Double Bass G-K MB150S Cabinet Rattle

[desert hardwood]

I have an older (2002) MB150S and the other night I was getting a metallic rattle when pushing the amp.

In a previous thread dylanjohnson had mentioned his did something similar.

I checked all the screws and they were tight.

I took the amp apart and here is what I found;

The seam in the back of the cabinet (where a side panel attaches to the back) is open. There doesn't appear to be a weld or adhesive at that point. If I tap on it it rattles.

I sent pics of it to G-K and they determined I need a new cabinet. They have one in stock and it is a lot cheaper than a new combo.

To dampen the back panel they use a support that rests against the speaker magnet cover. The part that actually touchs the speaker is a rubber amp foot and it is was as hard as a rock.

There is also foam tape used to dampen the grill and amp where they meet the cabinet.

So if you have a MB150S with a rattle, it could be a few different things.

BTW, G-K support has been great (either via phone or e-mail).

 

[Marc Piane]

Those amps are famous for developing rattles as the foam degrades. They are great amp though so worth the trouble.

I had an old one that got a nasty rattle. I pulled that bad boy apart, went to the hardware store and bought some bathroom caulk and caulked the poop out of it. Fixed it.

 

[Greg Clinkingbeard]

Black latex caulk and a damp sponge will do it.

 

[robgrow]

FWIW the current Series III MB150 amps use a welded aluminum cabinet that doesn't have any seams to get loose and rattle.

 

[dylanjohnson]

Be careful, I bought a new cabinet from GK for my rattling MB150 and it turned out to be a series 3 cabinet. Screw holes were in the wrong place and I had to cut out a hole for the transformer. What I would do if i were you is send in the amp. I haven't done it yet, but I think I am going to. I have tried foam, caulk, epoxy, etc, and nothing works.... Oh well. It sounds so much better to me than the series 3.

 

[Marc Piane]

A digression but note about that amp.

It has been said, not by me, that the GK MB150 is the amp for guys that hate amps. Maybe a non-gearhead amp is a better description. I find this to be very true. They are not the most natural sounding amp around but they have a distinctive sound that is very plug and play. I have yet to find an amp as portable and consistent from room to room.

All that said they are NOT loud. I think they sound like poo if they are pushed too hard and the last one I had only had rattling problems when I turned up.

I bring this all up only to point out that if you want to do much more than a dinner set use a different amp. Personally I've been using the GK MBX extension cab with my Clarus and found that I have quite a bit more headroom. It is extra **** to plug though. Nothing is goin to take the place of the amp I can just plug into and it works.

 

[dylanjohnson]

Agreed, Fingers. I have always thought that the amp has a low mid presence that just makes things audible without being loud. I have always considered it to be a monitor.... Sounds awful pushed hard...

 

[desert hardwood]

Thanks for the input/ideas.

When using the amp at shows (without a large PA) I always use the extension cab. I play in a trio or four-piece with electric guitar and drums. So far it has had enough umph to keep up and sound good (except when the cabinet rattles).

I work in the car business and I had a chat with our body shop. I'm gonna strip the cabinet and have them weld the the seams on the inside. If it works it sould be a permanent repair.

They asked me what color do I like (the heat is gonna mess up the finish on the outside). Hmmm...Arctic Silver Metallic or Basalt Black Metallic might look cool.

 

[anonymous122511]

Those amps are famous for developing rattles as the foam degrades.

Specifically it's the speaker seal that often causes that "impossible to find rattle" and that seal can be replaced.

 

[desert hardwood]

I imagine if that speaker gasket goes it would make quite a racket. There are actually a couple areas where you could get noises. They use foam tape all over.

Well, welding won't do. At the factory, they must weld the cabinet seams from the outside and grind away the excess to make the cabinet smooth. This leaves the metal pretty thin (too thin to weld with confidence).

Plan-B is; use a panel bonding adhesive. BMW holds 1/4 panels on with this stuff and rivets. They are confident it will be a solid repair.

Meanwhile, I'm using my old 400RB...