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RE: Pre and Power amps

While I do agree that good components should have muting circuits that work and take care of these transients, you can also put your Mercedes into drive while rolling backward. (remember when they used to sorta roll up the back axle and raise the back of the car for backing out of driveways ?)

With a tube preamp it should be fine. The value of the power supply caps should have been chosen to take care of that. On turn on it should rise slowly and not put out a thump. On turnoff it should drop slowly enough that there is no thump.

There has been talk of only turning of the filaments but there is a rebuttal to that regarding what is called "cathode stripping". That theory is why guitar amps have standby switches and some advocate turning it on in standby for a few minutes before taking it out of standby mode which of course applies the B+.

The contention is that when it asks for conduction the cathode cannot supply there is some damage to the cathode coating. This is actually supported by statistics on television CRTs with chassis' with continuous auto color balancing, called AKB. In fact Sony set up a delay circuit to keep this from happening, which meant shit because their CRTs went bad just as fast as anyone else's, if not faster. So basically those facts prove nothing. We simply do not know and nobody is likely to do any research on it at this stage of the game. And these days, a high end tube preamp might just have a relay on the output, who knows ? Nothing stopping them.

I put it this way, do it wrong and see what happens. If you hear a thump don't do it that way. Hopefully you have gain controls on the power amp so you can keep it down to non-speaker destructive levels. If not, maybe just don't bother.


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  • RE: Pre and Power amps - JURB 15:46:11 11/20/16 (0)

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