# Open Baffle



## Bob in St. Louis

Hey Guys.

Due to some interest regarding my "speakers with no boxes", I thought I'd take this opportunity to tell you a little about Open Baffle, or "OB".
I'm no expert, so my knowledge is based strickly "on my own little world", so I'll do my best to explain the ins and outs of OB.
I had heard a few respected forum members (on other forums) talk about OB, with high regard. I had no idea what they were talking about until they started posting pictures of these wierd looking (unfinished looking) speaker designs. They talked about how incredible the sound was, how open, clean, and clear it appeared. The 'soundstage', and 'imaging' were one of the best they had ever heard, even compaired to some _VERY_ high dollar speakers. A guy that has little to no wood working experience could design and implement OB in his room for very little money. Sounded good to me. I took the bait. 
I tried it out with some drivers that I had been listening to for a few years in their factory, plastic boxes.
Removing the drivers and installing them in some scrap MDF I had laying around took very little time. Most of the time spent was disassembling my speakers and removing the 4" and 1" drivers and the crossover ("XO") being careful not to damage anything in case the project didn't work, I could put it all back together like it never happened. 
I was astounded at the clarity I heard. The speakers sounded better than they had ever sounded before, and this was with no adjustments to the receivers setting at all. All I was missing was some bass. 

==============PICTURE OF 1ST OB==========








I listened for a few weeks to my new discovery, all the while saving money "for the real thing".
I purchaced a pair of 15" Hawthorne Audio Silver Iris Coaxials that were specifically designed for OB use. Without being too technical, the "Q" of the driver is the key for use in OB. The 4" drivers I had experimented with were an unknown "Q" value, but it's safe to say they were most likely "unfit" for use in OB. Excited at the prospect of what the correct driver would sound like, I waited patiently for the delivery of the new drivers.

==============Link to HAWTHORNE==========
Hawthorneaudio.com
The drivers came, and with "youthful enthusiasm" I set them on their delivery boxes, propped up and aimed at my listening position. It was truely a religious experience. 
It changed my expectaions of what audio should sould like. It really raised "the bar". Next up.....Make some baffles.

==============The EVOLUTION==============








From right to left, you can see my original speakers, the drivers from the original speakers mounted OB, the Hawthorne Coaxials on the box, then the Hawthorne Coaxials in the "first generation baffle".
Now we're getting somewhere. The flexability of OB is unlike anything I've ever heard. The size and shape of the baffle is totally flexable. No rules. A few guidlines, things to keep in mind, but no rules. A fellow would have to work pretty hard to do it wrong. Use your imagination on baffle design, then make it. That's it. Some folks are even mounting the driver by it's magnet, supporting it totally by the magnet, then placing various experimental baffles in front of, but not touching, the driver to see if it makes a sonic difference. Amazing flexability. Powered by a dedicated multi channel receiver, the Harman Kardon AVR 645, the Coaxials will take the 90 watts per channel with ease. A match made in heaven. The 15" drivers have never reached XMas (maximun cone excursion --- "Death for a driver").
After listening to them in their baffles, I decided I wasn't quite ready to stop experimenting, so...I chose to have them mounted on a post with no baffle, or "baffleless", just like a stop sign. In the picture, you'll see the crossover attached to the back of the post.

==============The COAXIAL "STOP SIGN"=====








The manufacturer of the coaxial drivers also has an "Augie", the affectionate name given to the bass augmenting driver. You see, the biggest drawback to OB is the lack of bass. With no box reinforcing the bass, it gets lost. The upside however is a substantial gain, CLARITY. Without the boomyness/muddyness of the box, the sound is much more clear. Very "Open". Depending on your system, baffle size and shape, and mostly, your goals regarding your system, some folks might be finished here. The Home Theater type of fellow won't stop here though. We NEED more bass right? RIGHT!
After listening to the Coaxial for several weeks, I decided to purchace the 15" Hawthorne Audio Silver Iris Augies.

==============PIC OF AUGIE===============








Just to throw some numbers off the top of my head, if the Coaxial does 75% of the audio spectrum, the Augie fills in the rest. Powered by a $100 plate amp from Parts Express, now I'm finished. I've got enough bass to fill a large room with satisfying sound that runs the full spectrum of 99% of the music that exists. Fans on all genres of music are completely satisfied, everyone is happy with the exception of the most Die Hard,...Hard core fans of Rap, Techno, Or Pipe Organ. NOW we can stop, right? Maybe.......
Unless of course your a DEDICATED HOME THEATER, LUNATIC, "OFF THE DEEP END", DRYWALL CRACKING, BASS PHYSCO NUT (like me)!! (that's another story)

That's my OB rig. I'm very VERY happy with my system as it sits right now. 
That doesn't mean of course that I'm finished, are we ever....truly....finished? 

=============THE SYSTEM================








--Sorry, that one's a little dark--

BOB


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## Sonnie

Interesting stuff Bob... thanks!

What I would like to see are some REW measurements. If you get the opportunity to tinker with REW some and can take some measurements, that would be great... you can post the graphs for us.


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## Bob in St. Louis

Sonnie, I think I know what REW _"IS"_, but I know it by a different name possibly?
If your talking about 'in room SPL/DB numbers', I have played with graphing a few, but the verdict is still out on how to properly measure dipoles/OB's, or even whether they _CAN_ be accurately measured. That's an area I have very limited experience in, and am getting contradicting opinions on.

Bob


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## Sonnie

Room EQ Wizard ... available here at the Shack for free!

Anything can be fairly accurately measured if you have an SPL meter with a line out or a good calibrated mic. 

You can take nearfield measurements and measurements from your listening position as well.


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## Prof.

Very interesting Bob...So the 15" Silver Iris speaker has a different Q factor compared to your average 15" Woofer? 
Looking at the specs for that driver, the Q factor (Qt.) does seem to be considerably lower than speakers of similar size. This would explain why it can be mounted to an OB..

You mention that you don't get strong deep bass, just a very clean sound.. I would suggest that the reason for this is the size of the baffle...I think (as I mentioned earlier) you would need a much bigger baffle to get the deeper bass, but I realize that this is not practical.
The reason for the bigger baffle is to prevent the front wave interacting with the rear wave of the speaker. Obviously the lower Q factor helps this to some degree..

I noticed on their web site, they suggested also using these speakers in an Infinite Baffle system..
IB's are all the rage at the moment and anyone considering making up an IB would find these speakers ideal for that application..

I take it that your using your "stop sign" speakers as your left and right mid/highs in the theatre setup, with the OB's as the bass speakers?
Your centre speaker appears to be a standard box type speaker...Do the two different types blend in together to give a constant sound stage?


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## Bob in St. Louis

Prof. said:


> Very interesting Bob...So the 15" Silver Iris speaker has a different Q factor compared to your average 15" Woofer?
> Looking at the specs for that driver, the Q factor (Qt.) does seem to be considerably lower than speakers of similar size. This would explain why it can be mounted to an OB..


Yes prof. 100% true.



> You mention that you don't get strong deep bass, just a very clean sound.. I would suggest that the reason for this is the size of the baffle...I think (as I mentioned earlier) you would need a much bigger baffle to get the deeper bass, but I realize that this is not practical.
> The reason for the bigger baffle is to prevent the front wave interacting with the rear wave of the speaker. Obviously the lower Q factor helps this to some degree..


"_Good strong deep bass_",... Subjective description at best. The Coaxial and Augie combination will handle the bass in the vast majority of music. It's when a fellow wants to get a bit 'carried away',...shall we say...with the bass, that he would need "more". I've listened to the (4) fifteens very loud with some tracks that have pretty low bass, and didn't feel like I was lacking. Only when I want to make my eyeballs vibrate is when the Housewrecker comes out to play.



> I noticed on their web site, they suggested also using these speakers in an Infinite Baffle system..
> IB's are all the rage at the moment and anyone considering making up an IB would find these speakers ideal for that application..


The Hawthornes are experimenting with an 18" IB rig, but it is not in production at this time.



> I take it that your using your "stop sign" speakers as your left and right mid/highs in the theatre setup, with the OB's as the bass speakers?


Yes


> Your centre speaker appears to be a standard box type speaker...Do the two different types blend in together to give a constant sound stage?


NO. The center doesn't come out to play very often any more. With the introduction of OB, I just haven't been able to improve on it's soundstage with the use of a center channel. (I'll bet that raised an eyebrow or two somewhere.)

Sonnie, I like the look of the REW, I'll check that out.

Bob


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## SteveCallas

Bob, I also live in St. Louis - might you be willing to allow me a listen? I'm one of those fellows who likes to get a bit carried away with the bass aspect :cunning: , but as of late have been in long talks with a friend trying to find and build the ultimate DIY speakers. He's heard the popular designs from htguide - Modula MT, RS 3-ways, Arvo dipole - and wasn't very impressed. He just heard a large planar/ribbon array setup and that didn't do anything for him either. I'm thinking a quality line array might be the only solution, but I'd love to hear your speakers if possible. 

One thing I always wonder about dipoles or OB (and never really get an answer to) is how the rear wave reflections are controlled. The rear wave is gonna reflect off your front wall and come back at you without being significantly reduced in magnitude. Is this addressed?


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## Bob in St. Louis

Hey Steve, Controlling the rear wave can happen in a few different ways. If you think of the rear wave as being produced by another driver (just facing backwards), that may help you get "a visual" on what's happening. One way is by driver placement, angle, tilt, toe ect... We all know those angles can effect the direction of the front wave, but it changes what the rear wave does by bouncing it differently off the front and side walls and the floor. Another way is to use "wings", or side baffles. The extreme is to have a "U" or "H" shaped baffle with stuffing in the "crotch". The 'pro' to these, is more bass (confining the rear wave), but the possible 'con' is that it might adversly effect the overall soundstage/imaging. I have not messed with any side wings, so I'm not the right person to tell you about wings, "U"'s, or "H"'s. A less extreme wing than a 90 degree angle would be a 5-20 degree side wing, from a few inches, to a few feet wide. Some guys have build baffles for smaller full range drivers and mounted them on a front baffle that's 4' X 4', and have side wings that add another 2' to each side. Kinda ugly if you ask me, to have a couple entire sheets of MDF/Plywood in your room. Some guys will put hinges on the side wings for the ultimate in tweekability, but hinges tend to rattle from what I understand. One, quick, cheap and easy method of testing/experimenting with side baffles is to duct tape large thick cardboard wings on. They can be shortened, cut and altered very easily giving you pretty much instant results as to any audible changes it made. Then when your happy, you can make 'real' wings and permanently attach them.

The material your front wall would have a large effect to what happens to the rear wave before it gets to you. Absortion, diffusion, and varying materials are also one way to change the wave. The only experimenting I've done in this regard is to take several outdoor patio furniture cushions and line the rear wall (below the screen) and a few on each side of the side walls. It was an informal test to see if it made any major changes, no SPL/graphing done, no direct A/B test, just simply listened for a few days to see what happens. It ultimately didn't seem to make much difference (possibly due to a lack of absorber hieght??), but it IS an experiment I want to do again, just a little more scientific this time.

Since My Coaxials have no baffle whatsoever, I have a harder time playing with wings. my prefered method of changing things (imaging/soundstage, timing, ect...) is by placement of the drivers. it's amazing what major audible changes can be had by small driver placement changes. My "playground", as I like to call it, is 12'X10' (about 10') before the room open up into the "L" shape. So they have plenty of room to move around. When I get 'bored' with the sound, I move a pair of drivers around. Closer or further from the front wall, closer or further from the side walls. I've even taken the Augie baffles and set them side by side in the middle of the room, kind of like a two driver bass array.

Steve, I hope I've answered your question, and have not been added to the list of guys "not really giving you an answer". Once again, my OB impressions are from my own little world. Much more experimentation in my future. Nothing OB is written in stone.

I'll chat with the wife about a visit. She's a little hypersensitive/paranoid about visitors that she hasn't met yet.:sarcastic: She's given the ok for the guys she met at the last "Decfest" in Peroria IL.

Bob


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## BoomieMCT

A few questions, if you don't mind.

What would you guess is the frequency range of just the mains (no auggies)?

Is there a coaxial tweeter hidden in there? I sure can't see one!


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## SteveCallas

> Steve, I hope I've answered your question, and have not been added to the list of guys "not really giving you an answer".


You answered my question, but I still can't see even a combination of those things reducing the magnitude of the rear wave enough to not interefere with the front waves trying to reach your ears first. I'll take your word until I hear some myself though.

If it helps convince your wife any, show her the attached picture of my 7' tall sub to let her know I am also an audio nut. Wait, did I just hurt my chances? :scratch: :R


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## Chrisbee

I played with open baffles back in the 60s with 10" drivers. There was already considerable literature on the subject going back well before the 1950s.

I'm truly shocked at how small your baffles are despite the size of your drivers. 

You are getting very severe bass cancellation using baffles as small as these.

Run REW using an RS SPL meter at the listening position at ear height. 

REW isn't subjective like human listeners. Nor does it care which alignment you are using. Nor the size of your baffles. Prepare for a shock!

You ought to have your drivers off center in the vertical and horizontal planes to spread the cancellation effects more evenly. 

You can use shallow side panels at the rear of a baffle to increase the effective baffle size without increasing the visual aspect. This should not lead to colo(u)ration if the back panels are kept reasonably shallow or even mitered to slope away from the baffle to avoid parallel boundary resonances.


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## BoomieMCT

I was reading the "Loudspeaker Design Cookbook" a few weeks back. They have a whole section on the effects of baffles with some test data (I believe using a 4" full range driver in a sealed box). Interesting stuff. 

If I remember correctly there was a big difference in the bass response between an infinite (very large) baffle and no baffle but the difference between minimal baffle and the very large one was minimal. I'll look up the page numbers when I get home.

That being said, I'd also like to see any test results you got from using your different baffles (assumig you kept them).


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## Bob in St. Louis

Hello Boom.
The FR of just the Coaxial is going to depend on overall bafflesize/area. My low end, being with no baffle whatsoever, is on the 'high' side. But 45Hz with a resonable sized baffle isn't unheard of.

Regarding the construction of the Coaxial, it has a tweeter with it's very own magnet. The magnet actually screws into the larger magnet of the 15" driver. The hole in the center of the big magnet is about 1 1/4" in diameter. Very cool design actually. Check out this picture again, see the two magnets?
The smaller one in the rear is the one that unscrews:








I used this to my advantage for the mount. I used a piece of metal that is 3" X 6", bent it in half, and used a hole saw to make a hole slightly larger than the threads. I attached the "L" bracket to the post, screw the magnets together with the "L" bracket in between, and _BAM_, instant "baffless stop sign". :bigsmile: (AND, NO RATTLES!!)

Bob

EDIT: By the way, DON'T copy the baffleless Augie design. It didn't work _AT ALL_.... DUH!


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## SteveCallas

How about headroom? The lack of a baffle would be knocking sensitivity down what, maybe 3-6db?


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## Chrisbee

SteveCallas said:


> How about headroom? The lack of a baffle would be knocking sensitivity down what, maybe 3-6db?


You should ask: What is the sensitivity at a particular frequency? 

Here's something I found on the subject: 

http://www.tolvan.com/edge/help.htm


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## Bob in St. Louis

WOW, you guys are quick, Three replies while I typed that last responce.
(Sometime it takes me a few hours to type a short post while I'm here at work).
Let me see if I can get all those answers:

Steve, I've known about your sub for quite a while. I stumbled on that AVS pic months ago, Jeez man, that things cool. I _ALMOST_ PM'd you for the blueprints. I don't think she'd be impressed though. She likes nice heavy bass during a movie, but she isn't a bass monster like some of us. 
She says mine is "big enough"....is it ever big enough?.......
I just let myself wide open on that one, didn't I? :nono: :joke: 
I've read some of your lenthier posts, you are over my head on some of that. I was struggling to give you an intelligent answer. Regarding magnitude, I can't help on that one. I've reached the end of my "knowledge rope".

Chrisbee,


> You are getting very severe bass cancellation using baffles as small as these.


True, very true. However, I've got plenty of other drivers to 'uncancel' that cancelation, ha ha.



> Run REW using an RS SPL meter at the listening position at ear height.


I've not downloaded REW yet, however I did run a few FR graphs with a digital R.S. SPL meter.
The general concensus, is that regarding OB, there _IS_ no general concensus on how to properly graph FR in a room. Too many inaccuracies. I'm game though.....



> You ought to have your drivers off center in the vertical and horizontal planes to spread the cancellation effects more evenly.


Widely spread theories on that one too. Some guys will "go to thier grave" saying it doesn't matter, some say the opposite......
That's one of the MANY projects I have in mind, once I'm finished spending money on equipment.:spend: 



> You can use shallow side panels at the rear of a baffle to increase the effective baffle size without increasing the visual aspect. This should not lead to colo(u)ration if the back panels are kept reasonably shallow or even mitered to slope away from the baffle to avoid parallel boundary resonances.


Yea, I've thought about that. A "_Rear wave guide_",so to speak, like a bowl bolted to the back of the driver.

Boom, Yea, I've got a couple graphs. one was my first FR graph EVER! The second one was a "no-holes-barred" blast fest. not at max SPL, I set a baseline (pink noise), which was 20 DB (I think) higher than the first graph. But it was with the Housewrecker on full, Augies on full, Coaxials, everything....Bass boost, the whole nine yards (just not max SPL), just to see what the graph would look like.
basically I was playing around until I could get a goos answer on how to properly graph a OB rig, escpecially one with four drivers).
Far be it from me to argue with the folks at Loudspeaker Design, (THEY'RE MUCH but I've heard of too many people say too many things about baffle size effecting output. I, myself tried a baffleless Augie,....didn't work,...at all.

Bob


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## SteveCallas

Ok, forget the design questions - would you say they are the best speakers you've heard?


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## BoomieMCT

BoomieMCT said:


> I was reading the "Loudspeaker Design Cookbook" a few weeks back. They have a whole section on the effects of baffles with some test data (I believe using a 4" full range driver in a sealed box). Interesting stuff.
> 
> If I remember correctly there was a big difference in the bass response between an infinite (very large) baffle and no baffle but the difference between minimal baffle and the very large one was minimal. I'll look up the page numbers when I get home.
> 
> That being said, I'd also like to see any test results you got from using your different baffles (assumig you kept them).



I have my sources to cite now. I have the 7th edition of the Cookbook. For the theoretical case look on page 135, figure 6.127. For the tested case (using 3" full range Tang Band drivers) check out page 139, figure 143 and page 142 (case #2). In both cases the large baffle did have more bass response (3-5 dB @ 500 - 1000 Hz in the real case) but the subjective results noted more detail and imaging in the small baffle case. I wonder if a small baffle is better if you have a sub (or auggies) to take up the slack down low?


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## Bob in St. Louis

BoomieMCT said:


> but the subjective results noted more detail and imaging in the small baffle case. I wonder if a small baffle is better if you have a sub (or auggies) to take up the slack down low?


YES, AMEN BROTHER :T 
That's what I'm talkin' 'bout!!
"....NAIL ON THE HEAD!"
So, you gain detail at the cost of a little bass. So what, let's get some Augies and cross them higher.
_NOW_ we're covered.
If I was only able to have two drivers in my room I'd have two of these Coaxials on some very small baffles. Detail man. I can only 'get off' on the stupid low Hz bass for so long. Then it all comes back down to clarity, openness, detail, soundstage, imaging. I don't care what kind of music you listen to, you'll always hear more with detail and clarity than with bass. My drivers are "worst case senario" for reproduction of bass (having NO baffle), I'll take what I've got over anything else, anyday.
For a little over $300, they can't be beat.

Steve, A bottom line, no B.S. kinda' guy. I like that. End the 'fluff'. End the small talk.


> would you say they are the best speakers you've heard?


*YES* PERIOD.

Do I have as much experience as you?:.............NO
Have I heard as many systems as you?:............I doubt it
Does the system impress me?:.........................YES
Does it impress my "Non-audiophile" friends?:......YES
Would it impress you, in it's current state?:........Hmmm?
In it's current state, to be honest, I'd rather have some "final adjustment, tweek time" first.
Do I think the system has the potential to impress you?: YES


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## Prof.

Bob, I take it that this "Housewrecker" unit is your sub, which would augment your front OB's?
Is that an OB also? From the photo (unless you have more to finish it) it appears to be a type of OB , in possibly a "push pull" configuration..Is this the case, or am I misreading it?


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## SteveCallas

> Do I think the system has the potential to impress you?: YES


Well if the wife ever warms up to the idea, just send me a PM :T


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## Bob in St. Louis

Steve, Absolutely. Hey, Did you come to Decfest this year?

prof. No the Housewrecker (HW) is not an OB. It was a 6th order bandpass enclosure that you could install one, two, three or four drivers in. Pretty cool design. Originally designed by Steve Deckert, it has been modded from it's original design. It's been made a little more "one notey" than it used to be, but it thumps pretty good. I do NOT used it for music anymore, movie LFE's only.
The only pic I've got that you can see it finished, it's crammed back in the corner behind the 'tree'.
http://home-and-garden.webshots.com/photo/2699988420085868784oZxgUr

Bob


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## BoomieMCT

Prof. said:


> Bob, I take it that this "Housewrecker" unit is your sub, which would augment your front OB's?
> Is that an OB also? From the photo (unless you have more to finish it) it appears to be a type of OB , in possibly a "push pull" configuration..Is this the case, or am I misreading it?


The Housewrecker is a BIG 7th order bandpass sub designed by Decware.

EDIT: Man - Bob answered this while I was answering it! Ths is a popular thread!


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## Chrisbee

I built a couple of 6th order series bandpass subs using 10" SEAS woofers.

Flat from 120Hz down to 20Hz with slightly over 100dB capability in ~20" cubes.

They still had output below 15Hz. Superb on organ and well recorded percussion.

Designed to match Linn Kans and LS3/5as by David Purton.

He has a small Coupled Cavity Handbook for about £5 available from the UK's main hifi drivers/kits sales companies like Wilmslow Audio. Unfortunately Falcon Audio seems to be closing.

The booklet has a whole list of dimensioned bandpass designs using both hifi and pro drivers and their expected responses.


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## Bob in St. Louis

Chrisbee said:


> Flat from 120Hz down to 20Hz with slightly over 100dB capability in ~20" cubes.


Nice. Very nice. And much easier to move around comparied to a sheet and a half of 3/4" MDF with two 15's stuffed inside. 

So, anybody else try Open Baffle?????

Bob


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## SteveCallas

Can you use multiple drivers in an array, or is it best to stick to a single point source?


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## Bob in St. Louis

Steve, the only guy I know of that has done an array of Hawthorne products in a very knowledgeable guy in Costa Rica. You may have heard of him, "JohninCR" as he goes by in most forums.
Here's his latest project:
If memory serves, he's using one Coaxial, two Augies, and two Warriors (all 15"ers) per side. Kind of a WMTMW.
Here:
http://www.hawthorneaudio.com/forum/viewtopic.php?t=493&start=0

Bob


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## scott

hey bob.......i found a site that really helped me understand OB a little more and was wondering if you have seen linkwitz lab? or labs maybe.


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## Bob in St. Louis

Yes I have Scott, he's got some very good information there. I've not spent as much time there as I 'd like too. LOADS of information!!:T 

Bob


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## Prof.

Thanks Bob and Boom...
Well it just goes to show...you're never too old to learn...
I've never heard of such a system..

Bob, I saw that photo but couldn't make it out..Any chance of a better pic?..


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## Bob in St. Louis

Prof. said:


> Bob, I saw that photo but couldn't make it out..Any chance of a better pic?..


No problem prof.
(you are talking about the pic of the "twin magnets" on the Coaxials right?)
If so, I'll take mine apart and snap a picture or two for you.

Bob


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## Prof.

It's the finished cabinet of the Housewrecker that I would like to see...If that's the one that has the two drivers back to back..


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## Bob in St. Louis

Well prof, I can't take a picture of a "cut-out" side view, since the drivers are stacked (clamshelled) inside a glued together enclosure. I found the best drawing of a HW (lifted off the Decware site). It's not completely accurate since mine is modded.
Here's the picture:








Now, to get what I've got: 
Take the two bottom drivers out.
Block off one lower port.
Install 14" of PVC pipe in the other lower port.
Remove the top tube (but leave the hole).
Flip it upsidedown.
Build a "stand" with a large hole in the middle, rased off the floor about 5".

That's about all I did.
The four sides are now glued together, so I'll never be able to install drivers in the center chamber, but they can still be clamshelled, and installed in the upper or lower chamber.

Bob


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## Bob in St. Louis

I'll take a pic of the outside for you and post it tomorrow.

Bob


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## Bob in St. Louis

Here you go prof, kind of plain and ugly.









Bob


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## SteveCallas

> Steve, the only guy I know of that has done an array of Hawthorne products in a very knowledgeable guy in Costa Rica. You may have heard of him, "JohninCR" as he goes by in most forums.
> Here's his latest project:


Are there any that use no baffle like yours, but more than one driver? Like a tweeter at ear level, midrange, and woofer, no baffle on any, with their dust caps aligned, and supported in a fashion similar to yours. You've got me really wanting to hear your project - I could bring my Ascend 340s that I use for surrounds over to compare as some type of a baseline.


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## BoomieMCT

How picky are these drivers with regards to location in the room?


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## Bob in St. Louis

Steve, I know of no one that is using a baffleless array. Sounds like a cool idea.

boom, "_Picky_",...ummm No. i wouldn't say "Picky". I'd say "flexible". :bigsmile: 
Big audible changes can be had by small placement changes. If I feel like I'm wanting a "new sound", I can change thier relative distance from me/rear wall, or distance from each other, or by changing toe/tilt.

NEW DEVELOPMENT:

A buddy of mine is in the middle of purchacing a new house. He's "put me in charge" of designing, building, and purchacing equipment for the home theater he wants. A fellow on the Hawthorne forum was selling the Hawthorne "Duets" (since he found someone selling his 'dream' system that had been discontinued).
So my friend bought them and had them shipped to my house. He won't be ready to take them to his new house for, possibly, a few months. 
Now I've got "the real deal"....Darrel Hawthornes flagship speaker system _AND_ my drivers, which are the exact same drivers found in the "Duets".:jump: 

I'll let you know how they sound.

Bob


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## Prof.

Bob in St. Louis said:


> Here you go prof, kind of plain and ugly.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Bob


Thanks very much for the photo Bob...Looking at all the pics, It appears to be just a big, down-firing. push/pull, passive subwoofer..
My earlier subwoofer was a passive push/pull type..only smaller..and I always loved the tightness of the bass..It just didn't have the extension that I get now with the active sub..

I had a good read through the Decware site and forum and found it very interesting..
I was amazed at how versatile this system is..
In the same size box you can have between 1 and 4 speakers, in any number of configurations..You can even use relatively cheap speakers ( which appeals to me) and still get good strong bass.
You can even scale the box down and use smaller bass drivers...and from the drawings posted,and your pics, it would be very easy to build...
One thing I didn't see was any info about port sizes..I would imagine that this would be the critical aspect to the design..and would be dependant on the specs. of the speakers being used..

I can see a new project on the horizon!!!


----------



## Bob in St. Louis

Yea, the gentilemans agreement on the Decware site is not to give exact measurements regarding Steves products. The plans cost $10. I took the plunge and was very happy. I think you can pay $20 and have access to the plans for ALL DECWARE SUBS!! Iwas stupid at the time and paid $10 for just the HW plans..:duh: 
By the way, it isn't "ALL" down firing, most is out of the top port, of course mine is upside down. 

Bob


----------



## Prof.

When you've put your money down, do they give you access through the Decware site, or do they post them to you?


----------



## Bob in St. Louis

It's access to the site, then you can "print screen". If I remember correctly, it gives you an 'authorization number', I believe you can continue to use it in the future.
If I had it to do all over again, I'd have paid the larger amount for access too ALL speaker plans, print them all out at the same time, and create a file folder for future referance.

Bob


----------



## Prof.

Ok..Thanks Bob..


----------



## Bob in St. Louis

Steve, I just noticed I've neglected to respond to part of your post regarding the Ascend 340s. I'd love the opportunity to hear other folks gear. 
This weekend is out for sure, have to work :sarcastic: still haven't talked to the wife yet either.
Steve, did you go to Decfest this past October?

prof, You're welcome!

Bob


----------



## SteveCallas

> Steve, did you go to Decfest this past October?


No, I don't know what that is.



> Steve, I just noticed I've neglected to respond to part of your post regarding the Ascend 340s. I'd love the opportunity to hear other folks gear.


340s would work well because:

1) They fit in my car much easier than the VR3s :R 
2) Lots of people have them
3) They are a good example of midlevel speakers


----------



## Peter De Smidt

There's a nice review at : http://www.tnt-audio.com/casse/ha_si_part1_e.html Nick does a second review adding the bass only woofer. I really wish that I could hear one of these system, as they seem fun and affordable. Anyone have one that lives near Wisconsin?


----------



## Bob in St. Louis

Steve C., Decware is the name of the site/forum of Steve Deckert. Among many other things he designs and makes, he's the creator of the Housewrecker. Decfest, as it's called, is an annual 'get-together' of audiophiles. Good bunch of guys. My wife went with me last October, and was suprised to see that these "guys on the internet" aren't a bunch of axe murdering rapists after all.:yes: :rofl2: 

Main site: http://decware.com/

He's just North East of us in Peoria IL.

Thanks for the link Peter. Nick also links to Decware (But he calls it Decaware).

Bob


----------



## Zene

Bob and others, too .... Look at this if you haven't already -- http://www.tolvan.com/edge/
Download and after playing with program to get familiar, place your current speaker and panel into program just as you have it. Note frequency graph. Now, move speaker to extreme left 900 to 1000 mm from floor and watch hump come down and usually F3 as well. Then, leaving speaker alone increase or decrease panel size. It's a great tool. 
Also, look at panels narrow at top and wide at bottom. F3 goes way down. The idea of a speaker in the middle or just offset to make distances unequal went out with high button ... 
Zene


----------



## Bob in St. Louis

Thanks Zene, Quite a few of the OB guys have tried/used "The Edge". I've tried to access the site multiple time, but to no avail. All I get are four large white boxes with those little red "X"'s that signify it is unable to display the image.....:scratchhead: 

Bob


----------



## willy-be

Bob in St. Louis said:


> Thanks Zene, Quite a few of the OB guys have tried/used "The Edge". I've tried to access the site multiple time, but to no avail. All I get are four large white boxes with those little red "X"'s that signify it is unable to display the image.....:scratchhead:
> 
> Bob


At the top of the webpage the download links for the program still work.


----------



## Bob in St. Louis

Ok Willy-be, Thanks.
I was leary of clicking on anything since I couldn't read what was in those boxes. Was afraid if I couldn't read that, I wouldn't be able to read anything on the entire site.
I'll bookmark it guys, not quite ready to build baffles right now. Most of my time has been spent on other areas of the room. (Like researching a new Oppo!)

Bob

p.s. WOW, Hawaii. Cool. I don't see that very often. Welcome!


----------



## mgboy

Hey, since this thread is dedicated to OB, I was wondering (really quickly, as to not steal your thread, Bob) if these drivers would be okay to use in an open baffle situation? I'd get a mid range and a tweeter to put with it, but I was just wondering if the Q of that driver would work, as I don't know much about that.


----------



## Bob in St. Louis

Mike, Hello.
I have very limited experience experimenting with various drivers in an OB situation, but I'm thinking no, those drivers wouldn't work. A number around .9 is best for OB.
That Hawthorne specs are:
2" voice coil 
Power handling: 150 watts RMS
Impedance: 8 Ohms 
System Sensitivity: 95.8 dB 1w/1m *<-------The higher the better!!*
Le: 0.07
Re: 5.77 Ohms
Qt: 0.91 *<----------------- This is the key for OB!!*
Vas: 243.9 liters 
XMax: 3.45mm
Fs: 41.8Hz
Magnet weight: 38ounces
Frequency range: 41.8-18k (of course varies with baffle size/configuration)

Mike, don't worry about stealing the thread. 
This is an OB thread _NOT_ "Bob's OB Thread".
ALL OB talk is welcome.

Bob


----------



## mgboy

So, the lower the Qt. is not the better? A Qt. around .9? Or do you know for sure? I'm curious.

Thanks for having an open thread.


----------



## Bob in St. Louis

Mike, I am _ninety nine point nine_ percent sure that *.9* (actually .7 to .9) is best. 
Too high, or too low and you're getting into territory where the driver would do better in a different 'enclosure'. I've chatted with some very good OB guys, and those are the numbers that I've confirmed with them in the past. None of them said lower/higher is better. 



> Thanks for having an open thread.


Mike, no problem. I've OT'd more than a few threads in my time. *FAR* be it from me to deny a fellow time when he's ON topic! 
Beside, threads are why we are all here. To learn.:yes: 

Bob


----------



## mgboy

Do the specs on this driver (besides the SPL, which I have plenty of power to run) be suitable for an OB setup? Or is the .94 _too_ much?

*VCdia: 1-1/2" 
*Le: .28 mH 
*Impedance: 8 ohms 
*Re: 7.15 ohms 
*Frequency range: 35-2,500 Hz 
*Fs: 39 Hz 
*SPL: 85 dB 1W/1m 
*Vas: 1.39 cu. ft. 
*Qms: 4.07 
*Qes: 1.23 
*Qts: .94 
*Xmax: 4.6mm


----------



## Bob in St. Louis

That's better. What kind of driver is that?

Bob


----------



## mgboy

It's a Goldwood 8" Woofer from PE. I'm trying to look for some cheap, but suitable drivers just to experiment with OB as I'm not totally convinced that it's what I'm looking for. I've got a link to them somewhere, I'll post back in a min.


----------



## Bob in St. Louis

Hey Mike, do you have a pair of drivers laying around?
...and/or... do you happen to have an old pair of car 6X9 coaxials laying around?

Bob


----------



## mgboy

I don't have a pair of drivers laying around, but I have one ~6.5 in. driver somewhere. Are you suggesting that I listen to that on an OB first?


----------



## basementjack

Bob, 

I just want to say it's great that you're enjoying this hobby and I look forward to seeing you around the shack.


----------



## Bob in St. Louis

mgboy said:


> Are you suggesting that I listen to that on an OB first?


Yes, absolutely. Just for the **** of it. Keep in mind...this is most likely a driver that's "not right" for OB.
But neither were mine, and they still "opened my eyes".

Bob


----------



## Bob in St. Louis

basementjack said:


> I just want to say it's great that you're enjoying this hobby and I look forward to seeing you around the shack.


Thank you Jack! yes, I am having fun. I wish I knew more, it's a slow learning curve.
But it seems the possibilities are endless with OB. Lotsa fun!!

Bob


----------



## JCD

Don't know how I missed this thread in the past.. I've always wanted to listen to an OB/Dipole speaker setup correctly. Especially, the Orion. A baffle-less speaker was something I hadn't even considered.

Anyway, to my point -- and this may have already been addressed and I missed it -- but how big is the room you have your speakers in? My (very) limited understanding about OB/Dipole speakers was that they needed a big room to sound good.

I've tried reading some of the OB/Dipole stuff -- especially the Linkwitz site. My brain turned to mush and leaked out of my ears. :mooooh: 

JCD


----------



## SteveCallas

The curiosity is killing me Bob....so close yet so far


----------



## Bob in St. Louis

JCD said:


> but how big is the room you have your speakers in? My (very) limited understanding about OB/Dipole speakers was that they needed a big room to sound good.


My room is an "L" shape. The width of the screen wall is 12' wide. Distance from screen to back wall is about 25'. The left "leg" of the "L" (which I've never measured) is approx 10' X 10'.??
The drivers I have are the 15"er. The 10's are due out soon...(Better for smaller rooms)



> I've tried reading some of the OB/Dipole stuff -- especially the Linkwitz site. My brain turned to mush and leaked out of my ears. :mooooh:


Yea, I know what you mean. I spend more time looking up the meaning of a word or phase, than actually READING the article. Then of course, while looking up the meaning, I get sidetracked because I "found something cool". Ya know....

Steve:


> The curiosity is killing me Bob....so close yet so far


...?? I feel like I've left you hanging. (You are talking about coming over right)

Bob


----------



## BoomieMCT

mgboy said:


> It's a Goldwood 8" Woofer from PE. I'm trying to look for some cheap, but suitable drivers just to experiment with OB as I'm not totally convinced that it's what I'm looking for. I've got a link to them somewhere, I'll post back in a min.


I think I found what you were talking about - the Goldwood GW-8028 8" woofer. I modeled it in Unibox as an open (infinate?) baffle (closed box with 9999 Liters and heavy damping) and came up with this plot. What kind of highpass can you wire up to keep this from overexcursion below 80 Hz?


----------



## mgboy

Well, I don't know really. Want to suggest something? I could keep a finger on the volume button.


----------



## BoomieMCT

mgboy said:


> Well, I don't know really. Want to suggest something? I could keep a finger on the volume button.


Suggest sometning? Crossover and filter design is all black magic to me. I'm still trying to figure it out!


----------



## mgboy

Same here. >_>;


----------



## SteveCallas

> I feel like I've left you hanging. (You are talking about coming over right)


Yeah, I'll bring a gift if I have to :bigsmile:, I just wanna hear them.


----------



## Bob in St. Louis

SteveCallas said:


> Yeah, I'll bring a gift if I have to :bigsmile:, I just wanna hear them.


Oh well, if we're talking about an admission price, then **** yea!!
Come on over :T 

Actually, I did speak with the "female regulator of Bob's spare time" and she gave the thumps up.
Febuary dates that are clear: 10th-18th-24th. 
Steve: You will be the FIRST guy 'in the hobby' to hear my system.:raped: 
Although I have confidence that you'll like the pieces I've put together, I'm fairly nervous at the prospect of having somebody that knows what their hearing actually listen to it.

Bob


----------



## Bob in St. Louis

Here's what you'll see steve: (Sorry the pic is so dark, just got a new digital camera):sarcastic:


----------



## SteveCallas

Excellent! The 10th should work out nicely. 



> Although I have confidence that you'll like the pieces I've put together, I'm fairly nervous at the prospect of having somebody that knows what their hearing actually listen to it.


I wouldn't worry about it, it's all relative, and I haven't heard any super duper high end stuff before. What I'm finding is that after some level of performance is met, speakers just sound different, not necessarily much better or much worse. What I'm hoping to find is some speakers that break that mold and definitely sound "much better" :T


----------



## Bob in St. Louis

Interesting outlook on audio Steve, I like it. I've never heard it quite put that way. Cool.
I got the PM (check yours)
I've heard some super duper high end before, and wasn't impressed.

Bob


----------



## Bob in St. Louis

Hey Steve, wanted to give you another pic of what to expect....










:jump:  
Ha Ha Lol.

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Mike, I am _ninety nine point nine_ percent sure that *.9* (actually .7 to .9) is best.
> Too high, or too low and you're getting into territory where the driver would do better in a different 'enclosure'. I've chatted with some very good OB guys, and those are the numbers that I've confirmed with them in the past. None of them said lower/higher is better.
> Bob


The 8" Goldwood I was going to use had low frequency overexcursion issues (and I couldn't get a highpass to model how I wanted). Does anyone think this 6.5" Pyle driver would work?
It has a Qts of .89 and the natural rolloff makes it not need a highpass. Also, it can play higher then the Goldwood so it will be easier to cross with the tweeter I want to use.


----------



## willy-be

Historically the typical Qts for an OB driver (woofer) has been 0.69 The newer OB designs proposed by Linkwitz, et al, use significantly lower Qts drivers. 

In a OB alignment Qts = Qtc, so one might consider whether they want the significantly underdamped performance characteristics associated with higher Qtc drivers.

my $.02
WB


----------



## SteveCallas

> Hey Steve, wanted to give you another pic of what to expect....


Hahaha, that's great! :R :clap:


----------



## BoomieMCT

willy-be said:


> In a OB alignment Qts = Qtc, so one might consider whether they want the significantly underdamped performance characteristics associated with higher Qtc drivers.
> 
> my $.02
> WB


Doh! Well, I've started my open baffle experiment with my Qts = 0.89 driver. Here is a pic of the woofer, the baffle and the tweeter. This will also be an experiment as to whether I can build a good crossover AND whether I can use a router. :bigsmile: 

I did try out the driver with no baffle and no tweeter. It sounded okay but since I had no way to aim it I really couldn't test it.


----------



## Bob in St. Louis

That's a good looking ring there Mr. Boom. Appears to be a piece of laminate countertop maybe?
One thing I noticed, are your router bits digging into your workbench? It looks like you might have gotten a little bit of a screwhead there. When I clamp the workpiece to the workbench, I use a couple scraps of wood to raise the piece up a bit. It also lets sawdust have a place to escape through the bottom too.

I'm no router expert by any stretch of the imagination, but I've screwed things up enough times to not do it again. I'll pass on my failures in a attempt to help others not do the same.. :duh: 

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> That's a good looking ring there Mr. Boom. Appears to be a piece of laminate countertop maybe?
> One thing I noticed, are your router bits digging into your workbench? It looks like you might have gotten a little bit of a screwhead there. When I clamp the workpiece to the workbench, I use a couple scraps of wood to raise the piece up a bit. It also lets sawdust have a place to escape through the bottom too.
> 
> I'm no router expert by any stretch of the imagination, but I've screwed things up enough times to not do it again. I'll :duh:
> 
> Bob


The baffle is 3/4" MDF. The gouged workbench is actually scrapwood I put on my workbench to protect it.


----------



## Bob in St. Louis

Good deal. Can't wait to hear your listening impression.:yes: 

Bob


----------



## BoomieMCT

BoomieMCT said:


> Doh! Well, I've started my open baffle experiment with my Qts = 0.89 driver. Here is a pic of the woofer, the baffle and the tweeter. This will also be an experiment as to whether I can build a good crossover AND whether I can use a router. :bigsmile:
> 
> I did try out the driver with no baffle and no tweeter. It sounded okay but since I had no way to aim it I really couldn't test it.


Here is an update. The woodworking and painting (except for a gold stripe on the front) are done. I'm kinda stuck as I'm waiting for a particular resistor for the crossover to get back in stock so I can finish. In the theme of having the parts exposed the parts of the crossover will be on top of the base with the solder connections in a recessed area underneath it. You can see my template crossover in the picture with the bases.


----------



## Bob in St. Louis

Good lookin' woodworking there Boom! A+ :bigsmile: 

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Good lookin' woodworking there Boom! A+ :bigsmile:
> 
> Bob


Thanks dude. Here is one more pic and hopefully my next post will be a report of how they sound. Sadly, I have to wait for one resistor to come back in stock before I can finish the crossover. Doh!


----------



## Bob in St. Louis

Oh now _THAT'S COOL_!:yes: 
Let's talk about the tubing...Is that for non-insulated silver wire?
or just for looks?

Bob


----------



## Bob in St. Louis

Here's my latest Augie Baffle. (This is the version Steve heard).


----------



## BoomieMCT

Bob in St. Louis said:


> Oh now _THAT'S COOL_!:yes:
> Let's talk about the tubing...Is that for non-insulated silver wire?
> or just for looks?
> 
> Bob


Looks mainly. The leads off the tweeter were really dinky looking so I drilled two 3/8" holes in the frame to hold the clear tubing as a shroud. The leads also weren't long enough so I have to solder on an extension wire. I guess that could touch the back of the woofer and be bad.

The soldering for the crossover is going to be underneath the base in a recessed pocket. The caps and inductors will actually be on the top of the base - fully visible.

I pretty much got all my inspiration from my motorcycle. :bigsmile:


----------



## Bob in St. Louis

Nice :yes: Looks good.

Bob


----------



## BoomieMCT

So now I've built my first open baffle speaker and built my first crossover. I must say I'm very happy with the results. For a 6.5" woofer these things have a HUGE soundstage in my office. I have noticed that for rock n roll they really do need a sub to take care of everything below 90 Hz or so.


----------



## Bob in St. Louis

WOW Boom, if that's your first shot at OB, I have a feeling you're gonna do real well.
Lots of imagination used. 
It really puts mine to shame in the appearance category.

I think you deserve another A+ :T 
:yourock: utstanding: 

Ok, let's talk about that 90Hz. That really doesn't seems too bad for a 6" with almost zero baffle. 
Things can be done to lower that 90, but every one I can think of would destroy the looks.
(can't believe I just put looks over sound!!)
Is this the home office or the office at work? The reason I ask, is if it's at work, can you really crank it up with content below 90 anyway? If so, I want to work there too.
If this is home, then all bets are off. You can do whatever you want....

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Ok, let's talk about that 90Hz. That really doesn't seems too bad for a 6" with almost zero baffle.
> Things can be done to lower that 90, but every one I can think of would destroy the looks.
> (can't believe I just put looks over sound!!)
> Is this the home office or the office at work? The reason I ask, is if it's at work, can you really crank it up with content below 90 anyway? If so, I want to work there too.
> If this is home, then all bets are off. You can do whatever you want....
> 
> Bob


It's at home, in a living room. I have an x-sub to fill in the last octaves. The setup isn't great for critical listening but they provide a nice, house filling ambient sound. Also, I wouldn't say the baffle is small exactly - it is a 10" circle for a 6.5" driver. The area is comparable to most bookshelf 2-ways (I guess they aren't known for their bass though). I included the Unibox estimate of performance - it says the F3 should be 79Hz. I was guessing when I said 90.


----------



## Bob in St. Louis

Regarding baffle size, most of the guys with drivers that size are installing them on baffles about 2' X 3'.
So a 10" ring would considered smallish. Just for grins someday, grab some cardboard and poke a 10" hole (with a coupe inch hole at the top for the tweet) and rig up that cardboard so it'll set securely with the driver showing through the hole. Kind of like those plywood "things" that they have at amusement parks where the kids can stick thier faces through.
You'd be surprised at the bass output then.
It would absolutely destroy your good looking baffles, so it would be a temporary setup at best, but it'd give you a good idea of potential for future projects.

Bob


----------



## SteveCallas

Boomie, can you do something like a 1' FR sweep of the woofer?


----------



## BoomieMCT

SteveCallas said:


> Boomie, can you do something like a 1' FR sweep of the woofer?


I will but I want the drivers to break in first AND I have to wait for my fiancee's laptop to get fixed (stupid macs).


----------



## Bob in St. Louis

Boomie, if you check the FR, do it from several points: 1' - 3' - 6', on axis, then 30 degrees off axis at the same intervals again.
I'd be interested in seeing those numbers too.

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Boomie, if you check the FR, do it from several points: 1' - 3' - 6', on axis, then 30 degrees off axis at the same intervals again.
> I'd be interested in seeing those numbers too.
> 
> Bob


Sure can once I get everything up and running. I will caveat this with the fact 

1) Any room I do this in will have a decent amount of room coloration.
2) My best microphone I have is a (new) Radioshack SPL meter. 
3) The 3 ohm Mills resistors I need to properly cut down the tweeters are backordered. This may not be an issue as the reflected rear wave seems to boost the woofer's output to make it more equal with the tweet. Testing will confirm or deny this.


Please keep these in mind when I do finally run these. Hopefully, I'll have a good chance to Monday.


----------



## Bob in St. Louis

Don't forget you RS SPL meter calibrations!
Also, try testing them outside to eliminate the room, the weather ought to be nice enough in VA right now isn't it?:rofl: 

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Don't forget you RS SPL meter calibrations!
> Also, try testing them outside to eliminate the room, the weather ought to be nice enough in VA right now isn't it?:rofl:
> 
> Bob


Very funny. :wits-end: I had to push some ice boulders out of my way with my truck to get to work this morning. I can actually skate on my lawn with my shoes. 

Anyway, I'm probably not going to schlep my stereo outside for testing (definately not until Spring). Sorry.


----------



## Bob in St. Louis

Sorry dude, couldn't resist. Yea, we're frozen here too.:sarcastic: 

Oh, and by the way, you can play with some cardboard baffles and wings when you do the testing too.

Bob


----------



## BoomieMCT

BoomieMCT said:


> It's at home, in a living room. I have an x-sub to fill in the last octaves. The setup isn't great for critical listening but they provide a nice, house filling ambient sound. Also, I wouldn't say the baffle is small exactly - it is a 10" circle for a 6.5" driver. The area is comparable to most bookshelf 2-ways (I guess they aren't known for their bass though). I included the Unibox estimate of performance - it says the F3 should be 79Hz. I was guessing when I said 90.


Speakers still aren't broken in but I ran some tones on a test tone CD. It seems like they are dropping off a bit higher then previously thought - more like 140 Hz instead of the predicted 79Hz  . When I do my testing Monday I'll try running the woofers with no crossover to see if any problems could be there. I may also try replacing the woofers with these (which should drop in perfectly).

Now, I have noticed that their lower reach seems to improve if I turn them up. Could this be because I'm feeding woofers rated to 150 watts a signal from an amp that is 30watt/channel? I'm hesitant to do test tones at higher volumes. I have also noticed the tweeters seem to get brighter at higher SPLs - is this a human perception thing?

They sound good and detailed with a good sized sound stage but I'd really like to get down to at least 100Hz.


----------



## Bob in St. Louis

BoomieMCT said:


> I'd really like to get down to at least 100Hz.


Baffle Size!! 
Neeeeed Bigger!!:yes: 

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Baffle Size!!
> Neeeeed Bigger!!:yes:
> 
> Bob


Sadly, according to my calculations a 10" baffle corresponds to the maximum allowed WAF. I will test cardboard baffles though. 

I will also say as the woofers break in the missing 3 ohm resistors I need to cut the tweeters down become more and more apparant. Before is was "hey, maybe I don't even need those". Now I really need them.

I will also say that these pro-sound speakers can get VERY loud. I still haven't cranked them to full (which they should easily take) and they really dish out the SPLs. My fiancee' sings in a band - I may make a speaker cab for her using these (especially if I end up switching drivers in my home speakers).


----------



## BoomieMCT

BoomieMCT said:


> Sadly, according to my calculations a 10" baffle corresponds to the maximum allowed WAF. I will test cardboard baffles though.
> 
> I will also say as the woofers break in the missing 3 ohm resistors I need to cut the tweeters down become more and more apparant. Before is was "hey, maybe I don't even need those". Now I really need them.


Here are three tests. I'd like to point out a few things.

First off, the response seems to roll off from 700Hz down to the calculated F3 point of 79Hz. I'm not sure why this is - I can assume it is the small baffle. The drop off after the calculated F3 looks normal so I will assume it is the baffle (or lack thereof). It could also be something in the crossover - I'll test the woofers without the crossover later. 

Secondly you will see a step up in output at 3,500 Hz. That is due to the missing resistor to cut the tweeter. When my resistors arrive that should fix it.

Lastly, the tweeter seems to increase output with frequency - especially from about 7kHz up. There is a chance the missing resistor will fix this - otherwise I think I'll have to get a small inductor to make an R-L circut to compensate.

I apoligize that the horizontal axis is smeared. I did the tests with a Max laptop and it always screws that up.

So . . . since I'm not getting what I want between 70 and 700 Hz I'm going to try a different set of 6.5" drivers. If that doesn't work I will build a woofer section using a sealed DVC driver and make this a pseudo-3 way design.


----------



## Bob in St. Louis

Thanks for the multiple graphs Boom. 
Do you know what drivers you'd try? I believe Hawthorne will have some 10" Coaxials soon.

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Thanks for the multiple graphs Boom.
> Do you know what drivers you'd try? I believe Hawthorne will have some 10" Coaxials soon.
> 
> Bob


Well, my issues aren't with the crossover (see attached graph for the woofer by itself). So, I'll be ordering a set of these because they model well, they are cheap and they will fit the baffle I already made. As I said before, this is more for a learning experience then anything else. I may also make something like the "auggies" using one of these in a small sealed box. 

The Hawthornes would probably sound much better but even the 10" ones would be too big and the cost would be greater. Also, as I said before, I'm doing this largely to practice building and designing.


----------



## BoomieMCT

After reading this and comparing the calculated numbers to my measurements I'm 99% sure my problem is baffle step diffraction. Now the question is do I build a circuit to compensate (and reduce the sensativity of my speakers) or do I build a "auggie" like speaker to counteract the diffraction?

BTW, one interesting thing in that article is pointing out that baffle step diffration is based on the shortest width of the baffle and how low you want your speaker to go. It makes no mention of the size of the driver. So, Bob's baffleless 15"ers would be no worse off then my 6.5"ers with a 15" baffle. I suppose if you use a big enough driver you get to a point where you don't need any baffle.


----------



## Bob in St. Louis

BoomieMCT said:


> After reading this and comparing the calculated numbers to my measurements I'm 99% sure my problem is baffle step diffraction. Now the question is do I build a circuit to compensate (and reduce the sensativity of my speakers) or do I build a "auggie" like speaker to counteract the diffraction?


I'm not a curcuit builder, so I'm unqualified to answer that one, but when you say "Augie like", are you meaning a 15" fullranger, or a seperate baffled bass augmenting driver in addition to what you've got?
That is a good article, however halfway through John started losing me.



> BTW, one interesting thing in that article is pointing out that baffle step diffration is based on the shortest width of the baffle and how low you want your speaker to go. It makes no mention of the size of the driver. So, Bob's baffleless 15"ers would be no worse off then my 6.5"ers with a 15" baffle. I suppose if you use a big enough driver you get to a point where you don't need any baffle.


I agree that the larger the driver you have, the smaller baffle you need (for bass). Just simply due to surface area of the cone being so much more on a 15, it'll move a lot more air than a 6" or 8" driver would. That is not to say a larger driver is immune to diffraction, just requires less baffle size.
I'm not sure I'm explaining my thoughts correctly, but we're on the fringe of the end of my knowledge (where fluids start leaking from my brain and out my ears).
I feel like I was on the edge of an epifany, but it fizzled out and turned into a brain fart instead.onder: 

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> I'm not a curcuit builder, so I'm unqualified to answer that one, but when you say "Augie like", are you meaning a 15" fullranger, or a seperate baffled bass augmenting driver in addition to what you've got?
> That is a good article, however halfway through John started losing me.


When I say "auggie like" I'm talking about a driver dedicated to offsetting the baffle step diffraction. So, one that adds 6dB down low and has a first order roll-off up to about 1000 Hz. I think this is similar to the concept of a 2.5 way speaker. 

The alternative is to make a L-R circuit that attenuates the high frequencies to balance everything out - but that means I have 6 dB of attenuation up high and kills the sensitivity of the system.



Bob in St. Louis said:


> I agree that the larger the driver you have, the smaller baffle you need (for bass). Just simply due to surface area of the cone being so much more on a 15, it'll move a lot more air than a 6" or 8" driver would. That is not to say a larger driver is immune to diffraction, just requires less baffle size.



I believe the size of the driver is actually irrelevant to the size of the baffle needed. The diffraction effect seems to be based on the size of the baffle relative to the low wavelengths. A 100 Hz wavelength is the same length no matter what size driver makes it. Now, a 15"er will probably make more total, but the effects of the baffle would be the same. So, _as far as baffle step diffraction _a unbaffled 15" should be the same as a 6.5" with a 15" baffle.


----------



## SteveCallas

Hmm, isn't the tweeter in the coax essentially seeing the woofer cone itself as a baffle? Bob had some EQ in play, but I'm pretty sure his OB's also have somewhat of a rising response like that if measured naturally based on what I was hearing. It would be interesting to see how effectve the crossover is prior to any EQ.


----------



## BoomieMCT

SteveCallas said:


> Hmm, isn't the tweeter in the coax essentially seeing the woofer cone itself as a baffle? Bob had some EQ in play, but I'm pretty sure his OB's also have somewhat of a rising response like that if measured naturally based on what I was hearing. It would be interesting to see how effectve the crossover is prior to any EQ.


I don't think the baffle (or the cone as a baffle) is responsible for rising tweeter response. Baffle effects tend to be in the 100Hz to 1000 Hz range. From what I understand, some (most?) tweeters have a natural rising response at the high end of their output. A R-L (or is it RC?) contour circuit can fix it if one wants to dote on crossover design.


----------



## SteveCallas

As the output of the tweeter radiates, wouldn't it be getting some reinforcement from the forward sloped shape of the woofer?


----------



## BoomieMCT

SteveCallas said:


> As the output of the tweeter radiates, wouldn't it be getting some reinforcement from the forward sloped shape of the woofer?


As frequency goes up, wavelength goes down and therefore so does the required baffle size. A baffle a mere 1 inch across would have an F3 at 4500 Hz and would only see a maximum of a 3dB rise above that due to baffle diffraction. A 15" baffle (or a 15" driver) would stop seeing baffle diffraction effects at about 1800Hz - probably well below the tweeter's cutoff. 

The rise you sometimes see in tweeters (or what I see from people's projects on the web) I think is caused by some sort of electrical resonance, but I'm not sure.


----------



## Bob in St. Louis

BoomieMCT said:


> When I say "auggie like" I'm talking about a driver dedicated to offsetting the baffle step diffraction. So, one that adds 6dB down low and has a first order roll-off up to about 1000 Hz. I think this is similar to the concept of a 2.5 way speaker.


Ok, Gotcha. I understand.




> I believe the size of the driver is actually irrelevant to the size of the baffle needed.
> The diffraction effect seems to be based on the size of the baffle relative to the low wavelengths. A 100 Hz wavelength is the same length no matter what size driver makes it. Now, a 15"er will probably make more total, but the effects of the baffle would be the same. So, _as far as baffle step diffraction _a unbaffled 15" should be the same as a 6.5" with a 15" baffle.


Boom - Ok, as far as diffraction goes, ummmm I might buy that. Once again, it's an area I'm not totally versed in, but now I think we're on the same page.

Steve - Regarding the woofer reinforcing the tweet, (I think) it goes back to what you and I were talking about at my house; If the woofer radiates (the _FRONT_ half wave) like a sawed-off shot gun, the tweeter would be the rifle. I would think the tweeter would get much gain from it??:dontknow: 
Regarding my rising response: Realising OB has a natural rising response, I would say that my rig has an un-natural falling response, if you know what I mean.
I tried to show you the "pros", and didn't mention the "cons". I've got some wierd bass issues that make the accentuate the highs.

Bob


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## SteveCallas

Hmm, I've got some experimenting to do when I get back home :nerd:


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## BoomieMCT

IF the information in the previous article is true (and it certainly seems to be in my case at least) here is a quick graph that shows the effects. The x-axis is the baffle width in inches (the paper says to use the shortest width of the baffle). The lines are the frequencies where the rise starts (blue), the F3 (white) and where the rise ends (red). Above the red line there should be no baffle diffraction. Below the blue line you should be steady 6 dB down from predicted.

Also note, the article says this is only for speakers well away from boundaries (walls).


----------



## mgboy

So, for OB speakers, a high Vas and Q anywhere from .7-.9 would be about right? or does the Vas not matter as much as the Q value, or vise-versa? I want to start experimenting.


----------



## Bob in St. Louis

Boom, not sure how I missed your reply. Sorry about that sir... I've skimming the article you linked too. I'll need to read it again as the author started losing me about halfway through. I'll check that out again when I can dedicate more time. Looks like good information though.

mgboy, The "king" of all OB specs seems to be Q. And yes, you're right on the money for the range.
Reagarding Vas, that spec doesn't seem to come up very often. I'm not saying it doesn't matter, but nobody talks about it. I checked the specs of my 15" drivers and they are:

Coaxial:
Q - .91
Vas - 243.9 Lt

Augie:
Q - .92
Vas - 250.3

More specs here:
http://hawthorneaudio.com/drivers.htm

Steve, Have you done any experimenting?

Bob


----------



## mgboy

Bob in St. Louis said:


> mgboy, The "king" of all OB specs seems to be Q. And yes, you're right on the money for the range.
> Reagarding Vas, that spec doesn't seem to come up very often. I'm not saying it doesn't matter, but nobody talks about it. I checked the specs of my 15" drivers and they are:
> 
> Coaxial:
> Q - .91
> Vas - 243.9 Lt
> 
> Augie:
> Q - .92
> Vas - 250.3
> 
> More specs here:
> http://hawthorneaudio.com/drivers.htm
> 
> 
> Bob


Well, those drivers do have a large Vas, but maybe that is just because of the 15" driver? Any articles concerning that?


----------



## Bob in St. Louis

mgboy said:


> Well, those drivers do have a large Vas, but maybe that is just because of the 15" driver? Any articles concerning that?


I would think it's due to the lack of "spring" a box would provide. Much like an IB setup.
I don't know of any articles regarding the Vas of OB except maybe on "The Cults" IB site. Since IB and OB are reasonably close "relations" due to the lack of an enclosure (an enclosure that provides enough resistance on the cone to help wattage/Xmax/SPL problems.
Here's "The Cult":
http://ibsubwoofers.proboards51.com/index.cgi

It's a subwoofer site, but I think the theory between IB and OB have quite a few similarities.

Bob


----------



## mgboy

So, do you think I could start experimenting with these? I would assume they could be a place to start.


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## BoomieMCT

mgboy said:


> So, do you think I could start experimenting with these? I would assume they could be a place to start.


More people experimenting - yay! I looked at those but didn't use them because I was concerned with potential excursion problems (see attached). But, who knows, they could be great. If you use them please report back.

I used these 6.5" Pyle Pro PA drivers instead. I like the sound very much, the soundstage is huge and you can really put a lot of power into them. However I made my baffles too small (8.5" diameter) so I was getting nasty baffle edge diffraction effect. I built an auxiliary speaker (camera is broken - sorry) to make up for it and it sounds great. In a bit I'm going to make an electrical network to compensate instead and compare the two. The easiest thing to do (if you have the space for it) would be just to make big baffles.

Other drivers I looked at in the past (but never tested) include;

Goldwood GW-6028
Goldwood GW-1034
Goldwood GW-1248
HI-Vi M3N
HI-VI B3S
AUDAX HP170M0 
AUDAX AP170M0 
MCM 8" Aluminum Instrument speaker

That last one interested me the most (decent xmax, wide usable range, looks cool) but I can't justify building another set of OB's right now. I'm also interested in the AP170M0 because of the low Fs and because the magnet behind the driver is very thin.


----------



## Bob in St. Louis

Mike - What concerns me about that driver is a few things:

#1 The FR stops at 5,000. A minor problem if you're willing/able to add a tweet and build a XO network (I'm not, but have seen a very good thread on XO building that can help).

#2 SPL is rated at 86. That's pretty low man..... like REAAAL low! It's almost like the driver isn't willing to _DO anything_, you know what I mean?

#3 Vas -- I've said before that Vas does not come up in the OB conversation much, but it's soooo much lower that mine, it's another "strike" for me....and yes, I'm comparing ALL driver specs to mine. Whether my drivers are "The drivers that all others should be measured by", I don't know, but it seems awful low to me. If you've got a few bucks, try them out, buy a pair. They're for automotive application, so if all else fails, you can put them in your car...

#4 Like Boom said, the Xmas is pretty low, but then again, so are my Coaxials. However, the difference is, a 15" driver moving a given distance will move A LOT more air than 6-8" driver given the same Xmas.


Boom - Did you ever try the cardboard (bigger) baffles with yours?
Just curious what you found ?

Bob


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## BoomieMCT

Bob in St. Louis said:


> #2 SPL is rated at 86. That's pretty low man..... like REAAAL low! It's almost like the driver isn't willing to _DO anything_, you know what I mean?


That's not that low. It's about on par with most bookshelf systems. It should be easily driven by any modern amp. I drive my OB's (which has a sensitivity of 88dB) with 30 watts per channel and I never need to turn the knob more then a quarter of the way up. 



Bob in St. Louis said:


> #3 Vas -- I've said before that Vas does not come up in the OB conversation much, but it's soooo much lower that mine, it's another "strike" for me....and yes, I'm comparing ALL driver specs to mine. Whether my drivers are "The drivers that all others should be measured by", I don't know, but it seems awful low to me. If you've got a few bucks, try them out, buy a pair. They're for automotive application, so if all else fails, you can put them in your car...


I'm not really sure how Vas comes into play in an OB configuration. If you have the system Q in the right range the eqivalent compliance should be irrelevant. 



Bob in St. Louis said:


> #4 Like Boom said, the Xmas is pretty low, but then again, so are my Coaxials. However, the difference is, a 15" driver moving a given distance will move A LOT more air than 6-8" driver given the same Xmas.
> 
> 
> Boom - Did you ever try the cardboard (bigger) baffles with yours?
> Just curious what you found ?
> 
> Bob


Nah, the fiancee's laptop has been so wacky I haven't run any measurement tests (stupid Mac). I did play around with some test tones and my ears. I think electrical compensation or an auxiliary speaker would help out more then a larger baffle - especially since the fiancee' won't allow bigger speakers then what I got. The drivers I'm using have xmax to spare (6.5mm) so I'll be doing some step compensation tests in a week or so when parts come in.


----------



## Bob in St. Louis

Boom, agreed. 
I think I was being a bit 'extra' critical that day. What do you think? (Yea, I was)

Mike, have you made any decisions? 

A very knowledgable OBer told me something yesterday that surprised me. He said any driver is suitable for OB alignment. It's a matter of how much and where it's going to fall off the graph and how much EQ you'll have to put to it. Personnaly, I would also add to that; baffle size and shape would play a role in how well an "unsuitable" driver would work, or could be tweeked to work.

My first OB is what I called (at the time) a totally unsuitable driver. It was the 4" driver and 1" tweet removed from the sealed plastic box of a Niles OS-10. I mounted these on scraps of a formica laminate counter top. I has been listening to them for a few years in thier original (factory) seal configuration. After mounting them on the laminated MDF, I was sold on OB alignments before the first song ended. If memory serves, they were 88Db sensitivity. The rest of the TS numbers were unavailable. It was missing bass, Duh, they're 4" drivers after all. But the level of clarity I heard was something I'd not heard in my room ever before.

So bottom line guys: Try it. If you've got drivers laying around, give them a shot. MDF/Ply is cheap. ****, you can even use cardboard!
Those $12 drivers Mike found, you can't beat that price. You could have a small OB array for about $100, an afternoon, and a sheet of plywood.

Boom, instead of WAF, do you call that FAF?? haha

Bob


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## BoomieMCT

Well I built my auxiliary speaker and got my 3 ohm resistor to cut down the tweeters. While I was soldering the resistors in I noticed my tweeter's polarity wasn't inverted (they were supposed to be in the design) so I fixed that too. The sound is now *very* neutral. I'm going to test them with a mike this weekend.

I have pics but both my digital cameras broke (on the same day) so I have to use my ****** phone camera. I know the setup they are in is very non-optimal - what can I say, it's a WAF issue. Speakers move around a lot in my house so I get to hear their openess when they are in my office. Right now they are toed out for a more ambient listening experience. Does it suck that they have to be near the ceiling and in a corner? Yes it does.

As a seperate issue I tried hooking the OB's up to a simple BSC circuit without the augmentation speaker. It helped some but I still didn't get much output below 125 Hz - I think the manufacturer's specs from Pyle aren't quite accurate.


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## Bob in St. Louis

Boom, very good to hear that you starting to get that "OB sound". Would you go as far as to say you're an OB convert?

Yea that placement isn't ideal Boom, but you don't need me to tell you that. One in a corner and the other firing the rear wave up the stairs. But one advantage to OB is the overall clarity that can't be lost by the alignment. Placement with regard to what's behind the drivers gives the imaging and soundstage which you're probably missing. But my favorite part of OB is the amazing clarity which can be had by even the poorest of drivers in the poorest of settings. I've heard nuances from songs I've been listening to for years that went unnoticed until OB.
Nice too that yours are so mobile.

Bob


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## wig

I tkink I might try,but I don't think I have room for 15's whats the next best thing?And I don't know jack about x-overs.the speaker look great.


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## Bob in St. Louis

Hi wig! 
A few questions:
How big is the room? Dimensions?? (Pics?)
What's your budget?
What kind of equipment do you currently have?

Bob


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## wig

hi bob -I have a 12by14 living room.sony 32''crt (42'' plasma in the works)a old technics sa-dx940 I got for cheap and bose 201s.sorry I don't have more to work with.As far as budget there not one but I'm try to make one if you know what I mean.Thanks for the quick response.How much do you think the 10''s will be?


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## Bob in St. Louis

Scott, I typed a big long reply to your last post, but it didn't show up...It's gone! :explode: 

Ok, short story this time:

Never appologize for your equipment.
Someone will always have better, someone else will always have worse..or none at all.

I asked Darrel Hawthorne about the price of the 10"s...We're very cautious in saying this (because is isn't 'set in stone' yet) but *ABOUT* $125 per driver including the crossover for the compression driver. They are still in development.

15's WILL work in that sized room. (Probably better than 10's)

Bob


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## Prof.

Bob in St. Louis said:


> Scott, I typed a big long reply to your last post, but it didn't show up...It's gone! :explode:



Don't you hate that!!!?? It's happened to me twice when I was posting a 3 page tutorial on another forum....That's why I don't have any hair left!!


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## wig

Thanks for trying anyways bob.as far as the 10''s go thats a not as much of price cut as I wanted.One thing I like about the 15s is 8ohm and the sensitivity.I seen some nice baffles on their site. I'll try to get them so I can show you.Do think one on each side without augies would sound good for now.oh and later on when I do add them is there anyway to keep it all 8ohm?


----------



## Bob in St. Louis

Prof, Three pages!!! that would suck BAD! 
Usually, I'll 'right click and copy' my entire post before I submit so in case something happens I can still 'paste' it again. This time it appeared it posted ok....:dontknow: 

Wig, Yea.. Link or post some pictures of the baffles.
No way to keep two 8 ohm drivers 8 ohms. Either 4ohm or 16 ohm.

Here's mine so far:


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## wig

I'm sure you have seen the quasar's, but by some of of the hawthorne forum talk I don't know about the thickness, but do they look good.sorry about the dumb question about the 8ohms, found out I need sub amp to make it work and sound better.so how does the fiberglass ones sound.i have did a lot of paint work on cars and I don't have any wood working tool so I mite build something out of metal,just for the cool factor.but only If I can get BIG BOBS ok:bigsmile:


----------



## Bob in St. Louis

These: ??












wig said:


> I mite build something out of metal,just for the cool factor.but only If I can get BIG BOBS ok:bigsmile:


HAHA :rofl: 

I would think metal would be ok with a few suggestions. Metal that's thick enough to sound 'dead' when it's hit. maybe some angle iron welded to the rear to minimize ringing. and definitely coating the rear of it with something to deaden it further.
When you say metal, are you talking about a piece of boiler plate kinda' material?

Regarding the wiring of 8 ohm drivers, here a cool website I found for various driver configurations:
http://www.bcae1.com/spkrmlti.htm
Don't worry about 'stupid' questions dude. _NOBODY_ here was born with audio/video knowledge.

Bob


----------



## wig

no thats not them.I'll see if I can find them again.Thats good site ,I read that after ,I seen were you told someone else about it. Maybe a mod stop sign with some kind of thick metal baffel.


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## Bob in St. Louis

The driver being magnet mounted works great. I'm real happy with it. It cost $2.29, it's a "U" shaped bracket you would use to support a 4X4 piece of lumber when building a deck. I cut off one side to make it an "L" shape. A hole saw big enough for the coax tweet to fit into, then screw the tweet into the midwoofer. Works fantastic.
If you support the driver independantly of the baffle, and build a baffle that is 'self standing', you could experiment with baffle designs without even touching the driver.!:T 
My driver does not touch the wooden ring that surround it.

Bob


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## wig

Thats what I was thinking, I can almost fell my brain gettin bigger.plus with metal there's always chrome lol just joken .


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## Bob in St. Louis

Chrome would be fine. Provided you treat the rear to dampen any 'singing' from the metal.

Bob


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## Prof.

Bob in St. Louis said:


> Prof, Three pages!!! that would suck BAD!
> Usually, I'll 'right click and copy' my entire post before I submit so in case something happens I can still 'paste' it again. This time it appeared it posted ok....:dontknow:]


Yes, that's what I also do now...We learn the hard way!

Very nice job on the fibreglassing Bob...How do they sound compared to the previous baffle?

wig...If you're going to use metal for a baffle, then I would suggest that you coat the back of it with body underseal..that rubbery bitumenised stuff.
That should help to control any resonances...


----------



## wig

Hi prof.I was thinking about bedliner on they back of the baffel, but the rubber undercoating stuff mite work better.still trying to learn all about this ob stuff I can while I save up the money.does anybody near dallas have a ob set up.It would be great to hear some before I buy.There mite even be a free lunch in it.


----------



## BoomieMCT

I got my 6.5" OB speakers tweaked a bit more. I have inverted the tweeter and added a 3 ohm resistor to cut it down a bit. My results are posted in the attachment. Wheras before I had tweeter rise with increased frequency - now I have tweeter decay. I'm not sure why - I don't 100% trust my measurement gear (RS mike and a Mac sound card - neither is good).

Note that the baffle step isn't as pronounced as before. I did not add a BSC circuit, I just played around with placement. It makes a BIG deal with these bad boys. Because of this I am moving them out of the living room and into my office (where placement can be more flexible). Luckily I just finished some small full rangers that work well in the living room.

Also of note, with my aux speaker I'm flat down to 50 Hz. Yay me.


----------



## Bob in St. Louis

prof - Thanks for the complement. It sounds good. Hard to get a good A/B compare since I keep reinstalling the baffle back in the system as I build it. Slowly improving and adding fiberglass, resin, and expanding foam every weekend. So, such a slow change is making it harder to judge. Plus I've only got one build, the other is assembled but has no wire mesh or fiberglass on it yet. I suppose I could mono the system and A/B each baffle that way. Overall I'm very happy with it. Regarding the undercoating, good idea. I would add one thing to that: My wife gave me some material 'stuff' the other day thinking I might like it for padding on the rear of a baffle. It's original purpose was to be placed between the carpet in your house and an area rug. It keeps the rug from scooting around on the floor. It's kind of a soft foamy material with holes in it. I've seen a similar product for use in a wood working shop. You put the mat on your workbench and set your workpiece on it while you sand on it. It keeps the workpiece from scooting around. Pretty cheap stuff. After your coat your baffle with undercoating, you could lay this stuff on it, and press it in.

wig - A fellow by the name of Brad is on the Hawthorne forum, he lives in Texas. Either Dallas or Houston I can't remember. Look him up, He's pretty cool. Very helpful guy.

Boom - Flat to 50 with a 6.5! :yikes: COOL! Yea, the placement has a big effect, fun to play with.

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Boom - Flat to 50 with a 6.5! :yikes: COOL! Yea, the placement has a big effect, fun to play with.
> 
> Bob



No no no! Lest I be misquoted - the 6.5"ers aren't flat to 50Hz. They are flat down to about 150Hz with output down to 90Hz only. The integration of an auxiliary speaker takes them down flat to 50Hz. In this case it is a single ported 8" DVC driver that sits inbetween them. 

Whew! Glad I got that cleared up. 

As I said before, I moved these to a more optimal listening arrangement in my office. I love the speed of the OBs and the openess of the sound. I'm already cooking up ideas for a 3-way speaker with OB midrange.


----------



## Bob in St. Louis

Ok, gotcha boom. Understood.



BoomieMCT said:


> I'm already cooking up ideas for a 3-way speaker with OB midrange.


The Hawthorne Audio Coaxial will get to 50 on a resonably sized baffle. 
Proudly, I might add. :yes: 
Two drivers with XO's is just over $300.

Bob


----------



## BoomieMCT

Bob in St. Louis said:


> Ok, gotcha boom. Understood.
> 
> 
> 
> The Hawthorne Audio Coaxial will get to 50 on a resonably sized baffle.
> Proudly, I might add. :yes:
> Two drivers with XO's is just over $300.
> 
> Bob


Well, my home theater of the future may very well use that - I am a fan of OB and coaxials. For now, because of room sizes, I don't think any 15" drivers will fly. I need to satisfy myself with getting my bass in a smaller package.


----------



## Bob in St. Louis

Understood about the room size. But I've seen fellas running these in some pretty small rooms.
Let me know when you're ready, I'll hook you up with Darrel Hawthorne.


" I am a fan of OB "
Me too. I don't think I'll ever get back into boxes.

Bob


----------



## Prof.

Bob in St. Louis said:


> I suppose I could mono the system and A/B each baffle that way.


What I would do if you still have one of your speakers with the original baffle, is compare them left and right, and then reverse them..I find it easier to get a direct comparison betwen two different speakers by switching each one from one side to the other..



Bob in St. Louis said:


> My wife gave me some material 'stuff' the other day thinking I might like it for padding on the rear of a baffle. It's original purpose was to be placed between the carpet in your house and an area rug. It keeps the rug from scooting around on the floor. It's kind of a soft foamy material with holes in it. I've seen a similar product for use in a wood working shop. You put the mat on your workbench and set your workpiece on it while you sand on it. It keeps the workpiece from scooting around. Pretty cheap stuff. After your coat your baffle with undercoating, you could lay this stuff on it, and press it in.


That's a good idea..I am familiar with that material and think it would work well..


----------



## BoomieMCT

Bob,

Out of curiosity, how does one hook up a silver iris and an auggie? Do you just put them both in parallel? Is there an auggie crossover?


----------



## Bob in St. Louis

Hello Boom
If you think of an Augie as a subwoofer (which it is) it might make things a little clearer.
Yes, some form of crossover (XO) is needed. Depending on the construction (size, shape, material) the Coaxial will start to roll off at different frequencies. This is where the Augie needs to take over, and carry on the low frequency journey. The smaller the coax baffle, the higher the Augie would need to cross. The larger the coax baffle is, the more bass it will make on it's own, therefore the Augie would need to "pick things up" a little lower than in the first case. Other variables like room modes, can play a roll in the crossover point. Most of it is personal preference really. I've made several baffles for the HawthornAudio Coaxials and only one (The first one), sounded the worst. Go figure.
Now all that might sound like more than a fellow would want to take on, but it's not much different from a regular system. I've got my rig sounding very good by adjusting receiver settings and tuning by ear. Someday, sarcastic: ) I'll figure out how to tune the room, then I can tune the system. Someday....

A thread started recently on the Hawthorne Audio forum regarding this very subject. Ideas have come up raging from cheap (but complicated), to very user friendly (but expensive). Some of the options are:

- Hand making your own XO, component, by component. It can be cheap or expensive depending on quality of parts. Lots of knowledge needed to do this one. I _WON'T_ be trying this idea.
- PC based XO, EQ software. Inexpensive (usually), but the PC is in the equation now. Some guys aren't ready for this option.
- Hardware based 'pro' type units. Prices vary wildly, from a few hundred to $3,500....How much money you got?

Personally, I'll be deciding on one of the last two.

Here's the thread on Hawthorne about Active Crossover options, complete with a little O.T.-B.S. just for fun, but the topic always comes back to the point:
http://www.hawthorneaudio.com/forum...&start=0&sid=514f6e7a7ab1930895bf2dcbfd3c94db


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## Bob in St. Louis

Except for a few tweaks here and there, I'm (finally) finished with the fiberglass baffles:

Bob


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## BoomieMCT

Bob in St. Louis said:


> Hello Boom
> If you think of an Augie as a subwoofer (which it is) it might make things a little clearer.
> Yes, some form of crossover (XO) is needed. Depending on the construction (size, shape, material) the Coaxial will start to roll off at different frequencies. This is where the Augie needs to take over, and carry on the low frequency journey.


So, Bob. As the local Hawthorne expert what do you think about this idea for a 3-way OB system:

One baffle with a Hawthorne 10" coax (when they come out) crossed over to a 15" auggie at about 200 Hz or so. I prefer passive crossovers and my hope is that the big auggie can be used to offset baffle step problems without loss of sensitivity (as there would be in a BSC circuit).


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## Bob in St. Louis

BoomieMCT said:


> So, Bob. As the local Hawthorne expert........


:yikes: "Local" Hawthorne expert, maybe. But in the big picture, I'm an infant.




> what do you think about this idea for a 3-way OB system:
> One baffle with a Hawthorne 10" coax (when they come out) crossed over to a 15" auggie at about 200 Hz or so. I prefer passive crossovers and my hope is that the big auggie can be used to offset baffle step problems without loss of sensitivity (as there would be in a BSC circuit).


I like the idea. Sounds like a doable plan Boom. I would *HIGHLY* recommend coming over to the Hawthorne sandbox. :yes: The fellas there are ultimately much more skilled/knowledgeable than I regarding altering 'recipes'. Throw around a few ideas there, you'll get plenty of replys (unless you'd like me to post the question "in your proxy", I'd be more than happy to.)

Bob


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## BoomieMCT

Bob in St. Louis said:


> Throw around a few ideas there, you'll get plenty of replys (unless you'd like me to post the question "in your proxy", I'd be more than happy to.)
> 
> Bob



Please do. I'm on *way* too many forums right now.


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## Bob in St. Louis

Here you go dude, your very own thread on HawthorneAudio : :bigsmile: 

http://www.hawthorneaudio.com/forum/viewtopic.php?p=9721#9721

Bob


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## BoomieMCT

Bob - thought you'd enjoy this. One year later and here is the view from the listening chair in my office. Note the full dipole floor standers and dipole sub.


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## Bob in St. Louis

Very nice Boom. I've peeked in on your thread a few times. I like the way you do things, nice and methodical. No 'willy-nilly' stuff. If I'm seeing it correctly, the 12" drivers you're using from P.E. are no longer available? I like seeing folks experiment with OB. So, how are you liking them so far? (and have you gotten the drivers broken in yet?)

Bob


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## BoomieMCT

Bob in St. Louis said:


> Very nice Boom. I've peeked in on your thread a few times. I like the way you do things, nice and methodical. No 'willy-nilly' stuff. If I'm seeing it correctly, the 12" drivers you're using from P.E. are no longer available? I like seeing folks experiment with OB. So, how are you liking them so far? (and have you gotten the drivers broken in yet?)
> 
> Bob


You are correct that the 12" drivers I'm using aren't available anymore. Everything is definately broken in and I finally fine-tuned the locations of all the speakers in the room yesterday. What a difference that makes*! I'm very happy with it so far - I'm relistening to my CDs to see what I may have been missing.

* I've noticed dipoles are easier to get a good response out of but you generally can't put them anywhere convenient (i.e. anywhere near a wall). I also noticed they REALLY don't like being parallel to a wall.


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## Bob in St. Louis

Yes, OB does "re-invent" your music collection, that's for sure! 
When you say 'parallel', do you mean having one speaker right next to a wall? I'm sure you've played with distance from the front wall as well?
Is it my imagination, or are the bottoms of the baffles raised off the floor a couple inches?

Bob


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## BoomieMCT

Bob in St. Louis said:


> When you say 'parallel', do you mean having one speaker right next to a wall? I'm sure you've played with distance from the front wall as well?
> Is it my imagination, or are the bottoms of the baffles raised off the floor a couple inches?
> 
> Bob


I don't mean having a speaker right near a wall, I meant having the baffle of a speaker parallel to the wall behind it (or perpendicular to the one next to it). I was getting some odd measurements when I did that. Toeing them in, even just a little, changed that. This held true for the sub as well.

Is this just my room or have you noticed this too?

Yes, the mains are on 1 1/2" spikes so there is a small gap underneath them. There is a "floor" to the speaker so the bottom isn't open. The sub is also raised, but only by 1/4" or so (different spikes).


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## Avus_M3

I love reading these OB threads. It makes me want to try some new things!

Here is a quote I found interesting in the link you provided regarding speaker placement in a baffle:


> The worst case appears to be placing the driver at the center of a circular baffle so that it is the same distance from all diffracting edges.


Would this hold true for the Sonotubes everyone builds? Curious...


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## BoomieMCT

Avus_M3 said:


> I love reading these OB threads. It makes me want to try some new things!


Go for it man!



Avus_M3 said:


> Here is a quote I found interesting in the link you provided regarding speaker placement in a baffle:


This is true. Download Edge (free) and play around with it to see what I'm talking about. I intended these to be test speakers that I'd build cheap and fast then throw away. I liked them so I added on to them instead and they displaced the speakers I was using. If I knew how much I was going to like them from the start I would have offset the drivers two inches or so.



Avus_M3 said:


> Would this hold true for the Sonotubes everyone builds? Curious...



Technically yes but practically no. The weird effects that happen are because of how the speakers transition from half space to full space. In a very simple view an offset driver means that the distances from the driver to the edge of the baffle in all directions is more spread out. 

The frequencies subwoofers make is low enough they should be playing into full space all the time. If your sub is crossed high there will be a very teeny tiny amount of content that will be affected but I doubt anyone could hear the difference.


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## Bob in St. Louis

Go for it Dave. You'll never look back.

Bob


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## Avus_M3

Here's my current setup (Pioneer Elite)...just been thinking about trying something new. Might post a for sale ad.

http://www.stereophile.com/floorloudspeakers/148/


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