Hi all,
I am reaching the end of the development of my latest amp. After a few ups and downs it seems to be panning out well.
However I have a weird hum issue. Let me describe the input circuit a little. I have input transformers with the input floating on the primaries. The secondaries are biased at -300V via a negative rail, and drive both inputs of a LTP. The problem is I have some buzzing hum. This goes away if I touch the sleeve of the input phono plugs. It doesn't respond to grounding the input sockets to the case at the case. I haven't yet attempted to ground the sockets to the main star ground. This seems to be the opposite of the usual situation where touching the screen induces hum.
Has anyone got any ideas whats going on.
Shoog
I am reaching the end of the development of my latest amp. After a few ups and downs it seems to be panning out well.
However I have a weird hum issue. Let me describe the input circuit a little. I have input transformers with the input floating on the primaries. The secondaries are biased at -300V via a negative rail, and drive both inputs of a LTP. The problem is I have some buzzing hum. This goes away if I touch the sleeve of the input phono plugs. It doesn't respond to grounding the input sockets to the case at the case. I haven't yet attempted to ground the sockets to the main star ground. This seems to be the opposite of the usual situation where touching the screen induces hum.
Has anyone got any ideas whats going on.
Shoog