Any idea what's causing this pop / fluttering noise?

[Molly]

Not as much evidence of the pop, pop this time but you can hear the fluttering noise. Goes away once the amp's hot. Any thoughts?

Thanks.



A fly followed me in to the shed. Disregard any fly noises...

[GrantB]

Pull the tubes, clean the pins...start there.

[olegmcnoleg]

For the GoT fans

Valvular morghulis!





(All tubes must die)

[Molly]

Pull the tubes, clean the pins...start there.

Thanks Grant.

I'd just done that actually. Just before I turned it on. Used some proper electrical spray / lube. Maybe that's why there wasn't the usual pop, pop.

[Molly]

For the GoT fans

Valvular morghulis!





(All tubes must die)

I may go digital. Yet again...

[RectifiedAmps]

Turn all the controls to zero, then turn it on and see if it crackles. Also, even though you’ve cleaned them, give each tube a wiggle in its socket and see if it brings the crackling back.

[Molly]

Turn all the controls to zero, then turn it on and see if it crackles. Also, even though you’ve cleaned them, give each tube a wiggle in its socket and see if it brings the crackling back.

Will do. Thanks for that.

[GrantB]

Start removing pre amp tubes...one by one. If it stops, then the last one was it. If it's still there....power tubes.

If you search this online there will be lots about resistor replacement etc....meh...just try all other options first. Tubes are more often than not the issue for this sort of noise.

[Molly]

Noise remains with all controls at zero. V1 and 2 are a bit ringy but swapping them out for known good ones didn't change that really. Tubes are mostly US made RCA. Power tubes too with a Mullard GZ34.

It'd warmed-up by the time I'd finished messing with the preamp tubes and the fluttering had gone. I'll come back to it later and repeat the exercise with a pair of GT 6V6.

[Molly]

It was the power tubes. Pair of new GTs and not a peep.

Now I just need to figure-out how to bias them.

[GrantB]

It was the power tubes. Pair of new GTs and not a peep.

Now I just need to figure-out how to bias them.

If it sounds good, meh...I change my Princeton valves around without biasing. I've talked it through with the guru's and if it sounds great, and I'm not churning through the tubes...leave well alone.