May 10, 2010 01:40 pm ...did you pirate your amp???
Just kidding, maybe Rob knows...
Problems with my Vox AC30
Posted on May 10, 2010 11:46 am
Marius
Member Since: Jan 17, 2010
Hi, so I have this amp, VOX AC30 CC2, it's like 2 or 3 years old and it's great but I'm having some problems with it.. Every 10 seconds or so it makes this "noise" that last for maybe 3 seconds and then it's quite and after 10 seconds it does it again, and again, and again... It's really annoying and it also gets on the recording when I record. Anyone have a solution for this? Or answer to what could be the problem or is it normal that this occurs?
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May 10, 2010 01:40 pm ...did you pirate your amp???
Just kidding, maybe Rob knows...
May 10, 2010 02:05 pm Well, that certainly aint normal.
Knowing what the sound is would be of great benefit. Is it a BZZT, or a WUMP, or a EEEE, or a SSSS, or maybe a ssss.
I'll overlook the possibilities of tweet, or maybe a fan yelling their approval =). Maybe it's the neighbor yelling "turn it down!" =)
One thing that pops to mind, is that in tube amps (not sure if this is, presumably so, as it AC30), the electrolytic capacitors can go bad, and then not 'hold' the electricity like they're supposed to anymore. Sometimes, this can present itself as a motorboat type of sound. I've not heard of the 10second wait before, but i suppose anything is possible.
And, in such a new amp, I'd not think that an e-cap would go south this soon, but I guess it's possible.
I guess knowing what the sound is would help a lot. Sorry I don't have any concrete ideas.
May 10, 2010 02:56 pm So what if I recorded the sound and uploaded to my channel, would that help you? x) Well yeah it's a tube amp, it was actually new tubes a year ago when I bought it I believe.
May 10, 2010 03:28 pm I have now uploaded the noise, I recorded it. It's on my channel and called "amp noise!!!" check it out please? At first you hear the actual weird sound it makes then it calms down and then begins again.
May 10, 2010 09:36 pm Hey Marius.
Can you do something for me? Unplug your guitar and cable from the amp. See if the noise is still there.
This is just trying to isolate what is causing the noise.
May 12, 2010 06:58 am I've allready done that, it generates this noise even then... Even when I turn the stand by button off so that the amp is only turned on with the power switch this noise comes like every 10 seconds or so and sometimes it's unstable and happens when it wants too. I take it that you took a listen to what I uploaded? If not you should. Thanks.
May 12, 2010 09:00 pm OK. Good! This will narrow all possibilities with this information.
Sorry it took me a little to get back to this. And sorry that it's going to take me just a little bit longer to completely answer this as well.
All of my schematics are back in my shop. But, with the guitar unplugged, and the standby off, there can only be two or three things that can be wrong with your amp.
One, it could be the summing tube.
Two, a rectifier tube.
Or three, a power filter cap.
Once I look over the schematic, I should be able to give you a better answer.
May 12, 2010 11:36 pm I've heard some reissue AC30's have weird stand-by design that cause the rectifier tube to prematurely bite the dust. Gz34's are soft start anyway, so don't even use the stand by :).
Can't really offer much more than that, but I'd check that the GZ34 is glowing, and probs pull the tubes (but not rectifier) to see if it still makes the noise, even though its on standby. If a friend has an amp with a GZ34/5ar4 rectifier tube, steal it and pop it in. If it breaks, tell him it was like that when he gave it to you.
Apart from that, if you're comfortable inside one (remember kids, high voltage), start testing voltages from the schematic and filter caps for shorts?
May 13, 2010 09:21 am ok, thanks. I don't know how to tell the difference of the tubes in my amp though, I don't even know where they are, lol !
May 13, 2010 02:59 pm That sure sounds like a cap going bad. Even young on age, they can go early.
Quote:
If it breaks, tell him it was like that when he gave it to you. Nice =).
Tubes are the glass things, probably hanging underneath the top part of a combo amp. They get hot, so don't touch when running.
It doesn't sound like you're well versed with tube amp innards, so I would STRONGLY suggest taking it to a reputable fix-it house. Over on the weber boards, he has a list of tube amp fixit shops, but I can't seem to find it now.
May 13, 2010 08:07 pm Well, on an AC30, the tubes are on the backside of the amp. So, you have to remove the amp entirely. Output tubes are EL84's, and yes, the rectifier is an GZ34 as CS said.
But, after looking over the schematic, I do believe that pjk is absolutely correct here. It's time to take it to the repair shop. There are a few differences between the years. And without additional info, it's impossible to know which one you have. And since you not sure of where the tubes even are........ I don't think that it would be wise for you at this time to go poking around your amp with 480V looming about.
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