Calling DBX 202 experts!

[rob_gould]

A while back I bought these DBX 202 black cans to use in a Mixbuzz 500.  The seller told me that all the cans came out of a desk he was stripping down.  I'm doubtful of this now because the two cans he sold me have different types of serial numbers.  One has a six digit number, and one is simply labelled 'MCI'

Also, looking at the reverse of the cans, I can see that one resistor is definitely a different value on one can than the other (see photo).

So both of these are labelled the same - DBX202.  Are these the 202X version?  Or would they be specifically labelled as 202X if that was the case?

And what about this change in resistor value?  Can anyone explain that?

I also have DBX 202Cs which have a much more trustworthy history, but I'm not sure whether these can be added to the Mixbuzz or not.  Checking the datasheets for these VCAs on Gyraf's site does not make it clear to me...

Cheers

Rob

 

[topcat]

Hi Rob,
IIRC there were suggestions that when certain mixer manufacturers started using 202's in largequantities Dbx couldn't meet the production requirements for full spec units.  The happy compromise was that some users allegedly bought the out of spec versions...could this be the case here?...c

The data sheet referenced in this old dbx discussion http://www.groupdiy.com/index.php?topic=40622.0
makes mention of selected resistors... is that the case in your units?..... also noted is the use of IC technology in the X version.

Cheers

tc

 

[Harpo]

...DBX 202 black cans to use in a Mixbuzz 500...

good luck with that. The value of the trimmer for sym.adjust probably will be the only part you keep...

 

[rob_gould]

Hi Rob,
IIRC there were suggestions that when certain mixer manufacturers started using 202's in largequantities Dbx couldn't meet the production requirements for full spec units.  The happy compromise was that some users allegedly bought the out of spec versions...could this be the case here?...c

The data sheet referenced in this old dbx discussion http://www.groupdiy.com/index.php?topic=40622.0
makes mention of selected resistors... is that the case in your units?..... also noted is the use of IC technology in the X version.

Cheers

tc

Thanks - I hadn't seen this thread

 

[rob_gould]

...DBX 202 black cans to use in a Mixbuzz 500...

good luck with that. The value of the trimmer for sym.adjust probably will be the only part you keep...

Hmm, I though that these were the cans that the standard resistor settings were for, but anyway I found this in the Mixbuzz 1 thread here :

Using DBX202C gold can VCA's in MixBuzz1:

DBX 202C GOLD CANS
RXX APPLY TO BOTH L AND R (R100L, R100R)
R6 40K2
R2 1MEG...1.5 MEG
R100 710R
R4 JUMPER/FERR BEAD
R3 40K2
C1 5PF

So looks like I can go ahead and use the 202Cs after all since as far as I can tell from the schematic, the Mixbuzz500 and the Mixbuzz 1 are the same electrically speaking.

 

[JohnRoberts]

I've posted a link to it before, but I'm too lazy to search for it again. There is a paper on the THAT corp website describing the different historical variants of DBX vcas, There were some tweaks related to control voltage sensitivity, etc.

JR

 

[mattamatta]

About the serial numbers:  I've actually recently been playing with a bunch of gold can 202Cs out of modules from an MCI desk, and of the ten or so total all but one say MCI and the other has a numbered serial, so they still could be from the same desk. 

 

[Harpo]

Using DBX202C gold can VCA's in MixBuzz1:
DBX 202C GOLD CANS
RXX APPLY TO BOTH L AND R (R100L, R100R)
R6 40K2
R2 1MEG...1.5 MEG
R100 710R
R4 JUMPER/FERR BEAD
R3 40K2
C1 5PF

C1 might need a doubling up if the I2V stage should oscillate.

So looks like I can go ahead and use the 202Cs after all since as far as I can tell from the schematic, the Mixbuzz500 and the Mixbuzz 1 are the same electrically speaking.

nearly (IIRC Mixbuzz1 has additional ratio setting).
From Johns reply, have a look at http://www.thatcorp.com/datashts/dn127.pdf to get the main parts differences.
Adapting for the different VCAs control law of the DBX202 (6mV/dB vs. 50mV/dB) if you want to use this part instead of the DBX202C, easiest fix might be to decrease R55. You'd still have to adapt for the lower allowed signal current (R6/R3), VCAs output capacitance (C1), symetry control voltage (R2) and control port impedance (R100).