uncontrollable feedback

Pickups, wiring schemes, switch techniques and onboard active electronics for guitars and basses
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Ed G.
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Post by Ed G. »

I've been having trouble controlling feedback at high volumes and with a lot of gain from the bsiab2. I cover the strings with my hand and there's still feedback I think my problem is the guitar itself. It's got the 'swimming pool' route and I think this allows the pickguard to flex more than normal and it becomes microphonic.
The pickup is a Bill Lawrence and it's epoxy potted. So I don't think the pickup is the problem. When I tap the pickguard it's pretty loud.

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modman
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Post by modman »

Shielding your guitar will help. That means covering the cavity and the pickguard inside with alumium foil. Now that I think of it -- perhaps your guitar already has shielding on the pickguard and it somehow conducts with the signal path.

Don't see any other explanation if the pu's are ok and the pickguard really is mircrophonic, as you say.


http://www.guitarnuts.com/wiring/shielding/shield3.php
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Redhouse
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Post by Redhouse »

Ed G. wrote:I've been having trouble controlling feedback at high volumes and with a lot of gain from the bsiab2. I cover the strings with my hand and there's still feedback I think my problem is the guitar itself. It's got the 'swimming pool' route and I think this allows the pickguard to flex more than normal and it becomes microphonic.
The pickup is a Bill Lawrence and it's epoxy potted. So I don't think the pickup is the problem. When I tap the pickguard it's pretty loud.
When you say you tap the pickguard and it's loud, it's definately microphonics.

When you have time, take the pickup out of the guitar completely, hook up a wire to it, and plug into the same rig that is exhibiting the feedback, if you're still getting feedback from the pickup, fosus on that because the guitar is out of the equation at that point.

Microphonics are the hardest thing to tame. I once had an SG that had a early 80's DiMarzio Super Distortion (Dual Sound) humbucker. It had a totally shielded control cavity and I even potted the SD. I was never able to get that pickup to stop squeeling when plugged into a high gain amp.
(though it sounded great if you ignored the squeel, ...which I couldn't)

Anyway you have to isolate what is causing it, removing the pickup and plugging back into the effects/amp setup will tell you instantly if it's the pickup.

Epoxy potted pickups can still squeel, and if they do, and you need them to stop, there is nothing that can be done to fix them short of the trash can.

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Redhouse
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Post by Redhouse »

Any progress Ed?

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