3.11.2003
More ST-35 info from Tubes Asylum:
The Dynaco ST-35 is "Cathode Self Biased" and has a common 90 Ohm resistor attached to all 4 power tube cathodes to Ground that determines the current flow through the power tubes at idle. There is no adjustment. This requires use of a fairly well matched quad of power tubes.
This 90 Ohm resistor causes the power tubes to idle a little "hot" in my view, so in my ST-35 I changed this resistor value to a 120 Ohm (about 15 Watt) resistor.
Also, the tall silver Multi Cap can has 4 Capacitors in it. They are 3 filter caps for the power supply that may or may not need replacing. The forth Capacitor in the Can is the Cathode Bypass Cap, and I would replace it with a better quality cap, but one that would fit in the very small space (barely 1/2 inch) available on the underside of the top chassis
Also, you might wish to upgrade the coupling caps on the two PCB's with a bit better quality. I found that Solens fit the PCB space available nicely.
With just a few upgraded capacitors, and a new set of NOS tubes, the ST-35 will perform at a very high level, as it is one of the very best Push Pull designs ever.
- Ivan303
The Dynaco ST-35 is "Cathode Self Biased" and has a common 90 Ohm resistor attached to all 4 power tube cathodes to Ground that determines the current flow through the power tubes at idle. There is no adjustment. This requires use of a fairly well matched quad of power tubes.
This 90 Ohm resistor causes the power tubes to idle a little "hot" in my view, so in my ST-35 I changed this resistor value to a 120 Ohm (about 15 Watt) resistor.
Also, the tall silver Multi Cap can has 4 Capacitors in it. They are 3 filter caps for the power supply that may or may not need replacing. The forth Capacitor in the Can is the Cathode Bypass Cap, and I would replace it with a better quality cap, but one that would fit in the very small space (barely 1/2 inch) available on the underside of the top chassis
Also, you might wish to upgrade the coupling caps on the two PCB's with a bit better quality. I found that Solens fit the PCB space available nicely.
With just a few upgraded capacitors, and a new set of NOS tubes, the ST-35 will perform at a very high level, as it is one of the very best Push Pull designs ever.
- Ivan303
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