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In Reply to: RE: Please which are the best sounding Altec BiFlex I need to know more about these speakers posted by corerosin on June 22, 2007 at 05:26:20
rosin--The Bozak 207s I was recently playing with were real screamers, Heresey-like in their ability to mimic a Skilsaw. I wonder if this was because the foam dampers behind the aluminum cone tweeters had rotted away?
Which leads me to wonder if the older paper cone Bozak tweeters aren't really the ones to get?
Follow Ups:
...The older paper cone Bozak tweeters also use(d) some kind of foam ring bonded to the back of the cone as a damper. Unfortunately, over the years, whatever this foam is becomes brittle, looses its bond with the cone and either becomes gritty dust that binds in the VC gap or stays in tact but rattles and buzzes against the cone at numerous frequencies. How do I know?... I was being driven crazy by HF harshness in a Bozak speaker that uses that 12" LF driver with two of those tweeters splayed across the front (forget model #). I disassembled the tweeter and the dust fell out. I used a small amt of acoustistuff carefully placed in the tweeter housing to provide the damping effect of the original foam. This totally removed the harshness but it was a PIA to do. When I get the ambition, Im'm going to fix the other one.
A similar situation exists with the metal cone midrange except the foam is locked away under the dustcap. How do I know?...
I documented the tweeter renewal rather extensively. Maybe I should post some pics and narrative.
For me, the bottom line is that vintage Bozak just isn't worth the effort considering the materials they used were not very durable and the sound even when operating properly is mushy.
My dilemma is what to do with the Bozak tweeters. Although they (will) operate better than unmodified, they're no longer stock and so probably worthless to the typical Bozak afficianado. Probably chalk it up to experience, sell the woofers and trash the tweeters.
Interesting. Too bad in a way, I liked the midrange from the Bozak coaxes and the way they did vocals. Anyhow I gave them away and thats the end of my Bozak phase.
Rudy Bozak made quite a few contributions to the art. He may have been the first to use edgewound voice coils in woofers, in the Cinaudagraph line of high quality speakers in the late 1930s. He also built 27" full range drivers with 450 lb. field coil magnet structures (yes!), one of which is apparently in the Klipsch Museum. RCA-fan met Mr. Bozak years ago and was given a factory tour.
In the link below are the interesting recollections of Peter Ledermann, who knew Mr. Bozak toward the end of his career.
I didn't know that there were foam dampers behind the tweeters' cones. I never disassembled one. The aluminum cone Bozak midrange speakers just have the backside painted like the front. But even with that, the original owner of the one larger Bozak midrange speaker that I still have wound up putting an additional layer of paint on the face of the cone. I only wish he hadn't chosen a peach colored, flat wall paint........two coats.
Anyway, I'm certain that you're right. Metal direct radiators always have resonances that have to be damped, one way or another. I guess there is a uniformity of manufacture which is appealing to speaker manufacturers. Also, it seems like every 15 or 20 years, metal drivers become popular for some reason. Lately I think rock musicians are using the current crop of metal drivers. Better them than us, I suppose.
I never liked metal midrange drivers either. Even the LE 5-2, Jbl midrange speakers left me flat. I always wound up replacing them with one of the old KLH yellow midrange/full range drivers from the 1960's. Now that's a great driver. And just a little rat-tail file work on the bolt holes and it bolts right up where the LE5-2 fits. Much smoother, and capable of a much lower crossover without getting anywhere near it's resonance.
So anyway, I do agree with your original statement. If the OP can find the paper cone Bozak tweeters, I'm sure he will get a much smoother high frequency response.
Well thats interesting.I will search some more on them cheers
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