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Bozak Fans & Owners - Assistance Requested

Goggle1824

Goggle1824

Well-Known Member
So sometimes I get a little a head of myself and I partially blame this site and it's "inhabitants" for informing and supporting my problem...

So I have just hauled-in 310B Concert Grands with the 8 woofers, 4 mids, 16 tweeters (in array) and the original NON-Tobin crossovers.

The downside is everything is in very non-original cabinets.

So... am I foolish for even considering building anything else other than a CG cabinet since I have all of the drivers, OR should I build what is best for my current layout or musical tastes and hold the remainder for spares, a different set, etc.
 
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Goggle1824 said:
So sometimes I get a little a head of myself and I partially blame this site and it's "inhabitants" for informing and supporting my problem...

So I have just hauled-in 310B Concert Grands with the 8 woofers, 4 mids, 16 tweeters (in array) and the original NON-Tobin crossovers.

The downside is everything is in very non-original cabinets.

So... am I foolish for even considering building anything else other than a CG cabinet since I have all of the drivers, OR should I build what is best for my current layout or musical tastes and hold the remainder for spares, a different set, etc.
Click to expand...
If you have the space for them then by all means build some new boxes for the Concert Grands. :thumbsup:
 
What cabinets are they in? Got any pictures?

Personally, if you don't have room for Concert Grands, I wouldn't bother trying to replicate them. Replicas won't have much value. I'd either build what you want, look for a pair of vintage enclosures, then store or sell the leftover drivers.

bs
 
Hey,

What size is your listening room, and can we get pictures of the DIY CG's cabinets inside and out? Do you know the date codes on the drivers? If you can get a picture of the back of one of the mids, we can see. It would be helpful to know if you have the early paper mids/tweeters. Or, do you have the later aluminum cone mids/tweeters? I would also suggest joining the Facebook Bozak group. They've got a Files Section with all kinds of goodies.

I have the construction plans for the B-310A, which is probably a little different than what you have.

The issue with rebuilding these rigs into something smaller is that the CG's have 2 16ohm B209 mids. Pretty darned useless for the small Symphony or B302A's. So, you'd have to source their 8ohm cousins for that project.

Biggles
 
The secret to a Grand is the size of the cabinet. It allows the bass to develop and the curtain inside absorbs standing waves etc. The large baffle focuses the sound to the listener especially for the 209's and also helps the B 200y's. The height guarantees the tweeters and mids are at ear height for best definition. Smaller cabinet also means less efficiency of the system and curtails the bass. Place two Grands side by side with a mono signal and they will reach below 20 hertz. I guess you could make the cabinets taller to decrease the foot print, placing two woofers on top and two on the bottom sort of like Dunlavy, but then they wouldn't be Grands. I added super tweeters to mine as the 200y heads for the basement above 12 KHZ. But for most older guys, that can't hear that high and women with sensitive hearing thats OK.

Plan on bi-amping, it will make a big improvement in the bass transient response. Frank Gow who's dad was president of Mcintosh had Grands in the house when he was a kid . When they bi-amped the Grands with new 2105's he thought there was a big difference. I didn't like the highs, so I went with DC 300'As. Now I'm using Mcintosh 207's.
 
Thank you for the replies so far, this is exactly the type of dialogue and information I am looking for.

I'll load pictures after I snap a few but I suspect the existing cabinets while maybe decent aren't taking advantage of the hardware inside. The cabinets are recently and admidditly home brew by the very cool gentlemen I bought them from, they measure 48" x 24" W x 17" D. I know that because they barely fit laying down flat next to each other in the bed of a 2016 Chevy Silverado pick-up!

I opened one cabinets and wrote down the driver info and can share that the hardware includes the following:

Four, B-199AC woofers, sequential series numbers K07723 - 26, with an inked on code below of 7112;

Two B 209-B mids, didn't write down any date code, need to double check those;

And Eight tweeters, four 200YC and four 200Y;

And the big old crossover network with that big ol' iron core inductor, not sure where to find the identifier on the XO, there are so many numbers on there...

I suspect (and hope,) I will find four of each in the other cabinet and will work to confirm that today along with requested pictures of the DIY cabinets.

And oh yeah, I've requested permission to the Bozak FB group.
 
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Well, dang fire! It looks as though you got the good stuff in regards to the drivers! But the cabinets are far too small, they should be approximately 36" wide, 18" deep and 50" high.

Biggles
 
Great to hear, I was hoping I'd have something solid to work with! :banana:


I opened the other cabinet and confirmed I have matching parts in there:

All of the drivers are inked/stamped in faded white on the magnet face: 7112, is that a December 1971 manufacturing date?

The second cabinet contains:

Four: B-199AC, with identifier info as: K07711, 12, 13, & 15 (found the identifying 8 ohm plate on these);

Two: B-209B marked with K06145 & 59 (16 ohm); and

Eight tweeters: four 200Y & four 200YC (8 ohm)

Found the label on the XO, it's a N102

I'll post the crappy phone pics next, but I'm starving so I need to grab some lunch first.
 
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Hey,

It sounds like your drivers are all the ones you want, along with the crossover. Although, I don't have permission to view the images.

Biggles
 
YUP !!! Dang. Okay, go on the net and do an image search for Bozak Concert Grand. You can see immediately the driver layout difference between yours and the factory cabinets. These drivers are all over the darned place. Getting these to image properly will be impossible, no matter how large your living room is. You must have at least 10 cubic feet of internal volume for the 4 B199 woofers to work properly. Also, the internal batting is just stuffed into the cabinet like a racoon did it, not cool.

Save the internal batting, that's gold right there pally boy. The sides, top and bottom get it loosely attached. And then the curtain must be installed. You can get an idea as to how this looks by checking google images.

You've got a real collection of the best Bozak drivers for Concert Grands there is, factory cotton batting, and you have the proper crossovers. All you need are proper cabinets and you're done. That may seem like a lot, and it is a fair amount of work. But the fact you have everything else is really huge.

Congratulations!

Biggles
 
WooHoo! Awesome news, I have "some" woodworking experience so doing a ginormous cabinet built could be a lot of fun.

Is the FB group the place to go about locating a set of appropriate plans?
 
Hey man,

This is GREAT news, fantastic. They've got the same plans for the CG's that I have, it's a B-310A. Once you get in there, you can see what the scoop is. The tweeter configuration is a little different for that model of CG. There's a lot of CG owners on there and will be able to give you some direction. David is really fast about getting people approved quickly. Good stuff is coming!

Biggles
 
As Biggles has noted, driver convergence is a profound issue. He experienced this with his Symphony which is half of a Concert Grand. You need some serious distance for the drivers to converge and it most definitely will not sound right near field or even in a small living room. Listening space is crucial when using multiple drivers of the same type.

BTW, I believe the cabinets in those photos are shown rotated 90º. They likely should be horizontal, as the B-400 Distinguished is a lowboy configuration. This is similar to the B-305 Elegant configuration which used dual B-199's, single B-209, and quad B-200's.

If you think about, this is the obvious placement because the geographically separated midranges make no sense in a vertical configuration. Why place the drivers so low and so high? Horizontally makes more sense, as a sort of MWTWM configuration. Although horizontal creates more comb artifacts as the waves combine.

Yet that makes no sense for the tweeter placement. Those would be too low if the rotation is counter-clockwise. Or the midranges would be too low if the rotation were clockwise.
 
The gentleman I bought these from said he had them for about six years and traded them to his boss at the time for two large leather recliners, that were being changed out for a couch.

The original cabinets were "pretty rough shape" according to him so he fabricated the cabinets pictured above. It's too bad really, because we know now a lot can be done to bring these classics back, but it happens.

I'm guessing by the layout and some of the build quality that he just copied the previous cabinets layout and overall dimensions? I'll look again online for pictures and information on the low boy configuration Ultimately the upright layout is what will fit my (intended) location best.
 
MarZutra said:
Congratulations Goggle. I'd probably build as close to original as possible. They still fetch good $$ on the used for properly built Bozaks. If I came onto the drivers I'd surely build a pair of CG. Just me. I like fun projects... If I'm not mistaken, don't the lowboy use single mid and not two? Might they be from the Moorish?
Click to expand...

No, dual midranges.

The B-4000 Moorish uses a different driver layout

The lowboy simply turns the cabinet on its side.
 
The intended location is a carpeted open/shared space, living room that opens fully into the adjoining dining room. The living room is approx. 15' D x 23' W, with vaulted ceilings 8' at each end and 11' in the middle, the 11' peak of the ceiling runs along the width of the 23'.

The intended specific spots for the cabinets can be between 6 1/2' & up to about 9' apart (assumed vertical) array to array.

Is this "enough" space for CGs?
 
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