DC5 Buzzing due to resonating cabinet?

[MrMcTritone]

Hello.

When I hit a low C on the 6th string, I get a buzzing sound that gets worse if I slide the 750 EQ to the bottom. This occurs in the clean and lead channel. If Iput my ear up to the EQ and hit the C, I can definitely hear a buzzing from within the chassis. If I sit on the cabinet the buzzing tends to almost go away. If I bypass the speaker in the DC-5 and connect up an external speaker, it's gone completely.

So, it seems to me, that the low C is resonating the cabinet, and in turn vibrating some component.

Any ideas what this might be? I live in Nor Cal, so I could drive it to Petaluma if Ihave to. Are we talking big bucks here?

Thanks.

- Ron

 

[Fxrs]

Check that the long screw in the middle of the chassis(pointing up, thru the chassis towards the handle) isn't too tight or loose. It should be making contact, but not making anything bow.

 

[edward]

Is your DC5 a Sus-4 cabinet? Maybe try loosening the 4 chassis screws a bit, then play and tighten up to see if you can get it to go away. Perhaps you can isolate it to one part of the cab or chassis. Worth a try anyway.
Oh, and take the grill off to make sure it's not that easy.

Edward

 

[MrMcTritone]

Thanks, guys. I tried both of your suggestions, but no luck. Since the problem exists when I slide down the 240 and 750 EQ, I thought it might need a quick spray of contact cleaner, but still no change.

Looks like I'm doomed and will have to cart it off to Petaluma.

If anyone know a good technician in the East Bay, let me know.

Thanks again,

- Ron

 

[geenads]

I've got the same problem with my DC 3. I had it checked out by a tech.. maybe he didn't know what he was doing.. cause it passed the "bench test," meaning i guess the electronics are good. Then i replaced the speaker, same problem... I ended up using my EV theile via the speaker out, unplugging the speaker in the DC's cab. works fine. If you bang on the cabinent, you will get the same effect coming through the theile. So it must be something vibrating in the cabinent. I've just been too lazy to figure it out yet.. just been using my "back up" MKIV. FWIW..
kg

 

[MrMcTritone]

Thanks, for the comment. I'll post a reply when I get it fixed. It may be awhile, though.

- Ron

 

[Setzer]

As you say yourself its something inside the cab thats rattling.

It must be part of the cabinet itself if when you sit on it and the buzzing almost goes away.You are putting pressure on something structural inside and its almost curing the problem.

If you take it to a tech he is gonna do the same things that you are gonna check and he will charge you for his time.

There really isnt much inside the cab to check if its something loose in the carcass.

If its possible get someone to play your guitar thru the amp and when he is playing you get inside the back and try to figure out what is loose or overtightened.

 

[JOEY B.]

Tune your guitar to standard "E" and try to replicate the noise. If you can't hear the noise, you know the cause of the problem :wink: . Or take up playing the bass guitar :shock: .

 

[geenads]

I'm gonna keep bumping this thread, I've got the same problem.. any solutions yet?

 

[Blasted]

Don't know about your problem, but a good tech in the East Bay is Craig @ Powerage.

http://pwrage.com/

http://www.yelp.com/biz/powerage-amp-and-electronic-repair-oakland

 

[MrMcTritone]

I just replaced V1 and V4 with the Mesa 12AX7s and also a new pair of Mesa 6L6's. I was getting some hissing and that's now gone.

As far as the buzzing goes, when I hit a low C, it seems to have subsided, but it's not gone completely. By that I mean, I can still hear some buzzing coming from within the EQ when I put my ear up to it. Interestingly, that buzzing doesn't seem to be coming through the speaker itself. Yesterday, at a rehearsal, I had the Gain at 4, Master at 4, and Output also at 4, with no buzzing coming through the speaker. I have an outdoor gig in a couple of weeks, and I plan to crank it up so, we shall see.

 

[MrMcTritone]

Thanks, Blasted.

Yesterday, I was browsing the Mesa Website for authorized repair technicians and noticed Powerage was on it. Good feedback from yelp. I may be giving him a call. Beats the trip to Petaluma.

 

[MrMcTritone]

Well, I took my amp to Craig at Powerage and he fixed the problem. It turned out that on the EQ board, there were leads on two coil inductors that were broken. They were still barely touching, so when I would play the low C, the cabinet would resonate and it was was enough vibration to cause them to short out.

Although the breaks in the leads may have been caused from cabinet vibration over time, I have another possible theory. I noticed that if I carry the amp with my right hand with the knobs inward against my leg, my leg would be right up against the EQ sliders. So I can say that from now on, just as a precaution, I'll make sure to carry the amp with the knobs facing out and not rubbing the EQ sliders against my leg. I should probably get some some wheels and quit carring it.

 

[geenads]

thanks, i do the same thing, always worrying about knocking the knobs around when i exit a gig.. then throwing the amp in the side seat of my truck. I bought the DC30 for it's convienice and great sound, I can carry the amp, guiter, and gig bag in one trip. Guess i'll have someone look for a cold or broken solder at the EQ.... trial and error..

 

[acorkos]

did you make sure the speaker bolts are tight? back panel screws tight, too? go through and tighten every screw on the cab, inside and out. it'd be a drag to pay a tech to solve your problem by simply turning a screwdriver.

 

[MrMcTritone]

Yeah. I even swapped speakers thinking it might have been blown. I told Craig I was hearing a buzzing from within the EQ when I put my ear up close to it. After installing the the coil inductors, he said he put silicone around them to keep them from vibrating.

Thanks, everyone, for all the suggestions. Much appreciated!