Those that have bridge & pickup covers, feedback?

2400 · #1 02-12-2011, 01:17 PM

As in literally, my J's bridge cover starts vibrating on its own and is, in extension, prone to feedback. How weird is that? It's not even under certain conditions, I first figured it had something to do with resonant frequenties, but that doesn't seem to be the case.

It does so under the same angles as my bass normally feeds back. I've got a handle on that with muting during performances, but I can't be expected to mute the cover the whole time, too. I tried to dampen the vibrations with some tape stuck to the bottom where it contacts the bass, but since the thing's shaped like a bell, it doesn't seem to make that big of a difference.

You guys got any tips for me? I love the chrome cover look, but not the sound.

C.Linton · #2 02-12-2011, 02:11 PM

You could try sticking a big piece of foam rubber under the cover, behind the saddles (so it doesn't interfere with the strings)

SurferJoe46 · #3 02-12-2011, 07:45 PM

Are you thinking what I'm thinking?

I bet the p'ups are microphonic and just picking up the Sondern inside the housing.

Turn the amp on, bass plugged in and tap on the pickup(s) and listen if that sound comes through the cab.

I won't swear to it as I haven't had my VM-Jazz out in a gig yet - a few jams - but they don't count --- but I THINK it sounds 'bigger' somehow after the covers.

Oren Hudson · #4 02-12-2011, 08:33 PM

You may need to tighten the screws for the cover(s.) I've had some work loose and vibrate and rattle. I've also had the strings vibrate/rattle from underneath. Pickup height could be a problem too.

2400 · #5 02-13-2011, 02:40 AM

Alright people, thanks for those tips, I'll try them out! I'll report back.

EDIT: Pickups weren't microphonic - they're '08 AmStd so I'd be surprised if they were. Checked PU height, they were fine. Decided on the foam behind the saddles. The bridge cover doesn't ring out so much when I tap it, haven't had a chance to try out at full volume though, diff. rig @ diff. location.

2400 · #6 12-18-2011, 12:58 PM

I've decided to bump this thread, as the issue persists. (read OP for context)

I've just been informed by a friend of mine that wax potting the pickups and the contact point between the cover and the body might be useful. Any thoughts?

SurferJoe46 · #7 12-18-2011, 01:13 PM

OK - there's gotta be some other dynamic going on here.

Let's play 'It's Obvious, The Game' here for a bit.

1) Make sure you have an INSTRUMENT cable you're using here, not a speaker cable.
2) Make sure that you are actually hearing something that comes from the bass and not some other device.
3) The p'ups, since they are what you say they are, should NOT be the trouble maker.
4) I'd discount the strings here as a problem too - unless you're repeating the same mistake over and over and getting them twisted or somehow out of position.
5) The cover(s) cannot add any sort of echo to the output since you're not dealing with a sonic problem, but an electrically-generated sound of some sort.
6) Likewise, discount the wood of the body as a problem.
7) Echoes or some sort of a parasitic oscillation have to come from something that is complimentary to the note or series of notes, and it cannot be the tuners, headstock or neck either.
8) Take any and all pedals, effects and stomps out of the circuit if you have any, no matter how strongly they aver that they are transparent in bypass mode.
9) Try a different cable and amp.

Other than the above, I's gotz nuthin' else.