SET Asylum

Posted by Kyle K (A) on February 12, 2013 at 17:48:08

In Reply to: RE: Wright 3.5s posted by Paul Joppa on February 11, 2013 at 13:25:43

Output tansformers on the early ones were the tiny MQ TFA-204, not DS-025 (later switched to Onetics). As you said, George used resistors on the rectifier cathode in all his designs, mainly to extend rectifier life, but for the WPA 3.5 he had to drop the voltage some due to the crappy Hammond 200 series power transformer he used in the early ones (poor regulation, ran real hot and often ended up buzzing). On later ones he used custom power transformers made by DeYoung.

There's a 522K resistor from pin 2 to pin 6 of the 6SN7. I asked George about it and he said he always used it in that type of circuit (direct-coupled) for sonic reasons. Do you know what it does?

On the WPA 3.5 I looked at, the choke was in the ground leg