Reply To: SC2.2 voltage regulator

[Ted Fletcher]

I can’t diagnose that from the description ‘low level hum’. How low? is it 50Hz or 100Hz? Hum is usually a power supply problem; or more likely, a ground path problem, and it’s often associated with things external to the equipment, particularly as the hum is on one output only.

With equipment of this vintage (up to 2002 say), you can never ‘cure’ hum, you can only minimise it. Nowadays with switch-mode power supplies the designer can eliminate it.

Dealing with hum on older equipment can be very complex, but on the other hand, the SC2 compressors are relatively simple and don’t have high-gain stages so it’s unusual to find it as a problem.

First, be sure that the problem is not external to the compressor.