In Reply to: Can the plate standby switch damage posted by Alex on February 25, 2005 at 19:24:02:
Hello AlexYour concern is legitimate. I'm having the same "pop" trouble with the 5U4GB, and fear harm to my beloved vintage Klipsh forté. The easiest solution i found was to replace it altogether with an old TV-damper diode (6AX4, 6W4 etc..) These have slow-warmup times of at least 10 sec, so the other tubes will be "warm".
They use the same octal basing as the 5U4 family, except it is a single diode. So if you put one in series with a full bridge of two silicon diodes (vanilla-style ultra-fast UF4007 is the best Q/R IMO), you get the "slow-start" feature at the cost of some voltage drop. The vaccuum diode tends to "sink in" the noise from the silicon diode bridge, so you get that "tube rectified" sound as well.
YMMV--SomeJoe
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Follow Ups
- Use SS diodes in series with a slow-warmup damper diode - SomeJoe 20:20:58 02/25/05 (3)
- Re: Use SS diodes in series with a slow-warmup damper diode - Ray Moth 19:31:54 02/28/05 (0)
- ...And forgot to mention, switching the damper heater off acts as B+ standby as well - SomeJoe 20:24:32 02/25/05 (1)
- Last thing 8O) don't use more than 40 uF as first cap in C filter with those(nt) - SomeJoe 21:57:13 02/25/05 (0)