Bozak Mystery

[schoonbeke]

I bought some Bozaks in custom cabinets about seven years ago. They were made for the seller's parents in about 1959. They gave me the original documents, including a Bozak catalogue and price list. I thought they were Symphony speakers until recently when I replaced the (cat damaged) grill cloth on one. To my surprise, instead of two 12 inch woofers, a midrange and eight tweeters I found two 10 inch woofers, a midrange and four tweeters. See attached photos.

I didn't think Bozak made a 10 inch woofer, and no such speaker appears in the catalogue or price list. Yet here they are.

Does anyone have an explanation? Did the Bozak 12 inch woofers actually measure 10 inches?

 

[Steve Smiley]

No ten inch woofer from Bozak that I know of...try and post your photos again. They are not attached.

 

[schoonbeke]

No ten inch woofer from Bozak that I know of...try and post your photos again. They are not attached.

Just added the photos.

 

[drbiggles]

That's one of them foreign measuring sticks. Trust me, you got the real Bozak B199 12" woofers.

Biggles

 

[Steve Smiley]

Yep, those are Bozaks. The B-199 woofer. It is a 12 inch, an early one, but they never changed. I find the cut out for a rear mounted woofer from the factory to be 11 inches. A factory cut out for a surface mount is 11.5 inches. That has the paper mid and the B200x tweeter.

BTW those cabinets look very nice.

Smiley

 

[schoonbeke]

Yep, those are Bozaks. The B-199 woofer. It is a 12 inch, an early one, but they never changed. I find the cut out for a rear mounted woofer from the factory to be 11 inches. A factory cut out for a surfqace mount is 11.5 inches. That has the paper mid and the B200x tweeter.

BTW those cabinets look very nice.

Smiley

Thanks for your informative response. The cabinets are nice. I've attached another photo including the grill cloth bane.

There was originally a 9 foot top with three feet between the speaker enclosures, but I had to cut it down to two separate three foot tops. The original owners lived in a suburb of Philly and were ardent members of the Philadelphia Orchestra. I didn't manage to get their Thorens turntable or the smaller Bozaks, but I was invited to take any records I wanted. The speakers were dirt cheap ($300), but I had to rent an SUV to transport them. Seems that people don't want such large HiFi equipment any more, but I find it useful to accommodate other components.

 

[Steve Smiley]

You are very welcome. The grill covers look great as well...I hope that cat of yours isn't eyeing those woofer cones Bozaks led me to bigger and bigger cabinets...I have Concert Grande cabinets in the garage waiting for me to work on. The bad news is my wife's car is not in the garage this winter because of it. I'm in a little bit of trouble right now. I'm not holding up my part of the bargain now.

I don't plan on going small with my hobby, but I certainly can understand the draw of downsizing.

Let us know if there is anything we can do for you. You've already attracted the attention of drB (hello @drbiggles , I hope all is well) who has advised and mentored many a member of the Bozak cult, including myself. Retrovert is around as well, who is an absolute wiz with everything Bozak! And it's because of him that I can speak with confidence about Bozak (and a few other things as well). Now that you are taking things apart, maybe you want to do a little updating, if you haven't already...

Enjoy!

 

[schoonbeke]

You are very welcome. The grill covers look great as well...I hope that cat of yours isn't eyeing those woofer cones Bozaks led me to bigger and bigger cabinets...I have Concert Grande cabinets in the garage waiting for me to work on. The bad news is my wife's car is not in the garage this winter because of it. I'm in a little bit of trouble right. I'm not holding up my part of the bargain now...I don't plan on going small with my hobby, but I certainly can understand the draw of downsizing.

Let us know if there is anything we can do for you. You've already attracted the attention of drB (hello @drbiggles , I hope all is well) who has advised and mentored many a member of the Bozak cult, including myself. Retrovert is around as well, who is an absolute wiz with everything Bozak! And it's because of him that I can speak with confidence about Bozak (and a few other things as well). Now that you are taking things apart, maybe you want to do a little updating, if you haven't already...

Enjoy!

I've kept him away from the speaker cones and the living room rug (though all our other rugs are tragically clawed).

What updating do you suggest? I've seen a lot of posts about Bozak crossovers.

My biggest annoyance is my radio reception, especially on the Yamaha CR-2020. I've thought about putting an antenna on the roof, but it would be expensive, and I'm not sure it would help. Plus I can just stream the stations (though it goes against a long lifetime of habit). (Great jazz stations here--WBGO and WKCR.)

I had some Urbans but they didn't cut it with orchestral music. These are acceptable. Your Concert Grands would do the job, but I've read they are better heard from another room.

 

[drbiggles]

I've kept him away from the speaker cones and the living room rug (though all our other rugs are tragically clawed).

What updating do you suggest? I've seen a lot of posts about Bozak crossovers.

My biggest annoyance is my radio reception, especially on the Yamaha CR-2020. I've thought about putting an antenna on the roof, but it would be expensive, and I'm not sure it would help. Plus I can just stream the stations (though it goes against a long lifetime of habit). (Great jazz stations here--WBGO and WKCR.)

I had some Urbans but they didn't cut it with orchestral music. These are acceptable. Your Concert Grands would do the job, but I've read they are better heard from another room.

3 way Bozaks are essentially all the same speakers, it's just the size of the cabinets that vary. So, you don't like orchestral music in 5 cubic foot cabinets? And if any speaker sounds better in another room, that room is too small or has incorrect treatments. It's not the speakers fault.

Biggles

 

[jcidave]

Does anyone have an explanation? Did the Bozak 12 inch woofers actually measure 10 inches?

You don't measure the cone of the speaker to determine its size. You measure the diameter of the outer edge of the cone basket frame. In your case, as these speakers sit, you can't do that because the speaker frame is hidden behind the wood baffle. If you remove the woofers from the cabinet and put your ruler across the widest diameter of the woofer frame, it will be 12 inches.

Knowing you already had to fix the grills due to cat damage, and having that cat sitting there looking ready to strike again would make me very nervous.

 

[Steve Smiley]

I've kept him away from the speaker cones and the living room rug (though all our other rugs are tragically clawed).

What updating do you suggest? I've seen a lot of posts about Bozak crossovers.

My biggest annoyance is my radio reception, especially on the Yamaha CR-2020. I've thought about putting an antenna on the roof, but it would be expensive, and I'm not sure it would help. Plus I can just stream the stations (though it goes against a long lifetime of habit). (Great jazz stations here--WBGO and WKCR.)

I had some Urbans but they didn't cut it with orchestral music. These are acceptable. Your Concert Grands would do the job, but I've read they are better heard from another room.

Ok, let me see what I can offer, although with Bozaks, some might call me a butcher...

As far as your Yamaha is concerned, I have no experience with that one, other than understanding it is a well-respected unit! I will offer that I have a Luxman receiver that had trouble with reception. I played with a simple dipole FM antenna and after playing a bit, got it just right and have been enjoying a local classic rock station quite a bit. I would expect a improved antenna situation might be your answer. Is the investment for one on the roof worth it? Only you can judge. A great Jazz station would be worth it, in my book. Have you had your Yamaha serviced at all? Maybe you need some cap refreshes, etc.

On to the Bozaks... When a Bozak is right, I don't see a classic music lover, any music lover for that matter, passing them on, unless it is for a bigger cabinet version...as @drbiggles suggests.

So what you can do (and i'll try to do this in some sort of order...):

-Update the capacitors in your existing crossover, swap same value for same, but new- audio grade
-Swap out the four B-200x tweets for two B-200y, or B-200z, if you can find them
-Swap out the paper cone mid for a later version, aluminum cone, oooh so nice!
-Tobin mods on the crossover
-Add a super-tweeter and convert the crossover to 4-way
-Swap the two 16 ohm woofers for one 8 ohm...

That's a lot to digest, I know...start with new caps. Simple, and then you can see where that leads...

Smiley

P.S. Let me add, what you have there, in the end, should be quite impressive, flying right past acceptable

 

[schoonbeke]

3 way Bozaks are essentially all the same speakers, it's just the size of the cabinets that vary. So, you don't like orchestral music in 5 cubic foot cabinets? And if any speaker sounds better in another room, that room is too small or has incorrect treatments. It's not the speakers fault.

I don't pretend to any expertise. I only know what sounds good to my ears. I liked the Urbans at first, but then got frustrated--I wanted more. With these I can enjoy my favorite orchestral music (Stravinsky's Petrushka and Firebird) without that feeling of something lacking. As for the Concert Grands, I've never had the chance to listen to them.

You don't measure the cone of the speaker to determine its size. You measure the diameter of the outer edge of the cone basket frame. In your case, as these speakers sit, you can't do that because the speaker frame is hidden behind the wood baffle. If you remove the woofers from the cabinet and put your ruler across the widest diameter of the woofer frame, it will be 12 inches.

Thanks. I didn't know that. The speakers aren't visible from the back of the cabinets.

Knowing you already had to fix the grills due to cat damage, and having that cat sitting there looking ready to strike again would make me very nervous.

I think he's already given the new grill cloth a tug. I turned the original grill cloth upside down, put it back on, and installed the new grill cloth over it.

 

[schoonbeke]

Ok, let me see what I can offer, although with Bozaks, some might call me a butcher...

As far as your Yamaha is concerned, I have no experience with that one, other than understanding it is a well-respected unit! I will offer that I have a Luxman receiver that had trouble with reception. I played with a simple dipole FM antenna and after playing a bit, got it just right and have been enjoying a local classic rock station quite a bit. I would expect am oi,mp[roved antenna situation might be your answer. Is the investment for one on the roof worth it? Only you can judge. A great Jazz station would be worth it, in my book. Have you had your Yamaha serviced at all? Maybe you need some cap refreshes, etc.

On to the Bozaks... When a Bozak is right, I don't see a classic music lover, any music lover for that matter, passing them on, unless it is for a bigger cabinet version...as @drbiggles suggests.

So what you can do (and i'll try to do this in some sort of order...):

-Update the capacitors in your existing crossover, swap same value for same, but new- audio grade
-Swap out the four B-200x tweets for two B-200y, or B-200z, if you can find them
-Swap out the paper cone mid for a later version, aluminum cone, oooh so nice!
-Tobin mods on the crossover
-Add a super-tweeter and convert the crossover to 4-way
-Swap the two 16 ohm woofers for one 8 ohm...

That's a lot to digest, I know...start with new caps. Simple, and then you can see where that leads...

Smiley

P.S. Let me add, what you have there, in the end, should be quite impressive, flying right past acceptable

Thanks for the suggestions. It is a lot, especially since I am an electronics ignoramus. But I might manage to do at least some of this. If anyone reading this has B-200y or B-200z tweeters or aluminum cone mids in good condition for sale at reasonable prices, please contact me. I have previously read that the aluminum cone tweeters are inferior to the paper ones. Funny to hear you say the aluminum mids are better than the paper ones, but I believe you.

 

[drbiggles]

Schoonbeke,

You're going to want to take a back off one of your cabinets and see if you have 8ohm woofers or 16ohm woofers, 16ohm mids or 8ohm mids. You'll also want to get into your crossover to get an inventory of the capacitors you have to buy so you can replace them. Capacitors age, your non-polar electrolytics had a shelf life of about 10 to 20 years at best. If you join the facebook Bozak users group and post something there, you can surely find someone who can update those for you. That way you can hear your rigs as soon as possible, as they did 70+ years ago.

Then you can decide if you'd like to upgrade your paper tweeters and midrange drivers to the more desirable aluminum cone versions. You misread the post you were reading, the later versions are the better ones. Your tweeters die and are gone by 8k. The aluminum version get up to 10 and 12k before they up and die, and they're far cleaner in their presentation. They do what they do very well. The aluminum cone midranges are are absolutely stunning, world class midrange drivers. They'll stand toe to toe with modern drivers, many times wiping the floor with them. If your Urbans were properly updated, you could have smelled the wood in a cello concerto. The strings would have made you cry. Also keep in mind your early woofers don't have the power handling capability that the later woofers do, so be judicious with the volume knob. The later Bozaks are rated at 50 watts, yours is less. Your ear will tell you when to stop. All Bozaks absolutely excel at orchestral music. There was something wrong with your Urbans, it wasn't their fault.

There are other little things to look for that we can do to update your Bozaks to improve them. They must be lined with 100% cotton batting, have the signature swinging curtain, and the midrange driver must have the back covered. This can be done with a plastic flower pot over the back. The backwaves from the woofers beat the midrange and muddy the performance of the mid, the flower pot isolates it. All things to consider.

Biggles

 

[schoonbeke]

Schoonbeke,

You're going to want to take a back off one of your cabinets and see if you have 8ohm woofers or 16ohm woofers, 16ohm mids or 8ohm mids. You'll also want to get into your crossover to get an inventory of the capacitors you have to buy so you can replace them. Capacitors age, your non-polar electrolytics had a shelf life of about 10 to 20 years at best. If you join the facebook Bozak users group and post something there, you can surely find someone who can update those for you. That way you can hear your rigs as soon as possible, as they did 70+ years ago.

Then you can decide if you'd like to upgrade your paper tweeters and midrange drivers to the more desirable aluminum cone versions. You misread the post you were reading, the later versions are the better ones. Your tweeters die and are gone by 8k. The aluminum version get up to 10 and 12k before they up and die, and they're far cleaner in their presentation. They do what they do very well. The aluminum cone midranges are are absolutely stunning, world class midrange drivers. They'll stand toe to toe with modern drivers, many times wiping the floor with them. If your Urbans were properly updated, you could have smelled the wood in a cello concerto. The strings would have made you cry. Also keep in mind your early woofers don't have the power handling capability that the later woofers do, so be judicious with the volume knob. The later Bozaks are rated at 50 watts, yours is less. Your ear will tell you when to stop. All Bozaks absolutely excel at orchestral music. There was something wrong with your Urbans, it wasn't their fault.

There are other little things to look for that we can do to update your Bozaks to improve them. They must be lined with 100% cotton batting, have the signature swinging curtain, and the midrange driver must have the back covered. This can be done with a plastic flower pot over the back. The backwaves from the woofers beat the midrange and muddy the performance of the mid, the flower pot isolates it. All things to consider.

Biggles

 

[schoonbeke]

Thanks.

I took off the back of one as you suggested (28 screws). The cabinets are lined (top, bottom, sides and back) with fiberglass, and there is a two piece fiberglass baffle. I've attached photos. I don't know whether this is the "swinging curtain" that you mention. The woofers are 8 ohm. I'm not sure about the midrange speaker. The four 200x tweeters are enclosed in a plywood container so not visible from the back. The aluminum cone on one (farthest left) is damaged. I've attached some photos, including the crossover, which I don't pretend to understand. I assume the boxy thing is a capacitor. What are the doughnut shaped components?

I'd appreciate any explanations and advice. I will look at the Facebook Bozak group.

 

[schoonbeke]

I've been looking at crossovers online and understand now that the round things are inductors and that the capacitors are inside the black box. I could probably handle replacing the capacitors, lining and baffles. I've found the Bozak group on Facebook and asked to join. Perhaps I can find someone in the NY/North Jersey area to advise and help.

 

[Steve Smiley]

Thanks to @drbiggles for suggesting to get the backs off those things, as it goes a long way in providing you direction for action.

It looks to me like you have Bozak B-305 components in your speakers, as opposed to the Symphony components. If that is an accurate guess, the mid is probably a 16 ohm mid. I'm not very familiar with the B-305 crossover network, but the info is readily available.

The boxy thing is an enclosure that actually contains the capacitors. The doughnuts are the inductors. The inductors are good, the caps you will want to replace.

The fiberglass insulation is something you will want to replace with cotton batting. I know people have found a source for the batting but I haven't seen it posted. Hopefully someone can chime in. You will not get the performance you want with the infinite baffle design (that's Bozak) without the appropriate batting. You will also want to add the flower pot over the mid. When I get a chance, I can share a link to the Home Depot version to give you an idea.

You can replace all four of the B-200x with four B-200y for the same layout on your baffle.. Those are most likely set up on a series/parallel configuration so that it shows as a 16 ohm load...heck, you can just use one of them for that matter. A B-200y single is a 16 ohm load.

I would recommend you become an AK subscriber and then you can post a WTB for parts. It's only $25 for the year and a good resource. There is also a few online marketplaces. You should also join the Facebook Bozak group. There is good info and help there, knowledge and possible parts.

 

[Steve Smiley]

I see your update now. Yes, I think all of this is doable for you. And there is good help available. You will be very happy with the improvements. Along with that will also come a sense of satisfaction from rolling up your sleeves and having some hands on success with your project!

Hang in there! The effort will be well worth it!

Smiley

 

[Steve Smiley]

Here is the planter i've been using from home depot as an enclosure for the midrange. You will want to line this with the cotton batting as well. Not a bad idea to wrap the outside of it as well...

https://www.homedepot.com/p/Dynamic...x-7-in-Black-Resin-Planter-NB0824BK/203629859