#1
I recently bought a used AT100 head and matching cabinet for a low price. I get a distorted clean channel if I turn it up loud. Like a crummy gain sound where I don't want it. It sounds great at low volume. What could this be? I'm new to tube amps. Should I just take it in or is there something I could do/learn to do to fix it?
#2
It could be a bad tube or two.

I suggest you get 2 new 12ax7 preamp tubes and roll them one at a time in the preamp to see if you get anything better sounding. If this doesn't work, then take it to a good tech
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
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#3
Quote by Robbgnarly
It could be a bad tube or two.

I suggest you get 2 new 12ax7 preamp tubes and roll them one at a time in the preamp to see if you get anything better sounding. If this doesn't work, then take it to a good tech


I already put a new tube in to the V1 slot. I did just read about changing the phase inverter tube to a lower gain type. I will take your advice and get some new preamp tubes to change out on it. Can't hurt.
#4
Quote by cotyculbz
I already put a new tube in to the V1 slot. I did just read about changing the phase inverter tube to a lower gain type. I will take your advice and get some new preamp tubes to change out on it. Can't hurt.

Yeah without actually seeing the amp it is just a guess, but that is the cheapest way for you to check by yourself.

Are you sure you put the 12ax7 in V1?
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#5
Quote by Robbgnarly

Are you sure you put the 12ax7 in V1?



Positive, I found a schematic online for it and everything
#6
Quote by cotyculbz
Positive, I found a schematic online for it and everything

what brand did you get and was it from a reputable dealer that tests them?
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#7
Quote by Robbgnarly
what brand did you get and was it from a reputable dealer that tests them?


Tungsol, ordered from BnB tubes on Amazon.
#8
Quote by cotyculbz
Tungsol, ordered from BnB tubes on Amazon.

it would be cheap to order another tube just to test.
I have had great luck with www.tubedepot.com and www.eurotubes.com and several others. These sites actually test the tubes they sell to make sure yours aren't microphonic or noisy. Best case scenario is the "new" one you bought is bad and a tube swap will cure it.

It also may not be V1 that is the issue, one of the other preamp tubes could be bad
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#9
Quote by Robbgnarly


It also may not be V1 that is the issue, one of the other preamp tubes could be bad


It definitely isn't the V1 cause it still had this problem before and after I swapped it out. I was already looking at eurotubes and they seem to have a retube kit for my amp. I was told that I would have to have a tech retube my power tubes however.
#10
Quote by cotyculbz
It definitely isn't the V1 cause it still had this problem before and after I swapped it out. I was already looking at eurotubes and they seem to have a retube kit for my amp. I was told that I would have to have a tech retube my power tubes however.

Well it is not that hard to learn to bias your own amp.
I have one of the Eurotubes bias probes and I taught myself by watching some youtube videos. Eurotubes has some decent videos also.
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate
#11
Quote by Robbgnarly
Well it is not that hard to learn to bias your own amp.
I have one of the Eurotubes bias probes and I taught myself by watching some youtube videos. Eurotubes has some decent videos also.


Awesome, and really quick...anything I need to know about discharging my amp before touching the preamp tubes? Or just leave it unplugged and let it drain on it's own for a half hour? I'm a little confused and have read different things. I already replaced the V1 by just letting it drain on it's own but maybe I got lucky and didn't get electrocuted? Lol
#12
Quote by cotyculbz
Awesome, and really quick...anything I need to know about discharging my amp before touching the preamp tubes? Or just leave it unplugged and let it drain on it's own for a half hour? I'm a little confused and have read different things. I already replaced the V1 by just letting it drain on it's own but maybe I got lucky and didn't get electrocuted? Lol

pulling tubes you have nothing to worry about. Just pull the tubes straight out and push them straight in. You may have to wiggle them a little.

Really the only time you need to drain the caps is when your doing internal work on the circuit boards. replacing tubes you don't need to worry about it
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate