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  #1  
Old 06-01-2004, 11:26 AM
Theijz Theijz is offline
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Question An error in the Bozak Schematic of Mics Music Page???

And again a question about the Bozak CMA 10 2DL:
In the Line or Monitor Amps schematics of Micks Music Page,
the schematic on the right side (wich is NOT the 'Right' Channel) has two resistors R21 and R16, wich don't exist in the Resistor tabel.
If I use the numbering from that below tabel, R21 will be R31 and R16 = R26.
Now comes my problem, its a bit complicated:
If R26 is 68 ohm, than there will be a very large current running through the transistor Q6 (ohms law:the voltage of 1 diode divided by the value of the resistor), wich isn't possible because of the value of R9 and R10.
So my first question: Is the value of R11 and R31 realy 68 Ohm???
Second: has anyone the DC voltages at the output BEFORE de condensator C10, and of the bases of Q6 and Q7 ? (or A service manual would be very usefull)
If not, is Anyone willing to measure these? if needed, I can give instructions. (maybe a Life Insuarance if wanted )
Thanks again
Thijs
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  #2  
Old 10-27-2005, 06:52 AM
coprohead coprohead is offline
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Old topic but

The schematics seem to be of an old version of the mixer.
They came from Sheldon A. Goodman Associates in NY (Who ever that is?)

The actual values in mine are:
R1, R21 100K RED
R2, R22 2K2 5%
R3 15K 5%
R23 5K6 5%
R4, R24 10K
R5, R25 470 RED
R6, R26 2K7 5% (R26 mislabled as R16 on diagram)
R7, R27 220 RED
R8 5K6 5%
R28 2K2 5%
R9, R29 4K7 5%
R10, R30 2K2 5%
R11, R31 67 5%
R12, R32 15 10% (stated 1/2W on sch looks like a 2W)
R13, R33 15 10% (stated 1/2W on sch looks like a 2W)
R14, R34 10 10% 2W

C1, C6 3.3u 35V Tant
C2, C7 47u 16V Elec
C3, C8 22p 1kV 20% Cer
C4, C9 47u 16V Elec
C5, C10 220u 40V Elec

D1, D11 1N4003
D2, D12 1N4003
D3, D13 1N4003
D4, D14 1N4003
D5, D15 1N4448
D6, D16 1N4448
D7, D17 1N4448

Q1, Q5 BC550B
Q2, Q6 BC560B
Q3, Q7 2N6290
Q4, Q8 2N6108


I have also gone thru the RIAA preamp:
R1, R21 1M 5%
R2, R22 56K 5%
R3, R23 330K 5%
R4, R24 56K 5%
R5, R25 1K 5%
R6, R26 150 5%
R7, R27 15K 5%
R8, R28 180k 5%
R9, R29 47 5%
R10, R30 8k2 5%
R11, R31 150 5%
R12, R32 100K 5%
R13, R33 470 5%
R14, R34 12K 5%
R15, R35 1K 5%

C1, C21 3.3u 35V Tant
C2, C22 22u 40V Elec
C3, C23 560p 1kV 10% Cer
C4, C24 100u 16V Elec
C5, C25 22p 1KV 10% Cer
C6, C26 47u 6.3V Tant
C7, C27 10u 63V Elec (stated as tant on sch but elec on board)
C8, C28 6n8 400
C9, C29 18n 250

Q1, Q4 BC560B On one board replaced with 2N5087
Q2, Q5 BC550B
Q3, Q6 BC550B

The values on yours could be different?

-Dale
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  #3  
Old 02-04-2008, 12:59 PM
Mistick Krewe Mistick Krewe is offline
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Quote:
Originally Posted by coprohead
The schematics seem to be of an old version of the mixer.
They came from Sheldon A. Goodman Associates in NY (Who ever that is?)

The actual values in mine are:
R1, R21 100K RED
R2, R22 2K2 5%
R3 15K 5%
R23 5K6 5%
R4, R24 10K
R5, R25 470 RED
R6, R26 2K7 5% (R26 mislabled as R16 on diagram)
R7, R27 220 RED
R8 5K6 5%
R28 2K2 5%
R9, R29 4K7 5%
R10, R30 2K2 5%
R11, R31 67 5%
R12, R32 15 10% (stated 1/2W on sch looks like a 2W)
R13, R33 15 10% (stated 1/2W on sch looks like a 2W)
R14, R34 10 10% 2W

C1, C6 3.3u 35V Tant
C2, C7 47u 16V Elec
C3, C8 22p 1kV 20% Cer
C4, C9 47u 16V Elec
C5, C10 220u 40V Elec

D1, D11 1N4003
D2, D12 1N4003
D3, D13 1N4003
D4, D14 1N4003
D5, D15 1N4448
D6, D16 1N4448
D7, D17 1N4448

Q1, Q5 BC550B
Q2, Q6 BC560B
Q3, Q7 2N6290
Q4, Q8 2N6108


I have also gone thru the RIAA preamp:
R1, R21 1M 5%
R2, R22 56K 5%
R3, R23 330K 5%
R4, R24 56K 5%
R5, R25 1K 5%
R6, R26 150 5%
R7, R27 15K 5%
R8, R28 180k 5%
R9, R29 47 5%
R10, R30 8k2 5%
R11, R31 150 5%
R12, R32 100K 5%
R13, R33 470 5%
R14, R34 12K 5%
R15, R35 1K 5%

C1, C21 3.3u 35V Tant
C2, C22 22u 40V Elec
C3, C23 560p 1kV 10% Cer
C4, C24 100u 16V Elec
C5, C25 22p 1KV 10% Cer
C6, C26 47u 6.3V Tant
C7, C27 10u 63V Elec (stated as tant on sch but elec on board)
C8, C28 6n8 400
C9, C29 18n 250

Q1, Q4 BC560B On one board replaced with 2N5087
Q2, Q5 BC550B
Q3, Q6 BC550B

The values on yours could be different?

-Dale

Is this an accurate "shopping list" for a CMA-10-2DL if someone wanted to refresh their Bozak with new components?
i am going to try to get this working myself, and wanted to double check...

i am bouncing this listing up against the schematics i found online, and will check against my unit's boards as well before ordering...




thanks a bunch,
Mistick

Last edited by Mistick Krewe : 02-04-2008 at 01:17 PM.
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  #4  
Old 02-04-2008, 03:21 PM
thermionic thermionic is offline
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If you check out This Thread, you'll notice that the Bozak uses 3 different types of circuitry...

Taken from Vinyl Junkie's thread
Quote:
There are 3 (not including the original D, which is different, but so rare it doesn’t bear discussion) types of Bozak circuitry – and you can interchange between transistors and various other options such as caps and I/O features freely. This means that the mixer can be customised exactly to a configuration that suits your ears – some people prefer the ‘hairier’ sound of the early Bozak, and some prefer the ‘sweeter’ sound of the later models – you can even have an interim version which isn’t as quiet as the last DLA-onwards version, but is just as smooth – for example.


What's amazing is that people talk about the Bozak having a 'particular sound', yet the 3 versions all sound very different (this is also complicated by the fact that each version is sensitive to setup, which – again - affects sound).

Due to its design, the Bozak is particularly sensitive to transistor beta. The 3 grades of circuitry used each have very different transistors, each with completely different noise specs / Hfe.

Anyway - as I said response to your PM, MC, because Bozaks were hand-built, they often substituted parts - you find many inconsistencies and anomalies. I regard finding out which quirks apply to your mixer as one of the joys of owning a Bozak - each one has a different story to tell.

BTW - In the 2nd post in this thread, the poster is talking about the DLA-onwards type of circuitry, which would explain the confusion!

I find it absolutely amazing that, in all the 5 years I’ve been visiting this group, this and VJ’s thread from last December are the first times I’ve seen it mentioned that the Bozak uses 3 different kinds of circuitry!

Justin
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  #5  
Old 02-04-2008, 04:36 PM
Mistick Krewe Mistick Krewe is offline
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Was this change in transistors more related to the production run than model?

for instance, if one had a DL model but is it a "G" series serial number (indicative of a 'late' unit), i would
bet it's parts nearly identical to the other units produced in that time-frame...

that's my guess at least...

thanks for the 'heads up' to look for more into on this topic Justin, much appreciated!!


Last edited by Mistick Krewe : 02-04-2008 at 04:40 PM.
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  #6  
Old 02-04-2008, 07:14 PM
thermionic thermionic is offline
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Quote:
Originally Posted by Mistick Krewe
Was this change in transistors more related to the production run than model?

for instance, if one had a DL model but is it a "G" series serial number (indicative of a 'late' unit), i would
bet it's parts nearly identical to the other units produced in that time-frame...

that's my guess at least...

thanks for the 'heads up' to look for more into on this topic Justin, much appreciated!!


From what I've seen, there are 2 versions of DL, and the DLA-onwards (DLO/DLC etc) all use the ubiquitous BC550/560

The 'C' designated 550/560 has the best Hfe - and IMHO - is therefore best suited to the Bozak (Bozak updated the mixer as the parts became available from what I understand - you could say they "moved with the times" - the DL / DLA mixers were quite forward-thinking in terms of their component choices, and - with massive silicon developments occurring during the seventies - the designs moved ahead as semiconductor technology enabled it to).

Justin
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Bozak CMA 10-2-DL Full Rebuild

How Mixer Level Controls Work

Important Differences Between Types of Bozak

Last edited by thermionic : 02-04-2008 at 07:16 PM.
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  #7  
Old 02-06-2008, 01:09 AM
Mistick Krewe Mistick Krewe is offline
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sometimes the answers are right there in front of you...

Quote:
Originally Posted by thermionic
From what I've seen, there are 2 versions of DL, and the DLA-onwards (DLO/DLC etc) all use the ubiquitous BC550/560

The 'C' designated 550/560 has the best Hfe - and IMHO - is therefore best suited to the Bozak (Bozak updated the mixer as the parts became available from what I understand - you could say they "moved with the times" - the DL / DLA mixers were quite forward-thinking in terms of their component choices, and - with massive silicon developments occurring during the seventies - the designs moved ahead as semiconductor technology enabled it to).

Justin


notice the note about bipolar transistor replacements on the lower center...

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  #8  
Old 02-06-2008, 07:41 AM
thermionic thermionic is offline
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MK - As I've said before, one of the most fulfilling aspects to working in audio is being able to unite the empirical with that which is objectively proven (I don't believe in magic). It's really good to know that my 'hunch' was on the right track - thanks for posting the page

BTW - Did you get a schematic with your mixer, or just a manual?


Justin
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Bozak CMA 10-2-DL Full Rebuild

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  #9  
Old 02-06-2008, 08:53 AM
Mistick Krewe Mistick Krewe is offline
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it's a manual that i've had for many years that seems to fit the new unit...

with a larger one page schematic

I have BC-237Bs in my unit..


Last edited by Mistick Krewe : 02-06-2008 at 09:01 AM.
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  #10  
Old 02-06-2008, 09:52 AM
thermionic thermionic is offline
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You have what I would term a 'second generation' DL

The 2nd DL measures on-a-par with the DLA for distortion, but is not quite as quiet.

Be very careful if you decide to fit more modern transistors - the pin out will be different and there can be a concern of stability.


Justin
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  #11  
Old 02-09-2008, 04:34 AM
clubman5 clubman5 is offline
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I have an original BOZAK CMA - !0-2DLB wih AB balance pots,and alps volume pots.

I also have a later CMA-1010-2DLB WITH 9 AUX INPUS, INSTEAD OF BALANCE CONTROLS, AND %5 CARBON FILM RESISTORS ( TAN COLOR ), UNLIKE THE ORIGINALS AB DARK BROWN CARON COMP RESISTORS AND A DIFFERENT BRAND O CAPACITORS. THE ORIGINAL HAS ALL FRKO CAPS THOUGHOUT, FROM PS, to phono cards, to to preamp sectiomns. Thanks to BUZZY BECK AND MARIO G! IT A KILLER MIXER!

THERE IS A SLIGHT DIFFERENCE IN TONALITY, I prefer the older BOZAK FOR IT,S WARM SOUND OVERALL, LUSH MIDRANGE, AND SOFT HIGHS and ORGANIC sounding bass punch. It just kicks the right way! The most tubelike sound from SS I have yet to encounter.

BUT, When insserting any device in the Effects Loop,
there is a noticable loss od gain, say maybe 3 o 5db!

However,the Bozaks charm makes up for this loss, and is the BEST sounding mixer/preamp; ever produced, IMHO!
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Last edited by clubman5 : 02-09-2008 at 04:51 AM.
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  #12  
Old 02-09-2008, 04:39 AM
clubman5 clubman5 is offline
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Misprint, or deliberate mis-information?
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  #13  
Old 02-09-2008, 04:46 AM
Mr ZDUR Mr ZDUR is offline
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I guess mine is transistional. I have BC237/BC177B on phono cards, mic cards, output cards and the main card, but on the middle (140-12, 180-12) cards I have BC237/2N087 trannies. I also have some carbon comp, but mostly metal film resistors. I don't hear any white noise unless I crank it really loud with no signal. It is an incredible sounding mixer, even through headphones.
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  #14  
Old 02-09-2008, 04:59 AM
clubman5 clubman5 is offline
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Metal films? Bozak never used metal films, AFAIK! Search eBay for AB carbon comps of the same value, replace the metal films with AB,s and be prepared for the shock of your life.

BETTER sounding in every way!

OR, get fancy, and replaces with Riken Ohm audiophile carbon composition resistors, available from www.partsconenxxion.com!

They sAY Im crazy, BUT you you can hear a difference!
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  #15  
Old 02-09-2008, 05:05 AM
clubman5 clubman5 is offline
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IF THE SIGNAL passes through it, YOU CAN HEAR IT, good , bad, or indifferent!

RIKEN OHM carbon comps, and Kiwame Carbon Films, Japanese Handmade audiophile grade resistors!

Join me in my crazy qwest, and see what YOU HEAR!


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  #16  
Old 02-09-2008, 05:17 AM
clubman5 clubman5 is offline
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OH, AND BTW, dont take the color bands as the gospel. MEAUSURE YOUR resistors with an ohmeter!

I have RLA MODIFIED MIXERS, AND CROSSOVERS, WHICH THE COLOR BANDS INDICATE STOCK VALUE, BUT MEASUREMENTS TELL A DIFFERENT STORY!

EVEN A CHEApo Multi-meter from RS ( RAdio Shack ) works well! %5 accuracy is fine, 22K IS 22K, AND ID YOU HAVE A 22K THAT MEASURE 43K OR REALLY UNDR 22K YOU KNOW THE METER IS RIGHT, THEY DID SHIT LIKE THIS BACK IN THE DAYS!

Measure with a meter, and BE SURE, rather than sorry and/or stupid!
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  #17  
Old 02-09-2008, 02:24 PM
Mistick Krewe Mistick Krewe is offline
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you have to take components out to measure them properly, right?

nice cleanup
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  #18  
Old 02-09-2008, 02:48 PM
Mr ZDUR Mr ZDUR is offline
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Oh, sorry they are carbon film and carbon comp. Carbon film are tan right? Yeah, I always measure resistors. Some you can measure in circuit, some you can't.
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  #19  
Old 02-10-2008, 06:43 AM
clubman5 clubman5 is offline
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When Im done with winter work, Ill post pics of the system.
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