matthias

under the hood: DBX 162 stereo compressor/limiter
« on: September 11, 2005, 09:30:19 AM »
I bought a DBX 162 compressor some days ago...

this is a very nice and easy to use compressor, great for drums...

is anyone familiar with that unit and made some mods/upgrades??
it uses some old lm301a opamps...
I think an upgrade could increase the bandwitdth and speed...


here are some pics and schematic:


















schematic:

http://www.cmaudio.de/forum/dbx162/dbx162-schem.JPG


cheers,
matthias


KingKai

under the hood: DBX 162 stereo compressor/limiter
« Reply #1 on: September 11, 2005, 02:07:45 PM »
Obviously there aren't enough trim pots in that thing! :wink:

The old LM301's were a love/hate item. I'm not a real fan of them but there are those that say they are just fine in the proper usage. Perhaps I have just not crossed one of those proper usages or more likly a proper application.
Change one channel and compare as you go. Like smokey the bear always says: Only You Can Tell if it Better For You! :thumb:

Best 'o Luck
Peace - Out
Life in the key of BOOM!

PRR

under the hood: DBX 162 stereo compressor/limiter
« Reply #2 on: September 11, 2005, 08:08:05 PM »
> it uses some old lm301a opamps...

Are you sure? While the schematic I have shows 301s, mine was built with BiFET amps like LM353.

If you really have 301 with 33pFd for the input amp, and are throwing huge drum signals into it, yes you will be slew-limited. LM353 or TL081 is the fix.

If you stick with reasonable output levels, the 301 after the VCA210 plug-in card won't be a major bottleneck because of output stage gain.

Don't diddle with the opamp on the stand-up card OA230. It has a complex bootstrap thing going on. If you don't understand it, you will smoke something. However for short signal runs, you could take an unbalanced output from the C17 cap and bypass OA230.

The only mod I've made to mine is to give a high-gain unbalanced input to simplify my minimalist mastering chain. But then I don't feed it raw drums and I only ask for -10dBV nominal output.

Speed of limiting action is NOT adjustable by mere humans. OA11 and ALL that junk above it forms an exponential capacitor. Take what DBX thought was best (or worked); or use some other limiter.

Bryson

under the hood: DBX 162 stereo compressor/limiter
« Reply #3 on: September 12, 2005, 03:32:11 PM »
Did any of the 162s have the potted 202 vca like the 160?
Did any of the 160s have that stand up card instead?


 

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