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Bozak B-800 Cabinet Questions

G

guyhifi

New Member
Regrettably, due to room constraints where I am now residing, I was forced to sell my Bozak Concert Grand Speakers that I have built from scratch and enjoyed for many years. Needless to say, I am going through massive withdrawal.

I have a pair of mint-condition Bozak B-800BC Aluminum 8" Drivers still in the box that I acquired years ago, along with MDF and other material to construct a set of cabinets. The build from this point forward will not cost me anything other than a little time. I know that they will not sound anything near to the Concert Grands, but I need something to listen to that will work in my new environment.

I plan to build the cabinets utilizing "infinite" baffle, cotton batting, and hi-quality tweeters. I considered bookshelf size, or even a small column cabinet which will work in the room. The question becomes, for maximum performance:

1. What size cabinets do I build? Does anybody know what dimensions the cabinets should be?

2. Does anybody have a crossover schematic and parts list that I can use for the B-800BC and a tweeter?
 
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If possible, you need to determine the 800BC's resonant frequency (fs), equivalent cabinet volume (Vas), and the total "Q" (Qts) of the woofer. Due to the woofer's age, the parameters might not be available on a spec sheet. Measuring the woofers maybe the only way to determine the best cabinet size.

Something like this would be highly recommended. It will do a complete measurement for you.
www.parts-express.com

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Thanks, homebrew, that's a little too technical for me. I can build cabinets pretty easily, but the science/calculations are beyond my area of expertise. I was hoping that somebody built cabinets using the B-800BC and could provide the dimensions that would deliver best results.
 
Hay, 1.5 cubic feet would be about right. No ports, free swinging curtain if you can do it. 100% cotton batting. It's got a bit of cone breakup around 1750hz that you may or may not hear. I'd use a first order crossover and cut it off around there. Same with the tweeter, first order. Bring it in around 2k. The B800 rules.

Biggles
 
drbiggles said:
That B800 will give you big wide open Lush smiles.

Biggles
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I am counting on that! :)

drbiggles, you and retrovert once helped me with my Concert Grand N-104 crossover build that turned out phenomenally well, it was literally a day/night difference!

Can you supply a part list for the crossover that I will need for the B-800 and tweeter?
 
guyhifi said:
I am counting on that! :)

drbiggles, you and retrovert once helped me with my Concert Grand N-104 crossover build that turned out phenomenally well, it was literally a day/night difference!

Can you supply a part list for the crossover that I will need for the B-800 and tweeter?
Click to expand...

Yeah, can put something together easily enough. Probably in the next day or so. Gonna keep it simple and let the drivers do their thing.

Biggles
 
guyhifi said:
Yes they are 8 ohm. I'm not planning to use L-pads, I never cared for them, unless these drivers require them? I like keeping things simple also :)
Click to expand...

You'll know when you fire them up. If they chase you out of the living room, you'll need something to tame them. Unless they're not efficient enough.

Biggles
 
drbiggles said:
You'll know when you fire them up. If they chase you out of the living room, you'll need something to tame them. Unless they're not efficient enough.

Biggles
Click to expand...
Would it be much of a bother to provide a parts list and diagram for both with and without?
 
I'd look at the various speakers Bozak made that used the woofer. That should give you an idea of what size they thought was appropriate. The Bozak ideal is an infinite baffle, but I've thought of putting mine in tapered quarter wave pipes, and you might consider that option.
Another possible option is using them full range - I think the Full Range Speaker site is no longer active, but I remember they liked the B 800 as a full range driver, and if I ever get around the the TQWP project, I'll start with them as full range drivers - I think the dynamics might make up for the diminished high end and the slightly lumpy bass.
 
Here is a schematic and parts list for you. Assumes your tweeter is good down to 2k. Without putting your B800 on a DATS to see what is impedance vs frequency curve is doing, probably best to have it do as little as possible. Or just listen to it and see what you think. It may play well with the tweeter, it may not. Just get as close as you can on the parts. 10uF on the cap, 16 gauge wire on the inductor is fine, 18 is good too. Just use air-core inductors.

Biggles
 

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drbiggles said:
Here is a schematic and parts list for you. Assumes your tweeter is good down to 2k. Without putting your B800 on a DATS to see what is impedance vs frequency curve is doing, probably best to have it do as little as possible. Or just listen to it and see what you think. It may play well with the tweeter, it may not. Just get as close as you can on the parts. 10uF on the cap, 16 gauge wire on the inductor is fine, 18 is good too. Just use air-core inductors.

Biggles
Click to expand...

drbiggles, thanks a million! I will report back once the project is completed :-)
 
drbiggles said:
Hay, 1.5 cubic feet would be about right. No ports, free swinging curtain if you can do it. 100% cotton batting. It's got a bit of cone breakup around 1750hz that you may or may not hear. I'd use a first order crossover and cut it off around there. Same with the tweeter, first order. Bring it in around 2k. The B800 rules.

Biggles
Click to expand...
Biggles, I am almost finished building the 1.5 cf mdf boxes and will be hardwood veneering them.

I will be driving the speakers with my existing Van Alstine 100wpc solid state power amp with a Van Alstine hybrid tube pre-amp. This is what I used to drive the Concert Grands that I recently sold. I know that the B-800 bookshelfs will not handle that much power, so of course I will have to dial it down.

I plan to use the B-800bc speakers as an all-range with hope that they will be sonically satisfying. But in the event that they may possibly need a tweeter:

I don't have the funds to experiment with types or brands of tweeters. Can you recommend an inexpensive 8-ohm tweeter that will best compliment the B-800bc which will work with the schematic that you have provided? I have read pros and cons of the Bozak B-200 tweeters, Audax, and other manufacturers that are available at Parts Express, but don't have the means or the funds to A-B compare any of them. I will trust your judgement of what will be suitable if you don't mind making a recommendation?
 
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guyhifi said:
Biggles, I am almost finished building the 1.5 cf mdf boxes and will be hardwood veneering them.

I will be driving the speakers with my existing Van Alstine 100wpc solid state power amp with a Van Alstine hybrid tube pre-amp. This is what I used to drive the Concert Grands that I recently sold. I know that the B-800 bookshelfs will not handle that much power, so of course I will have to dial it down.

I plan to use the B-800bc speakers as an all-range with hope that they will be sonically satisfying. But in the event that they may possibly need a tweeter:

I don't have the funds to experiment with types or brands of tweeters. Can you recommend an inexpensive 8-ohm tweeter that will best compliment the B-800bc which will work with the schematic that you have provided? I have read pros and cons of the Bozak B-200 tweeters, Audax, and other manufacturers that are available at Parts Express, but don't have the means or the funds to A-B compare any of them. I will trust your judgement of what will be suitable if you don't mind making a recommendation?
Click to expand...
I'm such a poor person for this. Tweeter integration is my Achilles heel, and I have only a bit of familiarity with the B800 driver. Bozak in it's later iteration made a loudspeaker system with a B800 as the woofer and a B200y as the tweeter. Keep it simple, do that. Bozaks goof was that they ported it, don't do that. Line with cotton, make little swinging curtain. Use B200Y 16ohm tweeter with a 4uF capacitor. That'll bring it it at 2500hz. Run the B800 full range. Done.

Biggles
 
As a Bozak fan, I surprise myself by suggesting that it might be worth considering econowaving them. The original Selenium compression drivers aren't so econo anymore, and the original horn might be a little too large for your enclosure (assuming that domestic considerations don't allow for a bare horn on top), but Pete Basel has been diligent in trying out smaller wave guides and cheaper compression drivers. I used a very cheap JBL wave guide he recommended and thought it very satisfactory with the Seleniums I already had.
Another alternative might be just to slap a pair of the Linnaeum tweeters from a pair of those Radio Shack or RCA metal cabinet speakers on top of your creations - they are not not hard to find, I think, and, if you just use the existing crossover, a simple way to at least try a tweeter. You can always fine tune the crossover later etc.
 
guyhifi said:
drbiggles, thanks a million! I will report back once the project is completed :)
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Wondering if you finished this project… would love to hear how it turned out.

And, Happy Thanksgiving to all!

Never mind, I found it here… Thanks!

Bozak B-800 Speaker Build Completed, +Question

Thanks goes out to DrBiggles and homebrew for their suggestions, I was able to complete my Bozak B-800 speakers. All I can say is WOW! As All-Range drivers, I felt that the speakers lacked clarity and high-end, so I built and incorporated 2 way crossovers consisting of a 0.60 mH inductor and a...
audiokarma.org
 
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