DIY Audio Hybrid Gainclone Amp ECC88 E88CC Tube Buffered LM-3875 Gainclone Amplifier

This was caused mainly by a slow voltage increase on the ECC88 cathode, where the LM-3875 GainCone Amp input cap was connected, partly due to the slow charging of the filter caps and partly due to the slow heating of the tube. To get around this problem, I decided to add a “delay-on” circuit that would remove the noise. I had two options : the first one was to insert a relay at the output, which would connect the speakers to the amp output once the amplitude instability disappears; the second one was to short the amp input until the instability stops. I chose the first option because the second one required two relays and it was more difficult to implement.

When I’m working on a project, I somehow always seem to find out useful new information only after I’ve already tightened the last screw, which is not only frustrating but also means that I would certainly do things differently with the benefit of hindsight. In this particular case, I wish I had made 2 separate mono-blocks and a bit more complex buffer circuit. more detail project visit here.