# Designing mid-high speakers to match SUB



## Spadez (Oct 14, 2009)

Hi,

Im building this sub:
http://www.geocities.com/adrian_mack/

I now need to start looking into creating my 5 additional speakers for the mid-high frequencies to give me the 5.1 setup.

At the moment I have bose cube speakers, their sound isnt fantastic but the size is perfect. How possible is it to make my own "cube" speakers that will give good sound quality / performance? Can anyone recommend a driver for such a purpose?

James


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## evilskillit (Oct 7, 2008)

There are plenty of small designs out there you could use.

Zaph has 2 at zaphaudio.com
The Hi-Vi BS3 Single Driver System and The Budget Mini

There are a few posted on the partsexpress project showcase

There are a few posted here like the Overnight Sensations or the Orient Express
http://undefinition.googlepages.com/diy

Brando at the htguide just came up with a 5.1 channel mini cube design recently.
http://www.htguide.com/forum/showthread.php4?t=34341

and probably mini more to be found if searched for.


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## Spadez (Oct 14, 2009)

Thank you for the links, im reading through them now. I dont think I was specific enough when I said cube speakers, I meant like the "bose" cubes which are around 4" cubed. Do these style speakers have the capability to produce good sounds or is the size needed.


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## evilskillit (Oct 7, 2008)

Making a very small speaker that uses a 3" or 4" full range driver in a very small cube may be possible and might sound better than what you would buy but most DIY designs use slightly larger speakers because if you are going to spend the time to build something usually it is worth your while to make them slightly larger 2 ways, as they will usually sound better but not cost that much more than a very small speaker.

Things to take into consideration is when building speakers you usually have to use MDF at least 1/2" thick, where as manufacturers may use very thin plastic allowing more inner volume in a smaller enclosure. Also they can have the speakers designed to the specification of the small enclosure where as DIYers do not have that luxury and have to find a small full range speaker that does not sound horrible and can work in a very small enclosure. Usually due to the small inner cavity and the thickness of the building materials this precludes fitting in a tweeter and suitable crossover. I guess what I'm saying is there may be a design out there that would work for you and it would certainly be a good idea to ask around if you want a design that small and are worried more about size than sound quality and value you might be better of sticking with your bose system untill you have more space or more of a budget, or both.


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## Spadez (Oct 14, 2009)

Thank you for the reply. I don't want to stick with the bose because I want surround sound with a custom sub. I can go for a bigger speaker design, but if I can help it I would prefer to keep it small. I used to have iPod speakers that used a tiny 1 inch driver and these sounded incredible, is there nothing like that out there for the diy's?

Also is it possible to use a passive radiator design with tweeters to keep it compact and keep the sound?
_Posted via Mobile Device_


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## evilskillit (Oct 7, 2008)

These might be your best bet.
http://zaphaudio.com/audio-speaker18.html

Also check out these.
http://rjbaudio.com/Bandit/bandit.html

Check out these little cubes
http://www.hometheatershack.com/forums/diy-speakers/4122-4-full-range-speakers.html

Look at these little fostex cubes
http://diyaudioprojects.blogspot.com/2009/04/simple-diy-monitor-speakers.html

They should both be incredible small full range speakers. I know you're looking for something more cube like in nature, you could make them deeper but less tall. It might be possible to make them a little wider too but you would have to ask the designers as changing width is normally a big no no as it can throw off frequency response quite a bit.

Part of the reasons the boxes on these are larger than your bose cubes is because they're designed to actually be able to play low enough to properly mesh with your subs, smaller boxes would roll off the low end much more quickly and if the speakers drop off too much before 100hz there will be a funky area between them and the bass of the sub that causes them to sound like small speakers + a sub, instead of just one really big nice speaker.

Trying to make a really small 2 way cube probably won't be doable, look for very small designs that use a full range driver and see if you can find one that fits your bill as far as being small enough and cubelike enough.


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## Spadez (Oct 14, 2009)

Hi Evilskillit,

Has nobody tried a passive radiator Mid-High range speaker? Would that not give the bass required to mix into the sub and keep the size down?

Those cubes are still large than I was hoping for. Im going to have to look into how I can get around this? Perhaps two small tweeters for left and right with a larger mid for the center? (Im thinking about how I can place this setup for my desk, rather than a whole living room).


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## evilskillit (Oct 7, 2008)

Peerless does offer tiny little 3.5" passive radiators. I guess I could model the box for either of the designs I posted and see if they could be made smaller using a passive radiator tho to fit a 4" driver and a 3.5" PR into a cube it would have to be at least 5x5x5 outside to accomodate the driver, the pr, the terminal cups, the thickness of the lumber and maybe some crossover components. I'm not sure how small of a driver you really have in mind. Maybe if you could post a picture of your current bose setup it might give someone an idea and another sugguestion could be made but at this point I'm about out of ideas.


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## Spadez (Oct 14, 2009)

Ill post a picture of my setup tomorrow as I am currently away from my desk. I like the idea of a 3.5" driver and twin 4" radiators for the small left and right front drivers. Ideally I'd like them as small as they will go whilst keeping good SQ. My Bose cubes are two 5" cubes stacked on top of each other. 

I read about a problem with passive radiators where the radiators are out of phase with the driver, and this can be audiable at high pitches. Do you think this would be a problem with this kind of setup?

If you would be kind enough to model it I would appreciate it, otherwise I'll have a crack at learning the program at work tomorrow.
_Posted via Mobile Device_


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## evilskillit (Oct 7, 2008)

After doing a bit of modeling none of these very small designs seem to lend themselves well to passive radiators, there is almost no advantage because no passive radiators are tuned high enough to actually help increase the volume in a range that matters for these small speakers. eg 70-80hz.

I figured a cube with an inside dimension of 5x5x5 would give you 125 cubic inches of internal space. a 4x4x4 cube would give you about 64 cubic inches. Anything less than 125-130 makes all the small speakers I modeled have a hump in the response between 100 and 250hz so the sound in that range would be over emphasized, everything higher or lower than that would sound thin. The frequency drops off very quickly below 100-150hz which would require that you run your subs high enough as to sound directional and no longer blend seamlessly.

A 5x5x5 cube built out of 1/2" mdf would be almost 6x6x6, and a 4x4x4 cube made out of 1/2" mdf would be almost 5x5x5 so these are all a bit larger than what you are wanting. You could build something this size or smaller, it would probably sound at least a bit better than what you have right now. But maybe not that much better, and will cost your time and money so its up to you to decide if you want to take a stab at it or not. The other thing to do is ask around on the other DIY audio forums like diyaudio forums, http://diyaudioprojects.com/Forum/, htguide diy forums and others and see if anybody else has any ideas. I'm pretty much out


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## Yad (Oct 19, 2009)

Spadez said:


> I now need to start looking into creating my 5 additional speakers for the mid-high frequencies to give me the 5.1 setup.
> 
> James


 I think, the ScanSpeak 18W8546 + SS R29 or Vifa XT25 will be good. But? unfortunately those tweeters are too narrow ...


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## Yad (Oct 19, 2009)

James, why did you choose so heavy driver with not big Bl to Mms ratio?


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## Spadez (Oct 14, 2009)

> James, why did you choose so heavy driver with not big Bl to Mms ratio?


Im not really sure what this means! If your refering to the subwoofer project, I am replicating another persons passive rad sub project which seems to give very good results. Ive already brought the subwoofers so its too late to change 



> I think, the ScanSpeak 18W8546 + SS R29 or Vifa XT25 will be good. But? unfortunately those tweeters are too narrow ...


The scanspeak speakers look very cool, what do you mean about the tweeters being too narrow? If you mean narrow in size, In which case, why is that a problem?



> After doing a bit of modeling none of these very small designs seem to lend themselves well to passive radiators, there is almost no advantage because no passive radiators are tuned high enough to actually help increase the volume in a range that matters for these small speakers. eg 70-80hz.
> 
> I figured a cube with an inside dimension of 5x5x5 would give you 125 cubic inches of internal space. a 4x4x4 cube would give you about 64 cubic inches. Anything less than 125-130 makes all the small speakers I modeled have a hump in the response between 100 and 250hz so the sound in that range would be over emphasized, everything higher or lower than that would sound thin. The frequency drops off very quickly below 100-150hz which would require that you run your subs high enough as to sound directional and no longer blend seamlessly.
> 
> A 5x5x5 cube built out of 1/2" mdf would be almost 6x6x6, and a 4x4x4 cube made out of 1/2" mdf would be almost 5x5x5 so these are all a bit larger than what you are wanting. You could build something this size or smaller, it would probably sound at least a bit better than what you have right now. But maybe not that much better, and will cost your time and money so its up to you to decide if you want to take a stab at it or not. The other thing to do is ask around on the other DIY audio forums like diyaudio forums, http://diyaudioprojects.com/Forum/, htguide diy forums and others and see if anybody else has any ideas. I'm pretty much out


Ive looked into my bose speakers a little more. My estimate was a bit off, the interal volume of the bose mini cubes is just *27 Cubic inches*. To my mind, these actually do sound very good but I do understand what you are saying about the gap between the high frequencies and the low, there isnt really any mid. I dont want to use the bose cubes anymore because I only have two and I want a 5.1 setup. It will end up costing a lot for the cubes.

In the interest of good sound quality im going to make the cubes a little bigger but im going to try and find a comprimise. Im going to set my target for *80 cubic inches*. Ill do this by enlarging the size and also using a different material like plywood (or even hardwood) rather than MDF to keep the thinckness down and ensure it is strong. It shouldnt resonate but if it does at these frequencies Ill play around with the weight to fix the problem. Im going to try and search the forum for a speaker which is optimised for this size box, or at least is designed to come with a smaller enclosure better.

I would also like to pitch this idea to you. What would it sound like if I went for this setup:

1x Sub
1x Small cube for front left [~80 CI]
1x Small cube for front right [~80 CI]
1x Larger box for front mid [~140 CI]
1x Larger box for back left [~125 CI]
1x Larger box for back right [~125 CI]

This way im still getting plenty of mid, but the sound from the front left and right will be slightly biased to the higher frequencies, but it will allow me to keep the space on my desk. Feel free to shoot this idea down if it is bad, it is just a possible solution.


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## Yad (Oct 19, 2009)

Spadez said:


> The scanspeak speakers look very cool, what do you mean about the tweeters being too narrow? If you mean narrow in size, In which case, why is that a problem?


I mean, they radiates too narrow directed soundfield. (sorry for my english)


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## Spadez (Oct 14, 2009)

Ah, I understand now.

EDIT: B&O have produced the speakers below. These are tiny and are said to have very good frequency responce and sound quality. How do they do it!? 

http://www.audiojunkies.com/blog/506/beolab-3-big-sound-small-size


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## Yad (Oct 19, 2009)

I was compared R29 & XT25 with other SS tweeters/ (9500 9700) some Seas exel tweeters... So, it seems to me that R29 & XT25 have less colouration & have good reaction. 6600 could also be a good choice. Morel MDT 33 - are good, but sounds similar with SS 9700


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## Yad (Oct 19, 2009)

to my ear, most dome tweeters sounds like to each other. My choice - ring radiators & True ribbons. They have the best BLM/Mms ratio. & light membranes with small number & level of their own resonances


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## Yad (Oct 19, 2009)

Spadez said:


> Ah, I understand now.
> 
> EDIT: B&O have produced the speakers below. These are tiny and are said to have very good frequency responce and sound quality. How do they do it!?
> 
> http://www.audiojunkies.com/blog/506/beolab-3-big-sound-small-size


Well... Such acoustic lens is good idea for making sound field wider. But, notice, that it increases demands for your listening room. 

The second thing - (IMHO)- that it's not necessary to use R29 for lens application. XT25 will be better idea. (it's much cheap & Lens will make it's own parameters)


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## Spadez (Oct 14, 2009)

Hi, thank you for tehe reply. Its benefit not only getting a wide sound field, but also a small container.

It is the small container I am most interested in. It looks like the XT25 is very nice, but it needs around 125 Cubic inches (i think?), but the B&O seems to need a lot less space.

This is what I want to achieve, as long as I can keep performance high.


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## Yad (Oct 19, 2009)

do you have a special idea to place it in your room design? or any demands to dimentions ? You can tell me. I'll think about it more specific.


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## Yad (Oct 19, 2009)

I have B&O catalog here. Let me see... aha BEOLAB 3 model dimentions: 16.2 x 13.5 x 22.3 centimeters. For example, XT25 diameter is 10.5 cm.


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## Spadez (Oct 14, 2009)

Unfortunatly my design is very constricted. My left and right channel speakers have to sit upon my desk, so the bigger my speakers are, the less space I will have on my desk and the less space there will be between me and the speaker.

Im suprised at how large the BEOLab3 is actually. In an ideal world I would like to have the left and right side speakers at around: 80 cubic inches. This could be in a formation of about 4.5x4.5x4.5 inch outer diamter. If I can get it any smaller and still have it sounding good then fantastic!

What cubic inch does the XT25 recommend?

EDIT: Also I can stuff the internal to help compensate for the small cubic inch size.


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## Yad (Oct 19, 2009)

Well, there is another choice. You may use coaxial 2 way drivers. It will be better at the small listening distance, that 2 separate drivers. 

It will sound not such detail and reference, like XT25+SS18W, but be sure - they ll give you perfect localization and phase response like "real point source". 

Look at this link: here is 5" coaxial www.madisound.com/catalog/product_info.php?products_id=8494 

here is data sheet with filter & possible construction :T You also could make a smaller box for it (!):
http://www.madisound.com/catalog/PDF/e0051-and-appl notes.pdf 

but this is good idea to. http://zaphaudio.com/audio-speaker18.html (i've seen this link above). But my audiophile's nature tells me about 2 problems: 1) Doppler distortion at hi-frequencies; and 2) this driver will not give a crystal-clear hi frequencies. (too heavy diffusor for HF)


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## Spadez (Oct 14, 2009)

Thank you for the link. Ive looked into it, but the recommended size of this box is 5Liters (305.050 Cubic Inches). This is huge compared with what im trying to do. Im trying to keep it small!


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## Yad (Oct 19, 2009)

I know... (but i did not know, how deep is a rabbit's hole :dontknow


well try this one: http://www.madisound.com/manufacturers/fountek/fullrange.php 

http://www.madisound.com/catalog/product_info.php?manufacturers_id=132&products_id=8585



it may operate with 1...1.5 liters of net. volume (closed box) with hard damping inside (wool or fiber-glass) .


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## Spadez (Oct 14, 2009)

Aha, thank you, now we are on to something! This looks very promising, especially this bit:



> 0.75 liter (46 cubic inches) sealed and stuffed for an F3 of 150Hz
> 
> 1.5 liter vented (92 cubic inches), stuffing, 1" diameter vent x 3" long, F3 90Hz


If I was to go for the 0.75L enclosure, would the F3 of 150Hz mesh well with my subwoofer or is this cutoff too high?


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## Spadez (Oct 14, 2009)

Ive also found this, it says it is good for 0.5 to 1 liter:

http://www.madisound.com/catalog/product_info.php?cPath=45_234_264&products_id=8593

How about if I went with one of those and a very small tweeter in each 0.75L enclosure?


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## Yad (Oct 19, 2009)

yes. good driver. But it is not necessary to use the tweeter here. Because you will not have a free volume inside the box to put the crossover. But if there is free to use extra volume 0.5-1L approx - you may try. 

Frankly speaking, i would advise you to try it without tweeter. Then you will make your own decision about "2-way or not 2-way"


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## Spadez (Oct 14, 2009)

Woo hoo!


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## Spadez (Oct 14, 2009)

Will the lower frequency end of the mid range posted above mesh well with the upper range of the sub im designing, or will there be a frequency gap or over emphised freqency range? Ill look into the tweeter thing a little more now.


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## Yad (Oct 19, 2009)

You should make crossover point as low as possible. 90Hz is much better than 150 There fore it's better to use larger volume that 've been recommended above


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## Spadez (Oct 14, 2009)

I think ive got around the tweeter problem, I think Ill mount the crossover in an external box which will sit under the table and conntent to the speakers.

Im going to have a go at modeling my first speaker to see how low I can get that driver in that given volume.


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## Yad (Oct 19, 2009)

ok. Try to find very small 20 mm-dome tweeter. Do you have the IKEA store nearby ?


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## Spadez (Oct 14, 2009)

About an hour away, why is that?


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## Yad (Oct 19, 2009)

http://www.ikea.com/ru/ru/catalog/products/20066660 
This is IKEA in russia. 

You may try to use this kitchen thing as acoustic lens for the tweeter (like B&O's)


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## Yad (Oct 19, 2009)

http://www.ikea.com/us/en/catalog/products/20066660 in the USA 

i mean to use a cone part of it )))))


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## Spadez (Oct 14, 2009)

Haha I love the idea of using a spoon to reflect the sound! Ive modelled the speaker for my enclosure. I wasnt able to put in all of the values as I couldnt find them, but most are there. If anyone is free, can they have a look at this file.


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## Yad (Oct 19, 2009)

oo-ops... :huh: what program do you use ? I have a mistake while opening


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## Spadez (Oct 14, 2009)

I used winisdalpha, is the file broken?


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## Yad (Oct 19, 2009)

no, it is not....just my software does not understand it (LEAP & LSPcad)


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## Spadez (Oct 14, 2009)

Oh. Well might you be able to model it in your program if I give you the spec?

Nominal impedance [ohm] 8 
Voice coil resistance [ohm] 5.5 
Nominal power [W] - 
Short term max power [W] - 
Long term max power [W] - 
Operating power [W] - 
Sensitivity [dB] 86 
Frequency range [kHz] 0.1-15 
Free air resonance [Hz] 81 
Voice coil diameter [mm] 20 
Voice coil height [mm] 5.1 
Air gap height [mm] 3.8 
Voice coil inductance [mH] 0.33 
Eff. diaphragm Area [cm²] 38 
Moving mass [g] 3.2 
Magnet weight [g]/[oz] 210/7.4 
Force factor [Bl] 3.8 
VAS [l] 2.5 
Qms 3.40 
Qes 0.60 
Qts 0.51


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## Yad (Oct 19, 2009)

ok. Specify the driver please.


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## Yad (Oct 19, 2009)

o, sorry. it's VIFA shown above ?


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## Spadez (Oct 14, 2009)

Hi,

Yes the vifa one on this page I think, since you said it is a good choice.

For enclosure size im looking at around 60-90CI


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## Yad (Oct 19, 2009)

data


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## Spadez (Oct 14, 2009)

Super, I dont fully undserstand the units in that picture, but ill look into it. Is your program able to plot this info on a graph with Hz to see what range the box would give it?

EDIT: Also I beleive that speaker is a mid range and not full range.


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## Yad (Oct 19, 2009)

this is model of "cubic" (LSP cad) 
well... you can see strong difraction (black line). blue - is half space response. 

It's better to make spherical box...


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## Spadez (Oct 14, 2009)

I cant see the graph with the black and blu line, am I missing something? 

A cube is a bad idea then I guess, Ill look into round ones. Is it important to have mid ranges pointing at you when you listen, can you point up at the ceiling for example?


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## Yad (Oct 19, 2009)

this is model of "cubic" (LSP cad) 
well... you can see strong difraction (black line). blue - is half space response. 

It's better to make spherical box... 

wow at least.... too much troubles while uploading ))))))))


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## Yad (Oct 19, 2009)

diffraction - re-reflections from the facets of front panel (usually it's called baffle step)


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## Spadez (Oct 14, 2009)

Wow. Thank you so much for all the good information! I will make a cylinder then since you said it gives better results. Is 1.28L the optimum inside volume based on your findings then?


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## Yad (Oct 19, 2009)

notice, cylinder is worth than cubic (((( sphere is the best! (use 2 half-square IKEA's dishes )) ) or you can make cubic with rounded facets (R10-R20 routed) and use soft carpet/wool to finish design of the box. 

1.1 -1,28 of net. liters range is OK. Closed box. 

smaller volume wil make "boom's - colouration" in sound )


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## Spadez (Oct 14, 2009)

Im not sure I can make a sphere without buying dishes from Ikea! 

If I go for rounded cubic, do I need to make the internal space rounded as well as the external facets for it to sound better?

Also when you say R10-20 routed, are you saying use a radius of 10-20mm?


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## Yad (Oct 19, 2009)

no. just external. internal shape is not so critical and does not cause difractoin. Anyway, you will use wool-fibered damping inside. 
Don't worry. ) 

yes, i mean Radius in mm. Bigger one - is more effective


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## Spadez (Oct 14, 2009)

Can you tell me one final thing. If I keep with the cube with rounded corners of 20mm, what effect does lowering the internal volume from 120 to say, 80 have? Is it a big difference or a very small change?


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## Yad (Oct 19, 2009)

oh, i forget to specify, that you should rout front panel (which carries a driver) at first. sides may be routed or may be not.


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## Yad (Oct 19, 2009)

Spadez said:


> Can you tell me one final thing. If I keep with the cube with rounded corners of 20mm, what effect does lowering the internal volume from 120 to say, 80 have? Is it a big difference or a very small change?


you have to keep net inside volume (without driver's magnet volume) not less than 1.1 liter. a material for your box is 12-14 mm for sides and 18-20 for front. driver is better to make flush mounted. Inside part of the hole is better to rout 10x10 (45 degree router bit) 

PS your dimensions may change a little (130x130 x ....) or like this


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## Spadez (Oct 14, 2009)

On the website it says it can be 0.75, is that bewcause it is stuffed, or will 0.75L just give very bad results?

Im a bit concerned, because now this speaker box is getting big again, maybe too big to be on my desk.

EDIT: Ive done a little mock up of the speaker size, and while its size is still bigger than I had hoped, if 1.1L will give me the best results then I will go for that.

EDIT2: Will this size box allow me to go down to around 90Hz?


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## Yad (Oct 19, 2009)

well, less volume will give you approx 150 Hz at lo end ; bigger-lower. And you may notice some rising of mid-bass frequencies. it s better to try 2 boxes.


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## Yad (Oct 19, 2009)

> Im a bit concerned, because now this speaker box is getting big again, maybe too big to be on my desk.


ok. try to do less.


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## Yad (Oct 19, 2009)

it will give you about 100 hz LF-end 

PS R10 routing will be ok.


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## Spadez (Oct 14, 2009)

1.1L internal will give me 100 hz LF-end? 

If so, that sounds pretty ideal. Im going to do with this.


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## Spadez (Oct 14, 2009)

A quick bump. How come people can design mids like this:

http://i32.photobucket.com/albums/d44/dlneubec/BaSSlines/DSCF0156-a.jpg

At the top, the speaker isnt even in an enclosure. What type of speaker is this and why wouldnt it work for my application?

EDIT: Dipole or open baffle it seems. When I was suggesting tiny mid speakers, how comes nobody suggested these to me? I could make these tiny


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## Yad (Oct 19, 2009)

This is open baffle. You may also call it "dipole", because driver radiates in to both sides with 180 degrees of phase difference (between front & rear sides). That's why it is also a problem. Lowest frequencies are canceling out. The lowest freq. that you can reach - is nearly F=340/d (F-freq. 340 (meters per second) - sound speed in air, d - is a 1/4** of the distance (in meters) between the middle of driver & edge of the baffle). So, for your 100 Hz at -6 db point you will need approx 3.4 x3.4 meters baffle. 

Furthermore, your driver in the open enclosure will not work properly at the lo end ('cause of it's Thiele-Small parameters) 


** sorry, i wrote 1/2 at first. if you will use the "1/2" coefficient, you should mean the width of your baffle.


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## Spadez (Oct 14, 2009)

Hi Yad,

Thank you for your reply. I just dont understand this, because you obviously know the maths behind this, but so many people seem to be building these small OB systems and they claim that their responces and frequencies are very good.

http://www.hometone.org/entry/jamo-s-new-r-907-open-baffle-speakers/

This one above doesnt have anywhere need 3.5m baffling and yet its specs are very good. Is there a way to get it working well, or these people lying about the performance of their speakers?


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## Yad (Oct 19, 2009)

Jamo R909 & other speakers have a specific LF drivers with very big square + very high sensitivity of them. Those speakers have very complicated networks. This is necessary to correct lo-end frequency response. And they also very demanding for listening room and your position. 

For small drivers 1 or 2 with 8-10 inch diameter it' impossible to realize it without deep electronic correction and loosing of the resulted SPL. For smaller drivers - this is impossible even with electronics. ... or you will loose more than 20 db (may be much more) of SPL while flattering the frequency response (( 

note, i gave you a true mathematics formula :nerd:


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## Yad (Oct 19, 2009)

I made a calculation for you. 
the - picture - is the 3D math. model of enclosure 1x1 meters sides. 
graphs are: 
green - SPL at 1-2 mm distance from the driver 
brown - resulted SPL at 1 meter or more 
black - is not interesting in this discussion 

don't worry about highs freq. the idea was just to show you LF. And I took not wide range 3" vifa driver (anyway, it does not matters in this example)


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## Yad (Oct 19, 2009)

Spadez said:


> ... or these people lying about the performance of their speakers?


It's not an a lie exactly. But they don't tell you some truthful details. It calls "the Marketing Tricks".


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## Spadez (Oct 14, 2009)

Yad, I hold my hands up to you, you clearly know a lot about speakers and you have given me loads of useful information, im not going to fight you on it anymore! If you feel that the best way to get good mid range performance in this size is to go for a 1.1L sealed container then I will do this.

I had a phone call with the people at madisound and the mentioned this driver is good for small space, is it worth looking at:

SB Acoustics SB12NRXS25-4


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## Yad (Oct 19, 2009)

Dear Spades, I did not fight with you ))) I'm just trying to help you.


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## Yad (Oct 19, 2009)

about the least driver. It seems to me, that it needs 2 way construction with volume that bigger, than 1 liter. Do you really need it ?


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## Spadez (Oct 14, 2009)

Hi Yad, its a figure of speech, I was only joking about fighting 

I was recommended that driver, so I thought I would mention it. If the one you suggested is better, I will use your suggesion.


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## Yad (Oct 19, 2009)

i know. my english is not so bad :bigsmile:


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## Yad (Oct 19, 2009)

This driver is pretty good, but look above


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## Yad (Oct 19, 2009)

Spadez said:


> A quick bump. How come people can design mids like this:
> 
> http://i32.photobucket.com/albums/d44/dlneubec/BaSSlines/DSCF0156-a.jpg
> 
> ...


Looks very interesting. I think, the LF-MF x-over point is about 300 -600 Hz. One interesting thing: OB application of midway driver allows you * to use lower order (6 db per oktave) cut off electrical filters. It is very good for impulse response and "group delay" factor. 

* because you will almost have an acoustical hi-pass filter.


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## Spadez (Oct 14, 2009)

> This driver is pretty good, but look above


Are you saying this one is better then?



> OB application of midway driver allows you * to use lower order (6 db per oktave) cut off electrical filters. It is very good for impulse response and "group delay" factor.


Does this mean that OB still isnt as good as a sealed box for the size requirement I have? So far, im assuming the driver posted in this post with a 1.1L sealed container is my only option for half decent sound at this size. Is this correct?


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## Yad (Oct 19, 2009)

>> Does this mean that OB still isnt as good as a sealed box for the size requirement I have? 

yes. Because you want th box size not much bigger than cube with 5-inch sides. For baffle (with every driver) dimensions could be counted as shown above. Even with 1 m baffle you ll have 10 dB loss @100Hz. 6 db point could be reached with 3.4 m sides. (note, i mean the result without deep electronic correction)


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## Yad (Oct 19, 2009)

I'm sure - the closed box with good wool damping inside - is the best choice for your application. 

OB - is good think, but it does not fits everywhere. But i forgot one interesting application. If you have walls made of hyproc (walls with cavities inside) you also could use them as Infinite baffle (Likely OB, but not dipole). Use usual car-installation drivers and mount them directly in to the wall. Or you may use your chosen drivers anyway. But for such installation the Qts driver-factor should be not less than 0.7 (but not more than 0.9..1)


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## Spadez (Oct 14, 2009)

Ok, I'll go with that then. The vifa driver is the best too?
_Posted via Mobile Device_


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## Yad (Oct 19, 2009)

all of them are good. Frankly speaking, I'm not the brand-fanatic ))) You just only should know, what do you want from the driver & the speaker : dimensions/design/frequency range/clarity & details in sound/ or may be wide angle of sound field/ or maybe high Sound Pressure Level/ or only the price matters ///. 

I'm only able to decide an engineering part of your task. 

The bigger driver needs larger volume. That's physics.


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## Spadez (Oct 14, 2009)

The trouble is I dont understand the specs, I just assume the Vifa is the best midrange for my budget based on the information youve given me 

I dont mind about the price, the size is the most important to me and so is the ability to go down to 80Hz, but I dont care how high it can go because I will have tweeters.


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## Yad (Oct 19, 2009)

that "small" VIFA is OK. If you'll have the lack of HF - you could use small tweeter with acoustic lens


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## Spadez (Oct 14, 2009)

When you say its "ok" you make it sound like there is something better though?


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## Yad (Oct 19, 2009)

mmm ... this is one of the best possible drivers for your extra-small-sized application ...


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## Spadez (Oct 14, 2009)

Ok, great. I think they stop making them soon so I will order them. Two more questions:

1. Does it matter if I point the mid at the ceiling, is it much better to point right at you
2. If I made the design into a rectangle instead of a square design, would this affect the sound?


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## Yad (Oct 19, 2009)

I think, yo better show your picture (drawn by hand) here. I'll model it & will show results for you.


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## Yad (Oct 19, 2009)

everything does affect the sound. But If somebody will think about all of that factors without exception - he could become crazy ))))) 

but there are myths also. For example the direction of the wire :unbelievable:


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## Spadez (Oct 14, 2009)

These are the three im looking at:

*1. Cylinder*
ID Diameter: 6.5"
ID Height: 2"
Volume: 1.088Liters

*1.Cube*
ID Width: 4"
ID Height: 4"
ID Depth: 4"
Volume: 1.049Liters

*1.Box*
ID Width: 5"
ID Height: 6.5"
ID Depth: 2"
Volume: 1.049Liters

I think the cylinder design would be very nice, but you said cylinder is sometimes not so good. The box design is good because it takes up little sufrace area on my desk, but again, may not soind as good.


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## Yad (Oct 19, 2009)

well... the cube is better. Are these dimensions are internal ? 
Yes the cylinder will have the worth frequency response.


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## Yad (Oct 19, 2009)

the model is at the 49-th post of this thread.


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## Spadez (Oct 14, 2009)

Hi,

Yes all of those dimensions are internal. Is it possible to model the other two designs. I know the cube may come out best, but this design is also the worst out of the three for my desk space. I would like to know how big the difference is if possible.


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## Yad (Oct 19, 2009)

Frequency range would be the same. But the difference will be in fluctuations of the FR curve. 
I found one picture for you. I think, it would be interesting for everybody. This picture shows the difference of diffraction distortion between different cabinet shapes.


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## Yad (Oct 19, 2009)

According to this picture you can notice the difference and make a decision by yourself.


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## Mike P. (Apr 6, 2007)

Yad, what program is that?


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## Yad (Oct 19, 2009)

what program do you mean, Mike ? The picture shown at the 92-nd post - was taken from the book.


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## mayhem13 (Feb 2, 2008)

WhilIe the idea and the thread are interesting in it's goals, truthfully there is little to be gained here over your current bose setup as LF extension is limited in such a small space with current driver technology.....small radiating area=poor LF extension....Not my opinion, but Newton's and the other physicists. I applaud your inspirations, but don't expect too much from this type of speaker. If space is the issue, In walls would be a better approach of which many are available commercially on the cheap.


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## Yad (Oct 19, 2009)

yep. it's true... 

some 3-inch drivers are able to give flat frequency response till to 100 Hz at the lo end, but no one will never give you a big total SPL level in it's full range (as 8" for example). That's physics : "The sound pressure level is proportional to diffusor's square & diffusor's displacement... and it's acceleration"

But it seems to me, Spades have some specific design boundaries (limits)...


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## Yad (Oct 19, 2009)

Hi everybody. I found some links about Open Enclosure (Open Baffle) and Infinite Baffle. 

http://en.wikipedia.org/wiki/Loudspe...nfinite_baffle 

http://www.diysubwoofers.org/ 

http://www.troelsgravesen.dk/OBS.htm


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## Spadez (Oct 14, 2009)

Yad. Im sorry I havent been on here recently, but your links are really useful, especially the troelsgravesen one, ive got some reading to do!

Can I assume that I cant get around these size issues by using more speakers in a container, which each having only a small dedicated range, instead of trying to get one speaker to do the whole shibang?


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