Repair Acoustic 260?

[Pimpernel Smith]

I have an Acoustic 20 mini combo which I really like, and that I've been using since August. It has a peculiar problem. When I hit the E or F notes on the G string the cabinet in the area of the 10 inch speaker produces a buzz and a kind of out of phase vibrato. It doesn't matter if I use my Casady bass with round wounds on it, or my Hofner with Pyramid flats.
But, it goes away if I turn the cabinet UPSIDE DOWN. Nor does it make these sounds if I lay the cabinet on its side. Clearly, I've tried various things to isolate the cabinet and to de-couple it from the floor.

I never play this loudly because I play with an acoustic guitar finger picker and a few singers.

I have no idea as how to get the grill off, and I hesitate to do so because the amp has a 3 year warranty.

Any practical suggestions, or speculations?

Thank you.

[Crater]

Did you mean an Acoustic B20? The speaker grill prys off the front, it's held on with velcro. I've taken mine off so I could line the cab with polyfill. Sounds like your speaker screws might be loose.

[Pimpernel Smith]

Crater:
I mistyped , but now edited my post. It's an Acoustic 260 mini stack. There's a 10 inch speaker in a tenant cabinet, which has an empty space below the speaker, and a 1 inch wide bottom ledge port at the very bottom. It gives a nice deep sound, when it's upside down or on its side.

[zon6c-f]

Still under warranty??

Take it back to GC.

I have friend who bought the largest A C combo; had issues. GC gave him a replacement.

Our local GC would probably rather give you a new 260 mini, as opposed to dealing with repairs. This makes for happier customers too.

[Pimpernel Smith]

Crater:

Thanks for your idea about the grill frame being held by velcro. After a little fussing, I got it off and tightened up the exposed screws.
I still have no idea as how to pull out the wooden speaker mounting. I wonder what keeps that in?
The speaker screws themselves are put in from behind, so I still couldn't get at them.
Never the less, when I put it all back together the buzz and the bad frequency vibrato where gone.
So thanks for your guidance and encouragement.
All's well that ends well.
If anyone knows what keeps the wooden speaker mounting in the cabinet, I'd still like to know.

Zon6c-f:
If I do get the problem back, I continue to pursue things with Guitar Centre. I have put an e-mail into the local manager - but no reply yet.
Thanks

[zon6c-f]

In U S A , G C would rather ..and readily.. give you a new-in-the-box relacement than to deal with waraanty/ repair. I know 2 very happy customers who were instantly given new replacements...under warranty and no questions asked.

And no, I am not employed by G C nor affiliated with any music companies.. just my personal experience with the brand. I LOVE MINE.