HELP amp noise (video sample)

  • Thread starter Thread starter metalj
  • Start date Start date
Are sure it's caused purely by the amp....you got all that other stuff in the rack.

If you just plug the amp straight into the wall, without and of the rack gear involved or connected...does it still do that?

Yes...it could be a tube (it's easy enough to check that)...or maybe some other is going...?
 
miroslav said:
Are sure it's caused purely by the amp....you got all that other stuff in the rack.

If you just plug the amp straight into the wall, without and of the rack gear involved or connected...does it still do that?

Yes...it could be a tube (it's easy enough to check that)...or maybe some other is going...?
Click to expand...


Yep, does it even with nothing else plugged into it. In the video clip it didnt make the noise as long as it usually does because it had been on for a while already due to me just finishing up with a rehersal. If it sat cold for a while then I turned it on, the noise is louder and lasts a bit longer.

Hows that for a amp actually "farting out" ;)
 
My best guess is bad or poorly matched power tubes. Does that amp have an adjustable bias?
 
ocnor said:
My best guess is bad or poorly matched power tubes. Does that amp have an adjustable bias?
Click to expand...

I was told by the store i bought it from that all I had to do is buy matching sets of each tube and Im good to go. So i did

After talking with a rep at JJ's I was suprised to find out that this amp in fact does have an adjustable bias so maybe that is the problem.

I was worried that noise was a sign of another component going bad or something.
 
metalj said:
After talking with a rep at JJ's I was suprised to find out that this amp in fact does have an adjustable bias so maybe that is the problem.
Click to expand...

Even so, you'll still find that it's best to have matched power tubes, since most amps give you a single bias point for both/all power tubes, so if the tubes aren't closely matched, the bias setting can only get you somewhere "in-between" them (though some amps give you separate bias for each tube, so you can use unmatched tubes too).

I set my own bias (I have the tools) on all my amps, and I've messed with a variety of settings on some amps, going from their minimum to maximum desired points (and even a beyond)...and I've never had any make that noise when powering up even with the bias way off the mark and with unmatched tubes.
Bad bias settings would show up more during playing...I would think...not so much during the power-up cycle. Anyone have opinions on that?

Does the amp have a Standby switch?
If so, does it make the noise during Standby or only when power ON is applied?
 
miroslav said:
Even so, you'll still find that it's best to have matched power tubes, since most amps give you a single bias point for both/all power tubes, so if the tubes aren't closely matched, the bias setting can only get you somewhere "in-between" them (though some amps give you separate bias for each tube, so you can use unmatched tubes too).

I set my own bias (I have the tools) on all my amps, and I've messed with a variety of settings on some amps, going from their minimum to maximum desired points (and even a beyond)...and I've never had any make that noise when powering up even with the bias way off the mark and with unmatched tubes.
Bad bias settings would show up more during playing...I would think...not so much during the power-up cycle. Anyone have opinions on that?

Does the amp have a Standby switch?
If so, does it make the noise during Standby or only when power ON is applied?
Click to expand...

Great info there. Thanks.

The amp does not have a standby. In only has one on/off switch
 
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