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In Reply to: Sonic Observations - Replaced Selenium on PAS posted by crooner on September 16, 2004 at 22:57:13:
Well, when I replaced the filament voltage doubler with 6A2 6-amp 200 PIV diodes. I also use two 4700UF caps with 1.5 ohms resistance @ 10-watts installed in the transformer lead that goes to the center position of the two caps in series.
This resistance lowers the voltage to 12.6 volts as solid-state replacement rectifiers over-voltaged the tubes with my modification. Another benefit is lowering the high peak to average current. This is easier on the transformer & reduces noise as well. My preamp produced no audio hum after modifications.
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Follow Ups
- Re: Sonic Observations - Replaced Selenium on PAS - Jimmy 17:41:19 09/17/04 (3)
- I was tempted to use higher value caps... - crooner 18:39:18 09/17/04 (1)
- Re: I was tempted to use higher value caps... - Jimmy 19:09:51 09/17/04 (0)
- Re: Errr..... - Jimmy 17:50:40 09/17/04 (0)