Cabinet noise question

[mattnorthrop]

Hello, fellas!

I just built a Mission 5E3 kit and installed it in a mojotone cabinet with a Weber 12A125 speaker. The amp sounds awesome, except for one thing:

I notice than when the amp is cranked up past 1.5-2 (almost distorted, but not quite), I get some sort of cabinet rattle/noise when I hit the low E string whether its open or fretted at the 1st, 2nd or 3rd fret. I've tightened the speaker to the baffle, the transformers and most everything else, but still can't isolate the noise. It sounds like a speaker cone rubbing, but I just got the speaker brand new direct from Weber just a month and 1/2 ago. It also seems to be altered a little when the chassis is pushed hard up into the cabinet, but I've tightened the chassis bolts as much as possible and its still present.

Is cabinet noise just an inherent problem with this amp? Have any of you experienced anything similar and, better yet, been able to fix it?

Thanks so much for any help you guys could provide!

-Matt

[Bruce / Mission Amps]

Tweed cabinet noises are such a problem that a few years ago Victoria even started advertising that's just they they are and many tried to turn it into a "vintage tone" thing. Loose tweedy cabinet = great tweed tone... etc.

Many times it is the actual baffle board (floating, remember?) buzzing in the carcass.
A few times I have found the threads of the grille cloth buzzing in the floating baffle board.
Sometimes it is the upper or lower rear valance panel.
These thin panels can buzz at the chassis lip or on their left or right edges.
In the case of the lower valance panel, right dead center of the bottom at the cabinet will buzz many times.
Sometimes the actual chassis gets a sympathetic vibration going and the even the eyelet board will sing out... sometimes a main filter cap will sizzle... sometimes the pilot lamp bulb or the actual red lens will buzz.
I think I've found every possible joint or seam buzzing in a tweed cabinet in one way or another and I have pulled many hairs out tracking them down.

[mattnorthrop]

Thanks for all your past and present help, Bruce! I'll keep troubleshooting it.

[mattnorthrop]

Something else occurred to me:

When I installed the new speaker, I got kind of greedy and cranked it when I first powered it up. Do new speakers need to be gently broken in? Could I have messed up the speaker doing this?

Thanks!

[n5oet3h]

Something else occurred to me:

When I installed the new speaker, I got kind of greedy and cranked it when I first powered it up. Do new speakers need to be gently broken in? Could I have messed up the speaker doing this?

Thanks!

No, that shouldn't be problem. Speakers do "break in" in that they sound better after some use. But playing it loudly right away should not cause damage.

n5oet3h

[mattnorthrop]

Thanks, that makes me feel better (and not as stupid)!

[tbryanh]

I have heard that plywood can buzz.

The typical plywood can have voids or air pockets in it, small places where wood is missing inside the laminations.

The pockets are hidden, so you cannot tell by looking at the plywood if it has pockets or not.

I have heard the pockets can buzz real bad and that there is no way to fix the problem.

I don't know first hand from experience, I have never built a cabinet out of plywood.

I built a beefy isolation cabinet out of pine. My own design. It does not buzz.

[tbryanh]

Oh yeah, there is supposed to be special plywood you can by for speaker cabinets that is not supposed to have pockets in it. Marine plywood might be another alternative, but it is supposed to be real expensive.

[RickyD]

Plywood grading gets a little involved. I would use AC exterior or better with confidence. Marine is not necessarary, that's a glue spec.

[petemoore]

Only way I found is to separate and compare.
take the speaker into a different cabinet, put a different speaker in that cab.
mojo-tones rep at stake here somewhat, can you see 'slop' anywhere the glue joints are, I would imagine if they're turning these out that the rattle isn't in the cab..knock on wood, possible...
I'd take the amp out of the cabinet first, see if that helps.