I can’t recall how it happened; and we knew nothing about it at the time.
The SC2.2 was the first stereo compressor that used the ‘sum and difference’ routing….. the L and R signals are converted to Sum and Difference before compression, then at the output stage they are re-converted to L and R. The problem is that the output stage does not behave correctly and provides a very near ‘mono’ output….. BUT it only does this if the output is being used as a balanced line!
I would ask that you try using the compressor in ‘unbalanced’ mode (that is, link pins 3 and 1 in the output XLR connectors) and there is a chance that the problem will be solved.
Normally I can offer to correct any faults in any equipment that was designed by me originally, but in this case, it was an original problem caused by a mistake somewhere in the manufacturing process. I have only ever seen one of these faults, and that one worked perfectly in unbalanced mode.
In case anyone needs the circuit diagram of this model, please email me at