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DIY 5F6A Bassman balance problem solved - Thanks!
People,
Just a follow up to say I sorted my balance problem by re-jigging Mr. Fender's Long Tail Phase Inverter.
I ended up setting up the LTPI with a 680ohm cathode resistor (instead of the design 480), 47k tail resitor (in place of 10K) and 470K Grid resistors (instead of 1M). Crucially I set up the plate resistors as 120K and 130 K instead of the original 82K and 100K. This was based on Morgan Jones books equation for calculating the difference between Plate R1 and R2. I have also changed the 12AX7 for a 12AT7.
I now have a more balanced sound, Farty distortion gone! I know the signal is more balanced as the clipping occurs evenly on top and bottom half signals. Getting about 24V RMS Sine Wave at output into 8 ohms, about 70ish watts!!
Thanks all for your contributions! (even of the bitten lip type!)
People,
Just a follow up to say I sorted my balance problem by re-jigging Mr. Fender's Long Tail Phase Inverter.
I ended up setting up the LTPI with a 680ohm cathode resistor (instead of the design 480), 47k tail resitor (in place of 10K) and 470K Grid resistors (instead of 1M). Crucially I set up the plate resistors as 120K and 130 K instead of the original 82K and 100K. This was based on Morgan Jones books equation for calculating the difference between Plate R1 and R2. I have also changed the 12AX7 for a 12AT7.
I now have a more balanced sound, Farty distortion gone! I know the signal is more balanced as the clipping occurs evenly on top and bottom half signals. Getting about 24V RMS Sine Wave at output into 8 ohms, about 70ish watts!!
Thanks all for your contributions! (even of the bitten lip type!)
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