Re: EL34 power amp reworked as a stereo amplifier
Did lots of thinking last night and came up with a few more suggestions!
Are both your input RCA jacks connected to chassis? If so fit an insulated variety to one of the channels. It could be the problem.
Main earth for the WHOLE amplifier should be at the input socket.
That means your star earth point as well. The earth point for the input socket "should" be across the grid to earth input resistor, obviously the end connected to ground. Also connected at that point should be the cathode cap ( if your using one) and the cathode resistor of the input bottle ( EF86 in your case)
Another thing to try is to lift the whole heater wiring above ground and fitting the standard sharing resistors ( 50 -220 ohms) and tying the centre tap of these resistors to the output stage cathodes of one channel. That will set the heater line at EL34 bias voltage, about 30 volts or so with your amp. If that helps you can fiddle around with a voltage divider across the HT line and set the "sweet spot" voltage with a pot, and then replacing the pot with a fixed resistor.
Joe
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