Microphonic Feedback

Benye

Benye

New member
Ok folks,..i've heard about this microphonic thing million times, but never REALLY know how does it sound when it happens. Cant really tell the difference between
feedback you get if you get the guitar closer to an amp and the real microphonic feedback.

maybe i've heard the feedback but just didnt realize it was the thing.

does someone has soundclips when the pickups get microphoniced ?

the problem is i put metal cover on my PATB and DP 205 then wax potted em with paraffin and beeswax. the cover is soldered to ground. the dc resistances are quite ok , around 20 Ks.

With clean amp, they are superb. but under high gain situation, i heard slightly 60 hz noise ( not as loud as on single coil tho ) on both pickups, but not a high pitched feedback just like what i imagine a microphonic feedback is.
And it's really different when i flip to my Vintage stack which is dead silent.
well it's must be something because of the metal cover and wax pot, because
it was okay before i did all those things.

am i missing something here..?
 
Re: Microphonic Feedback

I guess no, Zang... the cover is solid metal with no holes.

but one thing i notice :...are the square slugs on the PATB should contact with the baseplate so they're grounded ? On regular humbucker, the metal spacer and slugs polepieces grounded by touching the baseplate, rite ?
 
Re: Microphonic Feedback

That shouldn't be a problem with the feedback. How long did you leave the pickup in the pot?
 
Re: Microphonic Feedback

about 10 minutes at 160 degrees F.

ok i guess it's not a mic feedback. but could the hum cancelling effect change after heated ? with the PATB, now one coil measures 10.9 K, and the other 11.3 K . haha is this normal ?
my ears detect it's not as hum cancelling as before.., like a single coil hum only lighter in massive distortion mode.

i checked the dc, no broken coil. i turn off all electromagnetic sources, but the " rrrrrrrrrr" is still there slightly.
 
Re: Microphonic Feedback

Benye said:
about 10 minutes at 160 degrees F.

ok i guess it's not a mic feedback. but could the hum cancelling effect change after heated ? with the PATB, now one coil measures 10.9 K, and the other 11.3 K . haha is this normal ?
my ears detect it's not as hum cancelling as before.., like a single coil hum only lighter in massive distortion mode.

i checked the dc, no broken coil. i turn off all electromagnetic sources, but the " rrrrrrrrrr" is still there slightly.
Click to expand...

A soak of 10 minutes is not very long. Did you notice little bubbles coming out during the soak? I potted a DMZ Paf Pro and a Evolution for 20 to 30 minutes at 140 to 150 degrees F with great results. Used solid metal chrome covers similar to yours. No problems. You might have air gaps.
 
Re: Microphonic Feedback

10 minutes ought to be plenty, unless the wax is really thick.

You have to wait for the pickup to cool off before you can get any reliable DCR readings. Resistance goes way up in that kind of heat.
 
Re: Microphonic Feedback

panamang said:
A soak of 10 minutes is not very long. Did you notice little bubbles coming out during the soak? I potted a DMZ Paf Pro and a Evolution for 20 to 30 minutes at 140 to 150 degrees F with great results. Used solid metal chrome covers similar to yours. No problems. You might have air gaps.
Click to expand...

yes all bubbles came out for ten minutes, no more bubbles after 10 minutes even i jiggled em. i just finished em now, reinstall the pickguard, and the PATB's perfect. no feedback, no "brrrrrrrr".

just still hum with the SM abit, maybe it's because my trying to largen the hex holes when replacing with alnico rods :) . but no big deal.

Zang : yes, now it's cool and the DCR is back to normal. Thanks
 
Re: Microphonic Feedback

you'd know microphonic feedback if you hear it, just the most gawd awful, high pitched uncontrollable squealing you've ever heard! Sounds nothing like feed back from playing at high volumes or that "solid" ringing feedback, it just squeals and screeches! AGH! Sorry, I used to have an LP that was horrible with the whole microphonic deal...
 
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