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71.106.119.211
My apologies for this duplicate post. I hung it out yesterday, but buried so many days deep I was afraid few would see it. Mea Culpa.
Hi Folks. Having just returned to 'the faithful' at AA, I want to tell what everyone should know about Bozak speakers.
I first heard Bozaks in 1954, as a callow youth of course. I worked at a shop that sold them in the late '50s.
In the early '60s, Bozak ran into a sales problem. The dealers were hollering that the Bozaks weren't 'first time' buys. Most new buyers chose a flashier sound than the ultra-smooth early Bozaks. After living with their first choice a while, many came back and said, "Uh...Could I hear those Bozaks again?" That was OK with Rudy Bozak, who knew he would get most of them eventually. But it wasn't OK with the dealers.
Bozak reacted to the pressure and 'pimped up' the sound so that it was a bit more flashy and would appeal to first time buyers who weren't mature, experienced listeners.
Problem was, in doing so they ruined the midrange smoothness and imaging. And there is a broad hump in the middle highs centered around 5 kHz (the artificial 'brightness hump'), but the upper highs roll off above 10 kHz.
I'll never forget the first time I heard a pair of the 'new ones.' It literally made me sick with disappointment. They no longer had the real 'Bozak Sound.' I continued to use the older ones.
Some years later, in the late '80s, as a pro audio engineer, I found time to analyze what they had done. I designed fixes to the xovers. My mods remove all the mischief that Bozak had done in response to lagging sales. (Sad to say, Rudy Bozak had passed away in early '82 and anyhow, the company had been sold in mid '77.)
Here's the clincher: Few, today, have heard the 'real' Bozak sound. With the world-class drivers free to sing, unemcumbered, in their full, natural voices. If you think you like the Bozak sound, "you ain't heard nothin' yet." You should hear them with the corrections. It is an amazing transformation.
I have been rebuilding/modifying Bozak xovers for several years as a service. Without exception, every user has proclaimed great enthusiasm.
But my mods are not secret. It was not my mission to help Bozak sell speakers in the '60s through '80s. But it is my mission to put them straight, free of the artificial bells and whistles which Bozak thought were necessary to sell in the day. I believe, to the core of my being, that if Rudy had not been faced with the problem of making speakers that were too good for the market, the xovers would have been done exactly the same as I now do. I do it not to 'correct' Rudy Bozak, but to honor him by letting present-day owners hear what those fantastic drivers will REALLY do.
My xover rebuilds are very moderate in cost. If you're interested, jerk my chain at the email address. For those who want to 'roll their own,' I am happy to provide the circuit at no cost.
BTW, it is a terribly erroneous myth that Bozaks are 'mellow.' They are whatever you feed into them, more so than any other speaker I have heard. They have incredible transient response if driven with enough power. The midrange driver, for example, has a motor (magnet and magnetic plate size, voice coil diameter etc.) the same size as that of the woofer. All that power to drive an extremely light. I liken it to putting a hemi V8 in a VW bug, the power to weight ratio is stupendous. If the recorded sound has bite and an edge, that's exactly what you will hear, without sacrificing any overall smoothness.
The 'mellow' judgment about Bozaks might be due, in part, to the B-207 2-way systems, an economical way to get into Bozaks. The midrange driver and full 3-way xover could be added when finances permitted. But some didn't, and the 207's, while very smooth and full, lack the brilliance and bite of the world class B-209B midrange driver. Also, the early paper-coned midrange and tweeters were not as bright and powerful as the later aluminum-coned ones.
I am happy to answer any and all Bozak questions. And I'm on Vintage and Amp/Preamp Asylums to talk electronic issues.
With best New Year wishes to all,
Pat Tobin
I have a story...
Just a few weeks ago one of my best friends father gave me his Bazak Speakers. He told me he first bought the B-207a two way drivers and then later added the B-209b Mids. Then, had them put in a custom cabinet. The crossover is N-101a - He told us that this was all done right around 1964.
Two questions...
1. I want to start on building new cabinets right away. Should I keep the current measurements or enlarge them? (current inside cabinet measure = 24.5" x 9.5" x 16.5")
2. Does this crossover need the modifications you speak of?
Thank You
Max, Are the tweeters the early, paper-cone B-200X or the later aluminum-cone B-200Y? The X's have bright metal foil caps about 3/4" in dia. at the center of each cone. The Y cones are all black.
< 1. I want to start on building new cabinets right away. Should I keep the current measurements or enlarge them? (current inside cabinet measure = 24.5" x 9.5" x 16.5")>
Those custom cabinets are too small for the Bozak woofer. Bozak recommended at least 5 cu. ft internal volume for the cabinet (single 12" woofer models). It must also be very solid and tight, with no port of any kind. The Bozak woofer is designed to work in an 'infinite baffle,' or closed box. An 'active' enclosure, such as one with a ducted port, helps the low bass end, but degrades bass transient response. One of the things I like best about Bozak bass is the gutty growl of a well-recorded string bass. That's bass transient response, at which the Bozak woofers excel.
<2. Does this crossover need the modifications you speak of?>
Any system with the Y tweeters has the screwed-up Bozak xover and needs the modern rebuild/upgrade. If the now-rare X paper-coned tweeters are in use, the xovers are so old that the 'paper' capacitors used in the day are all bad by now.
With best wishes,
Pat Tobin
I had Bozak - I think they were 302A's - but had a real heck of a time returning them for tweeters that were always getting mis-aligned
Stringreen, pls explain. I don't know what you mean by the Bozak tweeters getting mis-aligned.
Pat Tobin
I wish I had heard this when I had my Bozaks, because you have accurately described the problems I was hearing. I don't remember the model I had, but it used 4 12" woofers, a single midrange, and a vertical array or 8 tweeters and I was bi-amping with the Bozak electronic crossover. If I had known that the crossovers could correct the faults, I would have hung on to them.
Best wishes,
David
I'm wondering...You make reference to the early 60's as the time that Bozak made the "compromising" changes. Does that mean that all Bozaks made after this time have the "brightness hump", or was it confined to certain models? Was the change ever reversed?I ask because I have a pair of Symphony's made in Nov. 1968 that have had thier caps replaced and I think they sound very nice.I've never been aware of any undue brightness, as you decribe. The mid-range, reproduced by the B-800 driver, is very smooth. Should I be concerned that I'm not hearing the "genuine" Bozak sound?
*"I'm wondering...You make reference to the early 60's as the time that Bozak made the "compromising" changes. Does that mean that all Bozaks made after this time have the "brightness hump", or was it confined to certain models? Was the change ever reversed?
I ask because I have a pair of Symphony's made in Nov. 1968 that have had thier caps replaced and I think they sound very nice.I've never been aware of any undue brightness, as you decribe. The mid-range, reproduced by the B-800 driver, is very smooth. Should I be concerned that I'm not hearing the "genuine" Bozak sound?"*
I should have been more clear about that. The mid-high hump is worst in the 302A, single woofer 3-way 'basic' systems.
The key fact here is that B-200Y aluminum-cone tweeters are 9 dB louder than the woofer(s) and midrange(s). However, they roll off gently above 10 kHz.
In the big 2 or 4 woofer systems, Bozak chose to bring in the tweeters an octave or even two above the nominal xover frequency with the midrange. This is because the B-209B aluminum-cone midranges do not begin rolling off at the nominal 2,500 Hz. They sing along quite nicely up to 10 kHz. Bringing in the tweeters at 5,000 Hz or even 10,000 Hz in some cases, reduces the doubling of the lower range of the tweeters with the extended upper range of the midrange. This lessens the midlle-high hump compared with the 302A's. But the tweets still roll off gently above 10 kHz.
The disadvantages are that the output from the extended upper range of the midrange is more directional and has lesser transient response than the light tweeter diaphragms.
The situation is a little different with the early Symphonies which have the B-800 8" midrange. That midrange does not have quite the bright upper end as the 'standard' B-209 midrange. So there was less doubling with the tweeters and not so much of a middle-high hump.
But none of these variations yield the flat, extended top end that occurs with the right xover mods. It is a credit to Bozak that, even with these built-in 'flaws,' the sound is still considered great by many. But if you heard them 'right,' the improvement is amazing.
Sorry this got so long, but it represents years of my investigations and Bozak developments.
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