godwentpunk
New Member
- Joined
- May 16, 2018
- Messages
- 20
Is this normal for this amp? Seems loud to me. My volume pot definitely sounds bad, I sprayed some cleaner but that did not help.
Joe...
Joe...
So you think it's a preamp issue versus a power tube?I’d swap some tubes and see how that works. Hiss is mostly a tube thing. Lead channels usually employ an additional tube (or more than one).
So you think it's a preamp issue versus a power tube?
Joe
The hiss is only on the CLEAN channel, the CLEAN sounds great. I've cleaned all of the tubes and that has not helped. I purchased an extra preamp tube and tried to put it in slot V1, V2 and V3 but nothing helped. My next option to get an entire new set of preamp tubes but that's over $100 for JJ's because this amp has 6 of them. I'm really stumped in this.Most likely, since if it was a power tube it’d make noise on both channels.
Have you tried tapping the tubes with a chopstick to see if you can find the possible culprit?
The hiss is only on the CLEAN channel, the CLEAN sounds great. I've cleaned all of the tubes and that has not helped. I purchased an extra preamp tube and tried to put it in slot V1, V2 and V3 but nothing helped. My next option to get an entire new set of preamp tubes but that's over $100 for JJ's because this amp has 6 of them. I'm really stumped in this.
Also, is the bias adjust slot the 1/4 cable looking slot on the bottom side of the chassis where the power tubes are located?
joe...
As I said because the noise is only on the clean channel, it’s not likely that it’s the power tubes, because the power tubes work on both channels.
To find the bad tube, you should try the spare tube in all six spots, not just 3 of 6. You’ve only gotten halfway through! Just be patient, and go through them one at a time.
Often you can find a microphonic tube quickly, by lightly tapping the preamp tubes with a wooden chopstick, or pencil, with the guitar/pedalboard disconnected, but the speaker connected and the amp turned on. It doesn’t have to be cranked up loud. Try it on both channels.
You’ll hear the tapping clearly from V1 through the speaker, because it’s the initial gain stage of the amp, and unless it’s weird, don’t worry about it. The other tubes will tap a lot quieter, until you find the microphonic tube. That tube will be very sensitive to tapping and make the loudest noise through the speaker. If you find the bad tube that way, try the known good tube in it, and see if that helps.