Member #52302

Member Since: November 9, 2008

Country: United States

  • P.P.S. Another reason to bring the HT up slowly is to the electrolytic caps time to polarize (especially if the amp has been shut off for a long time). Tubes worked good with tubes-- mixing them with solid state is a tricky business (as a lot of guitar amp designers have learned the hard way).

  • P.S. Normally there's no DC though the output xformer, so no big field. But funny things happen during start up, or when speakers are connected or disconnected. Also relays contacts can bounce. All it takes to get a big voltage spike is to get a field going and then suddenly collapse it. You're starting with 350 VDC...

  • Great project. As you probably know, you're getting the pop when the HT comes on because the HT supply is solid state and comes up in a hurry--no cathod heaters to warm up. :-) Putting a relay on the speaker connections is a bad idea because of self-induction in the output transformer. It could easily exceed the max. plate voltage and blow the output tubes or a cap. One possible solution would be to use a use the regulator to switch on the HT gradually (say was a capacitor w/bleeder resistor chargers on the regulator input). Speakers should never be connected or disconnected from a tube amp while the amp is turned on.

No public wish lists :(