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Vintage Asylum Classic gear from yesteryear; vintage audio standing the test of time. |
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In Reply to: Bozak with KLH ONE'S posted by sweetube@earthlink.net on December 29, 2003 at 22:46:49:
Hi Bob - I know a little about Bozak, but nothing about KLH. So I can't even begin to guess about the relative efficiencies. Except for one observation - "in the early days" Bozak was considered a system of low reference efficiency when compared with other large systems - Altec, JBL and others, especially Klipsh. But when the acoustic suspension systems came out with very low reference efficiency, suddenly the Bozaks were at least medium efficiency, and I haven't heard anyone call them low efficiency since! So it's possible that the Bozak mid and tweeter pair might even be higher reference efficiency than the KLH woofers. If that is the case, you could lose an easy 6 dB by using the 16 ohm version of the Bozak midrange. But if the 8 ohm version is closer in efficiency, there is nothing wrong with using a mix of 16 and 8 ohm drivers, so long as the xover is optimized for the individual driver.I think that likely no better midrange has ever been made than the Bozak B-209B/C, so it's a worthy project. But there is the danger that the superb transient response of the midrange might contrast audibly if the KLH woofers aren't as good in that respect; it is discomforting to hear a clear difference in any parameter of audio response from one frequency range to another. The Bozak woofs are damned good in transient response. If you use the recommended first order xovers, you would want to cross over at about 400; stay at least an octave away from where the KLH woofers roll off naturally.
There are two ways to go with the tweets. I don't suggest the 4-pair array; that was great for the mono concert grands, but the very wide dispersion, great for a single mono system at the center of a wall, is not as effective for stereo. Furthermore, that array was brought out to handle (with 8 individual tweeter units) the 100 watts that the Concert Grands could eat, using the early B-200X tweeters. With their paper cones, they couldn't handle the power of the later B-200Y and B-200Z, whose aluminum cones offer the world's best heat sink for the VC.
Depending on the power the KLH woofs will handle, I would suggest either a single tweeter pair, or an array of four (two pairs). Yes, I know the Bozak Symphonies and stereo Concert Grands used a row of 8. That's convenient for impedance matching, but not otherwise necessary except in a 100 watt four-woofer system such as the CGs; certainly not necessary for power handling in the Symphonies. If you are going to run more power than 30 watts, I suggest an array of four. I can make suggestions for impedence matching off line; this is getting too long already.
For tweeters, definitely not the paper-coned B-200X, the ones with the bright center caps. By far the best are the B-200Z, but they were introduced only in 1977 and are relatively scarce. But they are flat to 20kHz and cleaner than the law allows.
Far more plentiful is the B-200Y, made for about 15 years. There's good news and bad news about the Y. The bad news is that, like the B-200X, the Y's roll off softly in the top octave. The good news is that the Y's are 9 dB hotter than the Bozak B-199A woofer and B-209B/C midrange, so unless you want to run them that hot, there is level to play with. I use a T pad to drop the excess 9 dB, bypassed by a 2.0 uF cap to tilt the highs back up above 10 kHz. Works like a charm; with that setup it's hard to hear the difference between them and the Z's.
Bob, while an exhaustive treatment would be far too lengthy for this forum, and I don't know anything about the KLH woofs anyhow, I hope this will give you some starting pointers. Feel free to rattle my cage for further discussion.
With best holiday wishes,
Pat Tobin
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Follow Ups
- Re: Bozak with KLH ONE'S - AudCon 00:44:44 12/30/03 (2)
- Re: Bozak with KLH ONE'S - sweetube@earthlink.net 09:57:41 12/30/03 (1)
- Re: Bozak with KLH ONE'S - AudCon 21:48:47 12/30/03 (0)
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