I have an ST70 that I built custion, years ago.... It includes an SDS70 Cap board and a PC3U. EL34's and 6922's
The board I have was without any bias options. However I found that I had removed the connections
V1 pin 8 to V2 pin 1
V6 pin 1 to V7 pin 8
and replaced the 15.6 ohm resistors on each side with 10 ohms to ground on each of the four tubes . the same as the DC balance option wiring in the PC3U instructions.
Ill assume electrically, that I should set 1.0v on the bias port up from on each side of the amp.
Why did I do this though. Im sure I had a good reason. But am I now just reading the values of one tube to set the bias in the hopes that the EL34's on each side are perfectly balanced?
Am I wrong but didnt the connection between the tubes read an average voltage drop in support of the bias when using a 15.6 ohm resistor for a reading of 1.56v
If I set the bias now to 1.0v.... what am I really reading? just the front tubes on each side.
help!
Jordan
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Topic - Does anyone know this setup - jrubin 15:41:09 08/23/15 (7)
- RE: Does anyone know this setup - Joe Curcio 08:28:54 08/26/15 (0)
- Re:Does anyone know this setup - Joe Curcio 17:47:23 08/23/15 (4)
- Re:Does anyone know this setup - jrubin 15:54:42 08/24/15 (3)
- Re:Does anyone know this setup - jrubin 15:55:31 08/24/15 (2)
- Re:Does anyone know this setup - jrubin 16:54:50 08/24/15 (1)
- Re:Does anyone know this setup - jrubin 17:16:00 08/26/15 (0)
- RE: Does anyone know this setup - jrubin 15:42:09 08/23/15 (0)