GK-3 - Wax Potting = Improve tracking and eliminate microphonic feedback

Started by Elantric, January 23, 2008, 07:22:36 PM

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Elantric



https://www.amazon.com/gp/product/B005QSI52G





(Wax Potting the GK pickup improves GTR-MIDI / DSP ALT Tuning tracking by eliminating vibrating internal parts in the adjustable radius GK PU )

If the offending guitar has Piezo pickups, typically high pitched squeals at High SPL Stage Volume are due to mechanically coupled ribbon cables inside the guitar.



If the offending guitar has a divided Magnetic pickup, the GK-3 or GK-2A Hex PU may be potted in Wax - to eliminate microphonic feedback problems - use the identical techniques employed by Seymor Duncan on all his PU's . 50/50 parafin and beeswax, heated in a double boiler to 180 degrees farenheit, use candy thermometer to verify mixture never exceeeds 180 degrees farenheit, then submerge into the hot wax the GK-3 hex PU only, wave it up and down to get all trapped air out of the PU, while always keeping it submerged. 5 minutes max then remove it out of the wax double boiler, and let it sit on a paper towel for 1 hour. - re assemble into guitar and feedback will be gone.


more details here:


Solve with hot wax dip

http://www.premierguitar.com/articles/How_To_Pot_Your_Own_Pickups



http://www.stewmac.com/How-To/Online_Resources/Learn_About_Guitar_Pickups_and_Electronics_and_Wiring/None_of_your_beeswax_Potting_pickups_with_paraffin_.html

http://www.guitarnuts.com/technical/electrical/index.php

How do I know if my pickups need potting?  Pickups will squeal and make a loud whistling noise similar to a microphone when it feeds back.  Some pickups are so bad that if you touch them you hear a loud noise through the amplifier.  If you have a metal cover on the pickup, it could make a loud "clank" or start humming loudly when you touch it.

This is not to be confused with the musical feedback that you get when you crank your amp up and your strings sustain indefinitely – that is the good kind of feedback and this will not effect that type of feedback.  Potting pickups will actually make it more likely that you can safely turn up loud enough to get that type of feedback.

Also if your feedback goes away when you mute all strings  - then potting the pickup will not change anything or impact that behavior.

What does potting do to my pickup anyway? The term "potting" refers to the sealing of the coils in a solid material.  Potting stabilizes the components of the pickup so that they cannot move relative to each other. This elminates vibration-induced signals that make a pickup microphonic. Potting can also protect the inner coil from corrosion.  The technique described here is not just potting, but also "coil immersion."   Coil immersion is allowing a solid (wax) to be absorbed into the coil.  Wax is used because it works well, is inexpensive, and it makes it possible to work on the pickup later.  A correctly potted pickup coil will have the wax absorbed throughout the coil as well as the surrounding parts such as magnets, polepieces, and metal covers.  This eliminates movement of parts inside the pickup.

What guitars/pickups are good candidates for this? I have done this on humbuckers and single coils of many types.  It works on pickups with or without covers.  If your pickup has a metal cover then pot it with the cover in place.

Any guitar with a pickup that is microphonic but otherwise a good sounding pickup is a good candidate for potting.  If your pickups aren't microphonic then there is little point to potting them – and they may even have been potted at the factory.  Many better-quality pickups are potted at the factory, and some others are so solidly constructed that potting will provide little or no improvement.  Often a pickup that has been fine will become microphonic as handling and environment take their toll.  Such a pickup then becomes a good candidate for potting.  Even a pickup that was potted from the factory might become microphonic after much use.  If the pickup was potted with wax it can be repotted.  If it was potted with epoxy or plastic fillers it cannot be repotted.

Recent Epiphone humbucker pickups especially seem to benefit greatly from potting.  These pickups sound pretty good once microphonic feedback is eliminated.  Since many of the Korean imports are actually made by one company, it stands to reason that the other Korean models likely have similar noise problems.  I have done this on many American, Japanese, and Korean made guitars over the years.

The bottom line? If a pickup is microphonic it needs to be potted.  Of course, we can't recommend potting the pickups on a valuable vintage guitar because doing so will decrease its collector value.

What tools and supplies will I need?  To remove and reinstall your pickups you need:

    * soldering iron (an inexpensive 30-watt pencil type is fine)
    * electronics grade solder (not acid core)
    * screwdrivers

To pot the pickups you will need:

    * double boiler (see these instructions for making a safe double-boiler)
    * safety goggles
    * electric cook top -- avoid open flames!
    * candy thermometer (optional) [but highly recommended - Ed.]
    * pliers or tongs
    * wax - I have always used readily available canning wax (parafin) available at grocery stores.  Recently, I've heard that some manufacturers add a little beeswax to keep the wax soft and prevent it from becoming brittle and flaking or cracking with age.  [Ed. note – John hadn't tried this yet and didn't know what percentage of beeswax manufacturer's use.  I'm guessing about 10%-20% beeswax based on other applications I've seen for wax.] [Later Ed. note– that wasn't a bad guess – I recently stumbled across a Fralin article at the StewMac website where he recommends 20% beeswax.] [Still later – I (editor) recently potted some single coil pickups using these instructions.  I couldn't find beeswax at WalMart so I bought some Kiwi "Camp Dry Beeswax Water Proofer" intended for sealing boots and such.  This stuff contains beeswax and a small amount of lanolin.  A seven ounce container was two bucks and worked beautifully with two pounds of parafin.]
    * paper towels for cleanup

top of warning frame
sidesideside       

Wax is highly flammable (wax is why candles burn, remember).  Always use a double boiler.  Never use open flames (like a gas stove) as a heat source.

Hot wax can cause severe burns.  Hot wax splashes easily.  Always wear safety goggles.  Gloves and an apron are highly recommended.
      sidesideside
bottom of warning frame

Are there any potential problems besides the safety warnings above?  Yes.  There is always a small risk that you could damage a pickup.  If you have a particularly collectable instrument or a pickup that is of questionable construction – don't do it.  That being said, I have done very many of these over 15 years and have never damaged a single pickup.

What about removing the pickup covers?  It is not neccessary to remove the metal pickup cover from a humbucker.  It is easy to damage pickups by trying to take them apart – bad idea!  Be careful if you choose to remove your covers – remove at your own risk!  If you have a metal cover on your pickup - leave it on for the potting.  Some pickups (especially older inexpensive models from Japan in the 70s) look like a regular Gibson™ humbucker but unlike the Gibson pickups the covers are not made to be removed.  Most full-size humbuckers made in the 90s can have their cover removed.

If the coils are wrapped with tape do not try to remove it.  Pot the pickups with the tape in place.  Trying to remove it may damage your coils.

If a pickup is already potted in a hard plastic material (some older Ibanez™ models, Bartolini™ stacked humbuckers, and Select™ pickups come to mind) then you are out of luck – do not try to remove a sealed plastic cover.  Do not pot Lace sensors.

The plastic covers on Stratocaster™ single-coil pickups should be removed.  These just slip off once the pickup is removed from the guitar.  Some have tape around the coil, some do not.  Leave the tape on if it is there.

Why not replace the pickups with new potted ones?  Replacement pickups can cost $200 or more.  Enough said!  I had a newer model Epiphone™ and potted the pickups and an astonishing thing happened – they actually sounded really good.  Potting your existing pickups costs very little and can save you a lot of money if you like their sound.  Many people are happy with the tone of one or more of their stock pickups and may not want to replace them.  If you later sell the guitar, many potential buyers would rather have the "correct" pickups.

Instructions for potting a pickup

    * Make a sketch of your wiring before you remove your pickups so that you can use it as a guideline to put your pickups back in later.
    * Remove your pickup(s) from the guitar.
    * Mark the pickups with a piece of tape on the wire if you cannot easily tell what position in the guitar each was removed from.  (Remember that markings on the bottom of the pickup may be difficult to see after the pickup has been potted.)  Put the tape near the loose end of the wire, not near the pickup where it will become encased in wax when you dunk the pickup.
    * Use a double boiler to melt the wax.  I heat until it is only just hot enough that it completely melts (you can use a candy thermometer to determine the minimum temp, but I wing it).  You will need to have enough wax melted to more than completely submerge the pickup.  If you heat it without checking the temp, you run the risk of warping or melting your pickup.  [Ed. The Fralin article at the StewMac website recommends 150 degrees F. I highly recommend a candy thermometer as the wax goes over 200 degrees suprisingly easily (though when it did it didn't damage some plastic-bobbin Tex Mex pickups I was potting).  A candy thermometer will set you back a whole four bucks and is available at most grocery stores.]
    * With a pair of pliers or tongs lower one pickup into the melted wax.  Do not actually touch the coil windings with the pliers or tongs as doing so will almost certainly destroy your pickup.  Grab the pickup by the tab used to mount it.  [Ed. note. – instead of tongs you could use pieces of stout string or picture hanging wire tied through each mounting hole. This ensures that you won't drop the pickup, splattering hot wax, or accidentally grab the coil windings with tongs or pliers. Tie something to the loose end of each string so it will hang outside the pot and not end up in the wax.]
    * Leave the pickup submerged and jiggle it gently until no more air bubbles seem to be coming out of it.  This takes a while (up to fifteen or twenty minutes) because the pickup has to heat up to the temperature of the wax around it before wax will adequately penetrate the coils.  Move the pickup every few minutes to different angles to get the bubbles out.  Try to avoid letting the pickup stick to the side of the double boiler.
    * Remove the pickup and allow to dry and cool on a paper towel.  Remember it is hot coming out of there!  Let it cool naturally in room-temperature air – don't try to speed up the cooling process.  You may want to wipe the face off a little while the pickup is still warm because it is easier to clean.  Getting wax off after it has fully cooled is a pain.  Wipe off only the outside of a metal humbucking cover or the top of the coil bobbins (where the pole pieces are) and not around the bottom or sides of the coil.
    * Repeat the previous three steps for any remaining pickups.  Work on one pickup at a time.  Don't try to clean one pickup while soaking another.  Pickups are expensive and each deserves your full attention throughout this process.
    * After the pickups have cooled clean any excess wax out of the mounting holes and reinstall them in your guitar using the wiring diagram you made earlier.

You have now potted your pickups.  Enjoy the benefits of less feedback and noise — John Thornburg



Update: Here's a quick photo of the process.  Last spring I potted some pickups and took a quick photo of my setup.  The inner pot of the double boiler is a camp pot with a cover.  When I'm done I just put the cover on and let it cool and it's sealed up until the next time I need to use it.  I used two pounds of canning wax.  I couldn't find any beeswax at WalMart so I went to the shoe department and got a 7 ounce jar of Kiwi "Camp Dry Beeswax Water Proofer." This is beeswax with a bit of lanolin mixed in and is about the consistency of a soft, moist paste.  It mixed readily with the canning wax (parafin).  This mixture seemed to work just about perfectly.  You can see the nice golden hue in the photo and it even leaves your pickups smelling nice!
Potting a Pickup

Note that the inner pot is suspended by loops of picture-hanging wire.  This isn't as stable as it could be so you have to watch that the inner pot doesn't tilt to the side and spill melted wax into the water in the outer pot.  Using an outer pot that is not too much larger than the inner pot helps in this respect – this setup wouldn't work well if the outer pot was much wider.

I also used picture-hanging wire tied through one mounting hole on the pickup to handle the pickup without risking damaging the coils by grabbing them with tongs or pliers.  I was able to shake the air out of the pickups just by gently jerking on the picture-hanging wire.  I missed getting a picture of the free end of the picture-hanging wire.  The free end was tied around the handle of a screwdriver so that it wouldn't spring back against the heating coil of the stove and get hot.

The candy thermometer near the top of the picture is highly recommended and costs about four bucks.

Finally, notice the small air bubble that has just reached the surface.  I potted a total of five pickups in two sessions a couple of weeks apart and never saw what you would call a rush of bubbles.  Instead, bubbles would kind of percolate to the surface one or two at a time for several minutes.

J. Atchley – July, 2000

Elantric

If your Roland GK-3 or GK-2A PU has microphonic feedback at High Volume, then it
may require "potting" - which is a traditional technique employed on
magnetic Pick Ups to control un-wanted hi pitched feedback at High
volume levels.

Inside the Roland GK Pickup; are six discreet small coils wrapped
around 6 magnets. ( many newer versions employ humbucking coils for each of the 6 string positions   = 12 coils total)
The technique to "Pot" the pickup requires removal
from the guitar - and using hot Parafin Wax at +180 degrees
fahrenheit( +82 Celsius) - immerse the GK PU in melted Wax (use a
double boiler) until all air bubbles stop - (Approx 10 minutes) and
then remove it from the hot wax pan - and let it cool down to air
temperature for an hour. Then reassemble back to the guitar.

I had to do this with an older Roland GK-2A PU - as it was
impossible to play hi volume live gigs with a power drummer. All I had
was "SQUEEEEEL!" when I cranked up the volume - even with muted
strings. Not cool.

Potting the GK Hex Pickup solved the problem - and now this guitar
with VG-99 can be cranked up and compete with a Les Paul thru a
Marshall Stack - with out annoying squeals!



sixeight

I have a few feedback problems with my new guitar on high gain patches. Because it is not a solid body guitar, feedback comes too fast. I have been playing a bit with the anti feedback effect. It will do something with low frequency feedback, but not high frequency. Also I am not sure where to put it in the signal chain, I assume after the amp. I have more succes with notch eq, but was hoping the anti feedback would help out. Any help would be appreciated...

DrJustice

I have no idea if it will help, but you could try adjusting the delay in each of the A and B channels. In theory this could affect the feedback; a bit like changing your distance to the speakers, except that the amplitude doesn't change, only the phase.

DJ
--

Rojoyinc

Is this using GK pu only?  or do you have  regular PU in the mix?

I've never had any feedback - even with my T5 (hollow) would should be prone to feedback typically.
If you plug in headphones to VG99 phone out - do you still get it?

try turning down the PU volume and to compensate for lower vol - up the COSM amp level (mixer level, Patch level or VG99 output level).

You might try turning down the gain in the COSM amp - and using FX distortion instead, or if you're using FX dist... reduce that and up the amp gain instead.
Ron, GR, MI
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sixeight

Guitar is a Crafter SA-TMVS, posted here: https://www.vguitarforums.com/smf/index.php/topic,359.msg7526.html#msg7526

I have a GK3 on it. Feedback is only there when playing high gain patches and having a real amp. I am thinking about stuffing the f-holes with something, that will probably fix it.

Main reason for the post was the vague desciption of the anti feedback effect.

I play in a church setting, where feedback in guitar solo's is not common.

Elantric

QuoteI have a GK3 on it. Feedback is only there when playing high gain patches and having a real amp.

I would do the following.

Temporarily remove the GK-3 from the Crafter SA-TMVS.

Connect the GK-3 to your VG-99 and crank up the volume. ( GK-3 does not have to be installed on a guitar for this test )

If you still get feedback - its time to "pot" your GK-3 hex PU.

Brent Flash


soundman101

I know this is an old post....but do you remove shell of gk3 to pot......any pics of this
Roland G707, gm70, us2, bc13,  GR20,  VG88 (2), VG99 (2), FC300, us20, Godin spectrum steel SA, Roland Ready Strat, 1970 Gibson SG Deluxe with GK3, Epiphone Joe Bonamassa Goldtop with GK3.

admin

No need to disassemble

Hold GK PU under hot wax and watch the Air bubbles be replaced by wax

Just be sure your radius is pre adjusted to the correct setting and working  - Before you wax pot the GK PU

And do not get the wax too hot ! StewMac website recommends 150 degrees Fahrenheit. (65.5 Celsius)
http://roland.com/V-Guitar/howto.html

soundman101

Thanks sustaniac
I assume I scrap the wax off the outside and mounting holes after
Roland G707, gm70, us2, bc13,  GR20,  VG88 (2), VG99 (2), FC300, us20, Godin spectrum steel SA, Roland Ready Strat, 1970 Gibson SG Deluxe with GK3, Epiphone Joe Bonamassa Goldtop with GK3.

admin

QuoteI assume I scrap the wax off the outside and mounting holes after
Correct

admin

I  experience a Tracking improvement / immunity to mistriggers by wax potting my GK-3 pickup

I find the GK-3 with its adjustable radius to have too many moving parts, and these internal GK Pickup components often rattle while playing.

Often Wax potting the GK-3 pickup ( after setting the radius adjustment for your instrument), yields improved tracking with all VG/GR/GP units
And can cure alt tuning warbles on GP-10 and improve GR-55 PCM pianos

carlb

On the new GK3 install, the treble E string output is much lower than the rest. I'm hoping the potting didn't short a few windings. To balance the strings, other strings are in the 40s and 50s when the treble E string is at 100.

Wax Potting GK-3
https://www.vguitarforums.com/smf/index.php?topic=43.msg71#msg71

The hex pickup is centered pretty well, such that the treble E and bass E are equally off center of their pickup poles. I'm considering elongating the GK3 mount holes to allow the treble E to be more centered.

What other causes could I be looking for? I doubt a bad connection, there's no intermittency.

Would very much like to normalize the output to my Carvins, which have string output reasonably balanced. That way I won't have to mess with GP-10 string level adjustments when I change guitars.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

Brak(E)man

I have the same problem with two of my guitars.
One on high E and one on low E.
They're both Gk2 internal.
swimming with a hole in my body

I play Country music too, I'm just not sure which country it's from...

"The only thing worse than a guitar is a guitarist!"
- Lydia Lunch

GuitarBuilder

I suspect misalignment of the string to the pickup, either laterally or horizontal.  Can you share some close-up pics?
"There's no-one left alive, it must be a draw"  Peter Gabriel 1973

carlb

I'll have to take a pic or two.

I think I might need to slot further, align the high-frequency E string more toward the center, let the low E align to the edge of its pole.

A gauge for 1mm I still have the GK3 install kit, I'll look for that too.

Thanks all.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

gumbo

"A gauge for 1mm I still have the GK3 install kit, I'll look for that too.

Use a credit card, Carl...it's almost there!

...although usually I find my Debit Card is thinner!  ::)

Cheers,
Peter
Read slower!!!   ....I'm typing as fast as I can...

carlb

I wonder if a "pole shim" would help:

1) Add height to the poles that are the weakest responding.
2) Shift the pole surface area toward the string to channel the mag flux lines closer toward the string (for Gibson bridge spacings).

I envision a bit of flat, square shim of a similar alloy to pickup pole pieces. Place them over the weak-response poles, adjust overall pickup height accordingly. Magnetic pull would keep them in place, otherwise a drop of superglue or such once the desired placement is found.

Worth investigating?

(Unfortunately, manufacturing GK-compatible mags in a Gibson-compatible mechanical design is a bit beyond the level of "dive" I'm willing to invest.
Would entail manufacturing humbucking singular-string pickups, and some kind of tray to space them correctly. 3D printing could be helpful for prototyping.)
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

mooncaine

Carl, that's an intriguing idea. I have no idea if it would work, but it would be great to know!

GuitarBuilder

"There's no-one left alive, it must be a draw"  Peter Gabriel 1973

carlb

Top view has the low and high E strings equally off-center from their poles, balanced. I'll have to take a pictures, tonight or this weekend.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

carlb

Looking for ideas toward small, slim, low-carbon iron alloy pieces to sit on top of low-output GK pickup poles.

The idea is to bring the mag flux closer to low-output strings.

Ideas?
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker

admin

Quote from:  carlb on May 17, 2018, 06:31:48 AM
Looking for ideas toward small, slim, low-carbon iron alloy pieces to sit on top of low-output GK pickup poles.

The idea is to bring the mag flux closer to low-output strings.

Ideas?

In my opinion I doubt that's going to really solve anything

if you read the GK-3 wax dip steps outlined,  I state it's important to 100% mount and adjust the GK 3 radius first, before you wax dip-  so you can lower the height of those middle D & G coils on GK-3 when you encounter a guitar with a 12 inch ( or  higher 14 -16 in radius with a flatter fretboard)



Placing metal object on top of the existing GK-3 high E pickup coil  will tend to load the pickup and reduce magnetic flux compared to the other coils


I would really suggest working on this using the string sensitivity to balance the strings.

if you can't get any more out of the high E, then knock down all the other strings after you set the high E string sensitivity on 10,  but set the other strings on 6 or 7,  whatever it takes to get balanced output on each string.


QuoteStarted by carlb - Last post by carlb
Top view has the low and high E strings equally off-center from their poles, balanced. I'll have to take a pictures, tonight or this weekend.


Also be sure the GK-3 is not mounted TOO CLOSE to the Bridge (  = low output signal for all strings)
Details
https://www.vguitarforums.com/smf/index.php?topic=13322.0
http://roland.com/V-Guitar/howto.html
http://roland.com/V-Guitar/howto_lp.html

When determining the final mounting  location for GK-3, I'll tend to place it so more of the High E string sits directly above the GK PU high E coil,  versus worrying about the Low E String to Coil alignment.
Because as the strings vibrate, the low E generates a much hotter signal due to its mass, so even if the low E string is not sitting directly above thr GK PU coil,  you'll still hear the low E.
It's the high e that has the problem of naturally being weak output,   so I'll make sure that the GK-3 PU is mounted a bit to the right, to provide more pickup  underneath the high E string.


carlb

Yah, I'm going to have to keep working on this. Right now the treble E  sensitivity is at 100%, the rest are in the low 40-50% range.

Two problems with it at present: balancing the output with the Carvins; and balancing the pickup output with the "real" pickups. Too low in both situations.
ES Les Paul, internal Roland GK
Boss SY-1000, Valeton Coral Amp pedal
Morningstar MC8 & MC6
QSC CP8 powered speaker