AC30 and tubes

[NJLK]

I recently got my hands on an AC30CC2. It sounds great, for the most part. But, it breaks up really easily and has very little headroom. I have to set each channel's gain no higher than 1.5 or 2. Otherwise, I start getting very obvious breakup. Also, when using gain pedals, I often get a layer of really unpleasant high frequency fizz/distortion (on top of what the pedal is producing). This happens regardless of whether reverb is turned up or down, or off. When I do need the amp to overdrive, I find that the breakup is much more fizzy than what I used to get with my old AC15C2. Finally, the master tone cut has very little effect - it has basically no effect from 1-9, and then removes all treble when turned up past that point.

I opened up the amp, and it looks like the tubes are from multiple manufacturers. Some are EHX, others I can't quite make out. I should also add that there is no obvious damage to any internal component, including the speakers.

I figured re-tubing this amp may be a good place to start (or if someone has a better idea, please let me know). But, having never re-tubed an amp myself, I have no idea what brand to go for. This is my main gigging amp, and will continue to get beaten up. So, I'd like to stay away from expensive NOS options.

I see EHX and Ruby and JJ tubes going for about $60 for a set of power tubes. Any of those good options?Also, EHX has options like "hard," "medium," and "soft." Hard apparently gives you the most headroom, which I would want. But, I also don't want to make the amp sterile sounding.

Any input would be much appreciated!

[VinceT]

Re: AC30 and tubes

I had a AC30CC2X for a while - and those symptoms definitely aren’t right! I used TungSol tubes for preamp and matched JJs in the power amp.

Does your model have the switches on the rear panel? Experiment with those to get the lowest gain you can.

Best of luck!


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[NJLK]

Re: AC30 and tubes

yup, I tried all sorts of settings. In fact, switching between full and half power on the back does very little. Is it possible that one or more of the power tubes has gone bad and the amp is effectively functioning at half power, even when set to full power?

[Nostalgic Distortion]

Re: AC30 and tubes

I recently got my hands on an AC30CC2. It sounds great, for the most part. But, it breaks up really easily and has very little headroom. I have to set each channel's gain no higher than 1.5 or 2. Otherwise, I start getting very obvious breakup. Also, when using gain pedals, I often get a layer of really unpleasant high frequency fizz/distortion (on top of what the pedal is producing). This happens regardless of whether reverb is turned up or down, or off. When I do need the amp to overdrive, I find that the breakup is much more fizzy than what I used to get with my old AC15C2. Finally, the master tone cut has very little effect - it has basically no effect from 1-9, and then removes all treble when turned up past that point.

I opened up the amp, and it looks like the tubes are from multiple manufacturers. Some are EHX, others I can't quite make out. I should also add that there is no obvious damage to any internal component, including the speakers.

I figured re-tubing this amp may be a good place to start (or if someone has a better idea, please let me know). But, having never re-tubed an amp myself, I have no idea what brand to go for. This is my main gigging amp, and will continue to get beaten up. So, I'd like to stay away from expensive NOS options.

I see EHX and Ruby and JJ tubes going for about $60 for a set of power tubes. Any of those good options?Also, EHX has options like "hard," "medium," and "soft." Hard apparently gives you the most headroom, which I would want. But, I also don't want to make the amp sterile sounding.

Any input would be much appreciated!

I have two AC-30's (One vintage & one modern) & a AC-15C2 which is a AC-15 in a AC-30 cabinet with two Greenbacks. I can tell you one thing, they should not be breaking up that quickly & the cut knob should have a much more notable effect!!! I mean they are EL84 amps so if you hit me with humbuckers your going to get some mild breakup but it shouldn't be much until you get both the volume & gain up past noon on their dials, even then they clean up with the cut knob some. If I were you I'd completely re-tube it.....

Tubes are pretty subjective but Ruby' & J.J.'s will both sound pretty good in a VOX however I'd stay away from the E.H. tubes, IMHO they have a piercing metallic quality to them in AC's. I think it's because they are already really bright/trebly amplifiers but that may be something that you're after & would enjoy?

Personally I think TAD's in the power section & Mullard 12Ax7's sound best in modern VOX amps but there's not a lot of differences between them & decent J.J.'s... I have NOS Mullards throughout my vintage 1963 AC-30 but only because that's what was installed when I bought it, I wouldn't spend that much on NOS tubes unless I couldn't run anything else in it!!!

I rarely ever use that one so what's in it should last a good long while but when they do eventually go I'll probably just use what the TAD/Mullard combo in it, perhaps even a J.J. re-tube kit?

[hamerfan]

Re: AC30 and tubes

Take it to an amp tech and have a look over it.