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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: RE: using a solid state rectifier for amp start up... posted by cpotl on June 15, 2019 at 13:28:28:
I can think of some reasons why one would want to delay the application of B+ other than the B.S.'y cathode stripping argument. One, to prevent no load over voltage on the PS caps (especially with cascaded RC filters) where replacing with higher rated caps is impractical. Or in my case, I use CCS fed active B+ shunt regs. on every stage. The stages are differential thus the shunt current can be low (~5mA). If the tubes are cold the entire current output of the CCS is dumped through the shunt device. In my case the heatsinks to handle this surge would be impractical. If SS active loads are used having the B+ on before the tubes can conduct can lead to misbehavior in my experience. My power amps use four KT-120 tubes in PPP. Their cathodes are all connected to a single active CCS "tail". Without B+ delay the CCS will push all 285mA through the first tube that starts to conduct. The tube will survive the experience but at what cost to its longevity?
"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln
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- RE: using a solid state rectifier for amp start up... - JKT 06/15/1915:00:03 06/15/19 (0)
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