Bosak in Custom Cabinet

[Scuby22]

Ok, so this is my first post and it would be great if I could get some guidance. I picked up what appear to me as custom made Bozak speakers as I cannot find them in any catalog. These things are approx. 100lbs+ and the maple looks beautiful in person. These were purchased from an estate sale and the doctor that owned them had some very nice furniture. I brought them home and hooked them up to me receiver and they sound very very good.

I'm more inclined to leave well enough alone but I've included some pictures because there was one thing I found odd. There is an N-4 crossover on the sub basket and the wire is cut? I've read lots about the Tobin mods, but haven't seen anything referencing cutting this wire.

The cabinets are 36"x24"x19" and sealed tight with 3" wood screws. My fiance and I hauled them up to my third floor apt. and that was not fun. But once I hooked them up, she was really impressed.

Many people want to improve upon something to make it "better" but sometimes it's pretty cool to have something restored to it's original state.

1. Should I re-connect the N-4 orange wire?
2. Should I recap the 10104? I've read always recap as they degrade over time...
3. Should I do the Tobin mod?

I'd just like to get your .02

Thanks,
Scuby

 

[Rybeam]

Bozak, I love them, I have three different pair. Are all the speakers working ? If so get you a nice amp and enjoy IMO.

 

[Scuby22]

Thanks! That's whats happening right now!

So how do I correct the thread name to Bozak??

 

[jobrewer1983]

Z

 

[Scuby22]

lol

 

[quiet]

Are you familiar with the damping material Bozak used?

 

[Scuby22]

No. It appears to have the typical pink insulation currently.

 

[toxcrusadr]

Paging @vinyldavid, Bozak nerd! Er, expert.

Or @SamCogley

This might be a cap for a tweeter that was mounted in front of the woofer in some versions.

http://audiokarma.org/forums/index.php?threads/bozak-n-4a-crossover-condenser.664676/

In which case you wouldn't need it and that's why it's disconnected.

Edit: After reading the posts below and looking at the pics and smacking my head, I now realize the mid is mounted separately but the tweeters are probably in front of the woofer.

 

[bshorey]

Do a search, there are many Bozak discussions on AK.

The first thing to do is determine which drivers you have, are the mids and tweets paper cone or the later metal cone?

If they're paper cone, I'd probably move the jumpers to lower the low/mid crossover point, and recap the crossovers. If they're metal cone, then Tobin mods are nice, but I removed the resistor that pulls down the tweeter - the initial result was too dull for me. Some put in L-pad in series with that resistor.

One thing you absolutely should do is build the subenclosure for the mid. Eliminating woofer backwaves from the mid makes a big difference.

As good as these sound to you now, you can make them sound even better.

bs

 

[quiet]

You appear to have Y tweeters. Not as good as Z but better than X. I think.

No. It appears to have the typical pink insulation currently.

Typical for large Bozak infinite baffle speakers such as the popular 302a that use your drivers and crossover is a blanket of cotton batting on the walls. Bozak used fiberglass to completely fill some of their small acoustic suspension speakers. Such as the 301a Tempo book shelf speaker that use your woofer and tweeter with a similar and very good mid driver. Mr. Bozak never said anything good about the small box speakers he made.

 

[Scuby22]

Wow, that was a quick response! Currently, I'm not sure how to confirm paper vs. metal tweeters. The reason is the speaker cloth seems to be glued to the front panel with the driver bolted to it.
The only way to check which tweeters is to remove the back panel that has approx. qty (24) - 3" wood screws and pull out the subs from the inside.

I'm just describing this so if anyone else has a better idea on how to determine if I have paper or metal cones?

 

[quiet]

Your crossover indicates a metal tweeter. If so the mid will be also. I think.
You're good to go. Get some cotton batting for the walls and curtain that goes behind the woofer. Read, you'll see. Then you'll hear.
This is not going to be a smoking fast bass with super highs type of speaker. I have 302As. I like them.

 

[drbiggles]

Your crossover indicates a metal tweeter. If so the mid will be also. I think.
You're good to go. Get some cotton batting for the walls and curtain that goes behind the woofer. Read, you'll see. Then you'll hear.
This is not going to be a smoking fast bass with super highs type of speaker. I have 302As. I like them.

Nope, he has the B209 mids. They have a date code of September of 1958. He's got a mishmash of drivers. One shouldn't assume the original builder knew what they were doing and gauge the drivers by the way the crossover is configured. Especially since they used fiberglass batting instead of Rudy Bozak's choice of 1" 100% Cotton Tufflex (Tufflex is no longer available). And the glaring absence of Rudy's secret weapon, the swinging cotton curtain.

If you shine a light through the grill cloth over where the woofer is mounted, you may be able to see the 2 tweeters mounted over the woofer. If you see 2 shiny dust caps, you have the 1950's X tweeters. If no shiny dust caps, you're good to go for those. And that's what I suspect you have.

Biggles

 

[toxcrusadr]

To the OP, not to put too fine a point on it, but those are woofers, not subwoofers. Subwoofers are typically in their own cabinets and are designed to operate below where woofers normally do. Two different animals.

I'm going to let the Bozak cavalry handle this one since they have arrived in force.

 

[drbiggles]

To the OP, not to put too fine a point on it, but those are woofers, not subwoofers. Subwoofers are typically in their own cabinets and are designed to operate below where woofers normally do. Two different animals.

I'm going to let the Bozak cavalry handle this one since they have arrived in force.

I figured more of a firm ebb.

Biggles

 

[Scuby22]

Yes Tox, sometimes my younger 80's kid refers to the woofer as a sub. I discovered 12's and 15's only as subwoofers when I was young in 90'. Now i'm discovering the beauty of music with 12" woofers playing a broader range and still incorrectly refer to them as subs.

Quiet, I'm going to hope that I have the shiny dust caps. I'll get a flashlight and try to see what's behind there.

Biggles, would you mind explaining the mix-mash of drivers? Is the date code for 1958 mids earlier than the other drivers?

 

[quiet]

I think you got it backward on the shinnies. And it's the Y or Z you want.

 

[Nat]

Hard to tell from the pictures, but it actually looks as if you have two snipped wires, one very short and to the right of the longer one. I suspect someone was piggybacking another driver onto the tweeter cap (which is mounted on the woofer basket), and removed it when the full crossover was added. It was typical to start with just the woofer and coaxially mounted tweeters and then add more drivers and crossovers, but it leads to some confusing wiring.

 

[drbiggles]

I think you got it backward on the shinnies. And it's the Y or Z you want.

Nope, I got it right. The early paper cone tweeters were B200X with an alnico magnet. The later B200Y's had the aluminum cone with alnico, then moved to ceramic magnets later on. The Z tweeters are so darned rare, come up so seldom, I don't mention them. They don't need the Zobel network in the Tobin 104T schematic. The Z tweeters can be problematic depending on when they were built. NEAR kept veering off track and causing manufacturing issues. Rudy had to come back and set things straight. There are specific dates to stay away from.

Biggles

 

[quiet]

I was responding to Scuby22 on the shiny tweeters..