Problem: Tube Amp "Light Saber Noise"

[ogcaleb]

When I flick my 2005 Ampeg Classic to Power On, nothing.
When I flick the standby to on, it makes a zooooom, almost lightsaber noise that lasts about 1.5 seconds, then it settles to a normal, playable tube amp with no hiss or crackle.

It plays wonderfully, however it's my first tube amp so I wouldn't know what it sounds like if some of the tubes need replacing. Has anyone heard of this kind of issue? If so, is it a power amp tubes or a preamp tubes problem?

If noone has any clue what i'm talking about i'll upload a video of it.

[Bassmec]

I would guess that the power supply caps or an electrolytic cap somewhere is drying out.

[BassmanPaul]

You ARE waiting for the tubes to warm up are you not?? Takes about 30-40 seconds.

Paul

[okcrum]

Sounds like it's oscillating. Caps, possibly power supply caps, possibly bypass or coupling, would be the prime suspects.

The tubes would need to be warmed up for this to happen, and the amp should remain stable even if you flip power and standby on at the same time.

[ogcaleb]

yeah i'm giving it plenty of time to warmup.

I guess I need to bite the bullet and run it by a repairman one of these days.