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Bozak B-4000 Questions

Some calculations and analysis I previously posted about the relative (more or less) volumes of the Bozak cabinets for three-way speakers, slightly revised for clarity. I omitted the tiny bookshelf units as those are slightly smaller than the B-313.

Cabinet Volume Comparison and Analysis for Bozak Line

Consider the dimensions (yes, I laboriously keypunched these and did the calculations, so errors may exist):
B-313 (Concerto 3)
Claimed Response: 40 Hz to 20,000 Hz
Dimensions ≈ 24 in W × 12 in D × 17 in H
Cabinet Volume ≈ 2.8 cu ft
Woofer Volume ≈ 2.8 cu ft per woofer

B-402 (Rhapsody)
Claimed Response: 40 Hz to 20,000 Hz
Dimensions ≈ 18 in W × 13 in D × 25 in H
Cabinet Volume ≈ 3.4 cu ft
Woofer Volume ≈ 3.4 cu ft per woofer

B-302 (Concerto V, Urban Cabinet)
Claimed Response: 40 Hz to 20,000 Hz
Dimensions ≈ 24 in W × 20 in D × 28 in H
Cabinet Volume ≈ 7.8 cu ft
Woofer Volume ≈ 7.8 cu ft per woofer

B-305 (Concerto Grosso, Century Cabinet, Dual Woofer)
Claimed Response: 35 Hz to 20,000 Hz
Dimensions ≈ 36 in W × 20 in D × 28 in H
Cabinet Volume ≈ 11.7 cu ft
Woofer Volume ≈ 5.9 cu ft per woofer
NB: Essentially a horizontal pair of B-302 (dual B-199, four B-200 tweeters) in a shared cabinet with a single B-209 midrange

B-4000A (Symphony, Modern Cabinet, Dual Woofer)
Claimed Response: 35 Hz to 20,000 Hz
Dimensions ≈ 27 in W × 16 in D × 45 in H
Cabinet Volume ≈ 11.25 cu ft
Woofer Volume ≈ 5.6 cu ft per woofer
NB: Essentially a vertical pair of B-302 in a shared cabinet with a single midrange, or a vertical B-305

B-310B (Concert Grand, Contemporary Cabinet, Quad Woofer)
Claimed Response: 28 Hz to 20,000 Hz
Dimensions ≈ 36 in W × 19 in D × 52 in H
Cabinet Volume ≈ 20.6 cu ft
Woofer Volume ≈ 5.1 cu ft per woofer
NB: Essentially a quad pair of B-302, or a double-pair of vertical B-305 with a dual midrange

NB:
(1) All systems are three-ways unless otherwise noted.
(2) The cabinets slightly vary with style, an inch here or there, so anything after the decimal point is not significant.
(3) Volume calculations use Bozak's published exterior dimensions, rounded down to somewhat account for cabinet thickness. Loss of interior volume to bracing, curtain, crossover, or actual drivers was not considered. (Left as an exercise for the reader)​

Conclusion

Given Bozak's claims about the high-end performance of the B-200Y running to infinity and beyond, I suggest disbelieving the low-end performance claims without qualification for dB output at that frequency, but the relative changes may be indicative of inter-model performance.

Yet we may, nonetheless, observe that the better rated systems B-302 Concerto V and B-301B Concert Grand have larger volumes, respectively 7.8 cu ft and 5.1 cu ft.

The claim is made that the multi-woofer systems synergistically work so the increment space per woofer need not increase, but this is conjecture. What I can say is that if the Concert Grand followed the same rule of 7.8 cu ft per woofer, and the height and depth remained constant, it would be 55 inches wide, an increase of 1.5 times the original.
 
So, enjoyed the Symphonys all day today. Just great with the previous mods. I did notice a bit of sibilance, which was pretty much tamed by toning down the 200y's and the Morels. That's probably the only small issue I still notice. Perhaps a different tweeter would reduce this. Regardless, so lovely. (Listened to Bread, Greatest Hits, Pink Floyd, Yes, Led Zep. ok, don't judge me re: Bread. Child of the 70's!).

I find myself wanting to listen to all my stuff again. Re-discovering music I've listened to for years.

Got my Philips back after frying it, and it's just wonderful. Love the sound of the that receiver. So clear.

Kudos to Ak'er Tom B. Great guy and wonderful job.

Anxious to try the Marantz 2270 , which is out for a full restore.
 
Any thoughts on how the Bozaks would do with a tube amp or tube pre-amp. I know they were designed with SS in mind, but thought tube amplification might also complement the Bozak's strengths.

Thanks
 
Still, going to accumulate parts for my next project....the five-way...as previously mentioned, using the B800 as a mid-woofer. (so much fun!)

I guess I'm officially a member of the Bozak cult!.
 
the Symphony was first made available in 1961 being based on the Concert Grand which had been first released 10 years earlier. Both would have been designed with tubes in mind and in fact Rudy had a close relationship with both McIntosh and Saul Marantz. 'Odds are good they would sound lovely with tubes, particularly if you can afford vintage kit from the golden era of one of those two. A Marantz 8b or say a McIntosh 275 would be bliss.
 
Bozaks will successfully function with either solid state or tubes. Audio fetishism is not required for Bozak listening, as its speakers were sold for both types of amplifiers, and Bozak itself sold solid-state amplifiers.

The key issue in amplifier selection is (a) the amount of power required to drive the speaker at normal volume levels, (b) the amount of power for dynamic peaks which may be delivered to the speaker prior to clipping, and (c) the sound of clipping when if or when it occurs.

Because of the Bozak's efficiency, a small number of output watts is sufficient to drive the speaker, and most amplifiers have sufficient reserves such that the dynamic peak does not move the amplifier into clipping.
 
not required but oh so nice. Tube v transistor is even more of a black art than speaker design but when you get it right, it can sound very, very nice. I haven't the patience for it personally but some of the better systems I've heard have made liberal use of tube designs. There is a sweetness to them, a bit like vintage speakers really. Not clinical necessarily but often quite involving which in the end is what matters, at least to me.
 
Final update.

Been using my Symphonys with both the restored Marantz 2270 and my Philips 787. I prefer the Philips. Much more punch, cleaner, transparent.
Just sounds wonderful.

Using the Marantz with my new project, Dahlquist DQ-10's, but it's just not up to the tasks. Those things needs tons of power to properly drive them.

Will dip my toes into the 'tube' pond shortly, but for now, just enjoying the music!

Thanks to all.

Frank
 
fjdds said:
Will dip my toes into the 'tube' pond shortly, but for now, just enjoying the music!
Click to expand...

Just picked up a pair of these a few days ago. Stock and all original ‘62’s. After reading through this thread I think I’ll change out the caps first and then go from there. Magical sound though ain’t it? I’ve been running mine with a Marantz 170DC, 86+ watts per channel and they are very happy with that. Eager to power them with tubes but for now SS is a lot of fun. Currently playing Daft Punk - Random Access Memory and loving every second of it. Cheers to you fellow Bozakian :beerchug:
 
fjdds said:
Enjoy. They are really capable of some beautiful things. Have you opened them up yet?
Click to expand...
Thanks fjdds:beerchug: And yes I’ve opened them up and everything is stock. I’ll be doing the flower pots on the mids later this week so I’m looking forward to hearing the improvement.
 
Mine have the original Bozak covers, but the flower pot is the ideal shape, as others here have done the legwork to confirm.

Do they have the batting all around, and the hanging curtain?

Personally, I'd change the long out-of-spec caps to start, and live with them for awhile.

Also, if yours have the brightness control on the back, mine were not functioning, and when bypassed, my 200y tweeters were way too screechy. If you have these, perhaps see if they're functioning, and if not, replace with more modern l-pads.

My humble opinion, at least.
Others more knowledgeable than me are here.

Frank
 
Hey Frank. Yeah I did notice that your mid coverings are different from the usual black ones I’ve seen. I have the curtain and the batting all around. Got my flower pots today at the hardware store and they’ll be going on within the next few days.

I went to partsexpress and they are currently out of the 5.1mfd dayton so I might have to get them elsewhere.

I have the brightness controls on mine as well and they have some very obvious dead-spots on them. Not sure if deoxit will help but I’ll give it a shot and hope it works. If not, modern L pads will be ordered.

The good thing about owning these speakers is that there’s so much enthusiasm and knowledge coming from the guys and gals who own or have owned them as you’ve seen already, so you’ll never be left having to guess. Might get a little confusing admittedly, but that’s why I’m taking it slow.

How big of a room do you have yours in by the way? Currently mine are in the garage. I’m not sure they have enough room to breathe in my 15x20 listening room/music studio so they’ll just be out there for now.

-Ernie
 
angelaudio said:
The good thing about owning these speakers is that there’s so much enthusiasm and knowledge coming from the guys and gals who own or have owned them as you’ve seen already, so you’ll never be left having to guess. Might get a little confusing admittedly, but that’s why I’m taking it slow.
Click to expand...

Bozak Cult Rule 1: Tell Everyone About Bozak Cult.
Bozak Cult Rule 2: No Exceptions to Rule 1.
Bozak Cult Rule 3: Rebuild failure is never an option; no Bozak left behind.

The threads contain all of the information needed for successful rebuilds, no need to start a new one. It's all out there.
 
Retrovert said:
Bozak Cult Rule 1: Tell Everyone About Bozak Cult.
Bozak Cult Rule 2: No Exceptions to Rule 1.
Bozak Cult Rule 3: Rebuild failure is never an option; no Bozak left behind.

The threads contain all of the information needed for successful rebuilds, no need to start a new one. It's all out there.
Click to expand...
I dig it, Retrovert! Absolutely dig it. Bozak 4 Lyfe :rockon:
 
angelaudio said:
How big of a room do you have yours in by the way? Currently mine are in the garage. I’m not sure they have enough room to breathe in my 15x20 listening room/music studio so they’ll just be out there for now.
Click to expand...

Actually, mine are in a basement, approx 15 ft x 40. I need to get pretty far back so that I can here just the sound and not the individual drivers.
 
angelaudio said:
Hey Frank. Yeah I did notice that your mid coverings are different from the usual black ones I’ve seen.
Click to expand...

The metal domes are what was there, so I left them in place and covered with cotton batting. (The insides already had the batting in place.)
Might switch to the flower pot at some point, but for now, they're fine.
 
fjdds said:
Actually, mine are in a basement, approx 15 ft x 40. I need to get pretty far back so that I can here just the sound and not the individual drivers.
Click to expand...

Which, sad to say, is the precise problem with multi-driver speakers widely spaced and why coaxials/triaxials are preferred for near-field listening.

Biggles dismantled his Symphony — see cabinet specifications for the B-4000A Symphony which are above set forth — project for precisely that reason: the drivers would not, and could not, converge in his space. Much time and expense went into acquiring the 16 Ω woofers for those speakers, but if the speakers don't work, they don't work.

The B-302 Concerto V and B-402 Rhapsody are better for smaller spaces. My space is so small I only have room for the B-313 Concerto 3 which trades low-end response for physical size, and it is still a larger speaker compared to the other bookshelves.

I have seen photos of setups with Altec's Voice of the Theater speakers three feet from a couch, almost as if they were giant headphones. The speakers reportedly require ≈ 30 feet to converge, hardly surprising given the characteristics. Many audiophiles listen not with their ears, but with their eyes.
 
Anyone have thoughts on incorporating an external tweeter, (in my case, a Morel), to the inside of the Symphony without major surgery to the cabinet? Perhaps replace one of the existing y tweeters with a soft dome, wired/ and band passed as it is now?

Thanks
 
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