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Alternative To Potting?


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The bridge position of the Rocket 350 is a squealer --it's not the pickup, because I've switched the pickups around, it's definitely the position.

The neck position is a flat surface, with the pickup mounted on rubber matting stripped from a mouse pad. The matting covers pretty much the entire bottom of the pickup there. No problem with feedback.

The bridge position, on the other hand, has a channel in the center (to accommodate the poles of a Rickenbacker Toaster pickup if I decide to get one...I'm pretty sure I will).

So I'm guessing the channel is the reason this position squeals-- it becomes kind of like a hollowbody guitar in that way, right?

Right now I have the pickup mounted on foam 'rails' --i.e. there's nothing covering the center of the underside of the pickup. But I also had it mounted on the same rubber matting as the neck --it squealed less, but still gave out that nasty feedback if I approached the amp too closely.

Potting this pickup isn't really an option, since it's a toaster, not a humbucker, and the cover doesn't come off.

So what alternatives do I have? I'm thinking I could cut a piece of wood that will fill in the channel and cover the bottom of the pickup (so that the pickup will be more or less mounted to this piece of wood)?

Or, suppose I grabbed some wax and fashioned a bottom 'plate' out of that?

I need to sort this out before next band practice....a couple of the guys in the band have become extremely sensitive to feedback... I keep telling them to get fitted for earplugs, but they just won't listen... :D

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You can get squeel, microphonic feedback, from all kinds of loose fittings near the pickup. Mounting the pickup firmly is pretty important.

I'm not sure if that pickup itself might have some looser windings in it that potting would address, but having a flexible mounting is not going to help...the whole pickup can effectively move. It could be that the channel under the pickup which results in an uneven pressure on it accentuates this. If you fill that, even with a temporary removable piece of wood held in by the pressure of a full rubber mount, may indeed address these problems.

Any metal object that can potentially vibrate can be picked up and amplified in this way...often the culprute is the cover itself. An even pressure may indeed help. I'm not really familiar with this pickup construction, but I thought they did have a bit of a reputation for this. The bridge pickup is likely to be more sensitive as, being right near the bridge, it is very close to where the strings vibrations are transmitted to the body.

So...you could test them by swapping the neck for the bridge pickup to see if the results are the same, or if that pickup might have some internal looseness. You could also try and fashion a solid mount to see if that makes a difference

Good luck...there will be a way...and a mighty fine guitar that...pete

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I keep telling them to get fitted for earplugs, but they just won't listen... :D

And when they get earpugs they will not be ABLE to listen :D

I'm not familiar with the construction of "toaster" pickups, but if it has a bottom metal plate it might be a good idea to fill the channel to stop the bottom plate to vibrate.

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It could be that the position you picked for the pickup matches the natural resonant frequency of the guitar and so it is just keeps vibrating the note rather than decaying it. It happens with suspension bridges and other structures this is just on a smaller scale. The only other thing could be the mounting of it, but you say you have changed that.

Im asuming it has a pickguard :D maybe make another mock up pickguard to test another position.

edit: Even if the cover does not come off you can still pot it. Just soak it for a while and rub off the excess after it comes out. The wax will get in there. Soak till the bubbles stop.

edit again: just got a look at it, moving pickup is not possible. gotcha

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I'm hoping it's the way I mounted it, and the fact that there's a hollow channel beneath it too. So I've filled the channel with soft rubber strips, and I've remounted the pickup, this time cutting out a rubber backing to match the full bottom of the pickup. Then I screwed the pickup down tight. I'll know if it helps tomorrow...it's too late to push the amp too hard...

But I want to find a harder type of rubber to use, that will let me mount the pickup a little higher, but still keep it tight.

I've read through the potting tutorial, doesn't appear too complicated, and I think I can get the right wax at the hobby shop in town too, so I might go that route.

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I think I found the problem


The plastic insert isn't tight against the metal housing --that's where the squeal comes from. If I push on the metal a bit, it cuts off the feedback.

A candidate for potting, perhaps, though I'm worried about what that would do to the sound. Suppose I just drip wax into the edge where the plastic meets the housing?

The photo is of a real Rick pickup. As I mentioned, the housing is fixed on my pups, no way to take it off.

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