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The last couple rehearsals my guitar has started making this whistling noise when the volume is above 7, this only happens when I'm not playing & a drive pedal is on, either a Hot Cake or HM-2.

So the drive pedals are boosting the signal but how is the signal being produced?

...are you asking about feedback? Whoa, dude.

Okay, your strings vibrate slightly, the pedal boosts the signal, the sound comes out of the amp. The soundwave vibrations cause your strings vibrate more, which the pedal boosts again, amp produces the sound, over and over.

If damping the strings with your hand doesn't change it, feedback may be through something else. I used to get horrible whistling feedback on my Eko Cobra until I potted the pickup with candle wax (orange, ha ha). It wasn't necessarily the pickup; the scratchplate may have been vibrating the pickup but changing the pickup's mass changed the resonance either way.

theshadowofseattle wrote:...are you asking about feedback? Whoa, dude.

Okay, your strings vibrate slightly, the pedal boosts the signal, the sound comes out of the amp. The soundwave vibrations cause your strings vibrate more, which the pedal boosts again, amp produces the sound, over and over.

ha ha no I'm not. Think i'll just change the volume pot.

Johno wrote:The last couple rehearsals my guitar has started making this whistling noise when the volume is above 7, this only happens when I'm not playing & a drive pedal is on, either a Hot Cake or HM-2.

So the drive pedals are boosting the signal but how is the signal being produced?

Unrelated but when i turn my wah on then mexican radio stations come through. Every once and a while a weird christian station also will come through. Loud as hell. I guess it's shielded bad or something but i'm thinking about leaving it! ha! The guitar signal mixes in and it can be great or really terrible. I like it being unpredictable.

What guitar is it Johno? It does sound like a microphonic feedback issue and I doubt changing the pot will achieve much.

Fran wrote:What guitar is it Johno? It does sound like a microphonic feedback issue and I doubt changing the pot will achieve much.

It's a jazzmaster, never had any issues in the last 7 years. Just started happening in the past week. It whines like an elbow.

It's definitely microphonic feedback. It's happening with the increased gain of the dirt pedals and the higher volume of your band levels. It only seems like it's the volume pot because lowering it decreases the guitar's output as it hits the dirt pedals, and therefore the gain as well.
The Japanese Jaguars had the exact problem you describe from the factory, and it's known to happen even to potted pickups on occasion, when something works loose.

What kind of pickups do you have, and does it happen on either/both of them or just one?

I'd check the pup cover isn't loose, the foam underneath can get too compressed and if you have adjusted the pup height it will cause microphonic feedback.

Fran wrote:I'd check the pup cover isn't loose, the foam underneath can get too compressed and if you have adjusted the pup height it will cause microphonic feedback.

That is a good point. I recently found out how adjusting pup height can create more microphonic feedback at lower volumes so yeah, in reverse should get rid of it. Smart.

Its not so much the height, its the design. When you consider modern pickups, they are usually one concealed unit. This is because any loose parts or cavities can cause microphonic feedback, as example before the days of wax potting, Les Paul players used to remove the chrome covers. Jazzmaster (and more so Jaguar) pickups are prone by design because they aren't potted and the cover is not attached to the bobbin/baseplate. They rely on the foam and four screws for stability.

Fran wrote:Its not so much the height, its the design. When you consider modern pickups, they are usually one concealed unit. This is because any loose parts or cavities can cause microphonic feedback, as example before the days of wax potting, Les Paul players used to remove the chrome covers. Jazzmaster (and more so Jaguar) pickups are prone by design because they aren't potted and the cover is not attached to the bobbin/baseplate. They rely on the foam and four screws for stability.

Man that is good info. Thanks Fran.

This is what i was talking about. I posted this in another thread but it wasn't my words. It was from someone i trust. This is why your comment clicked for me.
"Another way to get feedback easier is to have lower output, microphonic pickups. You could even try lowering your pickup height on your guitars. That would force you to crank up your amp more to be the same volume, thus helping to achieve feedback."

Cheers for the info Fran, will check the poup covers etc. The pups are SD Ant II's which have been installed for a couple years now.

Johno wrote:Cheers for the info Fran, will check the poup covers etc. The pups are SD Ant II's which have been installed for a couple years now.

Are they my old ones? If so I never had any problems with them either.

johnnyseven wrote:

Johno wrote:Cheers for the info Fran, will check the poup covers etc. The pups are SD Ant II's which have been installed for a couple years now.

Are they my old ones? If so I never had any problems with them either.

yep still got them

To test if it's your pickups, press down on your pickups gently as to compress it a bit. If it stops when you're holding the pickups, it's definitely the pickups. Press a little more foam into that slot or get your pickups more wax potted.

Vol pots can fail but pots can't add anything, they can only subtract, so they can't whistle.