Ac15 help

wayneirie

My vox has started making a noise like a combination of an envelope filter combined with a shitty distortion pedal, every time i play a note. its not cables, i run two amps and the other is fine. I have out put valves but no spare preamp valves any pointers. I use it pretty much every day and the only thing I've had to do is replace a fuse. HELP please.

ICBM

Change the output valves first if you have those. No biasing necessary on this amp.

If it's not that, swap the preamp valves round - if the problem changes in some way it will be one of them, in which case buy a spare and replace each in turn until the fault goes away.

If it's not that, is it a model with a rectifier valve? If so a spare of those isn't a bad thing to have either, even if it proves not to be the problem.

Also try it through another speaker cabinet, if you have one available - it doesn't sound particularly like a speaker problem but it's worth eliminating. Any impedance or power rating will do for a quick test, as long as you don't crank the amp up too far.

If none of that cures it you need a tech.

wayneirie

valves swapped, no joy, loud hum developed, im guessing filter cap or something in power supply. id imagine its probably my fault as my little silvertone lives on top of it obscuring the vents. moron. off to tech as soon as i get chance.