#1
Hi, I recently bought a used ac30cc2 and are having some issues. When I play it seems to randomly start getting quieter and the sound fades away completely or almost. The green light next to the standby switch also fades away at the same time as the sound. It can happen after five minutes, half an hour or sometimes never. Some of the time I can get the sound back by turning off the amp, wait a minute or two and turn it back on. Sometimes that helps, sometimes the issue comes right back, and sometimes it takes longer and sometimes it fixes it for that session of playing. Is this a known problem? Any ideas?

(I should mention that this is my first tube amp, and I know nothing about anything regarding tube amps. So in-depth answers are prefered. The guy who sold it said it was newly serviced and tubes changed... but I dunno for sure.)
#2
I just had my first tube amp few weeks ago so I am not a tube amp expert either. But definitely this is not normal for a tube amp and there is something wrong with the amp itself.

As it is a used amp, I would return it if possible unless any experienced UG member here can say an easy and cheap fix for it !!
#3
Take it to a tech. Could be something as simple as the power tubes, even though "new", could be going out. Or could be something that stops working when it heats up. Anyhow, stop messing with it before something else desires to stop working. :/
#4
It may be the rectifier tube. I had an AC30CCH that had an issue with constantly blowing the rec tube and the fuse if I used the standby switch. I just ended up never using the standby switch and let the thing idle for a few mins to warm up before playing, and never had any issues after.
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#5
Quote by red.guitar
It may be the rectifier tube. I had an AC30CCH that had an issue with constantly blowing the rec tube and the fuse if I used the standby switch. I just ended up never using the standby switch and let the thing idle for a few mins to warm up before playing, and never had any issues after.

Yeah the standby switch on the AC30 at one point (maybe still do)was designed where it causes the rectifier tube to be eaten up. Lots of people leave the standby on and only use the power toggle because it saves the rectifier
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#6
I have never used the standby switch, I just leave it on at all times and use the power switch only.
#8
Quote by red.guitar
It may be the rectifier tube. I had an AC30CCH that had an issue with constantly blowing the rec tube and the fuse if I used the standby switch. I just ended up never using the standby switch and let the thing idle for a few mins to warm up before playing, and never had any issues after.


My first thought.

Let's get cath in here...
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#9
Quote by RosT3n

That's the correct rectifier tube.

Rectifier tube failure is a somewhat common failure with the Vox CC line.
Not that it happens a lot, but it is said to be a bit of a weak point.
But IME (I own an AC30CCH and have repaired 2 others, one which was a rectifier tube failure), when the rectifier tube goes, it goes and you get no sound.
I've never had that issue with mine though.

I replaced all the stock tubes maybe a year or so after I bought mine.
Getting the chassis out was a PITA.
Felt like a gorilla tightened the screws. And with the head, you don't have any room to get a powered screwdriver in there.
The Combos I fixed were easier to pull out.


You should probably have a look here before you take that on:
https://www.youtube.com/results?search_query=replacing+tubes+in+a+Vox+AC30
Last edited by CodeMonk at Oct 23, 2015,
#10
Trying to find a video of how to replace the rectifier tube, but no luck. Trying to determine how hard it is, if I should just do it myself.

Anyone have a video or even a guide how to do it?
#11
Code is right though, normally when rectifier tubes go, you get nothing. However, what you are saying sounds like the rectifier is messed up.

As far as changing tubes, it's just plug and play, as long as you have the right type and potentially biasing powertubes (not needed on ac30's).
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Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#12
Quote by RosT3n
Trying to find a video of how to replace the rectifier tube, but no luck. Trying to determine how hard it is, if I should just do it myself.

Anyone have a video or even a guide how to do it?

Look at my previous post.
There are a few videos listed.
#14
Hi again, here's an update!

I finally managed to get a new rectifier tube shipped to me and during the weekend I replaced the old one.

...

And I think it worked! Haven't had more than like an hour to play but no sound fading during that time!

Thanks for all your help!
Last edited by RosT3n at Nov 2, 2015,
#15
Quote by RosT3n
Hi again, here's an update!

I finally managed to get a new rectifier tube shipped to me and during the weekend I replaced the old one.

...

And I think it worked! Haven't had more than like an hour to play but no sound fading during that time!

Thanks for all your help!

With the AC30 is is a good idea to keep an extra recti8fier tube on hand just incase
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)
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Morley Bad Horsie 2
MXR Smart Gate
#17
Will LaneWill LaneI have an AC30TB/6, Marshall built. This is not absolutely on the point but it may help people in future. I had the top boost channel fading out completely when the amp became hot. Sometimes it would come back on when the amp was switched off and on again but usually not. I traced the fault to preamp valve at V4, which is the first in line for the preamp path for both normal and top boost channels. The normal channel worked as normal but the top boost did not. V4 routes the signal (via 5 and the splitter) to the power tubes. The paths for the normal and top boost channels are separate in this valve and the top boost side had failed leaving the normal channel ok. The valve was still lighting up and looked ok. Changing it solved the problem. I do not know which valve in the cc2 deals with this function but I imagine that , wherever it is placed, it will be similarly wired. As of today, the amp is producing no sound at all and the rectifier, which is unused and brand new is not lighting up and the standby light is not on. The switch, whether in the off or on position, has no effect. All the fuses F1-4 are ok on the multimeter. The power light is on and all the preamp and power tubes are lit. Anyone got any ideas on this one, please?
#18
Please don't post in old threads. Try starting a new one for better up-to-date advice without taking over someone else's thread.