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RE: phasing issue

Posted by vinnie2 on June 29, 2017 at 12:21:40:
Got a little time to mess with the amp, so I can answer your points in order.
1. Got rid of the high plate voltages by changing the 4.3k ohm resistor at the top of the schematic to 20k. This dropped the 150vdc to about 100 vdc and the 222vdc to about 120vdc. That is measuring from plate to cathode to get plate volts. Should be good there now.
2. The cathode resistor is now 130 ohms, as per recommended in the tube manual. This gives a plate current of about 67mA (8.8vdc/130 ohms).
3.Cathode to ground is 8.8 volts.
4.Plate volts (plate to cath) is 320vdc on the 6bq5, vs max of 300vdc in the tube manual, but I can and will reduce that when we get back from our trip.
As a side note, lowering the plate voltages seems to have smoothed out the highs a tad. Could just be me, but it sounds a bit smoother.
Next step is to do a a/b comparison with my se 26/26/45 when we get back.