Bozak b410 concert grande, room size

In an almost senior moment I told my wife I was buying her some speakers for her birthday, it was a joke, but she didn't think it was funny. Seriously.

I wont be pushing this agenda until April arrives. So they're still there.
 
So, I still covet the Bozak Concert Grandes, I think they're still there. He's been setting on them for 2 years. I've decided to hold back at that price point for now. But I would like to put them in the business. That way I can write them off and still listen to them everyday.

I have a couple of things I'd like to ask if any of you have any thoughts. Since I began this thread with the Bozaks' I don't know if this is appropriate or if I should start a new thread. The wife has given me permission to buy some EV Marquis in from AKer jstork in Detroit. They look to be in pristine shape.

I want some horns badly.

I think drbiggles suggested in one thread somewhere that one should pursue the speakers first. That makes sense to me.

There seems to be a bit of an issue with the EV horns for some. A Crites upgrade is suggested or a crossover change. I don't have any tube amplification yet. Tubes or both tubes and an upgrade? Any input positive or negative again would be greatly appreciated.

For shits and giggles any direct comparison between the Bozak Concert Grand and the EV Marquis

Please pardon my ignorance and lack of jargon to better explain this.

Most of my listening is Blues with some jazz and classical thrown in and the occasional scotch induced cranking of Vanilla Queen, the wife listens to pop piped in through the cable box.

Something else to ponder. Empire 7500 ii grenadiers. Cosmetically in pristine condition. Original family one owner, the wife used to babysit the kids. They have been in an attic for 20 years 5 blocks away. They seem to be rare, few mentions here on AK. The opinions of the sound quality are all over the place. I think I'm gonna pick them up just because they're rare. They will fit right in the house, background music, marble tops, cocktails and fondue. But are they any good? I don't really expect them to be.
 
I'd rather have the Bozak Concert Grands than almost any EV speaker ever built (short of Patricians, modded old Georgians, Sentry 500's, Georgian II's, and a few others). I own Sentry III's, 100A's, V's, Aristocrats/12TRXB's, modded older Georgians, a lone Patrician, and a few others. And Concert Grands. The Concert Grands run every day.

IIRC the EV Marquis are a very small Aristocrat corner cab that has very little in the way of low bass. The crossovers are potted in tar and are unserviceable. The tweeter will most likely be the absolutely horrifying T35, or the slightly more manageable but less extended and efficient T35B.
 
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IIRC the EV Marquis are a very small Aristocrat corner cab that has very little in the way of low bass. The crossovers are potted in tar and are unserviceable.

I agree with David's assessment that the EV Marquis speaker and crossover are nothing special.

But I'd qualify "unserviceable" as "unserviceable without a lot of stinky work". Which is usually indistinguishable from unserviceable for even moderate values of stinky work.

If the crossover is heated on a hotplate—do not ever do this inside your house or in your oven—just to the point of having the tar liquify it can be decanted and the guts removed. The tar doesn't stick all that well to components and the surface tension tends to keep it together.

Depending on the crossover type you may first need to unsolder the can's top with a torch, taking care to just melt the solder without scorching the can. Again, David is correct that these can be generally considered to be unserviceable.

No reason exists to re-pot the crossover so it can be left in its original shape and the can top need not be resoldered. The original potting was done to make a hermetic seal to keep water out of the wax-coated PIO capacitors which are hygroscopic. Horrible technology, best dead and buried. You can tell if the PIO capacitor is bad by dropping it in a trash can. If it goes "thunk" it is bad. If it makes a "plink" it is going bad.

The question is whether or not rebuilding the original crossover is worth doing becomes evaluating if (a) the inductors are sufficiently special or (b) having original equipment is important to you. YMMV. I would not touch those crossovers except as a learning exercise.

The tweeter will most likely be the absolutely horrifying T35, or the slightly more manageable but less extended and efficient T35B.

Yeah, pretty much. There is also a T-35a which is a ferrite magnet.

To be fair, it was a dark time in tweeter design, and most of the music was low-fidelity 78's played with a ceramic cartridge. The net effect was to add a low-pass filter at 8 kHz. Bozak B-200X tweeters have similar fidelity limitations.

Note: I do not own T-35s, having passed on the pair offered to me after doing some research. (Sometimes free is too expensive and too much trouble.) Here's the core of what I vaguely remember reading about them.

The original phenolic diaphragms (a) were apparently of poor quality compared to today's, (b) limited the response to about 10 kHz before impedance spikes ruined the response, and (c) the original diaphragms deteriorate over time. New diaphragms are claimed to move the response up to 14 kHz. Many replacements appear to exist, I have no idea what the differences between them might be or how well they fit.

Taking apart a T-35 and reassembling is apparently non-trivial because the magnet complicates alignment. Jigs were used for this purpose. My conclusion was that it costs more than an SEAS or AMT to have them repaired.

Smaller Bozaks will likely give you greater happiness than the E-V Marquis. Maybe even greater than the larger Bozaks if you lack the room size required for the drivers to converge and properly image.

You might want to first find someone nearby with a pair with rebuilt crossovers and an unreversed midrange. Audition them. Be amazed. Abandon quest for the Marquis.
 
I preferred the marquis over Bozak 302s with my Fisher 500c.

Did you have rebuilt crossovers with the un-reversed midrange and tweeter Zobel for the B-302?

Was this the later aluminum cone B-209B or Bc? Or the paper-cone or A version?

Just to be sure that this is an apples-to-apples comparison.
 
No work was done to either speakers, they were both estate sale finds. Btw if I ever find Concert Grands locally I would love to give them a shot
 
No work was done to either speakers, they were both estate sale finds. Btw if I ever find Concert Grands locally I would love to give them a shot

Well, that is the reason.

The Bozaks used horrible PIO motor-start capacitors (or similar) which are always bad, have high ESR/ESL, and which muddy the midrange. Since we live in the midrange, that means the speaker sounds absolutely terrible. A Bozak with a rebuilt crossover sounds so completely different, as many here can attest.

The smaller Bozak bookshelf speakers made that worse using non-polar electrolytics, ferrite-core inductors, aluminum inductors, and aluminum inductors with ferrite-cores. These are even more problematic than the PIO.

So it's always important to specify whether or not the crossover was rebuilt. It is a completely different speaker afterwards. It's like saying "oh, I listened to a McIntosh amplifier once. Had lots of noise and made a put-put-put sound. Total junk." Yeah, sure, send that junk my way.

The Concert Grands you find will sound terrible until the crossovers are rebuilt for the same reason.
 
Other than the B207 coaxial units that used a little metal-cased (possibly PIO) cap, almost every Bozak I've ever seen had wax-coated paper capacitors installed, which are indeed terrible and long past their use-by date.
 
Other than the B207 coaxial units that used a little metal-cased (possibly PIO) cap, almost every Bozak I've ever seen had wax-coated paper capacitors installed, which are indeed terrible and long past their use-by date.

Yes, Sam is absolutely correct.

The box has wax-papers, not motor start. The 2-ways used the motor-start capacitors.

All still horrible.
 
Glad to make your acquaintance Saltwater. You've got some concert grandes? ehh I'm not done with the search. I'm not convinced they are the way for me to go, I have always wanted some altec horns. That pair of EV Marquis seem very nice pristine on the inside. But I've also got my eye on a smaller (than the concert grands) set of Bozak 501 in very good shape. The reason I joined the fray was to quit buying over priced over rated vintage speaks. All this jargon about caps, crossovers, rolloff, is noise to me, it sounds political to me, which is fine, its nice to see people care about their equipment.

If it weren't for retrovert and sam cogley here at the end of this thread one might think Electro voice speaks are pure crap and Bozaks were constructed on the sixth day.

I did not buy them because of the price, advice I received in this thread, which like I said is one of the main reasons I joined ak.

Ive seen some of your stuff on the local C list place I think. Im not into this probably as much as you obviously are
 
ElectroVoice professional speakers are wonderful! Their relatively common 'classic' smaller consumer speakers are not. The potted-in-tar crossovers suck, too.
Aristocrat, Marquis, Low Resonance Compact System, are examples of speakers that would lose to Bozaks. Speakers that are pristene on the inside mean nothing to how they'll sound on the outside ;)

The EV Interfaces are quite nice, I've heard.

The EV Sentry 100A, 500, and V are AMAZING speakers, and ones I use to monitor recordings and transfer work. I plan on quad-amping my EV Sentry III's over 30" woofers jus to see what happens. Also the Sentry IVB will smoke an Altec VOTT in every way....once you biamp it with a 4th order crossover ;)

For pure musical and cinema enjoyment, I listen to Concert Grands. Rarely a day goes by that I don't listen to them, even if it's just for background music while doing chores around the house.

Recapping crossovers is apolitical. There are gargantuan improvements, which are easily audible. It's the cheapest and most effective upgrade you can make to a vintage system. Capacitors have a finite lifespan, which is about 20 years (especially for the older ones), and will have higher ESR (resistance), drift value, and sometimes even completely fail shorted, which means a blown speaker driver is in your future. Don't even get me started on amplification.

For instance, I recently got a pair of mismatched Altec Duplexes (604C, 605A), and with the stock crossovers, they sounded like crap. I bypassed them, went active with an Ashly XR-1001, and the difference was astonishing. The wonderful little details that were previously hidden were now in plain view. I went from wanting to just sell the speakers to deciding that I would keep them, and try to make pairs out of both. I had non-audiophile houseguests at the time, and they walked in the front door on day 2 (which is well out of the path of the speakers), and immediately noticed a difference for the better.

Bozak crossover capacitors are known junk. I almost left my Concert Grands in Mississippi because they sounded so freakishly terrible (and this was driven by a Krell KSA-100 and the TOTL Sansui preamp), but because I knew about the crossover caps, I took the plunge. I loaded $2250 speakers into my $1500 Astro van and drive back home from Mississippi to St. Louis. Replacing the capacitors was a revelation.

Crossover slopes work like this:
The steeper the slope, the faster the rolloff, and the less energy given to the driver after the crossover point. This is particularly critical for compression drivers. With steeper slopes, getting drivers to integrate well can be a bit of a challenge, but it's doable. With first order slopes, driver integration is much easier, if the drivers are well suited to handling a very wide range of input.
crossover_slopes.png

A 6db/oct (1st order) slope has 90º of phase shift, and sums together nicely. This requires one element (a capacitor or an inductor).
A 12db/oct (2nd order) slope has 180º of phase shift, thus necessitating reversing the polarity of the high pass section. This requires two elements
A 18db/oct (3rd order) slope has 270º of phase shift. This requires three elements.
A 24db/oct (4th order) slope has 360º of phase shift, and sums together nicely This requires four elements.

It's always advisable to have less elements in the crossover path, which is why I love active crossovers so much. 4th order slopes are possible with the amplifier connected directly to the driver.

Slopes are illustrated above for a 100hz crossover point.

Personally, I prefer 1st and 4th order crossovers. Anything else typically sounds weird to me, but most of the EV stuff uses 2nd order, and I just live with it. There's only so many active crossovers one can own, and a governor of the AES recommended that I buy Sentry 100A's, so I did, and I adore them stock. I'll be recapping them soon.

Bozaks, in order to sound anywhere near pleasing (and Sam will disagree with me on the tweeter thing) have to have B-800, B-800A, B-209B, B-209Bc or B-209C midranges, B-200Y, Yc, or Zc tweeters, and have the midranges operating in the correct phase with the woofers and tweeters. Typically, these were made after 1961. Anything before this will need to be updated. The B-209, B-209A midranges and B-200X tweeters are junk. Plain and simple.

Bozaks were designed to be flat sounding, and upon first comparison with a shouty Altec or JBL product, will sound dull and rolled off. After Rudy Bozak declared bankruptcy for the first or second time, someone decided to reverse the polarity of the midrange in order to make it 'pop' more. Listening to the Bozaks this way, it will sell well in a store, but will sound imprecise and incoherent (compared to proper polarity) when trying to dial in the best imaging and soundstaging.
 
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Glad to make your acquaintance Saltwater. You've got some concert grandes? ehh I'm not done with the search. I'm not convinced they are the way for me to go, I have always wanted some altec horns. That pair of EV Marquis seem very nice pristine on the inside. But I've also got my eye on a smaller (than the concert grands) set of Bozak 501 in very good shape. The reason I joined the fray was to quit buying over priced over rated vintage speaks. All this jargon about caps, crossovers, rolloff, is noise to me, it sounds political to me, which is fine, its nice to see people care about their equipment.

If it weren't for retrovert and sam cogley here at the end of this thread one might think Electro voice speaks are pure crap and Bozaks were constructed on the sixth day.

I did not buy them because of the price, advice I received in this thread, which like I said is one of the main reasons I joined ak.

Ive seen some of your stuff on the local C list place I think. Im not into this probably as much as you obviously are

I started with the 302a, then happened across cg's. haven't looked back really. I tried to sell them, then I bi amped them, Now I can't imagine selling them.

Caps, crossovers and roll offs will come in time. If you thinks it's not needed, pick up a stock epi 100 and change the cap in just one. Simple yet effective test.

If you need a hand with anything don't be afraid to message me, nice to see another local on here. There's a lot of good people here full of knowledge. Willingness to lend a ear is what's great about this site.

Bozaks were made on the 7th day, after a 3 day binge.
 
ElectroVoice professional speakers are wonderful! Their relatively common 'classic' smaller consumer speakers are not. The potted-in-tar crossovers suck, too.
Aristocrat, Marquis, Low Resonance Compact System, are examples of speakers that would lose to Bozaks. Speakers that are pristene on the inside mean nothing to how they'll sound on the outside ;)

The EV Interfaces are quite nice, I've heard.

The EV Sentry 100A, 500, and V are AMAZING speakers, and ones I use to monitor recordings and transfer work. I plan on quad-amping my EV Sentry III's over 30" woofers jus to see what happens. Also the Sentry IVB will smoke an Altec VOTT in every way....once you biamp it with a 4th order crossover ;)

For pure musical and cinema enjoyment, I listen to Concert Grands. Rarely a day goes by that I don't listen to them, even if it's just for background music while doing chores around the house.

Recapping crossovers is apolitical. There are gargantuan improvements, which are easily audible. It's the cheapest and most effective upgrade you can make to a vintage system. Capacitors have a finite lifespan, which is about 20 years (especially for the older ones), and will have higher ESR (resistance), drift value, and sometimes even completely fail shorted, which means a blown speaker driver is in your future. Don't even get me started on amplification.

For instance, I recently got a pair of mismatched Altec Duplexes (604C, 605A), and with the stock crossovers, they sounded like crap. I bypassed them, went active with an Ashly XR-1001, and the difference was astonishing. The wonderful little details that were previously hidden were now in plain view. I went from wanting to just sell the speakers to deciding that I would keep them, and try to make pairs out of both. I had non-audiophile houseguests at the time, and they walked in the front door on day 2 (which is well out of the path of the speakers), and immediately noticed a difference for the better.

Bozak crossover capacitors are known junk. I almost left my Concert Grands in Mississippi because they sounded so freakishly terrible (and this was driven by a Krell KSA-100 and the TOTL Sansui preamp), but because I knew about the crossover caps, I took the plunge. I loaded $2250 speakers into my $1500 Astro van and drive back home from Mississippi to St. Louis. Replacing the capacitors was a revelation.

Crossover slopes work like this:
The steeper the slope, the faster the rolloff, and the less energy given to the driver after the crossover point. This is particularly critical for compression drivers. With steeper slopes, getting drivers to integrate well can be a bit of a challenge, but it's doable. With first order slopes, driver integration is much easier, if the drivers are well suited to handling a very wide range of input.
View attachment 916657

A 6db/oct (1st order) slope has 90º of phase shift, and sums together nicely. This requires one element (a capacitor or an inductor).
A 12db/oct (2nd order) slope has 180º of phase shift, thus necessitating reversing the polarity of the high pass section. This requires two elements
A 18db/oct (3rd order) slope has 270º of phase shift. This requires three elements.
A 24db/oct (4th order) slope has 360º of phase shift, and sums together nicely This requires four elements.

It's always advisable to have less elements in the crossover path, which is why I love active crossovers so much. 4th order slopes are possible with the amplifier connected directly to the driver.

Slopes are illustrated above for a 100hz crossover point.

Personally, I prefer 1st and 4th order crossovers. Anything else typically sounds weird to me, but most of the EV stuff uses 2nd order, and I just live with it. There's only so many active crossovers one can own, and a governor of the AES recommended that I buy Sentry 100A's, so I did, and I adore them stock. I'll be recapping them soon.

Bozaks, in order to sound anywhere near pleasing (and Sam will disagree with me on the tweeter thing) have to have B-800, B-800A, B-209B, B-209Bc or B-209C midranges, B-200Y, Yc, or Zc tweeters, and have the midranges operating in the correct phase with the woofers and tweeters. Typically, these were made after 1961. Anything before this will need to be updated. The B-209, B-209A midranges and B-200X tweeters are junk. Plain and simple.

Bozaks were designed to be flat sounding, and upon first comparison with a shouty Altec or JBL product, will sound dull and rolled off. After Rudy Bozak declared bankruptcy for the first or second time, someone decided to reverse the polarity of the midrange in order to make it 'pop' more. Listening to the Bozaks this way, it will sell well in a store, but will sound imprecise and incoherent (compared to proper polarity) when trying to dial in the best imaging and soundstaging.

Complete agreement on the B200X tweeters. The B209A aluminum midranges are just fine, as long as the old, dried-out foam is removed. The paper B209 midrange is a better driver than its reputation, but it's not as clear as the aluminum version and can't handle as much power. The little B405 midranges that were used in some of the smaller Bozaks like the B301 are also underrated.

The B200Y tweeter was introduced right around the start of 1961. The B209A appeared in mid-1960 and was replaced by the B209B with the revised suspension allowing for the removal of the foam ring somewhere around 1963 or 1964.
 
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