My Trace Quatra Valve is making a noise. The amp itself, not through the speaker!

dave88 · #1 07-21-2010, 06:02 PM

I heard a loud sort of snapping/clicking sound a few days ago while playing my Trace Elliot Quatra and I figured it was a tube with an intermittent short . After swapping out the tubes and other stuff I realize that it's coming from the head itself!

It'll occur randomly between 5-30 minutes and happens even with the volume(s) all the way down, but it has to be "On" and not in Standby. I don't see a fan on this thing anywhere..is it possible that something is heating up and expanding??? What the heck!?

dave88 · #2 07-22-2010, 12:58 PM

Seans · #3 07-22-2010, 02:11 PM

Heating up may be it, with an older amp, cap's may be the first thing to look at ( although have a look for an outer plastic sheath shrinking while you're in there), but I would look for a dry/broken solder joint on a newer amp, its going to take some looking.

christw · #4 07-22-2010, 03:42 PM

My first thought is a bad / weak relay. Does it have any effect on the sound from the amp? It may be that your amp has a relay (probably related to the main power supply) that is turned "on" by the standby switch and it's going out.

dave88 · #5 07-22-2010, 03:48 PM

No effect on the sound out of the speaker, once again this sound is purely an internal (mechanical?) one so I doubt it could be a cap or solder joint as those things don't make external sounds that I'm aware of. Would a relay make an external noise?

christw · #6 07-22-2010, 04:09 PM

If it's really loud, then I take back my suggestion. A relay would be no louder than normally powering up the amp.

Is it a continuous clicking? A one off "pop"? Any chance you could get us a sound sample/video of it?

Jimbob Jones · #7 07-22-2010, 04:18 PM

It could be a cap going bad. My brothers VA350 used to make intermitant POP noises, we put it down to the suggestions above, but it was actually one of the 6 big caps slowly destroying itself. One day we turned the amp on and the head made this huge, horrible crackling noise and the protection circuit kicked in when we took it out of standby, as the cap actually stopped working. If you take the back off and see a cap with the top bulging, or with the plastic shielding damaged, there's your problem.

Turned out that the tech my bro had sent it to for a service put 350v caps in instead of 450, and they just couldn't cope.

We put new caps in with the right working voltage and the amp was fine.

dave88 · #8 07-22-2010, 04:25 PM

What do you guys think, 3 out of 4 of these caps appear to be bulging at the top

Seans · #9 07-23-2010, 12:23 AM

That's a very good reason to replace those, they should be flat on top and those look like they've been getting hot to do that.

johnk_10 · #10 07-23-2010, 01:45 AM

by the looks of those filter caps, i'd say that that is probably what your'e hearing. looks like the newest one was made in early '89 (8th week). i would replace all of them with the same uf value and the same or higher voltage rating.

ridgeback · #11 07-23-2010, 03:05 AM

just noticed this now,think i hvae the same problem as the op..anybody know where i can get these caps???(correct name????)never been into this sort of thing...are they easy to replace? also the 2 12ax7 tubes in the pic above look a little "off" or is that a refelection its hard to tell..quatra valves are great little amps once the tubes are replaced fairly often..

KramerBassFan · #12 07-23-2010, 05:42 AM

http://www.digikey.com/

dave88 · #13 07-23-2010, 08:47 AM

ridgeback: they're really cheap but you run a high risk of shocking/electrocuting yourself unless you know what you're doing and discharge everything properly, probably better to spend $50 to get it done by a tech

dave88 · #14 07-23-2010, 08:48 AM

12ax7's off? One's EHX and one's JJ, you mean they don't match or something else?

ridgeback · #15 07-23-2010, 09:04 AM

the tubes on the top right they look a little burned out on the top.. (i have 2 "12ax7s tubes in mine..standard i think)... it could just be the flash from the camera or a backround light reflection...
i never do electric stuff myself deffo leave it to the pros...the quatra is only a spare i dont use anymore but cant bring myself to part with it..great sound thats a little different from most other amps out there...its not been plugged in,in about 3 years.must have a look later this evening..

dave88 · #16 07-23-2010, 10:13 AM

Just got back from the local tech(used to be head tech at Marshall and at Korg) and he says that caps don't make noise on their own, only through the amp. So it's probably a transformer. Ouch, this is starting to get expensive. I should know by the end of the day.

Jimbob Jones · #17 07-23-2010, 10:26 AM

Those caps definately need replacing. You'll find the replacements are much smaller (cap tech has progressed in the last 20 years!). It's not a massive fix, just 8 solder joints.

Get the caps replaced before you even think about looking at transformers. That's exactly how the dead/dying caps in the back of my brothers amp looked.

dave88 · #18 07-23-2010, 10:54 AM

The caps don't need replacing. I just got a call back from the tech and he thinks it's exactly what I mentioned in my original post, the heat causing an expansion, what he referred to as a transformer "bucking". He's going to check it again at the end of the day. Hey, at least I only paid $35 to find out my amp won't explode. Better safe right?

BassmanPaul · #19 07-23-2010, 03:30 PM

Sorry Dave but whatever your tech thinks those caps will need to be replaced in the not too far distant future. His "bucking" comment about the transformer makes no sense to me. Bucking is when a coil of the transformer is wired out of phase to reduce a voltage.

Paul

Jimbob Jones · #20 07-23-2010, 03:57 PM

Quote:

Originally Posted by BassmanPaul

Sorry Dave but whatever your tech thinks those caps will need to be replaced in the not too far distant future. His "bucking comment about the transformer makes no sense to me. Bucking is when a coil of the transformer id wired out of phase to reduce a voltage.

Paul

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