Faulty SC-2.2?

[vinyl_junkie]

Hi I have a v4 SC-2.2 I recently purchased second hand, everything appears to work as it should but I honestly can’t hear the difference between the dry signal and the compressed signal…Even at the extreme settings and with the comp needle bouncing down like crazy I can’t hear the compression…is this compressor meant to be this transparent?
I found it a bit more noticeable (I think)on things like acoustic piano but on the mix buss I really couldn’t tell or hear any compression going on…
Is there anything I can do to check the unit? I have access to a multi-meter, frequency generator and oscilloscope if needed

[vinyl_junkie]

I personally don’t think there is any gain reduction happening but then wouldn’t the GR meter represent this?

I had a peep inside and you can see the LED’s working from the underside of the board as the top is covered but could the photo-sensors be faulty?

[Ted Fletcher]

It does sound as though there is a serious problem on the opto cells.
If you want to have a go at it yourself, on that model (SC2.2) the opto cells can be replaced with standard ORP12 cells. You can break away the glued opto covers to get at the cells. Strictly, they should be matched.
If you want me to fix it, that’s OK; for Joemeek equipment it’s a nominal £25 plus the cost of returning the unit to you. Email me at [email protected]

[vinyl_junkie]

Sorry Ted, think it was just me..

Stuck a 1k sine wave in there, cranked the slope to max and compression knob to max and sure there was gain reduction…although the meeter reads at something like -10db of gain reduction when switching to show output it only shows a -3db gain drop from 0

I think I just expected a more obvious compression sound but it’s a very transparent unit I think, one thing I noticed is that it sounds pretty good on real instruments…i.e piano and drums where’s I’m using synthesizers and drum machines.

[Ted Fletcher]

This is still a bit of a strange one….. The meter indication should not be that far out.
Maybe it is you, and you are not pushing it hard enough!!
Those SC2.2 compressors certainly work best with lots of input; it’s virtually impossible to overload the input.
If the LED operation is clearly visible from under the board, then the compression should be quite considerable.

[serenss]

Have the same problem with a v4 SC2.2. Would love to know what the outcome of this one was?

[Ted Fletcher]

The SC2.2 v4 seems to be causing a bit of a stir!

This compressor is a very standard opto compressor except that it uses a ‘sum’ signal to drive the sidechain.

If the incoming L/R audio signal is reverse polarity (out of phase) then the ‘sum’ signal is zero or very close to it and there will be no compression…. but this also means that the compression meter will not work.

If you have one of these compressors and there is no compression happening BUT the meter is working, then there is a fault.

I have had several of these recently and the fault is often the LED driver transistors going open circuit.

But, once again, be careful because the compression with the SC2.2 is extremely gentle and unobtrusive….. it is quite hard to make it over-compress!

These analog compressors are much better behaved than the nasty digital ones that everyone uses nowadays. 🙄

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