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Posted

Hope folk here can give me a few pointers.

 

Managed to pick up an old MK1 Barefaced Compact in a pawn shop today. All looked decent but when I got it home I found the when I am driving it at reasonable rattle or buzz generated when playing a low B up to about a D. Best I can tell, listening in close, the buzz appears to be coming from the driver itself. Not 100% sure though.

 

I am running the cab alongside my own DIY 1x15 (eminence kappalite) Compact style cab. Swapping the new Compact for my BF Midget removes the buzzing sound so I am confident it's the cab and not something else rattling (amp head, furniture etc.)

 

Started pulling the grill to check the driver I found the battens holding the grill were loose. Turns out they're just glued in place with silicone adhesive and this seems to be giving up. Pulled them off entirely but this hasn't stopped the buzz so they aren't the culprit. On removing them it did reveal reasonable gaps at a few points between the side panels and the front baffle. Not sure these go right through to the inner volume of the cab because there appears to be battens behind but it does make me worry the cab isn't fully sealed. Would a 'leaky' cab like this cause a buzz or distortion from the driver at low frequency?

 

Current plan is to fill these gaps with an expanding glue (gorilla) to try to prevent any potential leakage. If that doesn't change things I'll try swapping the kappalite drivers between the Compact and my own DIY cab. That should isolate whether the issue is cab or driver.

 

I would appreciate advice on how I might diagnose and fix this issue.

Posted

Have you pushed the element by hand? Does it make any extra noise while you move it? 

 

Any leaks that are not designed to be there, can be seen like a vacuum cleaner with a perforated tube. The leaks should not exist.

Posted

They may not even be leaks but I'm going to treat them as such to be safe.

 

I'll look at moving the element by hand and compare it with the one in my DIY cab since they should be identical.

 

Cheers

Posted

Check the handle before changing any bits.  Seriously.  My old Compact used to buzz annoyingly and I tracked it down to the handle vibrating.

  • Like 1
Posted (edited)

Another thing you can do is sit on the cab while playing and adjust your position to put pressure on the cab / brace joints. If there's a slightly loose brace you'll find it.

Edited by Downunderwonder
  • Like 1
Posted

Cabinet noises can be quite difficult to trace sometimes. I'd start by swapping the drivers in your cabs to eliminate the driver as the cause.

 

In answer to one of the questions raised, yes, leaks can certainly cause the kind of noise you're hearing. I'd advise against using PU adhesive to fill the gaps, however. It's fine as an adhesive but structurally weak as a filler. Aradaldite would be better, or fibreglass body filler.

 

Another tip: playing a recording of bass through the cabinet will make it much easier to locate the source of the noise.

Posted

I think I have fixed this. Filled the gaps (sorry Stevie, used PU before I saw your epoxy tip) but also when I opened it the wadding was quite loose. I tucked this back so I'm not sure if the noise was the leaks or the wadding somehow managing to touch the back of the cone. If the noise comes back I'll properly staple or bond the wadding to the side walls.

Posted

Glad to hear the problem's fixed. Wadding should always be held in place inside a cab. I'd recommend you staple it down (or used some spray adhesive) when you can find the time.

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