PLWO turnoff pops.. sometimes and sometimes not..hmm!

jbeckva

jbeckva

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Hey Joe/Lee - Do you guys experience a turnoff "pop" on the fully modded PL 400's, where sometimes you "do" but other times you "don't"? Why the inconsistency there? (just pondering... )
 
F(*& DON"T TOUCH IT JERRY!@!!!!!!!!!!!!!!



Just giggin ya Jer. I have powered down with the amp on and pre off, with pre on and I wait, and wait, and wait, and wait, can't hear a thing except maybe a little kerfluffle, sometimes, and ya really have to pay attention.
This weekend there will be an announcement by White Oak Audio about some stuff, IF we can get test results confirmed by then. Your question will be moot then Jer....
 
Rev A may produce a minor kerfluffle at turn off Jer and a small pop on turn on.
Rev B never went to production.
Rev C is very quiet on turn on and turn off. Hard to hear any noise due to the balanced power supply construction for the front end. My preamp makes more noise at turn-on/turn-off than the amp does. If your bulk caps are well balanced and your bridge rectifier is not leaky on one side (which leads to either the B+ or B- rail decaying faster than the other) then you should achieve very low to no noise.
then...

Are you running with or without a DC protect board installed?
 
Running with a DCP.

But now that you mentioned the bridge, yeah... remember me asking about that drain I saw on the caps?? I think you were dead on with the BR being a bit "leaky" on the reverse current! That's probably it, since when power is taken away one of the rails WILL definitely bleed faster than the other!

Think I'm going to put in a better BR then. I'll get it on order next week! Thanks for the tip, Joe!
 
If you are running with a DCP Jer, please explain how you can be experiencing pops on either turn on or turn off? Other than maybe the relay making noise on closure or opening?
 
Gepetto said:
If you are running with a DCP Jer, please explain how you can be experiencing pops on either turn on or turn off? Other than maybe the relay making noise on closure or opening?
Click to expand...

well.. joe... that's what I figured you could explain, lol....

I dunno.. some arcing somewhere could be switch or relay, but it doesn't happen all the time.
 
Jer
The old turn off thump would occur nearly 10 seconds after turnoff. If you have a DCP, then the relay should have opened way before that time.

Is the noise immediate upon turnoff? If it is, then Lee is probably onto it, that it is the AC switch arcing on turnoff. You should be able to cure that by putting a 0.1 to 0.22 uF 250V cap across the AC switch.

On my 700's, I notice nothing on amp turnoff at any time and I have no DCP either.

Try to see if the noise you are hearing coincides with anything.
 
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