DEfinitely the million dollar issue. I did measure the OT impedance - I use a 9V wall wart and it works quite well. Doing the calculations, this OT is about 5.5K into an 8 ohm load which is good for 6L6. The other transformer I temporarily used (which made no diff.) was about 4K. There's no nfb here, but I've tried reversing the plate leads anyway. No difference.
Amp is cathode bias, very definitely well grounded.
Here are some readings from this morning:
Idle, no signal:
pin 3: 410VDC / 4.9 VAC
pin 4: 404 VDC / 0 VAC
pin 5: .008 vdc / 0 VAC
pins 1/8 (tied, cathode bias): 33.4 VDC / 0 VAC
Signal applied:
pin 3: 377 VDC / 24 VAC
pin 4: 367 VDC / 0 VAC
pins 5: -8.2 and -4.1 VDC, 63 VAC and 56.7 VAC
pins 1/8: 57.2 VDC / 1.1 VAC
Amp is cathode bias, very definitely well grounded.
Here are some readings from this morning:
Idle, no signal:
pin 3: 410VDC / 4.9 VAC
pin 4: 404 VDC / 0 VAC
pin 5: .008 vdc / 0 VAC
pins 1/8 (tied, cathode bias): 33.4 VDC / 0 VAC
Signal applied:
pin 3: 377 VDC / 24 VAC
pin 4: 367 VDC / 0 VAC
pins 5: -8.2 and -4.1 VDC, 63 VAC and 56.7 VAC
pins 1/8: 57.2 VDC / 1.1 VAC
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