symetrix 525 compressor mods?

[wiz1der]

I just acquired 2 of these things at a very decent price. They sound ok, but it seems as if somethings holding it back from shining like it could.

I don't know anything about analyzing circuits, so I was wondering if anyone could glance at the schemo's and see if anything stands out that could be done different or better?

symetrix 525 schematics


If so, these can be had for around alesis 3630 money, and they used REAL Neutriks in back!!

[Matt Syson]

Hi
Is it the overall 'tone' of the unit, when it is not compressing or expanding, or is it the 'dynamics' that you feel could do with a boost?
There are better chips than the RC4560 available now and it may do with a sprinkling of new caps, possibly mylar bypasses as well. This may put a little sparkle to the audio chain (sheet 1 of schematic). Possibly best leaving the sidechain alone as you could spend a while unravelling it.
Be careful what you use for the U2 (102) positions as it is part used as a comparator and not all chips like being used in this way. U1 (101) should have np problems.
Matt S

[dementedchord]

beyond basic idea of using better parts what is it you dont like about it ...why does it need to change???? with out specific data cant really suggest in generic terms....sorry

[wiz1der]

Well there's nothing really WRONG with it now, and i know i shouldn't be comparing a 60.00 unit to my ssl G384, BUT:

I guess i was just wondering if there was anything really obvious, like cap values or chip changes that can open it up, make it a little faster sounding etc...

[Matt Syson]

I don't know what the 'sound' of the Alison gain element is, compared to the DBX VCA chips but otherwise the Symetrix COULD be cleaner as there is less 'stuff' in there, especially if you swap the op amps. The SSL uses 5534's or 5532's but do not immediately stick a 5532 into U2 position as part is used as a comparator (see above). You need a chip which does not get unhappy if you wrench it's input 'legs' apart (electrically). 5532 would probably not blow up but the indicator may not indicate as it should.
Otherwise go for fresh caps as I presume it is getting on a bit.
Matt S