#1
Hi all

Was having trouble with my new pedal layout, before realizing the problem was with the amp.

If the power and standby are turned on relatively quickly, you can hear louder this noisy hum comes from the speaker, warming up over about ten seconds to quite loud. If you turn on just the power and let it warm up before hitting standby, you hear a loud constant hum straight away, only when the standby switch is also on. Changing channels makes the hum sound a bit different from clean to lead, it is more trebley on the lead channel.

I believe all the leads are fine, to the speaker and for the PSU. Impedance is set to 16 ohms as it should be.

Possible I knocked it yesterday since I was moving some furniture, or maybe that's just a red herring.

Any idea what the problem is and how I can diagnose it, or should I just take it to a shop?

Thanks.
#2
Update: tapped each tube with a pencil to see if one would make a noise, and it seems to work fine now. Poorly seated tube, perhaps?
#4
Quote by dragonzrmetal
Update 2: Still broken. Halp? Please?

I thought you said reseating the tube fixed it?

If reseating it fixes the problem, then deoxit the sockets and/or buy new preamp tubes. If they're still the stock ones then they need upgrading anyway.

The symptoms you're describing in the OP could be caused by many different things. But nothing you've written would pertain to it being caused by one thing over the other.
Quote by Axelfox
Reeeeeeeeeeeeeeee

Quote by H4T3BR33D3R
I also have to do that. Cottaging this weekend
#5
T00DEEPBLUE It did for a time, I just swiveled the amp back round, plugged the effects loop back in and it was dead again. I didn't reseat any of the tubes, I only tapped them with a pencil. I don't think it was the seating on further thought, possibly an actual electrical issue... I have pushed them all in since, to no effect.

The power tubes can be ruled out as a cause considering that tapping them does not cause any noise, is that correct?

I'll replace the preamp tubes asap. Thanks for your help!
#6
Quote by dragonzrmetal

The power tubes can be ruled out as a cause considering that tapping them does not cause any noise, is that correct?

They're likely fine. But JJ's are still better
Quote by Axelfox
Reeeeeeeeeeeeeeee

Quote by H4T3BR33D3R
I also have to do that. Cottaging this weekend
#7
I had an amp once that did that. I wasn't playing very well, and it let me know. Just flat turned itself off and refused to fire up until I practiced more.
#9
Power tubes won't necessarily react to the pencil test. Are the power tubes warm when you turn the amp on? If not then the heaters in the tubes may have gone and which means you need new power tubes.