Hi Joseph, the gain difference on the two ‘bricks’ is quite understandable; I did alter the gain structure and so I’m not surprised that you have two that do not match exactly, but the quality will be the same, and it’s unlikely that there is a fault.
I recall that the lower gain one is the earlier one; I did change the circuitry slightly to improve the linearity of the gain pot, it was quite a trick at that time to get the very high levels of gain swing on a single pot.
I must advise NOT to let any regular equipment workshops loose on the ‘brick’, the mechanical construction is tricky and the circuitry is delicate…….. it’s a great example of the old saying ‘if it ain’t broke, don’t fix it!’
Regarding comp 1 and 2, yes, these are effectively ‘slopes’, the switch alters the shape of the compression curve. Comp 1 gives a very gentle compression, while ‘2’ starts gently, but increases to a maximum of about 6 to 1. The curves are very non-linear and it’s that fact that gives a compression that is very close to the natural compression response of the human ear, completely unlike other compressors……. this was the whole ‘magic’ of my early optical compressors.