Minor impact causing pickups to become more microphonic?

[Tom Karol]

I had a Rock gig at a bar Saturday night. I brought my guitar in and set the rectangular hardshell case down standing up on it's back - with the handle facing up - not lying flat - I should have learned not to do that by now! I thought it was well away from any foot traffic flow, but some guy bumped it and it (the case) tipped over onto its bottom (back of guitar facing down) on a hardwood floor. He said, "Oh Geez - sorry!" He was big and a bit drunk, so all I could do is grimace.

Now it's a study supportive case and the guitar is a Tele-type, so it wasn't going to sustain any physical damage, but during the gig I experienced feedback issues on certain overdrive settings that I've never had before. I thought it was the less-than-optimal acoustic environment. But I tested it at home on Sunday, and the issue was still occurring in an environment where it previously had never happened. I believe the impact may have caused the (single-coil) pickups - especially the bridge pickup - to become considerably more microphonic than they were before. I can compensate for the change in the way I set levels, but I don't want to. Any suggestions for a fix? Thanks!

[kenbennett]

It's possible.

Wax potting is the standard fix for microphonic pickups.

[Tom Karol]

Thanks Ken. It's a Hamer-T51 with Harmonic Design Vintage Plus pickups. I believe they are wax potted though I'm not sure. Would it be possible that the wax potting needs to be (and can be) redone? I'll email Harmonic Design and also have my Tech check it this week.

If it can't be addressed satisfactorily, I've been thinking of trying some single-coil sized stacked humbuckers - probably Bill Lawrence's Wilde L280TN/L-290TL combination, I love the sound of the current pickups, but not the noise (even before this incident).

[kenbennett]

How would you describe the feedback? Is it a squeal? Or is it the note you are playing?

And the noise. Is there noise even when there is no feedback?

I'm not familiar with the Harmonic Design stuff. Check with them about re-taping or re-potting.

[Tom Karol]

How would you describe the feedback? Is it a squeal? Or is it the note you are playing?

And the noise. Is there noise even when there is no feedback?

I'm not familiar with the Harmonic Design stuff. Check with them about re-taping or re-potting.

Squeal, but only with outboard overdrive on the bridge pickup or outboard overdrive and compression on the other settings. (Again, this didn't happen before the incident.) The clunk when you switch from the middle to the bridge position seems louder through the amp. If I tap the the bridge or the bridge pickup with my pick it's clearly amplified.

The noise I referred to was standard 60-cycle hum/buzz that is part of the package with single coils, which largely goes away when I touch the strings.

I did email Scott at Harmonic Design; I'll let you know what his reply is. I probably won't get back to the board here until tonight EDT. Thanks again.

[kenbennett]

I suppose it's possible that there is a loose solder connection somewhere else in the circuit.

Good luck.

[Tom Karol]

Response from Scott Perterson at Harmonic Design (Scott's the head guy and has always responded promptly to my emails):

"Hello. It's fairly unlikely that bumping the case would damage a pickup, but I suppose anything is possible. In any case you can always return the pickup here for re-potting. Our pressurized setup is much more thorough than the usual waxing setup. If it's a pickup problem - and not some other loose part on the bridge, etc. - that should take care of it.
Thanks,
Scott"

[stevedenver]

have you checked to see if the height adjustment was changed? ie the pup a good deal closer to the strings? just a thought

[Tom Karol]

have you checked to see if the height adjustment was changed? ie the pup a good deal closer to the strings? just a thought

Well no, because the balance between the pickups remains the same. But your question has caused me to start re-thinking about pickup height on this guitar.

These are fairly hot pickups for single coils, and I've had them adjusted for many years now to get a big bold sound through a clean amp. But certain things have changed without my lowering the pickups:

1) I switched from 10's to 11's.
2) I'm now using compression and/or overdrive for solos in a rock context.

So, it might be time to try lowering the pickups anyway. This might give me some nicer varieties of rhythm textures with this guitar, and I'd still have the boost capabilities from the compressor and ODs to add some heat for leads.

So this 'problem' may actually become an 'opportunity'!

[kenbennett]

General Rule for single coils... When you press a string down at the highest fret, the space between the pickup pole piece and the bottom of the string should be about 1/8" (3mm). Neck pickup [Edit: I meant to say bridge pickup] (or one side of either pickup) may need to be slightly closer to balance. No closer or pickup magnet may damp string vibration. Farther away is OK.

Hope you find the squeal.

Check bridge parts, springs tensioned, screws tight, saddles secure.

Check all wiring, no loose connections, resolder if necessary.

Check pickup switch and controls, wire pickup directly to volume control to bypass pickup selector switch, wire directly to jack to bypass all controls.

[Tom Karol]

Thanks again, Ken - that's good info to have. I'm sort of getting psyched about this as a learning experience! Who says you can't teach an old dog ... ?

[kenbennett]

Thanks again, Ken - that's good info to have. I'm sort of getting psyched about this as a learning experience! Who says you can't teach an old dog ... ?

OK. For the record, since you're taking it seriously... There's a mistake in my last post which I will correct. I said the neck pickup might need to be closer. I meant to say the bridge pickup...

The theory is that when you pluck a string, the distance that it travels during vibration is greatest at the center of the string and zero at the ends. It is the movement of the string through the magnetic field of the pickup that generates the signal. So if you have two identical pickups placed the same distance from the strings, then the pickup at the neck will be louder than the one at the bridge, because the string is moving more at the neck pickup and less at the bridge.

[Tom Karol]

I had my Tech check out the pickups. The bridge pickup has become very microphonic. It's possible to fix it, but I've had these pickups in there for 10 years and while I've liked them a lot, I've been thinking it's time to try something else anyway. So I called Becky Lawrence and ordered a set of Bill's noise-free singles (stacked humbuckers) - an L280TN/L290TL set. I don't expect them to sound just like single coils - more like a cross between single coils and humbuckers but without the 60 cycle hum and noise. We'll see ... and I'll let you all know in a few weeks!

[Tom Karol]

I got my new Bill Lawrence L280TN/L290TL pickup set installed in my Hamer T51 yesterday. I decided to go with 500k pots and a .022mf cap. I also have the pickups set a slight bit lower than suggested in the instructions on the website. (I use roundwound 11's.) They're not better or worse than the Harmonic Design Vintage Plus set I had previously - which I only replaced after 10+ years because they stopped working properly - but, being stacked humbuckers, they sure are quieter. I won't go into a detailed comparison, as it would be largely pointless without sound samples. But I must say I am extremely pleased with these new pickups' balanced tonal character and response to picking dynamics. I'm not sure if they sound just like "real" single coils, or if they sound more like crisp and clear mini-humbuckers. Frankly, I don't care: they still twang like Tele pickups should, but I anticipate that they will prove to be much more versatile. I'll try something else in another 10 years or so!

[ESCC]

+1 on Bill Lawrence pick-ups.

I have a T202N and L48 in my Tele, love them, very responsive to 11 rounds. Humbuckers but more reminiscent of single coils and absolutely noiseless. Love the sound when the tone is backed down, great for jazz.

[Tom Karol]

Update: I've played and tweaked and I'm quite happy, but ...
Question: What would be the effect of going to a higher value cap - i.e., going from .022 to .047mf for example? Thanks!

[SamBooka]

In a tone circuit there are, for simplicity sake, two parameters:
The amount of signal that is cut and the frequency above which the cutting takes place. Changing the cap value changes that cutoff frequency.

So if you have a .022 in there now the cutoff frequency might be 8KHz (totally made up value.. for illustration only). If you change to a .047 cap the cutoff frequency would drop to 5KHz. That means that as you roll back your tone controls all the frequencies above 5KHz would be attenuated.

So if you want only the highest of the highs cut go with smaller value caps. If you want more upper mids cut go with something larger.

Personally (and I am a freak and an exception and have lousy taste) I like a .011 cap. I just want a little of the edge taken off the high end.. not the marshmellow jazz tone some guys like by rolling the tone all off.

[Greco]

Update: I've played and tweaked and I'm quite happy, but ...
Question: What would be the effect of going to a higher value cap - i.e., going from .022 to .047mf for example? Thanks!

In theory, you should reduce some of the highs. However, it might not be as "dramatic" as you expect. This is what is reported by many of the folks that change cap values.
I assume that you have particularly "sensitive" hearing (being an accomplished musician) and you might hear subtle differences.

Cheers

Dave

Sambooka and I were typing at the same time...he obviously hears quite a difference when changing cap values. His thorough description is very helpful.

[Tom Karol]

Thanks, guys, great answers - I'm going to leave it as is then!

[Greco]

Thanks, guys, great answers - I'm going to leave it as is then!

Not a fan of "marshmellow jazz tone" ? ...LOL

One nice thing is that changing cap values is easy to do with a Tele-type guitar (especially compared to a hollowbody or or semi-hollowbody) ...if you are confident with a soldering iron.

Cheers

Dave

[Tom Karol]

Not a fan of "marshmellow jazz tone" ? ...LOL

As long as I never need to duplicate Stephen Still's solo from, "Wooden Ships," it should be fine just the way it is!

[stevedenver]

you should research caps-having swapped more than a few-not only the value but the make makes a significant and very muscial difference-oil in paper, Hovland-the difference can be between grating brittle and bright and musical-

while i have expertise re Les pauls-all of my teles are stock

since caps arent too pricey -when in doubt-buy a few, in pairs-im fond of hovlands-round and clear with humbuckers-but not shrill
also the quality of pots is significant as well to tone-and its not old wive's stuff

[Tom Karol]

After further sonic trials ...

OK, I'm sticking with the .022 uf cap, as I only want to attenuate the high end - not the mids - when I turn the tone control down. But what about pots (they're CTS audio taper by the way - very smooth)? I tried 500k pots because these pickups are stacked humbuckers, and I was worried about a possible lack of brilliance. (It is a 'Tele' after all!)

So, my assessment and my questions:

Volume - I can only turn it down 1/4 turn before the guitar starts to sound too wimpy. If I turn it down only 1/8 of a turn, however, it pretty much maintains the same tone as when it's all the way on - which I consider a good thing.
Tone - Generally a bit too bright when all the way on (see below for exceptions), but the whole 1st half of its rotation (i.e., from 10-5) is useful for dialing in the 'sweet spot' for varying styles.
So, what would 250K pots do the tone when they're fully on (i.e., at 10)? What about mixing and matching 250K and 500K pots?

Exceptions:

You can't add high end with passive controls, but you can attenuate it.
Playing live in a group usually requires a brighter tonal balance than playing alone at home.
These pickups actually sound really good with the Henriksen for jazz and blues and even clean country; the old ones didn't. For jazz on the neck pickup with the amp set flat, I've got the volume pot backed off 1/8 turn and the tone pot backed off 1/2 turn. For blues and country twang, I have the guitar controls flat out and the amp's 1k and 3k controls goosed a little bit (300k attenuated depending on room).
The ZT Club (the normal mate for this guitar, usually with a Carl Martin Quattro) is a whole different animal - I'm still experimenting - and I've got gigs with this setup on the next 2 Saturdays (I won't make any mods before then), so stay tuned ...

[Tom Karol]

Well, it looks like I've hijacked my own thread!

I've done some more sonic evaluation with the Club. I think I'm going to stand pat - at least until after the crucible of the 2 gigs.

With the old pickups and 250k pots, I just left the tone and volume knobs at 10 most of the time. With this setup, I'm taking a different tack: my 'flat' settings seem to be volume rolled back 1/8 of a turn and tone rolled back 3/8 of a turn (5/8 for jazz). This way, I think I'll have some available movement of the controls in either direction if the musical/acoustic environment calls for it. We'll see ...

[Tom Karol]

Are you guys bored yet?! I just ordered a couple of CTS 300k Audio-taper pots and a Sprague Orange-drop .022uf cap from a place called GuitarElectronics.com. Less than $20, and good to have in the personal parts bin anyway. The saga continues ... !