• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Big Bozaks - wow. Kit-made B-4000?

Susurus

Susurus

Resolution:6.62×10^-34
Big Bozaks - wow. Kit-made B-4000A?

There's a story, sometimes an adventure, behind your favorites.

My trunk... barely slipped in from the top direction, no clearance at all, and lifting it by myself straight upward out of the narrow side groove, without scratching the finish :sigh: .

Hey. Sometimes you just gotta listen right away... :yes:

The spare/replaced B199A is ceramic, 1971. Walnut venier? Gold thread on the grill striping. Modern or Classic? (not Moorish) [Modern B-4000A, thanks AKers!]

Got these beauties fired up, now I uh... 'understand'. :D

Infinite baffle? Bass is fast, musical, yet immense; totally unlike my old Klipsch powered subs.

Makes the Acoustic Suspension and Ported Bass ideas seem bleak compromises.

Line-array 8 tweeters, got to listen from a comfortable distance, or eerie comb filters...

The 'first true midrange' driver [nope, 8" was earlier], according to the ads. Strange that an aluminum cone is so smooth (and I know mids...). Must be in the xover, haven't popped it open yet...

More pics as I learn more. I know I need to check out that Yahoo group too.

Set separately wired Peerless 25mm domes as semisupertweeters, adds a little upper range, not quite got it right...still tweaking. 2 or 4? 19mm?

On AK this post has the same drivers in a different, smaller face. Which one is it?

Susurus
 

Attachments

  • trunkfull.JPG
    trunkfull.JPG
    78.1 KB · Views: 306
  • BozakTop.JPG
    BozakTop.JPG
    83 KB · Views: 190
  • BozakFrontOpen.JPG
    BozakFrontOpen.JPG
    72.2 KB · Views: 255
Register to hide this ad
That "smaller face" version picture is of my Symphony's. They are in custom cabinets that are supposedly the same height and width as factory, just made double deep. 16 cubic feet instead of 8 cubic feet. Are your factory ? Bozak label on the back upper center ?

Join the Yahoo Bozak group, post pictures and ask about size. I'll check the files there to see what factory measurements are listed. You may also find that your mid-range is wired out of phase intentionally. Gave them more of an in your face "hot" sound. They did this to compete in the show room with Altecs, JBL etc. The relaxed sound did not always make the best first impression in a show room. Had mine since May '07 and they sound better all the time. I would not trade mine for any other brand. In 1975 they were around $1500 a pair.

Unbelievable at low volume, nothing is missing, and up loud..... OMG !
 
more pics

attachment.php

size reference, that's a Sansui 4000. Dual 12" cast woofers, 1 x 6.5" mid, 8 tweeters (technically 4 modules). 6' Maggies behind them.
 

Attachments

  • Bozaksmbp50.jpg
    Bozaksmbp50.jpg
    47.7 KB · Views: 400
Rybeam said:
That "smaller face" version picture is of my Symphony's. They are in custom cabinets that are supposedly the same height and width as factory, just made double deep.
Click to expand...
Ah, that explains a lot. Mine are (41.5" H x 26.5" W x 16" D), with the 3.25" base it's ~44" H x 26.5" W x 16" D)

Internal volume estmiate is 7-8 ft^3

16 cubic feet instead of 8 cubic feet. Are your factory ? Bozak label on the back upper center ?
Click to expand...

Nothing, no label there. The orig. owner says he assembled them from a kit obtained from an authorized dealer in El Paso.

Join the Yahoo Bozak group, post pictures and ask about size. I'll check the files there to see what factory measurements are listed. You may also find that your mid-range is wired out of phase intentionally.
Click to expand...

I've been scanning the web, and did hear about the polarity issue. I'll examine the xover green [it's red]wire connection, but my ear says no, it's smooth, laid back... but ears can be fooled...

Gave them more of an in your face "hot" sound. They did this to compete in the show room with Altecs, JBL etc. The relaxed sound did not always make the best first impression in a show room. Had mine since May '07 and they sound better all the time. I would not trade mine for any other brand. In 1975 they were around $1500 a pair.

Unbelievable at low volume, nothing is missing, and up loud..... OMG !
Click to expand...

Seems you've got the internal volume and 'even more infinite baffle' of CGs with the better stereo imaging of the vertical tweeter array of B-4000s? How cool is that! :king:

Susurus
 
Last edited:
I cannot be sure, but the 2nd owner I got mine from thought the baffle board was bought from Bozak.
All I am sure of is these are flat out the nicest speakers I have ever heard in someones house.
 
The tiny Bozak metal logos are used as push-pins to hold the slide-up grills in place.

These apparently were pre-built, with venier, all edges and joints done. All the orig owner did was assemble.

Rybeam that 40.5 x 25 x 26.25" deep would make it ~12 ft^3 internal, but that doesn't seem to be the 8 ft^3 advertised cab volume for Symphony 1's.

Perhaps 12 is what the Yahoo list recommends for homebuilt cabinets. Should I accordian the backs out?

Susurus
 

Attachments

  • P1010040.JPG
    P1010040.JPG
    77.1 KB · Views: 155
  • P1010043.JPG
    P1010043.JPG
    84.2 KB · Views: 147
I always heard / read that you wanted a minimum of 4 cubic feet per woofer. I have done the math on mine and they are a bit over 16 cubic feet. Roughly 2 X 2 X 4 feet inside. I do have two other pair of Bozaks that are not that big, each with a single woofer.
The Symphony's used an acoustic curtain hanging inside the cabinet almost touching the magnets and a 1 cubic foot mid range enclosure.
I just did a quick look at the Yahoo site. Of course "plan one" would indicate there maybe another plan. Question needs to be posted there, many experts read the post, and answers are posted quickly.
 
Change those metal feet to rubber or spikes, it does tighten up the bass. You want that cabinet to sit rock solid. I also have mine tilted back slightly, one inch in back, two inch in front and angled in about 10 degrees. Also, are yours mirror images of each other? The original intent is to have the tweeters on the inside, factory models are labeled Left and Right on the back.
 
"The Fridge" standard unit of int. vol.

"The Fridge" standard unit.

Suppose a unit called "The Fridge" =def (16 ft^3). Then:

1.000 -- Bozak CGs, Rybeam's custom extradeeps
0.750 -- 'Plan 1'

0.500 -- my B-4000 (Symphony 1?)
0.350 -- Dukane 15" triax
0.250 -- Klipsch RF-7 towers
0.125 -- Dahlquist DQM-9
0.060 -- Advent 3002 (bookshelf)
0.025 -- M&K Sats

This unit has 2 descriptive advantages:

(1) it's always understood to be internal volume.
(2) it's metric friendly :thmbsp: (unless major appliances are smaller in Canada & EU :sigh: )

Mine contain 0.5 Fridges per side, your custom extradeeps (and CGs) contain 1.0, those Plan 1's-- 0.75 Fridges. (Maybe somebody calculated the T-S params instead of assuming 1/4 Fridge per woofer?)

Another unit, The Bookshelf, may be defined wrt those little dorm-sized fridges. Abbreviate to BS. :D

Susurus
 
Placement

Rybeam said:
Change those metal feet to rubber or spikes, it does tighten up the bass. You want that cabinet to sit rock solid.
Click to expand...

Day-um... >135 lbs ea, and spikes make a difference?! This is a whole 'nother scale than I'm used to. :scratch2: And Concept 16.5's high DF sounds amazing on bass already...

But maybe the airspace underneath spiked stands would improve airiness? (I'm used to Dahlquists' open mids) Surely these don't need floor-loading surfaces for bass in my proportioned room.

I also have mine tilted back slightly, one inch in back, two inch in front and angled in about 10 degrees.
Click to expand...

Tilt, does this reduce room modes? Or just better treble dispersion pattern for taller recliners...

Also, are yours mirror images of each other?
Click to expand...
Yes, mirrored. :music:
attachment.php


The original intent is to have the tweeters on the inside, factory models are labeled Left and Right on the back.
Click to expand...
I tested the in/outside tweeters before with my Maggies and decided the best imaging depended on the listener distance, far away/outside, nearfield/inside. But for these I'm trying:

E
|
----x---- :)
|
E


This 'T' arrangement, with X equal distance from the tweeter centers (high range is more directional) and the listener to the front planes.

So far, only two tests in my room, 3ft from the sidewalls, tweeters outside sound better; but many untested variables; toe-in, tilt, ...

Susurus
 

Attachments

  • bothfrontoff.JPG
    bothfrontoff.JPG
    81.9 KB · Views: 446
Last edited:
Still wondering about the correct designation. Has the 6.5" Al midrange (B-209A).
Seem to be 1971, ceramic, B-4000? B-4000A? Symphony 1A??

For somebody who has 'factory' tagged B-4000/Symphonies, what is your cabinet depth?
Thanks!

Also one of the 16-Ohm B199A's has been replaced (less brown, more gray cone shade), but the (included!) original seems just a little detached from the surround--an easy fix! :banana:

So I'll plop the orig. matching woofer [well I found it's not really, but maybe it's closer than the odd B199Bc ?] in there and still have a working spare!


Susurus
Considering this was $100 for the pair, could I be any more ecstatic...?
 
Chip - HP said:
I had a pair of Bozak B-4000A Modern for a while ... they sounded great ... but didn't have room for them.
Click to expand...

Cool! Now I know the grills on mine are the 'modern' style! Will open up the backs to see what your newer 1975 '-A' signifies. My replaced woofer is gray like yours, others are brownish, we'll see if they are ceramic/16 Ohms...

Exact h x w x d dimensions as yours; that helps tell me these weren't actually cut down from stock to 'fit' somebody's living room (the 'Plan 1' said 26" deep).

No room? :tears: After hearing these the walls are in danger of being ah...'pushed back' :D to give 'em more breathing room... (wait, you've got JBLs so you're not er... left in the desert... :)

Susurus
 
Bozak made the P-4000 (think that was the model designation) it was the front baffle board with the drivers mounted for either building into a wall or custom cabinet. The did sell plans but not knocked down cabinets. The dealer may have been bringing the cabinets in from Canada where they were produced and then the Bozak kits utilized to get around the tariffs. A common practice before free trade. I have a set of the Canadian produced units and they are the same as the US units but simply marked as "made under license".

I've had my Symphonies (this is the name for the B4000) for something like 9 years now (time passes fast) and they have been my main speakers. Mine were made in '68 but the original owner gutted them and replaced ALL the drivers NOS when he found out the company was closing and he wanted to make sure they'd be good for another 100,000 miles. I got the receipt for the drivers and the invoice from the store that did the replacing which is where I bought them. I've never had them open.

A BIG word of caution. Do not listen to these for long periods, often or long as big boxes are addictive and once you listen to 11 drivers in each, there is almost never going back to little speakers. As for amplification, you can not get good enough. The system was originally voiced with McIntosh and I run a MC2105 and love the sound. With it, I find no need for supertweeters. While a good 20 watter will run them, a really good 100 watter will get them to open up and provide for the dynamic range potential. I've tried a 210 watter and while it tightened up the bass a bit the extra 3 db did not add to the sound.

As for the midrange being out of phase, the jury is out as to whether to reverse or leave as is. Recommend you listen and try and then go with whichever sounds better to you.
 
First Inside Look

Thanks Rybeam, Chip, Brian, everybody; pics taken of the innards, I will post soon...

They say 'Modern B-4000A' inside on the crossbrace. One step closer to identifying...

They are older than I thought--or some parts are--with a 1969 ceramic and a 1980 A199Bc ceramic woof, 1970 200Y tweets,

Original N10102A xovers with horizontal axis Inductor Coils, not like Chip's modernized, larger yellow caps...

Not sure if those are reverse polarityized yet...could be at the driver terminals...

Somebody might have tried a funky arrangement/differing polarities on the tweeter array. Doesn't look like 2-2-2-2, which I expected. Looks like 2-4-2. (2 deep-backed, 4 shallow-backed, 2 deep (2 tops/2 bottoms are deep)).

pics taken, not yet posted...

Yes, that word of caution Brian...you may be too late :D

Susurus
 
You must log in or register to reply here.
Back
Top Bottom