It was an 8" midrange, not a horn apparently, with a vertical array of tweeters down one side.
Are the cabinets mirror-imaged, i.e., the woofer stack on the left in one and on the right on the other?
They're 8+ cuft closed boxes, looks like. Any subdivision of the volume inside?
Originally Posted by Zilch
Actually, the midrange was a 5.25".
This was taken from a review of the Bozak Concert Grand in Stereophile Mag...
http://stereophile.com/historical/1005bozak/
"The heart of every Bozak speaker is the 5¼" midrange driver, whose magnet structure is the same size and diameter as that of the 12" woofer. Bozak stated that, "based on the laws of physics, [this unit] is so sized that the diameter of the speaker cone does not exceed the wavelengths of the sounds they are designed to reproduce." The cone itself is made of uniform-density aluminum coated with a thin film of latex rubber on each surface. The aluminum is perforated to help bond the rubber coatings and damp the cone. Legend has it that Rudy Bozak worked on the voicing of this drive-unit to minimize the annoyance of LP tracing distortions."
Charles
Yes, you're correct. Sorry, I was looking at the wrong driver specs on this page...
http://www.hifilit.com/hifilit/Bozak/1968-4.jpg
Charles
Yes, as i mentioned previously, I think I can use a jigsaw to cut out the front panels and put in a new piece of plywood for front baffle and make holes for whatever size I want so existing holes really do not matter.......
or i could buy bozak parts and make them bozak; though i am a very horny guy and want to stay that i way.......
Zilch, they are mirror image. 12" woofers to the right vertically -1 in the middle and the other at bottom, midrange on middle's top and tweeter arrays to the inside. No subdivision inside cabinets.
I found some pictures on the bay: http://cgi.ebay.com/ws/eBayISAPI.dll...m=120153150900
Go ahead with your plan, but put an 18 mH SuperQ inductor in series with each of the bottom woofers, PE #266-958.
Block off the opening(s) where the tweeters were.
Those are rather wimpy woofers you've chosen, but they'll play at moderate levels down to ~29 Hz (-10 dB)....
This endeavor will require some work and iteration, regardless...
good news is you've got options. a single 4" port that's a few inches long will bring up the
low end in ultimate loudness and efficiency (with tradeoffs, of course)....
could also tune lower and try emulating the 4435 dual-woofer design (may require a
larger inductor than what Zilch has kindly suggested as might work with a closed box).
Might also want to consider dropping a multi-watt 32-64-ish ohm resistor across the low-passed
woofer (bringing down the impedance peaks and crossovers will act more as expected).
...your boxes... have fun
-grumpy
From many of your posts I gather you don't favor dual drivers. (I actually gather that your feelings are stronger than that) Is this from a study, several studies, personal experience? I'm neither agreeing or disagreeing with you, I'd just like to know where it came from. Thank you.
I'm sure that all this means is that I don't get around much but every bozac I ever saw had two tweeters mounted to the woofer.
It's axiomatic - two sources playing the same program material will interfere with each other.
The Bozak tweeters were splayed.
If they're arrayed, it must be engineered to make the interference work toward a specific design objective:
http://www.jblpro.com/pub/technote/fat_wht.pdf
You always here of multiple woofers coupling if placed close enough together.
I don't have the technical understanding to make that my statement, or to rebuke it.
Subwoofers, yes, mutual coupling below a specific frequency, Thom.
It's in the Eargle pro sound system design manual here:
http://www.jblpro.com/pages/tech_lib.htm
Even those interfere with each other, but it's pretty hard getting much differential distance to the listener in comparison to low frequency wavelengths when they're both mounted in the same box.
They can be "steered" with delay or placement offsets in separate boxes, tho....
Zilch, how about this:
I would cut out the front panel and put in a new baffle. Make a 15" hole for a subwoofer - using a plate amp driving it, a 12" for 2213H running fullrange (I believe 2213H is designed to run fullrange in 4312C), and a horns/drivers using one of those $10 wave guide from JBL - and a BMS 4550 driver (or some other driver that you think may be good for what i need) crossing at 1500hz with just a simple capacitor.
Not sure which 15" woofer to use for this seal box though. Please let me know if this plan sound OK and please give me some suggestion for a good 15 incher that would work well for my need. Thanks.
I'm trying to avoid chopping out the front baffles.
You'd need a subenclosure behind the 2213H
With two identical 12s, you should be O.K., if one is being used as a "helper," i.e., just augmenting the low frequencies, as I suggested above.
Depending upon the size of the cutout for the 8", the round OASR "Dr. Seuss" horn may be a better choice than the $10 PT waveguide, which is 6.5" high external, and may not cover and seal the hole.
In any case, just a capacitor is not likely to approach comprising an optimum highpass filter. The BMS will play HF better than most other compression drivers under those conditions, though....
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