Killing Microphonic Feedback

kevinT · 03-01-2008, 05:34 AM

I am finalizing my PAF-style pickups and wanted to ask folks that are also producing PAF-style pickups about microphonics. To stay with spec, i am not wax potting them.

My question is.... are you still getting microphonics with the volume way up?

Here is my issue, I am still getting a little bit of microphonics even after ensuring everything is tight. I have glued the wooden spacer, and I have some great bobbin mounting screws that really dig into the plastic to secure them to the baseplate. I have also placed silicon chaulk in the corners and around the cover and also on the slug coil to prevent any kind of vibration. And i've soldered the cover on securely. The pickup as a whole is solid as a rock. However, I am still getting a bit of microphonics when i'm near the amp at high volumes.

Is there anything else I can do to tighten things up to eliminate the pig squealing or is this something that is inherent and a tradeoff for not potting the pickup. I really love the tone and I don't want to wax pot.

mick · 03-01-2008, 05:41 AM

Lots of pickups will let go close to an amp on high volumes , It's not always unpotted pickups either..you might be being a bit cautious?? no offence intended..

Mick

corduroyew · 03-01-2008, 10:03 AM

Microphonics at high volume when close to the amp is one of the great things about unpotted PAF's. Don't try and get rid of it compleatly. Just warn people that it'll happen. Then advise that if they do want to sit on top their amp with the volume at 11 then they should have you pot the pickup. The pickup won't sound as vintage but in those days musicians didn't tend turn the amp all they way up and stand 2 feet away from it either. You have to change pickup design to conform to the way they are going to use the pickup.

Possum · 03-01-2008, 02:36 PM

You might want to take the cover off and then see if you're still getting feedback. If so then its a case of not winding tight enough and taping the coils tight. If you're doing that and its still squealing turn the amp down :-) Seriously though if someone is playing that loud there's nothing you can do but pot the pickup and make sure it soaks real good. You will lose alot of what PAFs are known for, the slightly vocal like tone that comes from the cover not being stabilized and the interior not being fillled solid, heck why even make a PAF type pickup for someone playing that loud, its just a humbucker and most of the cool PAF tonal qualities won't be heard playing really loud with alot of gain. Even EVH didn't use much gain or pedals playing loud, he did pot the PAF but he let his hands and talent create the tone rather than alot of gain....

Meowy · 03-01-2008, 05:14 PM

Is it commonplace for an uncovered nonpotted pickup to to amplify the sound of tapping on the bobbin with a pick? If this shouldn't be happening, would potting help, and/or what may I have done wrong? I don't get any squealing and I'm very satisifed with the tone.

corduroyew · 03-01-2008, 06:25 PM

Quote:

Originally Posted by Meowy

Is it commonplace for an uncovered nonpotted pickup to to amplify the sound of tapping on the bobbin with a pick? If this shouldn't be happening, would potting help, and/or what may I have done wrong? I don't get any squealing and I'm very satisifed with the tone.

Yes, it's normal. If it doesn't feedback and you are happy with the sounds then don't pot it.

kevinT · 03-01-2008, 06:41 PM

Quote:

Originally Posted by Meowy

Is it commonplace for an uncovered nonpotted pickup to to amplify the sound of tapping on the bobbin with a pick? If this shouldn't be happening, would potting help, and/or what may I have done wrong? I don't get any squealing and I'm very satisifed with the tone.

It will amplify the sound. however, if it's potted it will subdue some of the vibration. ...but you're still going to have the vibration, of the jolt of the pick hitting the bobbin, being induced into the coil. Not in the traditional sense of string vibration....

Which brings me to another question....microphonic feedback is caused by vibrations within the pickup structure...can someone help me understand why, if i am standing completly still and facing the amp 10 feet away at high volume, i get microphonics when there is no vibration that i can sense and i am holding the guitar still. If i take off the guitar and lay it on the bed next to where i was standing by my amp, the microphonics changes into the good feedback and then, once i touch the guitar (my hand on the neck), it begins squealing like a pig again. It just seems like its more of an electromagnetic problem with the electricity in our bodies interacting with the electricity properties of the guitar and pickup rather than a vibration problem.

I know our bodies shake/vibrate with heart beat and nervous system, but its weird that the guitar picks up those vibrations which may be causing the microphonic feedback?

Possum · 03-02-2008, 02:06 AM

maybe there's something else besides the pickup squealing, mounting screws, springs. Even if potted solid as a rock the pickup itself can vibrate as a complete unit, and don't forget strings can squeal too....

Sweetfinger · 03-02-2008, 04:18 PM

Quote:

Originally Posted by kevinT

..can someone help me understand why, if i am standing completly still and facing the amp 10 feet away at high volume, i get microphonics when there is no vibration that i can sense and i am holding the guitar still. If i take off the guitar and lay it on the bed next to where i was standing by my amp, the microphonics changes into the good feedback and then, once i touch the guitar (my hand on the neck), it begins squealing like a pig again.

The vibrations that cause microphonic feedback are generally too high pitched to feel. Generally, a guitar will not feed back microphonically while being played, but the instant you mute the strings, the amp is free to amplify other things, like the tiny noise coming from the parts in the pickups. this noise from the pickups goes around and around through the amp and pickups until a larger, more powerful signal overrides it(such as you playing again). Back in the day before noise gates you had to be real fast on the volume knob, or just keep playing! Given enough volume and gain, ANY guitar can feedback microphonically. For an example of 'working' the volume knob- listen to "Live at Last" by Black Sabbath(re-released as part of "Past Masters"). Every song begins with Tony Iommi rolling up the volume with a microphonic sssKWOOOOOOH..then the first note of the song.

One of the overlooked spots where microphonics occur is the springs over the mounting screws. If I'm working on a guitar where I know it is going to be played with tons of gain at stupid volume, I'll always use surgical tubing and even non-magnetic screws. At really stupid gain levels, caps, pots, trem springs, and the lengths of string behind the nut and bridge can be heard.

kevinT · 03-03-2008, 02:33 AM

Quote:

Originally Posted by Sweetfinger

The vibrations that cause microphonic feedback are generally too high pitched to feel. Generally, a guitar will not feed back microphonically while being played, but the instant you mute the strings, the amp is free to amplify other things, like the tiny noise coming from the parts in the pickups. this noise from the pickups goes around and around through the amp and pickups until a larger, more powerful signal overrides it(such as you playing again).

One of the overlooked spots where microphonics occur is the springs over the mounting screws. If I'm working on a guitar where I know it is going to be played with tons of gain at stupid volume, I'll always use surgical tubing and even non-magnetic screws. At really stupid gain levels, caps, pots, trem springs, and the lengths of string behind the nut and bridge can be heard.

Good points, i know it was stupid bringing up this topic because its well known that the causes are vibration. However, IMO sometimes you have to go back to the basic and take a fresh look at it and even question its causes in order to find a different possible solution.

kevinT · 03-03-2008, 03:32 PM

Quote:

Originally Posted by mick

Lots of pickups will let go close to an amp on high volumes , It's not always unpotted pickups either..you might be being a bit cautious?? no offence intended..

Mick

Hi Nick ...opps Mick

...i am a bit cautious. Especially when dealing with the public, i know I will get calls from folks complaining that their pickups are squealing like a stuck pig because they just don't know what a PAF is all about and the type of applications that it should be use for.

just trying to find ways to minimize the proverbial squealing pig hiding in the pickup galavanting around creating havoc with vibrations.

I guess i'll have to explain to them or provide a disclaimer that the unpotted pickup will feed back in high gain setups.

corduroyew · 03-03-2008, 07:16 PM

Quote:

Originally Posted by kevinT

Hi Nick ...opps Mick

...i am a bit cautious. Especially when dealing with the public, i know I will get calls from folks complaining that their pickups are squealing like a stuck pig because they just don't know what a PAF is all about and the type of applications that it should be use for.

just trying to find ways to minimize the proverbial squealing pig hiding in the pickup galavanting around creating havoc with vibrations.

I guess i'll have to explain to them or provide a disclaimer that the unpotted pickup will feed back in high gain setups.

Thats why I won't give out payment details to anybody before I get an email from them telling me what type of music they want to play. If they say hard rock a warn them that feedback might be a problem if the pickup isn't potted and if they say metal I tell them it will be a problem and that they should have it potted. So far I've never had anybody say no to potting when I have suggested it.

mick · 03-03-2008, 08:00 PM

Hi Nick ...opps Mick

It's " oops " Kevin

Ruel · 03-04-2008, 02:40 AM

Quote:

Originally Posted by mick

Hi Nick ...opps Mick

It's " oops " Kevin

It's now two oopses.

Possum · 03-04-2008, 02:23 PM

most feedback is coming from the cover, not the coils, unless your coils are real loose. covers we get aren't flat so there's space between the cover and the slugs, and thats where the squeal comes from. I sometimes clamp the cover on real tight then solder, but unfortunately this spreads the bottom of the cover out, but it does help with microphonics more than just putting the cover on and soldering. Old PAF covers were flatter than what we get now but not totally flat at least the one I have. Tom Holmes covers are dead flat, all sides are dead flat, they're the best I've seen so far....

kevinT · 03-04-2008, 03:02 PM

Quote:

Originally Posted by Possum

most feedback is coming from the cover, not the coils, unless your coils are real loose. covers we get aren't flat so there's space between the cover and the slugs, and thats where the squeal comes from. I sometimes clamp the cover on real tight then solder, but unfortunately this spreads the bottom of the cover out, but it does help with microphonics more than just putting the cover on and soldering. Old PAF covers were flatter than what we get now but not totally flat at least the one I have. Tom Holmes covers are dead flat, all sides are dead flat, they're the best I've seen so far....

Are you using anything for padding to dampen the vibration? ...silicon caulk?

Mystic · 03-18-2008, 08:33 AM

I also use a little stick glue under the magnet.

SK66 · 03-18-2008, 03:39 PM

I think we need to clarify terminology. This is not microphonics, this is harmonic feedback. Sometimes due to pickup components/mounting, sometimes due to stings/guitar. Even an unmounted pickup will give harmonic feedback when placed very close to an amp. The speaker magnet is very strong and the amp puts out an EMF signal. The pickup senses this and then outputs a signal which the amp then amplifies and so it starts.

Microphonics is when the coil windings themselves move when exposed to vibration (sound waves). The coil winding moving creates an output signal functioning like microphone. I've never seen microphonics in a pickup which was adequately taped or potted, other than very old pickups where the potting has broken down and resulted in loose windings.

Dave Kerr · 03-18-2008, 04:16 PM

I've been using snot tape for all the prototyping I've been doing lately, it's very high tack and conforms nicely to irregular surfaces, helps fill in the gaps for all the sloppy one-off bobbin cutting I've been doing.

Possum · 03-19-2008, 01:47 AM

what is snot tape?

Dave Kerr · 03-19-2008, 02:00 AM

snot tape

Quote:

3M Scotch or Permacel 1/2" ATG Tape is also known within the film biz as SNOT TAPE and is used to affix lighting gels to their frames and camera assistants use it sparingly to affix wratten gels to the rear of lenses. The ATG Dispenser, sold separately, helps manage this very sticky two-sided tape.

It's not unlike the stuff you'll see used to affix magazine inserts - you can wad it up to fill a spot, or lay it out thin and flat like a double stick tape.

Possum · 03-19-2008, 02:52 AM

does this stuff interact with nickel like silicone does? or mar plastic?

Dave Kerr · 03-19-2008, 02:56 AM

It's low acid or acid-free, iirc - it's sometimes used to splice film, so I'd expect it would be pretty inert.
edit - some, not all, atg tapes are acid and solvent free.

03-01-2008, 05:34 AM	#1
kevinT Tone Mechanic Join Date: Dec 2006 Posts: 1,005	Killing Microphonic Feedback I am finalizing my PAF-style pickups and wanted to ask folks that are also producing PAF-style pickups about microphonics. To stay with spec, i am not wax potting them. My question is.... are you still getting microphonics with the volume way up? Here is my issue, I am still getting a little bit of microphonics even after ensuring everything is tight. I have glued the wooden spacer, and I have some great bobbin mounting screws that really dig into the plastic to secure them to the baseplate. I have also placed silicon chaulk in the corners and around the cover and also on the slug coil to prevent any kind of vibration. And i've soldered the cover on securely. The pickup as a whole is solid as a rock. However, I am still getting a bit of microphonics when i'm near the amp at high volumes. Is there anything else I can do to tighten things up to eliminate the pig squealing or is this something that is inherent and a tradeoff for not potting the pickup. I really love the tone and I don't want to wax pot.

03-01-2008, 02:36 PM	#4
Possum Old Timer Join Date: May 2006 Location: Planet Mongo in the country of PAF Posts: 3,083	.... You might want to take the cover off and then see if you're still getting feedback. If so then its a case of not winding tight enough and taping the coils tight. If you're doing that and its still squealing turn the amp down :-) Seriously though if someone is playing that loud there's nothing you can do but pot the pickup and make sure it soaks real good. You will lose alot of what PAFs are known for, the slightly vocal like tone that comes from the cover not being stabilized and the interior not being fillled solid, heck why even make a PAF type pickup for someone playing that loud, its just a humbucker and most of the cool PAF tonal qualities won't be heard playing really loud with alot of gain. Even EVH didn't use much gain or pedals playing loud, he did pot the PAF but he let his hands and talent create the tone rather than alot of gain.... __________________ http://www.SDpickups.com Stephens Design Pickups

03-02-2008, 02:06 AM	#8
Possum Old Timer Join Date: May 2006 Location: Planet Mongo in the country of PAF Posts: 3,083	.... maybe there's something else besides the pickup squealing, mounting screws, springs. Even if potted solid as a rock the pickup itself can vibrate as a complete unit, and don't forget strings can squeal too.... __________________ http://www.SDpickups.com Stephens Design Pickups

03-04-2008, 02:23 PM	#15
Possum Old Timer Join Date: May 2006 Location: Planet Mongo in the country of PAF Posts: 3,083	... most feedback is coming from the cover, not the coils, unless your coils are real loose. covers we get aren't flat so there's space between the cover and the slugs, and thats where the squeal comes from. I sometimes clamp the cover on real tight then solder, but unfortunately this spreads the bottom of the cover out, but it does help with microphonics more than just putting the cover on and soldering. Old PAF covers were flatter than what we get now but not totally flat at least the one I have. Tom Holmes covers are dead flat, all sides are dead flat, they're the best I've seen so far.... __________________ http://www.SDpickups.com Stephens Design Pickups

03-19-2008, 01:47 AM	#20
Possum Old Timer Join Date: May 2006 Location: Planet Mongo in the country of PAF Posts: 3,083	... what is snot tape? __________________ http://www.SDpickups.com Stephens Design Pickups

03-01-2008, 05:41 AM	#2
mick Senior Member Join Date: Jun 2006 Posts: 320	Lots of pickups will let go close to an amp on high volumes , It's not always unpotted pickups either..you might be being a bit cautious?? no offence intended.. Mick

03-01-2008, 10:03 AM	#3
corduroyew Senior Member Join Date: Oct 2006 Location: Mid Wales Posts: 307	Microphonics at high volume when close to the amp is one of the great things about unpotted PAF's. Don't try and get rid of it compleatly. Just warn people that it'll happen. Then advise that if they do want to sit on top their amp with the volume at 11 then they should have you pot the pickup. The pickup won't sound as vintage but in those days musicians didn't tend turn the amp all they way up and stand 2 feet away from it either. You have to change pickup design to conform to the way they are going to use the pickup.

03-01-2008, 05:14 PM	#5
Meowy Member Join Date: Dec 2007 Posts: 62	Is it commonplace for an uncovered nonpotted pickup to to amplify the sound of tapping on the bobbin with a pick? If this shouldn't be happening, would potting help, and/or what may I have done wrong? I don't get any squealing and I'm very satisifed with the tone.

03-03-2008, 08:00 PM	#13
mick Senior Member Join Date: Jun 2006 Posts: 320	Hi Nick ...opps Mick It's " oops " Kevin

03-18-2008, 08:33 AM	#17
Mystic Senior Member Join Date: May 2006 Location: Kansas Posts: 135	I also use a little stick glue under the magnet.

03-18-2008, 03:39 PM	#18
SK66 Senior Member Join Date: May 2006 Posts: 133	I think we need to clarify terminology. This is not microphonics, this is harmonic feedback. Sometimes due to pickup components/mounting, sometimes due to stings/guitar. Even an unmounted pickup will give harmonic feedback when placed very close to an amp. The speaker magnet is very strong and the amp puts out an EMF signal. The pickup senses this and then outputs a signal which the amp then amplifies and so it starts. Microphonics is when the coil windings themselves move when exposed to vibration (sound waves). The coil winding moving creates an output signal functioning like microphone. I've never seen microphonics in a pickup which was adequately taped or potted, other than very old pickups where the potting has broken down and resulted in loose windings.

03-18-2008, 04:16 PM	#19
Dave Kerr Senior Member Join Date: May 2006 Posts: 373	I've been using snot tape for all the prototyping I've been doing lately, it's very high tack and conforms nicely to irregular surfaces, helps fill in the gaps for all the sloppy one-off bobbin cutting I've been doing.

03-19-2008, 02:52 AM	#22
Possum Old Timer Join Date: May 2006 Location: Planet Mongo in the country of PAF Posts: 3,083	cool idea..... does this stuff interact with nickel like silicone does? or mar plastic? __________________ http://www.SDpickups.com Stephens Design Pickups

03-19-2008, 02:56 AM	#23
Dave Kerr Senior Member Join Date: May 2006 Posts: 373	It's low acid or acid-free, iirc - it's sometimes used to splice film, so I'd expect it would be pretty inert. edit - some, not all, atg tapes are acid and solvent free. Last edited by Dave Kerr; 03-19-2008 at 04:23 AM.

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