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Bozak Crossover Differences

62sunbeam

62sunbeam

Raconteur
I have a pair of E-302s with matching cabs and matching paper tweeters but that's about it.

Here are the two different crossovers:





The fist one looks like it's been tampered with:



Mid drivers are also different:





As are the woofers:





The tweeters are the same paper cones though.

AND the speaker lead terminals aren't labeled + or -.

I have no idea where to begin.

Thanks

Eric
 
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Well, you have one cabinet with all Alnico drivers, which has the B200X paper tweeters. The second one has had everything replaced with ceramic magnet drivers (at least, presumably the tweeters on that B207 match the B199 woofer). IMHO, they're the best that Bozak made.

The crossover with the two oil caps has been modified, though cap changes are a big part of the Tobin mods. I built the new cap and resistor network in the old cap box, which you have on the other chassis. However, it's not necessary. Just use some solder lug terminal strips and wood screws to build some mounting points where the cap box used to be.

If I had these, I would start looking for ceramic replacement drivers for the all-Alnico cabinet. The B200X tweeters don't have much resale value, but the Alnico woofer and midrange should help recoup a fair bit of the cost.
 
So the alnico mid and low drivers should be swapped out for ceramic ones and the crossovers should both be modded to the Tobin specs?

The ceramic drivers are really the preferred way to go?

It really is a cluster F#%^ in there.

Any idea which should get the positive speaker lead? I guessed right but I have no idea if that's right and the right speaker sounds significantly different than the left and I don't know if it's a phase/polarity thing or the difference in the drivers and crossovers.

Thanks

Eric
 
The "1" terminal is common, "2" is signal. There should have been markings by the terminals on the outside, but sometimes they fall off. The crossovers should be marked.

That one with the oil caps and resistors looks like someone was trying to do something similar to the Tobin crossover modifications.

I experimented with the ceramic and Alnico magnet drivers side-by-side while I was scratching up enough parts to upgrade both of my cabinets, and I thought the ceramics sounded a bit more clean and tight. You also have what appears to be a 16 ohm mid in the Alnico cabinet where it should be an 8 ohm driver. I think you'll be happiest with the results, and they'll have the most resale value, if you get all of the drivers matching and the crossovers rebuilt to the same specs.

I think someone recently had some B200Yc tweeters in Barter Town. Might be worth a look. The tweeters used in the pairs are 16 ohm, wired in series to get an 8 ohm load. Oftentimes the impedance was just marked for the pair when they were sold that way.
 
Bozak on early production units had no labels that indicated terminals. Someone I suspect had a mono unit and if I got the photos right picked up a 300 and upgraded it to a 302. That is why there is a condensor on the frame of the woofer.

Looks like a bit of a project but drivers are still common as persons rip, strip and dismantle these great systems. In the end you will have a great speaker system. I only sold my Symphonys and 302s because I am downsizing and both are too large for a future system, sadly. I had the 302s for some 24 years and the Symphonys for 15.
 
62sunbeam said:
I'm talking about on the exterior of the cabinet nothing is marked. Inside or out.

Thanks

Eric
Click to expand...

Whoever owned them prior to you got creative as all that internal wiring should be pretty much green and orange like on your crossover below. The brown wire and scotch taped splices look to be new work.

I'll look at my backs later and see what the deal is.

image.jpg7_4.jpg
 
Sam Cogley said:
The "1" terminal is common, "2" is signal. There should have been markings by the terminals on the outside, but sometimes they fall off. The crossovers should be marked.
Click to expand...

Yep, I had it backwards; I thought the caps were on the positive leg, but the pic of the Tobin crossover, shows that not to be the case.

attachment.php
 
Just an FYI, that schematic is the 800Hz 101T. The 400Hz 104T gives an overall better sound. The B199 doesn't like trying to reach very high.
 
Sam Cogley said:
Just an FYI, that schematic is the 800Hz 101T. The 400Hz 104T gives an overall better sound. The B199 doesn't like trying to reach very high.
Click to expand...

But the wiring color is the same. The 104T goes to a 50 uf cap and switched the woofer to the 3.0 uf tap on the big coil. It's been over a month since I did my build.

attachment.php


FWIW, I think the B199 sounds fine in my E-waves and it's crossed there at 900. Tobin says it can go to 4500. The OP will have to determine what he suits him best.

From SHF...

"The B-199A's roll off at 4,500 Hz. In the Bozak B-207A 2-way 'coaxial' system, a capacitor of 4.5 uF is used in series with the 8 ohm tweeter pair to bring it in at 4,500 Hz.
"In the 3-way systems a 'full' crossover is used which rolls off the feed to the B-199A at either 400 Hz or 800 Hz, depending on whether it is a multiple woofer system or single woofer. The tweeter is brought in at 2,500 Hz in the 3-way systems.

Pat Tobin"

http://forums.stevehoffman.tv/threads/how-high-can-bozak-b199-go-up-to.125808/
 
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Hi Eric- Yep you have some early alnico drivers in the cabinet with the original crossover. I personally feel that the alnico and ceramic woofs sound pretty close but the x versus y tweeters are like night and day. I would sort the crossovers out and make sure you have all y tweets.

As Sam says someone had a boatload of y tweets on B-Town and that would be the main thing to replace as far as drivers go. I have never heard the ceramic mids but would listen to them before you try to match them you might not detect much of a difference. In general the magnet type has not sounded that different to me with the bozak drivers but the paper versus aluminum cone mids/tweets do. You already have two aluminum mids albeit different magnet types you might be good as is.

Double check the all black woofer (the later one, looks like it is from about '75 if I am reading the date code correctly) and unless tampered with might have the y's already or possibly even yc's. If you shine a light through the grilles and don't see a shiny dust cap shining back on you they should be the aluminum domes as the paper X's had shiny aluminum dust caps. Looks like someone was replacing the original "box 'o caps" with separate oil capacitors for the mid and tweeters.

Good luck with that project (should sound dynamite with the Pilot) The 302a's in the Utility E-300 cabs are exactly what I was using and they were an awesome match. :thmbsp:

Brian
 
Andyman said:
But the wiring color is the same. The 104T goes to a 50 uf cap and switched the woofer to the 3.0 uf tap on the big coil. It's been over a month since I did my build.

attachment.php


FWIW, I think the B199 sounds fine in my E-waves and it's crossed there at 900. Tobin says it can go to 4500. The OP will have to determine what he suits him best.

From SHF...

"The B-199A's roll off at 4,500 Hz. In the Bozak B-207A 2-way 'coaxial' system, a capacitor of 4.5 uF is used in series with the 8 ohm tweeter pair to bring it in at 4,500 Hz.
"In the 3-way systems a 'full' crossover is used which rolls off the feed to the B-199A at either 400 Hz or 800 Hz, depending on whether it is a multiple woofer system or single woofer. The tweeter is brought in at 2,500 Hz in the 3-way systems.

Pat Tobin"

http://forums.stevehoffman.tv/threads/how-high-can-bozak-b199-go-up-to.125808/
Click to expand...

It may well be able to, but after quite a bit of study on his part, Mr. Tobin advocated using the 400Hz crossover point for all Bozak implementations. I can only assume that the B199 starts doing something before 800Hz that isn't terribly desirable. I do know that my B302s developed a more clean and clear sound after switching to the lower crossover point.

Sandstrom said:
Hi Eric- Yep you have some early alnico drivers in the cabinet with the original crossover. I personally feel that the alnico and ceramic woofs sound pretty close but the x versus y tweeters are like night and day. I would sort the crossovers out and make sure you have all y tweets.

As Sam says someone had a boatload of y tweets on B-Town and that would be the main thing to replace as far as drivers go. I have never heard the ceramic mids but would listen to them before you try to match them you might not detect much of a difference. In general the magnet type has not sounded that different to me with the bozak drivers but the paper versus aluminum cone mids/tweets do. You already have two aluminum mids albeit different magnet types you might be good as is.

Double check the all black woofer (the later one, looks like it is from about '75 if I am reading the date code correctly) and unless tampered with might have the y's already or possibly even yc's. If you shine a light through the grilles and don't see a shiny dust cap shining back on you they should be the aluminum domes as the paper X's had shiny aluminum dust caps. Looks like someone was replacing the original "box 'o caps" with separate oil capacitors for the mid and tweeters.

Good luck with that project (should sound dynamite with the Pilot) The 302a's in the Utility E-300 cabs are exactly what I was using and they were an awesome match. :thmbsp:

Brian
Click to expand...

I thought the ceramic B199 sounded more tight and precise. YMMV. :thmbsp: Swapping out the tweeters and getting an 8 ohm mid in there are overall more important than the magnet material, though.
 
Well I've tracked down all the ceramic drivers as well as the later tweets and now it's a matter of economics. I might have to move some stuff.

A question about the Tobin mods. I have source for NOS PIO caps near me would there be any benefit to using these as opposed to new electrolytics?

Thanks

Eric
 
Should be. Bozak really only made one crossover design, they just changed the wiring around to make it do different things.
 
Are all 199B drivers ceramic? If mine has a tiny "c" after the "B" would that make it different than one without the tiny "c"?

Same thing with the mids. Does the tiny c mean something?

Thanks

Eric
 
62sunbeam said:
Are all 199B drivers ceramic? If mine has a tiny "c" after the "B" would that make it different than one without the tiny "c"?

Same thing with the mids. Does the tiny c mean something?

Thanks

Eric
Click to expand...

The lowercase "c" stands for "Ceramic," though not all ceramic drivers seem to have been labeled as such. The Alnico and ceramic drivers are easy to identify visually, though. The Alnico magnets are thicker and shaped differently. Bozak also did a hard changeover to ceramic magnets sometime in 1970 or 1971. I have yet to see an Alnico driver with a date code in 1971 or later.

Sam Cogley said:
Should be. Bozak really only made one crossover design, they just changed the wiring around to make it do different things.
Click to expand...

I should qualify this statement...they made one basic crossover design for the 302, Symphony, and CG. The 305 got a 16 ohm version, and the smaller B301, Bard, and pro towers got different crossovers suited to those applications.
 
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Not 100% certain, but if memory serves - per Pat Tobin, for Bozak drivers labeled "BC", the B pertains to mounting design (to baffle): B = Back; both are defintely ceramic.
 
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