wall studs are so I can determine exactly where to mount it to the back... 

I will mount them tomorrow and post some pictures of them in place & now that I have Acoustisofts RplusD software I will be able to check the theatres acoustic performance & placement of my room treatments thus far :daydream:....

Cheers...


----------



## cinema mad

Couple of pictures of the Diffusor panels mounted Next to the left & right side Surround speakers next to the Rear corner BroadBand bass traps & first reflection point traps for the second row.. But will be Repositioned to suit the smaller Bipole surround speakers when in place....

Because this is only A 5.1 set up there will be Bipole surrounds placed between the first and second row of seats and the larger 3way mono pole surround speakers picture will be placed at the rear for A 7.1 setup and the new theatre seats for the back row will be placed 2' to 3' of the rear wall...

Note that where the smaller 3' diffusors have been placed is close to the recommended 52% from back wall placement position ...

Cheers....


----------



## fredk

They look really good mounted in place.


----------



## Prof.

Looking good Jason...
I'll be interested to hear your evaluation of their performance..


----------



## thewire

Prof. said:


> Looking good Jason...
> I'll be interested to hear your evaluation of their performance..



+1. Have you tried clapping or having someone else clap to see if you hear the difference?


----------



## Lonely Raven

Jason, those look great! 

I built something similar from MDF years ago, and I want to use them on the back wall to kill flutter echo...but many of the acoustic experts tell me I'm wasting my time with diffusion...that I should just put up a bunch of absorption and be done with it...

But I've always had my audio rooms built with lots of diffusion to give a very live sound, and then only used absorption to deal with trouble frequencies and the low end peaks and nulls. 

Here is what I have currently (sold most of my diffusers just before I moved):










Mine are 4" deep, so they are a bit more broadband than yours, but they are also 60+lbs if I remember correctly. I'm doubting I'll be able to hang them on the wall the way I'd like to. 

I'm really liking your builds and would love to copy them, though I don't have a router table. I may just have to use a table saw for similar results. 

I'll be following this thread to see how you like the diffusion throughout your theater...I'm finishing up my first 7.1 setup, and stuck with the diffusion/absorption. Hopefully following your thread will help me figure out where I'm going to go from here. 

Great thread by the way!


----------



## cinema mad

Hi Lonely Raven & thanks for your post, 

Wow Your QRD Diffusors look great :T, Have you ever used them??

The reason I used A shallow well QRD design is because of the close facinity of the seating, the deeper the well of A QRD Diffusor the further away you should sit to alow optimum Diffusing performance... 

Yes I have heard the same type of comments from A couple of Acoustic experts, I think it goes without saying that Absorbtion will give the most noticable improvement to A point but both Absorbtion & Diffusion are just as important in obtaining A well balanced lively ambient sound.. 

The problem is Knowing what Types of diffusors/Absorbers will work best given the room you are trying to treat inc seating positions in accomplishing A good result...
Although there is A general rule of thumb for Absorbtion placement areas I think Room Acoustic software is A overlooked & vital part of the equation in helping to get A well balanced sound .... 

FWIW I am playing with Acoustisoft's RplusD software at the moment and having Doug Plumb perform A consultation... 

More Diffusors to come stay tuned: next Skyline Diffusor

Cheers....


----------



## Lonely Raven

I have used those diffusers a little. I used them between my main speakers when I was doing two channel listening. I also used several larger QRDs built from the Decware plans along the side walls. I never got enough made to do any on the back wall of my listening room, and wound up selling all but these two units before I moved. 

I really enjoyed the live sound of a bunch of QRDs. I had enough to give the discs I listened to added reverb...some may think too much. 

Which makes me wonder how it's going to work for you, with 7.1 speakers all throwing sound into diffusers...


----------



## cinema mad

At the moment I only have A 5.1 set up so the Diffusors work fine but I will soon Mount some Dipole surounds on the Sides and move the 3way Mono poles to the rear for 7.1, then I will have to reposition the Flutter Echo Diffusors on the back wall or something as I know they cant stay near those Diples :daydream:...

Cheers....


----------



## cinema mad

Couple pictures of 4ft'r QRD with hight udjustable stands...

Cheers....


----------



## Lonely Raven

I'm following closely in your footsteps, CM!

I couldn't sleep last night, so I started working on these.










I'm recycling some American Oak stair treads that have been in storage for the past 13 years. They happened to be the same thickness as the design that inspired mine, so I worked from those measurements. 

Unfortunately, just as I was cruising through the deepest cuts, the motor failed on my table saw! I can't afford this right now! I'm hoping I can figure out how to fix it myself. 










When/If I ever get these done (I have four of them I'm working on now for the back wall), I'll be staining them in a deep cherry color to match the trim I've still yet to install. LOL


----------



## cinema mad

Wow they look good so far Raven, I think staining them as aposed to painting is the best option Especialy with hard wood. Deep Cheery will look Awesome...

What happend to your saw :yikes: that is an induction motor & are usually very reliable,
Does The motor Hummmm or did smoke come out of the capasitor cover on top of the motor, because it could be the Start/run capasitor which is an easy fix...

Its A pitty I am across the pond or I would fix it for you, but if you discribe what it did before it stopped may help....

Cheers....


----------



## Lonely Raven

cinema mad said:


> Wow they look good so far Raven, I think staining them as aposed to painting is the best option Especialy with hard wood. Deep Cheery will look Awesome...
> 
> What happend to your saw :yikes: that is an induction motor & are usually very reliable,
> Does The motor Hummmm or did smoke come out of the capasitor cover on top of the motor, because it could be the Start/run capasitor which is an easy fix...
> 
> Its A pitty I am across the pond or I would fix it for you, but if you discribe what it did before it stopped may help....
> 
> Cheers....


The motor was having trouble spinning and popped the breaker. I took it all down (belt drive) and found it was *not* the arbor, belt, angle, or tension...so I started looking at the motor. It's a combination of things I feel. The bearing felt tight rather than smooth, the armature looks like it was rubbing a bit, I believe I did see a little smoke from the cap...and the little plastic looking disc that I believe the current passes through (not sure how but a copper leaf rides on this bakelite looking disc) is cracked and broken. 

I'm attempting to clean and lub the bearings, and epoxy the backside of this disc...but if it passes current the way it looks, then I'm betting it's no go. If all that works, I'll track down a new capaciter. At this point, I should probably just track down a new motor. I just really can't afford this right now...so I'm kinda stuck on all projects till I can get the table saw spinning again.


----------



## cinema mad

The bearings should'nt be tight at all and can lead to issues, It sounds like the Rotor (armature) was poling (rubbing on the stator)... The little Slip ring on the front of the Rotor is only used for Start up it basiclly Engages & disengages the start cap for higher start-up torque it works on centrifugal force, once the motor is spinning at A certain RPM the slip ring disengages the start cap...

Cheers Lonely Raven...


----------



## Lonely Raven

cinema mad said:


> The bearings should'nt be tight at all and can lead to issues, It sounds like the Rotor (armature) was poling (rubbing on the stator)... The little Slip ring on the front of the Rotor is only used for Start up it basiclly Engages & disengages the start cap for higher start-up torque it works on centrifugal force, once the motor is spinning at A certain RPM the slip ring disengages the start cap...
> 
> Cheers Lonely Raven...


Thanks for that education. I'll be shopping for a used motor and I'll chime in when I get my diffusers done.


----------



## cinema mad

If you can, See If you can fined an induction motor with higher hp rating than the original motor but runs around the same RPM as the old motor, "the RPM is the important thing to remember", also the shaft & Key way OD That way you can just swap the pully's straight over and your good to go....

Cheers...


----------



## Lonely Raven

I was poking around, and all the induction motors seem to be direct drive setups. Which just isn't possible with this particular saw. All the cap-start, belt drive motors that fit this table are 1HP, 3450RPM with the same pully diameter and shaft setup...which at least makes it easy to swap out another motor.


----------



## Lonely Raven

OK, I'm back on track to trying to get caught up with you! I picked up a replacement saw tonight! 










And yes, it happens to be the same 25 year old one as mine! LOL

Mine was more tricked out, so I swapped the motor into my old saw which has a cast iron top and better fence. And I got to work!










I'm *really* shocked as to how much this wood warped since Sunday when my saw died! Because I didn't get the relief cuts done before the saw died, it was starting to bow and twist a bit...so my cuts were off quite a bit on some passes because the wood was no longer square. It doesn't help that it was already checked and chipped from being in storage for 13 years....so dont' pick on me for the veins being off! :nerd:












OK, it's way past my bedtime...I need to be up for work in 5 hours. 

Mad, do you have any tips on how I should stain and clearcoat these? I have some nice oil based stain I plan on using...but I'm wondering if I only clearcoat the front side, will that cause it to warp badly because the backside is untreated?


----------



## cinema mad

Wow Raven you have been working very hard by the looks of it :yikes:, I am impressed.. your not mucking about gettin straight back into it LoL... Good to see you have your table saw up and running...

Yes those cuts in the back are very important to relieve the tension out of the wood & stop the Diffusors warping....

As far as staining I would say just stain the fronts and sides thats all I did & I have'nt noticed any warping, I used A little artist brush to get down into the Diffusion Wells and then used A piece of cotton sheet to quickly rub off the excess to get A nice even stain... 

Before Staining I spent A while sanding the diffusors first especially in the Wells, I started with 120grit then 240grit then 420grit to get A nice smooth finnish.... 

For the clear coats I made sure the Diffusors were free of dust and just painted on with A brush carfully so as not to get air bubbles, so I only stirred the clear in the tin not shaken..
I poured A little at A time into A cup so I would'nt contaminate the large tin of clear with the stain residue that is left on the paint brush after applying the clear coat....

Is that your Blue Suzuki Motor Bike ? what size is it, I am mad on bikes :devil:....

Cheers....


----------



## Lonely Raven

Yeah, my fiance and I have his and her's SV650. Her's is a red one just outside the frame. My motorcycling friends are giving me grief for not having covers on the bikes and getting saw dust on them. LOL We've only been riding for two years now...and honestly, it was her idea. I love to ride, but people are stupid, and I'm so afraid she is going to get hit by some motorist not paying attention!

Anywho, thanks for the info on stain and clear. But I should clarify my question. I'm trying to save a few $$ since I'm on reduced hours at work (replacing this table saw dipped into my savings, but I felt it was a need, not a want). So what I'm wanting to do is clearcoat the front side of the diffusers only. But I'm worried that clearcoating only the front, and leaving the backs open to the elements, will cause the diffusers to bow and warp even more. Should I just go ahead and clear every little bit of exposed wood to seal it from humidity/drying out?

If I can afford some more wood, I'm thinking about making some more of these diffusers, but more artistic. e.g. different woods, and cut up and reguled to form some sort of shape rather than just a wall of wells and veins....maybe in a star like shape or something. I have no idea where I'd put it, but it sure would be a conversation piece! LOL I have a similar idea of making some sort of 3D artwork out of absorber panels for an area that I know needs some absorbing to help keep the room balanced left to right. 

I've had these great ideas for a while now, but seeing your fine work has inspired me to get up off my rear and make it happen! Thanks for that!


----------



## kepople

These are awesome...
I saw you were using a router before, I might have missed the post, but did you switch to a dado blade in the table saw?

I think I will build some of these for my theater as I have been using absorption everywhere.

Most of the diffusors I see are a lot deeper than these. Have you noticed an improvment?

Kirby


----------



## Lonely Raven

Jason, check out this listening room!

http://www.soundscapes.nu/design.html

Now that is someone who's *very* serious about diffusion! :unbelievable:


----------



## fredk

Thats a very cool link Raven! I wish I had access to his shaper. Those diffusers look really good. I need to take a second look at the chapter on diffusers in the Master Handbook of Acoustics to see if I can apply them in my small room.


----------



## cinema mad

Raven That is A awesome room the guy has built, He can obviously see the importance of Diffusion LOL :heehee:... I also see that he made some Nested QRDs which are the best Diffusors IMO (Diffusor within A Diffusor Within A Diffussor), they offer BroadBand Diffusion but are by far the most complexed to build....

I like the idea he had of using A spindel moulder cutter to cut the wells its the picture of the 3 saw blades on the shaft, not A cheap tool though, the cheapest one we sell made by JET is A mear $2000au :yikes:....

As for sealing the back & sides of the Diffusers from the elements I would use some cheap paint ? I have no doubt that left untreated the Diffusors would/could warp over time..

LoL you are so lucky to have A Mrs that likes bikes I wish mine did...
I have had over 35 bikes from dirt inc KX500/KTM500 to road GSXR 1100 - YZR1000(R1) and so on... 
I always tell new riders to ride on the defensive be alert and when behined A car never ride on the blind side of the Driver, think as if the car does'nt know you are there... 

With motor Cycle accidents its most always the Driver of the car at fault and not the Bike rider no?... 

Cheers...


----------



## fredk

Drivers fault, rider suffers. Thats why I never owned a bike.

I guy I went to highschool with was good enough to play pro ball until he tangled with a truck with no tail lights, no signal lights and improperl rear view mirrors.

He broke his leg in 3 places as well as his hip.


----------



## Lonely Raven

Thanks...you guys make me want to sell off the bikes and buy a tank. :foottap:

Can we get back to talking about awesome DIY diffusers? :wave:

I'm stuck working a good portion of this weekend, so I'm not sure I'll make any progress on my flutter breakers. 

My final though with them, is to alternate them on my back wall with 12" wide absorbers of about the same height. So it would be Ab-Dif-Ab-Dif-Ab-Dif-Ab-Dif-Ab. I have some Black Expocloth ready to try out, but I'm too broke to buy material to frame the Absorbers right now...so I might try just cloth wrapping one first.


----------



## cinema mad

Sounds good to me Eric, but as you know every room differs so to be honest the best way would be using software like REW or Acoustisofts RplusD and taking measurments before and after placement to confirm you are placing the Diffusors & Absorbers in the optimum positions for your room.....

Cheers Jas....


----------



## Lonely Raven

cinema mad said:


> Sounds good to me Eric, but as you know every room differs so to be honest the best way would be using software like REW or Acoustisofts RplusD and taking measurments before and after placement to confirm you are placing the Diffusors & Absorbers in the optimum positions for your room.....
> 
> Cheers Jas....


Yeah, I get that, and I've played with REW. I know I have terrible flutter echo front to back, so this is more of a fun experiment than anything else. Anything I do is better then the crazy echo I have now. Even just speaking from the listening position is frightfull. 

I'll have to get off my rear and re-learn REW. It's been 5 months since I fired it up last. :whistling:


----------



## cinema mad

I know I should'nt Eric but Here's my little 6 year old son and his dad (me :heehee showing off for the Camara.... 
My Son is slightly Autistic & the little 125cc mini bike has been thereputic in helping boost his confidence...



Back to Diffusors and Absorbtion, For my back wall I have Bass traps for each corner floor to ceiling and A 4" 1240mm x 700mm bass trap mounted in the middle above the rear seats stradaling the rear wall and ceiling, I planed on Building some large BroadBand Nested QRDs using A prime number 11 or 13 sequence to fill the back wall which should give an affect of the room sounding larger than it really is.... 


Cheers.....


----------



## Lonely Raven

That's great, Jason! Anything that gets him interacting with the outside world is fantastic. And that's a great shot that I'm betting you'll cherish years from now as well. 

I'm not scared of the motorcycles, really I love them, and I wish I could afford to ride on the track where my only worst enemy would be me! LOL


----------



## cinema mad

Well I have A little time on my hands so Have decided to make some Broadband QRD based Abffusors (diffusor absorber in one acoustic panel) ... 

I have designed & drawn up my plans, I will be making A prototype first & then pump out A few of these for my back wall and so on...I am going to make the sides of the frame out of 1-1.5mm sheet metal (pre fab to my spec) this time to keep the weight down and give them A total prof manufacture look.... 

Bradfords Semi Rigid fiberglass 2" Ultratel" with brown kraft paper or thin plastic film will be used for membrane to reject high freq & 3mm plywood to form the veins of the Diffusor... 

Specs for abffusor:
-------------------
Diffusion (QRD)
Prime seed = 13
Frequencey = 945hz
Frequency low = 708.8 Hz
Frequency high = 3,448.9 Hz (My flutter Echo diffusors work from 3400hz up
--------------------------------------------------------------------------
Absorbtion: 800-700hz down
NRC=102, 2"ultratel(705) up to 7" thick
-----------------------------------------
The total outside dimentions (OD) will be:
H = 1.2mt (4') 
W = 70-75cm (2.4'
D = 17.4cm (7")
-------------------------------------
Colour: Black


Picked up my Ultratel so getting the rest of my stuff tomorrow :T
more step by step pictures to come 
Cheers....


----------



## Lonely Raven

Awesome! Sounds like you have it well planned out!

I'm still having trouble trying to fathom how it works, but the kraft paper part makes much more sense now!

I can hardly wait to see them!


----------



## cinema mad

Hi Eric, Good to hear from you mate..

Because my time is fairly limited (to many things going on) I will be running around tomorrow to source the parts for the prototype so I can then have A fully assembled/working Abffusor to relay to potential metal fab companys A clear understanding of what I will require them to manufacture/fabricate in regards to the metal frames only....

Cheers.....


----------



## Lonely Raven

That part sounds awesome!

I'm working on building up my first router table this weekend. I have the router, fence, and router plate arrived yesterday...I just need to build the table and cabinet!

It seems kinda backwards though, since I should probably be sticking with the table saw for the deeper flutter breakers I hope to build, but I think your way of doing the diffusers on the router is much easier than what I was doing on the table saw!

Looking forward to seeing your projects!


----------



## cinema mad

Hi Eric, 
Actualy I would think the table saw method would be much faster thus easier to produce the flutter echo tiles, where as the router method would be A lot slower but offer A more precision/ tighter tolerance diffusing well....
So each has trade offs LOL...

Cheers mate...


----------



## Lonely Raven

Thanks for those thoughts...that's how I was feeling about it as well. 

Good luck on your next build! These are a great inspiration to me, and hopefully to others as well!


----------



## Prof.

cinema mad said:


> I am going to make the sides of the frame out of 1-1.5mm sheet metal (pre fab to my spec) this time to keep the weight down and give them A total prof manufacture look...


Jason...Are you just going to use the sheet metal as side edging around the perimeter of the panels, for decoration purposes, or does it serve some other use.?


----------



## cinema mad

Hi Prof, Good to hear from you mate.. 
The Frame of the Abffusors will be fabricated/constructed of 100% 1-1.5mm mild steel sheet to keep the weight down as opposed to 20mm wood, The frame will contain 16 folds total to add to the rigidity and all precession lazer cut.. Also there will be some pattern in the side of the frame to further reduce the weight but not sure what at this stage....

Cheers...


----------



## robbo266317

cinema mad said:


> The frame will contain 16 folds total


What are the folds?


----------



## terry j

excellent work, will bookmark for when I can get around to it myself.

question/comment time, they must weigh a fair bit, as it is only for diffusion/scattering, how feasible would it be to use esky type foam?


----------



## cinema mad

Hi Robbo, Thanks for the Questions...
The 15mm 90 degree folds are to allow for spot welds or riveting (prototype) the top and bottom peaces to the sides and the 90 degree fold's along the lengths allow for the wells and veins to be held in place /add to the look & give much needed rigidity..

It will become more clear to understand as I start to post the Assembly of the components... 

Cheers....


----------



## cinema mad

terry j said:


> excellent work, will bookmark for when I can get around to it myself.
> 
> question/comment time, they must weigh a fair bit, as it is only for diffusion/scattering, how feasible would it be to use esky type foam?


Hi Terry, Thanks for your complement and questions..

This Abffusor will be very lite due to the choice of components used as compared to wood an the like..

With this type of Acoustic panel esky foam wont work because it wont absorb any frequancy's which is A critical feature of this 2in1 panel, If you just want Diffusion then Esky foam may work for lowering the weight but would be hard to get A nice finnish...

Cheers....


----------



## Prof.

cinema mad said:


> Hi Prof, Good to hear from you mate..
> The Frame of the Abffusors will be fabricated/constructed of 100% 1-1.5mm mild steel sheet to keep the weight down as opposed to 20mm wood, The frame will contain 16 folds total to add to the rigidity and all precession lazer cut.. Also there will be some pattern in the side of the frame to further reduce the weight but not sure what at this stage....
> 
> Cheers...


Wow!! Jason..that sounds like one fancy, complicated and expensive frame..
I'll be very interested to see how that turns out..


----------



## shift9999

Cant wait to see the end results


----------



## cinema mad

Well I have fabricated the first set of Prototype frame Using 1mm sheet panel steel (cold rollled), Going to get them folded tomorrow..

These peices were only cut with my angel grinder & A very thin cutting wheel using A Wooden straight Edge as A fence guide... Once I assemble this prototype Panel and check for fit I will then move on to the next stage and have A few frames fabricated "cut and folded" and some form of pattern cut out in the sides to further reduce the total weight, then all that will be left is final assembley by me....

The camera make's them look warpted but trust me they are stright...

Cheers.....


----------



## cinema mad

The Net weight of this Acoustic panel will only be between 12 to 13.5Kg max...

Cheers....


----------



## Prof.

Very neat job Jason..
How did you manage to fold the edges over so neatly by hand?
Whenever I've tried to do that, they always come out uneven..:scratch:


----------



## cinema mad

Hi Prof, The answer to your question is easy, In that picture they had'nt been folded yet:bigsmile:...

I am getting A metal fab place to fold the first set and will pick the frames up later today..
I know someone with A folding machine who owns A panel & paint repair shop so I will be hitting him up to bend the rest..

Cheers...


----------



## cinema mad

The biggest issue I had with this type of acoustic panel was finding A suitable membrane substrait to work the way I needed IE: reflect/diffuse down to the Diffusion limit of the QRD's 945hz-708 and below that point allow for absorbtion...

The simple answer to that problem is Kraft paper would'nt give optimum results also to fined acoustic coefficient data on A plastic membrane substrait to suit the above is far and few between....

After more research inc talking to Bryan Pape (thanks Bryan) I have found A way around this issue with A little design change using plywood as the membrane with A small air gap that will still work very well...

I should point out that the absorbtion performance of this diffusor/absorber panel will never perform as well as A 4"-6" thick fiberglass based panel but that was not my main goal/intention with this build.....

Cheers....


----------



## Prof.

cinema mad said:


> Hi Prof, The answer to your question is easy, In that picture they had'nt been folded yet:bigsmile:...


LOL!! I noticed that the long panels had the corners cut, ready for folding and the smaller panels looked like they had been folded, but it was obviously just the line marks on the panel..
I think I need a new pair of glasses!!.:bigsmile:


----------



## cinema mad

Been A bit slow coming together I had A lot of trouble finding the Very thin PLY wood used for the membrane & to form the wells also absorb at the right freq which is obviously critical but I have it now :bigsmile:..

I have the Frame folded and just needs to be filed/cleaned up and then ready for paint or powder coat..

I have cut some of the vains and done A ruff fit tonight, Hopefully I will start Assembly in the next couple of days :T...

Cheers....


----------



## Lonely Raven

Great start!

...waiting to see what you use for spacers.


----------



## Prof.

What type of timber supplier did you find for the 3mm. ply?
I haven't seen any 3mm. ply for years..these days it's all 3mm.MDF..


----------



## robbo266317

They occasionally have it at bunnings here in Ncle.


----------



## Prof.

I looked for it at Bunnings in Adelaide, but they only have it in 4.5mm..


----------



## cinema mad

Hi Prof its not 3mm ply 3mm is to thick for the membrane used with this Abffusor and wont work right, FWIW its thinner than that try 2mm...

Cheers...


----------



## cinema mad

Lonely Raven said:


> Great start!
> 
> ...waiting to see what you use for spacers.


 Thanks mate...

Cheers...


----------



## Prof.

cinema mad said:


> Hi Prof its not 3mm ply 3mm is to thick for the membrane used with this Abffusor and wont work right, FWIW its thinner than that try 2mm...
> 
> Cheers...


Wow!! I didn't think that it was even made that thin..:scratch:
But why use ply?..There are other materials that are more stable than ply and cut more cleanly, like Styrene (not foam) or Acrylic..both are available in 2mm. thickness..


----------



## Lonely Raven

Both Styrene and Acrylic would cost much more than 2mm ply me thinks. 

Though colored or even clear acrylic would sure look neat!


----------



## Prof.

You're probably right Raven..but it would give the panels a very nice appearance and a very smooth surface area..


----------



## cinema mad

Hi prof, Ply wood cuts very cleanly if you use the right tool with the right blade :bigsmile:.. I use A special 30deg Laminate blade 180mm x 60teeth cuts All PLY perfectly no chiping perfectly clean cuts :T... I will post A picture of the clean cuts and blade needed...

No its not that easy you just cant use any old substrait, remember I needed A membrane with A curtain mass to meet A transmission loss at A fairly high mid frequency IE: Membrane stops reflecting/diffusing at 700- 900hz so below 750-900hz the membrane allows high freq sound to passes through to be absorbed... 

There is A mathematical formula to work out the mass of A said substrait ,the math formula is also in the Master Handbook of Acoustics(4th edition) ..

So The reason I used thin 2mm ply wood is because it closely meets the criteria/mass required and with A small set air gap between the back of the ply and ultratel fiberglass(705) & applied attached in A certain way to the Vains as not to make the 2mm ply any more rigid in any way, the thin ply will transmit/pass the sound through at A mid frequency, which is what it needs to do... 

Hope this helps Cheers....


----------



## cinema mad

Some pictures of the clean cut 5mm and 2mm ply, straight off the saw not sanded, this blade does an amazing job cutting ply...

Cheers....


----------



## Lonely Raven

Sorry, I didn't notice any saw or blade...I was admiring the warm and sunny background...it's about to hit freezing and start to snow here Chicago today.


----------



## Prof.

cinema mad said:


> Hi prof, Ply wood cuts very cleanly if you use the right tool with the right blade :bigsmile:.. I use A special 30deg Laminate blade 180mm x 60teeth cuts All PLY perfectly no chiping perfectly clean cuts :T... I will post A picture of the clean cuts and blade needed...


Ah..yes..Having the right blade would make all the difference..
I used to work for a furniture manufacturer.. many years ago..and I remember they used a special blade for cutting laminate..The edges were so cleanly cut that you could cut your finger on them if you weren't careful..

I can't believe how critical these membranes have to be to perform correctly..:dontknow:


----------



## cinema mad

Lonely Raven said:


> Sorry, I didn't notice any saw or blade...I was admiring the warm and sunny background...it's about to hit freezing and start to snow here Chicago today.


Hi Eric,
Yes it is often sunny here in the state of "Victoria" Australia and else where in Australia inc the state of SA where Prof lives, A little to sunny as it hardly ever rains thats why my back yard looks A bit like A Dusty Desert:yikes: it has'nt always been that way here but we are in A drought.... It does snow but only up in the High country never down in the flat plains...

Do you prefer Sun or Snow Eric ? I would gladly swap some sunny weather for some snow LOL...

Cheers mate...


----------



## Prof.

cinema mad said:


> Do you prefer Sun or Snow Eric ? I would gladly swap some sunny weather for some snow LOL...


Me too!! :bigsmile:


----------



## Lonely Raven

I'm a cool weather person, but this 35 degree sideways rain and 30MPH winds just peel the life out of you. 

Chicago is funny, we can have weather change so drastically in one day, that we've had T-shirts and shorts on at noon, and snow that same night! Honestly, I'm really tired of it...but I have family here.

Oh, back on subject, I did manage to hang the *heavy* 4" deep QRD on my back wall as you suggested. I have one hanging, and the other the stain is drying. 

Yeah, I know they are MDF, but I figured I'd stain them a warm cherry red to match the oak stair treads I turned into flutter breakers. So I have one 4" QRD and one "stair tred" QRD up on the wall, and I'm working out an aesthetically pleasing layout to hang the rest of them. Photos to come later. Right now, I'm much more interested in your project!


----------



## cinema mad

Tonight I Glued & fitted the Veins of the Abffusor into place and Dry fitted the thin ply that form the wells... I am about to start fitting the ply permanetly to form the wells, Its going to be A very tedious job clamping each set of Veins untill the Ply is set permanently in place.....

Cheers....


----------



## robbo266317

That is so much effort. :unbelievable: I cant wait to hear what difference it makes.


----------



## Prof.

I admire your persistence Jason..I think I would have given up long ago..:thud:


----------



## cinema mad

robbo266317 said:


> That is so much effort. :unbelievable: I cant wait to hear what difference it makes.


Yes it is A huge effort to make this Abffusor, 88 components in all to make just one, and I still have 2 more to build :wits-end:....

You can only assembel A little at A time in A curtan sequance so it is long and tedious...
It took 6 hours just to set 7 wells in place :yikes:...
Cheers....


----------



## cinema mad

Prof. said:


> I admire your persistence Jason..I think I would have given up long ago..:thud:


 Thanks Prof, The way I look at it is To do it your self saves big $$$$ and the performance is often better than what you can buy for A reasonable price, For instance the RPG Diffractal is over $2000au A piece in Australia (making these nested Diffusors next), RealTraps Diffusor/Abffusor is $1400au & mine will outperform this Diffusor and cost one third as much.. So you see what I mean by the Huge savings if you can DIY, But I understand not everyone can... 

Cheers....


----------



## robbo266317

Now I know why the hardware store didn't have any clamps left.... :bigsmile:


----------



## Prof.

Out of curiosity..who sells these RPG Diffractal's and diffusers in Australia.?
I've never seen them listed anywhere..:dunno:


----------



## cinema mad

Hi Prof, The Australian RPG Distributor is Melbourne based Acoustic Vision...

Cheers....


----------



## Prof.

Thanks jason..

I had a look at their website...Some very interesting materials they carry..
I was most surprised to see they have GOM.! I didn't think it was available in Australia..
Something to keep in mind, should I ever re-build my theatre..


----------



## cinema mad

Getting close now to finnishing the first/Prototype Abffusor..
There is A fair amount of 2"705 being used for Absorbtion about 1200mmx1200mm sheet..

Because most of the wells being so deep I used my Wagner spray gun with A Matte Black Water based paint To paint the Abffusor, Making sure as to apply A very thin coat to the Actual membrane itself....

Just need to finnish up putting the Fiberglass in the back and closing it in with Muslin cloth then fitting the external metal frame after its painted....:daydream:

I believe the total weight should be no more than 15Kg but I will check for sure once assembled 

Cheers....


----------



## Lonely Raven

That looks fantastic after being painted black! Such a Pro looking job!

I picked up a cheap ($32 USD) HVLP spray gun somewhere many years ago...and never got it working right. The other day I took it apart and put it together again, which gave me a better idea of how it works (I've never used one before). It was a life saver for spraying the Warm Cherry stain on my two diffusers:










Not nearly as pro looking as yours, but they seem to do their job!

Now, after seeing yours, and reading your design thoughts...yours totally make sense! So the thickness and density of the parts were chosen so there would be a specific frequency that would pass through the paneling material and be absorbed, correct? And everything above the "cut off" would be then be diffused as normal. Clever!

And here, I was just going to stuff some 2" between my diffusers and the wallboard since mine are "floating" off the wall, suspended by some 2" X 2" I cut from some larger pieces of scrap. LOL


----------



## Prof.

Very nice job jason..:T
I love the little poser in the background..:heehee:


----------



## cinema mad

Looking good Eric, I like the way you have your diffusors layed out also the cherry stain looks very nice :T..

I replied to your post in my Mealstrom Subwoofer thread over at the AVS forum about your Diffusors and room acoustics, did you see it ??...

Yes you are spot on with your thoughts about the Abffusors and how they work....

Cheers....


----------



## cinema mad

Had A chance to install the Rigid fiberglass/ absorbtion membrane inc setting the pre determined air gap between the Back of the ply & front of fiberglass ... 

The ultratel Fiberglass was cut A little to big and hangs out A bit but I dont mined the Muslin keeps it set in place and stops the glass fibers becoming airborn... 

The reason I chose Muslin as opposed to Ply is because, 
1: so the Absorbtion cf of the Abffusor will be higher due to the open back 
2: Keep the weight down :bigsmile:....

Couple of pictures of the SLOW progress Just need to Paint the steel frame and rivet it together

Cheers....


----------



## cinema mad

Well I Spray painted the metal outer frame matt black using A new product: Dulux Quit Rust Water Based Gloss Enamel with Urethane but the paint did'nt stick :hissyfit:... 

Initally I was very happy with the way the outer frame came up straight off the spray gun (3 coats)
I left it for 6 days to dry but the paint didn't stick, thus wasted my time...

This paint is A Primer and paint in one with 7 years of protection to all metal surfaces..

When I first opened the one LT can of Matt black paint it had seperated as expected so I went to stir it but the primer down the bottom of the can was rock hard and near impossible to mix..
I went back to Bunnings and showed the guy who sold it to me, he then checked 2 other cans off the shelf but they were all the same so he attempted to mixed all three cans on there electric mixer and tipped all three cans into one and gave me that.. 

But obviously half of the primer was left in the bottom of the can's due to not mixing in with the paint, So there's your problem :unbelievable: 

Before painting I preped the 1mm cold rolled steel by bead blasting with Glass beads then whiped over throughly with prepsol, This is the class 1 standard to prepair the metal surface and remove scale for painting and what Dulux recommends...

I am going to get A price on powder coating :bigsmile: and attempt to get my $32 clams back off bunnings...

Check out the paint job...

Cheers...


----------



## Prof.

That looks nice Jason..It's a pity that the paint didn't stick..
You certainly did all the right preparation..
A "one off" powder coated job probably won't be cheap, but it will give a nice professional finish to the frames..


----------



## cinema mad

Actualy to get the metal frame powder coated costs around $50 in satin black so not to bad, I have to build 2 more of these Abffusors 3 total for my back wall so $150 for powder coating...

As they say you learn by your mistakes,

Cheers....


----------



## cinema mad

I draged my first Abffusor into my theatre and placed it in the middle of the back wall while I watched The Day The Earth Stood Still on Blu-Ray to see how it performed..

To tell you the truth I could'nt really notice much differance But once I build the other 2 and place them all against the rear wall mid hight with 6" thick bass traps under neath and QRD flutter Echo tiles placed Horizontaly on top of the Abffusors I am sure it will aid in the Acoustic performance of my theatre...

My standard room Dimentions are very good (R Walker BBC/ Pass) no integer multipule within 5% Pass according to the room mode calc, I am Thinking of trying/striving with help from Acoustisofts RplusD Modal Analyzer For Dolby's optimum ratios for film & music room/ an RT60 of 242ms...
Is this worth trying for??

Absorbtion to Achieve ITU/EBU Control Room Recommended 198ms RT60:443 Sabins 

To help with Room modes I Have been looking at using A Helmholtz Resonator Mainly because They can be tuned for very low room modes & I can use my front Riser as the chamber and have A very low Q thus larger bandwidth: 

According to the Room Mode Calc My room modes Dominate between 30Hz to 118Hz : 
I will be taking realtime measurments to get A more precise idea of the modes.. 

The most dominant are: Axial 30.2Hz, Axial 47.1Hz 35.8%)

Tangential 55.9Hz 15.7%) Axial 70.6Hz 14.1%) Tangential 76.6Hz 7.8%

This is what I have come up with : 
Helmholtz Dimentions: H:40cm W:130cm D:120cm
Specs:
Port length: 2cm
Port Diameter: 100cm
Volume:624lt
F res: 67.83
Q: .79
Bandwidth: 85.64Hz
F low:25.01Hz
F high 110.65Hz

Any advice and Suggestions would be greatly Appreciated..

Some pics of the Abffusor in the theatre

Cheers....


----------



## thewire

cinema mad said:


> My standard room Dimentions are very good (R Walker BBC/ Pass) no integer multipule within 5% Pass according to the room mode calc, I am Thinking of trying/striving with help from Acoustisofts RplusD Modal Analyzer For Dolby's optimum ratios for film & music room/ an RT60 of 242ms...
> Is this worth trying for??


242ms is low for a listening room but it can depend on the speakers, source, and at what volume level you are listening to. For very high quality sources such as blu-ray I think that a lower RT60 would be good to shoot for, but your ears must tell you what sounds right. You might have a conversation with someone in the room and see if it is comfortable since your room dimentions effecting <200 Hz is in good shape. I have found that maintaining a balance of symmetry is very critical. If you decide to use Helmholtz Resonators (usually in rooms +30' or so in a direction I think) it can be helpful to have two instead of one. They sometimes take some trial and error to get right more than most treatments. I like the new treatments. :T


----------



## cinema mad

Thanks thewire for taking the time to post what you have experienced and pointing them out , I see your using A helmholtz rasonator at the front of your room :T....

I was thinking of only using one larger helmholtz resonator in the left front riser to the above diamiter, but I can use both my left and right front risers if I need to to keep things balanced....

Cheers....


----------



## cinema mad

I have been playing with the RT60 app in Acoustisofts RplusD & ran A few sweeps in the main listning position "subs only", but I know that you need to run the RT60 with main speakers & subs together when taking readings....

I need A decent calibrated mic instead of my standard ECM8000 mic but good enough for now untill I am ready to do the final tuning of the theatre... 

I did notice that the real time analysis reconfirmed the big room modes from 47hz down like the room Mode calc predicted, But I am hoping to rectify the lower frequency room modes with one large or two 
smaller HelmHoltz Resonator(s).. 
1x large tuning: Volume 624lt,, Q.79, bandwidth of 85.64Hz , F,low 20-25Hz , F High 110Hz 
hopfully this will work but either way I will get there with much persistence...


Also Has any one read Floyd Toole's book: Sound Reproduction: The Acoustics & Psychoucoustics of Loudspeakers & Rooms ?? I just ordered it.. Kevin Haskins said it is A must read as well as S Linkwitz... 

Here is A croped RT60 graph of the subs running only, Subs crossed over at 80Hz...


Cheers :T...


----------



## cinema mad

Just picked up Floyd E. Tooles new book today: Sound Reproduction, Loudspeakers & Rooms, Looks like A good bit of usefull easy to understand info in it but its $80au ...

Also I was chatting to one of Australia's room acoustic experts and he seemed to favour the idea of the use of Helmholtz Resonator for treating the lower model region in certin applications hopefully my situation raying:, also pointed out A few ideas for bass traps that reach A little lower than the 3.0pcf (48Kg/m3 fiberglass 6" broadband bass traps I built that are only realy good down to around 100Hz when corner mounted...

So I am going to modify my rear Broadband bass traps and see how it sound & performs after running R+D...
It cost's another $150au for the extra membrane but there is none in my state so its A 2 week wait... If it works well I will be sure to post the build.... 


Cheers...


----------



## Prof.

cinema mad said:


> Just picked up Floyd E. Tooles new book today: Sound Reproduction, Loudspeakers & Rooms, Looks like A good bit of usefull easy to understand info in it but its $80au ...
> 
> Also I was chatting to one of Australia's room acoustic experts and he seemed to favour the idea of the use of Helmholtz Resonator for treating the lower model region in certin applications hopefully my situation raying:, also pointed out A few ideas for bass traps that reach A little lower than the 6.0pcf fiberglass 6" broadband bass traps I built that are only realy good down to around 100Hz when corner mounted...
> 
> So I am going to modify my rear Broadband bass traps and see how it sound & performs after running R+D...
> It cost's another $150au for the extra membrane but there is none in my state so its A 2 week wait... If it works well I will be sure to post the build....
> 
> 
> Cheers...


Jason...Is this something that fits over an existing bass trap, or a completely new design?


----------



## cinema mad

Hi Prof, yes it is/can be intergrated into the existing Bass Trap....

I have the membrane on order but its A 2 week wait...

Cheers....


----------



## Doctor X

cinema mad said:


> A few ideas for bass traps that reach A little lower than the 6.0pcf fiberglass 6" broadband bass traps I built that are only realy good down to around 100Hz when corner mounted...


I would have thought 6" thick fiberglass would be capable of reaching down quite a bit lower than 100 Hz (more like 80 Hz or slightly below that especially if using an air gap). But this guy is an acoustic expert so who am I to argue ?

Regards,


----------



## cinema mad

Hi Vaughan100 thanks for taking the time to post..

Yes I do have A big air gap especially for my front broadband bass traps and that is A must to get decent performance out of this type of absorber IE: 3x50mm 48Kq/m3 or 3cf fiberglass, But the reality remains while 6" may absorb A little down at 80hz the further up in frequency say 250Hz the more it will obsorb.. Even Broadband absorbers have an effective bandwidth (Q) that tapers off either side of that... Also the less the thickness the greater directional attenuation can accure, so I believe Ref (Floyed E Toole)..... 

So the thicker the fiberglass the lower it will absorb but also every time you add thickness say after 100mm & then double that to 200mm the less difference it makes compared from going from 50mm to 100mm in thickness... 

Cheers....


----------



## loupy31

Hi All,
I have been watching this post for some time now, Most of the info has been very informative, I am currently working on my humble Home cinema room, I like many others am having a few problems with the acoustics, I am in the process of drawing up a floor plan of my room with the hope that you guys and gals can help out.

Regards Peter


----------



## cinema mad

Hi Peter, 

I am sure that you will fined plenty of help on this forum mate, we are all hear to help each other where we can .. 

I started this thread to show & share my ideas about building my own acoustic treatments in the hope that others would fined it useful and also share what they have come up with ...

Cheers....


----------



## cinema mad

I am still waiting on my membrane so no progress has been made with my rear bass traps :waiting:
But hope I will have it next week at the latest...

Cheers....


----------



## cinema mad

Last week I finally recieved the Quietel 130kg M3 fiberglass boards From CSR Bradfords, By adding Quietel it will extend the low frequency absorption of the rear corner mounted Broadband bass traps..
Unfortunately the Quietel only comes in A max thickness of 25mm (1") 2400x1200 x2 per pack :crying: as apposed to ultratel 48Kg M3 50mm 2400x1200 x3 per pack..

I just doubled up the Quietel to 50mm and added it to the rear of the existing 100mm 4" of Ultratel, so making A total of 150mm "6" thick bass traps for the rear wall corners...

Also I changed all my first reflection absorption panels (ultratel) from 50mm 2" to 100mm 4" thick
so as to obtain more "even" absorption for Mid & High frequencys, Floyd Toole's new book points out the importance of this..

I also re plastered the theatre's ceiling with one layer 10mm dry wall and only used 4 can lights this time as apposed to 8 and enclosed all 4 liqhts in MDF boxes sealed with Acoustic silicon placed in the roof cavity..

To further reduce my 4 Subwoofers decay time/ ringing I installed CSR Bradford sound screen plus 120mm thick in the ceiling cavity above the theatre wall to wall inc over the side wall cavitys paying attention that the acoustic batts were cut to insure A tight fit between the joists, also doubled it up 240mm thick directly above where the 4 corner mounted Broadband bass traps are..
The difference this made was immediate watching Bolt on blu-ray the bass was just so tight punchy and detailed... 

At the moment I am fine tuning A helmholtz resinator placed in A high pressure zone to help smooth out the room modes,
Then the last thing I am doing with the room acoustics :daydream: is finishing my other 13 prime seed QRD abffusor for the rear wall :waiting:: So the back wall layout will have 7" deep QRD Diffusor/ 4" thick Absorbtion in the middel/ QRD Diffusor...

Cheers..
A couple pics..


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## terry j

go cinemamad! I'm rootin for ya.

will be going thru this thread again soon, picking your brains as it were.

Just finished my speaker build, and have begun experimenting with room treatments. Our local spotlight does not have anything really that looks like grill cloth (for any treatments), so will grab the details from the geelong store you mentioned, they should be able to get it in..fingers crossed.

I do think I will lean quite heavily towards diffusion rather than absorption. Strictly two channel here, you must be into HT with a name like that yeah!! ha ha

not to steal your thread, but this pic might be good for light entertainment!










Remember the old tip to just throw an unopened bag of f/glass in the corner and see? Well, I did that, and more! just hung the raw batts with string, quick and good for testing purposes.

Pretty heavily did the front of the room, very good results. But, I now get the feel of how easy it would be to overtrap, so will have lot's of diffusion. 

, throwing a few raw batts on the wall is only a couple of hours work (even tho I have to use an extension ladder!), but it is not so easy to test diffusion and find out is it.

"let's see, just where are those diffusors I just happen to have laying around??"



















anyway, thanks for your thread


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## cinema mad

Hi Terry J, Very nice speakers you have there mate, what Model/Brand are they ?? I love my 2 channel as well but more into HT now...

As far as the speaker grill cloth, Scott from spotlight Geelong will ship it to you no prob's, $10au to ship AU wide I think...

Cheers Terry 
Hope to see more pictures & idea's of what you end up coming up with mate...


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## terry j

cinema mad said:


> Hi Terry J, Very nice speakers you have there mate, what Model/Brand are they ?? I love my 2 channel as well but more into HT now...
> 
> As far as the speaker grill cloth, Scott from spotlight Geelong will ship it to you no prob's, $10au to ship AU wide I think...
> 
> Cheers Terry
> Hope to see more pictures & idea's of what you end up coming up with mate...


If the local cannot get it, then yeah for sure on to scott

diy speakers, bit of a write up here

http://www.hometheatershack.com/for...my-speaker-build-about-time-i-showed-you.html

actually, you may be able to help.

there is a dutch site that had a project very heavily into diffusion, heaps of pics. used tons of mdf to do the build.

this looks very much like it could be it, but randomly pressing buttons I have not come across the thing I am thinking of

http://www.soundscapes.nu/home.html

have you any idea of what it is I am looking for from my vague description??


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## cinema mad

Actually I am familiar with that web site, there is A link to it in this thread..

To make there QRD flutter echo diffusors they use A Spindel Moulder Cutter, The cheapest one we sell is made by Jet for around $2000au.. It makes it A lot easier than using A router like I did.. When making my Flutter Echo diffusors I used Tasman Oak as it is A hard wood and A lot easier to work when using A router to make precise accurate Vain/well cuts in these type diffusors ...

Cheers...


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## terry j

cinema mad said:


> Actually I am familiar with that web site, there is A link to it in this thread..Cheers...


well blow me down! it is too.

Ha, this must have been where I got it from originally, how about that! I started a thread today on diy hoping people would know of it, and tonight we find it here.

Someone linked to the home page over on diy, it looked suspiciously like it could be the right site, but even with an hour clicking all the links there I still did not find it.

Why cannot my lotto picks be this serendipitous??

Just quickly glanced the thread looking for links, so not read it again properly yet. But I do recall you saying you found some good cheap plywood, do I remember right? Where did you source it from and is it exe?


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## cinema mad

One of the guys on that website went sick on the diffusor treatments lol, I think its safe to say he knows the importance of diffusion :bigsmile: 
I think it was The same guy that posted on An acoustic's forum that he loves & recommends abffusors, absorbtion Diffusion in the one panel... 


I was able to get hold of 2400x1200 sheets of 2mm & 1.5mm ply through Belmont Timber from memory, also I think I bought some 2mm ply through my local bunnings store, I paid around $13au A sheet I think...

Cheers....


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## Prof.

cinema mad said:


> Last week I finally recieved the Quietel 130kg M3 fiberglass boards From CSR Bradfords, By adding Quietel it will extend the low frequency absorption of the rear corner mounted Broadband bass traps..
> Unfortunately the Quietel only comes in A max thickness of 25mm (1") 2400x1200 x2 per pack :crying: as apposed to ultratel 48Kg M3 50mm 2400x1200 x3 per pack..
> 
> I just doubled up the Quietel to 50mm and added it to the rear of the existing 100mm 4" of Ultratel, so making A total of 150mm "6" thick bass traps for the rear wall corners...


That's very interesting Jason..
What's the difference in density between the Quietel and the Ultratel?

I'm using 6" thick Supertel for the rear traps..
What improvement/changes did you notice in the low frequencies with the Ultratel added?



> Also I changed all my first reflection absorption panels (ultratel) from 50mm 2" to 100mm 4" thick
> so as to obtain more "even" absorption for Mid & High frequencys, Floyd Toole's new book points out the importance of this..


Also interesting..What improvements did you notice with the 4" panels over the 2" ones?


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## cinema mad

Hi Prof, Supertel is 32Kg m3/ Ultratel is 48Kg m3 or 3pcf( Same as owens corning 703)/
& Quietel is 130Kg m3 (oc 705 is 90 or 6pcf...

Here is A link to CSR bradfords Glass wool specs 
http://www.bradfordinsulation.com.au/Products/Commerical/HVAC.aspx

Hope this helps
Cheers....


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## cinema mad

As far as going from 2" ultratel with 2" air gap to 4" of ultratel for my first reflections the absorbtion cf will be more balanced for Mid & High frequenceys as Apposed to 2"...

Cheers....


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## Prof.

cinema mad said:


> Hi Prof, Supertel is 32Kg m3/ Ultratel is 48Kg m3 or 3pcf( Same as owens corning 703)/
> & Quietel is 130Kg m3 (oc 705 is 90 or 6pcf...
> 
> Here is A link to CSR bradfords Glass wool specs
> http://www.bradfordinsulation.com.au/Products/Commerical/HVAC.aspx
> 
> Hope this helps
> Cheers....


Thanks Jason..

Hmm...It looks like the Quietel is significantly more dense than the Ultratel and a lot denser than the Supertel..
I think I might try and pick up some Quietel next time I go to Adelaide..


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## cinema mad

Hi Prof, I should point out that The density of Quietel is better suited to bass traps "NOT" first
reflections & Ultratel is best suited for first reflections..

Personaly I would go with Ultratel due to being very good for both applications..
I used the 2" of Quietel & placed it behined the 4" of ultratel rear bass traps to help absorb lower in frequ...

Hope this helps,
Cheers....


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## Prof.

cinema mad said:


> I used the 2" of Quietel & placed it behined the 4" of ultratel rear bass traps to help absorb lower in frequ..


.
That's what I'm planning on doing as well..if I can get hold of some of the Quietel..
I'll leave the reflection point panels as they are for the moment..


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## ScruffyHT

Hey Jason ... wonder if you could make some suggestions as you have clearly invested alot of time on this subject

Theatre is at rough-in stage but planning for acoustic treatments ... room size is ~ 14' X 23' ... 7.1 surround using Axiom M80 LR, EPIC 600 SUB, VP150 center and 4 X QS8 surrounds ( another sub to be added later on if needed )










I had planned to put OC703 corner wedge bass traps on screen wall, linacoustic on rest of screen wall and for the first 4' of the side/rear walls and empty space above that covered with a AT fabric like GOM or Dazian

my questions for you are:

- would you recommend using diffusors above the linacoustic on the side/rear walls ?

- if yes, then due to the linacoustic being 1" thick would it possible to use strips of hardwood to create the channels for the diffusor and glue to the drywall to save space ? 

- if I build diffusors with a max depth of 1", would that be beneficial ? ( could go deeper on rear wall ... maybe 2" deep ) ... reason I ask is all your diffusors seem to be much deeper

- if all the above works out, I had planned to cover all the walls with a AT fabric, do you see any problem covering a diffusor with a AT fabric ?

I am very limited on the side walls due to the door location ( support post restricts entrance door location to be very close to side wall )

Thanks for any suggestions


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## cinema mad

Hi Steve,

Diffusors inc Flutter Echo Diffusors (around 25-30mm thick) will work fine on the rear sidwalls, you can place them over semi riged fiberglass or absorbtion substrait, but small cutouts in the deeper wells of the diffusors are needed as well as random spacing with an air gap behined the diffusors to allow for the lower frequencys to be absorbed below where there usfull diffusion stops...
Flutter Echo Diffusors can be mounted to small strips of wood that are attached to the drywall.. I have never cut varying depths of wood strips/vains based on QRD prime seed to form wells for diffusors, but they would need to be mounted to A hard backing such as wood and must be built very precisely to perform as designed....

The main thing to remember with QRD diffusors is the deeper the wells the lower they will diffuse
the larger QRD's I made are prime seed 13 & 7" deep but I chose to placed them on the back wall next to my rear bass traps...

I would'nt recommend covering diffusors with any thing due to affecting there ability to diffuse optimumly....

A good rule of thumb for the most important areas to cover when it comes to room treatments for A Home theatre is to first treat the 4 corners with bass traps either with super Chunk style or 6"thick floor to Ceiling if possable Also the first reflection points inc the Ceiling.. 
Then you can move on to treating the rear wall with absobtion directly behined the rear seats and diffusion on either side closer to the corners, Diffusion on the rear side walls also placing Accoustic insulation batts in the Ceiling cavity above the theatre can aid in low freq absorbtion...

It is important to not over treat the room with two much absorbtion as this will deaden the room to much, rather its A fine balance of Absorbtion reflection and Diffusion analizing the room with mic & Acoustic software then futher tweaking/refining untill you get A good balance & even decay time...

Hope this helps
Cheers Steve...


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## ScruffyHT

Hey Jason ... thanks for the response

Due to WAF and wanting to have the fabric theatre look where all walls are covered in fabric it looks like diffusors will be out for me then if they cant be covered with fabric

The ceiling will be R19 batt/rsic clips/hat channel/DD/GG ... walls staggered stud/R13/DD/GG 

If you look at the drawing I can only fit corner bass traps in the front of the theatre room as the rear of the room has 2 doors to deal with ... I can probably put 2" or 4" insulation on the rear wall though ... maybe even 6" if that will help with bass trapping ??? - Should I just cover the entire rear wall then with absorbtion or just where the first reflection point software indicates ?

I had also planned to put a sub built into my riser ( 4 X 12" Shiva drivers firing to the back wall - drawing in my build thread http://www.hometheatershack.com/for...075-steves-basement-theater-construction.html ) 










Also I plan to build a coffered ceiling with Linacoustic in the areas of first reflection as my center channel will be mounted in the soffit


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## cinema mad

Hi Steve, This looks as though its going to be an Awesome HT mate, I could only wish for A room this size to Build A HT..


You could use Polycylindrical diffusers "Polys" on the rear side walls and paint them the same colour as your Acoustic fabric or put acoustic fabric over them, they can be fairly easy to make with thin Ply, also I think Bryan GIK sells polys...

you could put some form of absorbtion 6" thick semi rigid fiberglass on the back wall placed between the Ceiling and rear wall thus providing an air gap to boost the lower freq absorbton, or placed against the rear wall.. 

I found the more Subwoofers (I have 4) which in turn brings up the LF sound pressure the more bass traping I needed to try and tame the LF decay time/ringing..

Also the down side to: more rigid you make your side walls IE:adding 2/3 layers drywall) the less LF they absorb so the more important Acoustic treatment's become, same goes for concrete walls... 

Cheers Steve,
RE: Jason...


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## jrisles

Hi All. I have been reading and re-reading this thread lately and there is some great information in this thread. I know this is a couple of years old now but i would be keen to hear where you are all at two years plus down the road. Changes made ... what you would definitely do again and what didn't really work out. The reason for these questions is because i am about to go down the same route with my room. Thanks a heap. cheers j


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