Dug out my old Laney Pro-Tube valve amp today and fitted it with a Celestion borrowed from a marshall 1960b cab turned it on and it worked fine for like a few minutes and a weird rustling noise started. It can be quite loud as well. Sounds like someones mic'd up a paper bag or something! Tried all the controls and it happens even with all knobs set to 0, all pull boosts off, master volume set to 0 and reverb set to 0 and no input. The noise dont start straight away, only once the amp's warmed up and it can go away for almost indefinate periods of time.
Heres a wave of the noise recorded on an MXL Condensor:
http://dl.dropbox.com/u/4744419/Pro-TubeNoise.wav
The amp itself is normally really quiet apart from this (considering how old it is). I was wondering if this could be some kind of mains-borne interference or transients finding its way in through the power supply (its a soldered power lead, not a kettle socket).
Heres a wave of the noise recorded on an MXL Condensor:
http://dl.dropbox.com/u/4744419/Pro-TubeNoise.wav
The amp itself is normally really quiet apart from this (considering how old it is). I was wondering if this could be some kind of mains-borne interference or transients finding its way in through the power supply (its a soldered power lead, not a kettle socket).
