Calling all P90 nuts!!

[BillWelcome Home Studios]

Hey, I make no claims for any P-90s other than those existant on my Gibson guitars from the 50s and 60s. Duncan or anyone else's may or may not react the same... goodness knows, the new Gibsons don't. But original P-90s sound great.

 

My favorite axe ever was my 1957 Gibson Les Paul goldtop with P-90s... yes, they made them with P-90s that year, too even though it was the year that they introduced the humbucker to the LP line.

 

Bill

[miroslav]

Originally posted by Guitarzan:

...tap a pickup or guitar body and hear the sound through your amp. that proves its not only vibrations from the strings that are being picked up.

Mmmmmm...no, not really.

 

Put one hand across the strings and muffle them...then tap the body or the pickup...you will get...pretty much nothing.

Now...let go of the strings and then tap the body...now you hear it.

It's the vibration/movement of the strings affecting the magnetic fields of the pickup.

 

With a piezo/transducers...that's a different story...there you are transferring the acoustic sound/vibration into an electronic signal, but with coil pickups, you have a magnetic filed that the metal strings disturb with their own separate vibrations.

 

I may be mistaken, but without the strings…your single coil or humbuckers will NOT pick up any body vibrations.

I'm sure someone else here who knows the electronics/mechanics of a guitar really well, can give their opinion.

[Guitarzan]

now i have to disagree, if i tap the body very lightly with the strings muted i get a knock from the amp, its not the strings because i very carefully silenced any movement. now this may have to do with the screws that attach the pickup. but that still gives weight to the theory that direct mounted pickups sound different. maybe the body vibrations travel through the screws and are "heard" by the pickup. another point was the strings affecting the magnetic field, a stationary pickup will sense the strings in the field differently than if the pickup itself is moving as well. like i said earlier this may be subtle.

[Blue Strat]

Originally posted by fantasticsound:

a pickup need not be mounted to the guitar at all to pick up vibrations from the strings. Magnetic pickups don't work that way. It's just a lot simpler to mount them then to have someone hold the pickup near your strings. Of course, the body does color the sound, but it's not required for the pickups to work.

I never said that the current method of mounting pickups doesn't work, just that it's not as efficient at picking up the vibrations of the strings. Magnetic pickups work because the strings interrupt the magnetic field of the pickup. If the pickup were moving along with the vibrations of the strings you'd get no sound. Therefore, I conclude that for the pickup to work at it's peak efficiency, it needs to be stable. For the pickup to be as stable as possible while still attached to the guitar, it must be bolted directly to the body.

[Blue Strat]

Originally posted by Guitarzan:

now i have to disagree, if i tap the body very lightly with the strings muted i get a knock from the amp, its not the strings because i very carefully silenced any movement. now this may have to do with the screws that attach the pickup. but that still gives weight to the theory that direct mounted pickups sound different. maybe the body vibrations travel through the screws and are "heard" by the pickup. another point was the strings affecting the magnetic field, a stationary pickup will sense the strings in the field differently than if the pickup itself is moving as well. like i said earlier this may be subtle.

Remember that the magnetic field of the pickup isn't just out of the top of the pickup, but all around it; sides, top, bottom, front, and back. Yeah, it's a subtle difference in tone, but I can still hear a difference between a thin, flexible pickguard and a thick, rigid one. I've been thinking of using some 3/8" dowel to make a set of spacers to mount the pickups on my Rogue. That will mount them as solid as I can get them without altering the guitar too much. Would you like to hear a recording of before and after to decide for yourself? We can be scientific about it.

[miroslav]

Originally posted by Guitarzan:

[QB]now i have to disagree, if i tap the body very lightly with the strings muted i get a knock from the amp, its not the strings because i very carefully silenced any movement. now this may have to do with the screws that attach the pickup. but that still gives weight to the theory that direct mounted pickups sound different. maybe the body vibrations travel through the screws and are "heard" by the pickup.

OK...if you turn up enough...yes, you do hear something even though the strings are muted.

But...I still don't think it has anything to do with acoustic sound vibrations...but rather that in some way, the magnetic fields are still being disrupted and are then generating a signal.

 

Hmmm....?

 

Is it the screws/springs holding the pickup...?

 

Maybe someone with a hard mounted pickup can try that same thing...tapping on the body while muting the strings...

...is it still "heard" by the pickups...or not?

 

That would maybe(?) prove that completely stationary, hard-mounted pickups WILL sound different from spring mounts.

But if there is still a sound heard when you tap...then there must be something else disrupting the magnetic fields...?

[Caevan O’Shite]

As for all this discussion about non-string sounds coming through pickups:

 

Muting the strings does not keep them from conveying vibrations through the pickups, it just keeps them from "sounding" a note of their own; mute them, and brush them with your free hand, or "ping" them behind the bridge or nut, and you'll very likely still hear that come through.

 

Only completely removing all of the strings and then thumping about on the body will reveal what non-string sounds are making their way through the pickups without the aid of the strings themselves. And much of that is dependant on the degree of microphonic sensitivity of the pickups; many vintage pickups, especially those without wax-potted coils, are very microphonic.

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Another point of interest is how much P-90 style pickups vary from one to another, just like Fender-style single-coils and Gibson-style humbuckers do. I mean, most P-90's sound like P-90's, so to speak, but may have a wide range of differences dependant on specifics of their design and construction, and their age.

 

My Les Paul Gem has that P-90 sound, yet sounds different from my friend's old all-original '52 "gold-top" Les Paul, or various old and vintage soapbar-equipped guitars I've checked out in shops. The polepieces on mine are definitely larger and more massive than the originals of '50s vintage, and it's a given certainty that the magnets in the oldies have lost some of their original strength (alnico generally has a "half-life" of about thirty years or so). Also, many vintage pickups do not have wax-potted coils.

 

The pickups in my friend's '52 also were screwed down quite low, while their polepieces were raised up very high, to the point where they resemble golf-tees or skeleton's-teeth to me! (NOT the way that Gibson would have set them up; more likely my friend's son did this when he was a young kid back in the early/mid '70s.) It aso has the original hollow-tube, trapeze-tailed bridge unique amongst Les Pauls to the earliest of production models. Between all that, the weaker magnets, smaller polepieces, and lack of wax-potting, the '52 LP's P-90's sound brighter, cleaner, twangier, more sparkly and shimmery, with more swirling harmonics as a note's envelope decays, especially on the lower wound-strings; incredible for wrangly low riffs and most deliciously ethereal for fingerpicking. Mine sound darker, fuller, louder, fatter, rounder, and at times even somewhat more suitable for heavily-overdriven blues-rock leads on the high plain-strings than the crystaline-highs of the '52.

[Lee Flier]

Yeah, I definitely agree with Bill and Caveman that P90's differ a lot from each other, and I can really only comment about those on the 50's Gibsons.

 

I would say the pickups on my LP were somewhere in between yours and your friend's, Caevan. I have the pickups themselves up higher and the pole pieces lower than your friend's Gold Top (and I don't have the wraparound tailpiece anymore either... I noticed a significant change in the tone when I replaced that). So I get a fuller, louder and meatier tone than it sounds like he does, although no doubt it can get more shimmery than the more modern P90's with the bigger pole pieces. Like I said earlier, I can get darn near any kind of tone out of that guitar if I really wanna.

[Blue Strat]

My point was that the pickup better reproduces the waveform that the string produces when it's bolted directly to the body. I know how a magnetic pickup works, and that's the basis of my theory. If the pickup is moving, how can it be relied upon to accurately reproduce what the string is doing? It can't, it's got to be mounted as rigid as possible to the same thing that the strings are mounted to, i.e., the body.

[miroslav]

Originally posted by bluestrat:

If the pickup is moving, how can it be relied upon to accurately reproduce what the string is doing? It can't, it's got to be mounted as rigid as possible to the same thing that the strings are mounted to, i.e., the body.

Hey blue...

 

...I'm a bit puzzled by this talk of "moving pickups".

 

What are you guys referring to when you say that they may/can be moving...?

 

I understand how screwing them directly to the body will be more rigid than the screw/spring approachbut how are they moving with the screw/spring approach?

 

Now I'm curious about all this...

[Blue Strat]

Originally posted by miroslav:

...I'm a bit puzzled by this talk of "moving pickups".

 

What are you guys referring to when you say that they may/can be moving...?

 

I understand how screwing them directly to the body will be more rigid than the screw/spring approachbut how are they moving with the screw/spring approach?

 

Now I'm curious about all this...

The whole guitar is vibrating when you play a chord or individual note, right? The pickup is mounted by using springs and screws. The springs and screws dampen a lot of that vibration, so in relation to the body, the pickup is moving whenever a chord or string is played. The pickup may be vibrating too, but it'll be at a different rate than the body. With the pickup mounted directly to the body, both would be vibrating at the same rate, or the pickup would be stationary with respect to the body.

[Caevan O’Shite]

Hey, blue'- ya know those "floating" fore-stock/grips for rifles, that allow less of your twitching, pulse, etc. to negatively impact the accuracey? I'd sooner think that a pickup mounted in a plastic pickguard would be like that, and that a direct-coupled mounting would convey more vibrations filtered through the wood of the body to the coils. Not a bad thing in itself, though; many folks feel that this is an important factor in the type of resonant tone that they like.

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http://www.musicplayer.com/ubb/icons/icon2.gif Lee- yeah, I meant to include that trapeze-bridge among the factors influencing the finer timbral qualities of my friend's (and, perhaps someday mine, we've discussed my buying it from him) old '52. (I'm gonna edit it in there.) I believe that the old hollow-tube trapeze-bridge really does color the tone of the guitar quite a bit. That guitar has such a distinctive tone that I think that I'd want to leave both the bridge and the oddball set-up of the pickups alone! I would be torn between having a special-made bridge piece (still keeping the trapeze-tail) that would allow a proper, over-the-top stringing, or a professional neck re-set to change the angle and allow that. (A guy at the Gibson Custom Shop has done neck re-sets on at least two old "gold-tops" for Billy Gibbons; he must be trust-worthy!) If I could have that guitar sounding the way it does, but somewhat improve the overall playability of it... mmmmnnn... !!

[miroslav]

Originally posted by bluestrat:

With the pickup mounted directly to the body, both would be vibrating at the same rate, or the pickup would be stationary with respect to the body.

OK...I see what you are saying now.

 

But...rigid mounting may not make them vibrate at the same rate anyway. Wouldn't they have to be made of the same material, and have the same density in order for them to vibrate at the same rate...???

 

Of course...now I'm interested in all this.

 

One thing I've done with one set (not because of this vibration issue, but because the pick up was twisting down at one side a bit)...

is to just stick something (I used a small wooden shim) in the space between the pickup and the body cavity.

That sure made it quite rigid!!!

And there was no permanent mod required.

 

So...how are you modifying those pickups that are normally hung with screw/spring?

[Blue Strat]

Originally posted by miroslav:

OK...I see what you are saying now.

 

But...rigid mounting may not make them vibrate at the same rate anyway. Wouldn't they have to be made of the same material, and have the same density in order for them to vibrate at the same rate...???

I think that is of a minor concern, and it's something you really can't do anything about anyway.

 

Of course...now I'm interested in all this.

 

One thing I've done with one set (not because of this vibration issue, but because the pick up was twisting down at one side a bit)...

is to just stick something (I used a small wooden shim) in the space between the pickup and the body cavity.

That sure made it quite rigid!!!

And there was no permanent mod required.

 

So...how are you modifying those pickups that are normally hung with screw/spring?

I've got some 3/8" dowel that I'm going to drill a hole through, then cut to length and use as a direct replacement for the springs. The screws will go through the pickguard, then the hole in the dowel, and then into the pickup. That would mount the pickup rigidly to the pickguard, which will still vibrate a little differently than the body, but the pickups should still be a lot more rigid than they were.

[Guitarzan]

surgical tubing works great as well. it fits the screw fairly tightly and when it compresses after you tighten the screws the pickups do not flop at all. fender has used this on strats. i don't know if they still do. it also gets rid of sympathetic vibrations that the springs sometimes give. the less metal rattling around that magnetic field the better. a real cheap and easy fix.

[Blue Strat]

Originally posted by Guitarzan:

surgical tubing works great as well. it fits the screw fairly tightly and when it compresses after you tighten the screws the pickups do not flop at all. fender has used this on strats. i don't know if they still do. it also gets rid of sympathetic vibrations that the springs sometimes give. the less metal rattling around that magnetic field the better. a real cheap and easy fix.

Yes, but even the surgical tubing rubber isn't as rigid as a poplar dowel.

[fantasticsound]

I understand, Bluestrat. However, you've only proven my point. The sensitivity of the pickups is hardly changed whether P-90's are mounted to a pickguard or directly to the body. Only the timbre is changed, for a variety of reasons you and K mentioned in previous posts. My point was only that the lion's share of sensitivity of P-90's is due to their Magneto-electric properties.

 

It would be nice to hear samples of your guitar before and after. I don't doubt you'll find differences in tone, but I don't think the difference in sensitivity will amount to much if at all.

 

And yes, most unpotted pickups are incredibly microphonic, meaning they pickup stray sounds due to the vibration of the coils. This is very much like an extrememly inefficient dynamic microphone. So tapping on a pickup of that is particularly microphonic, even completely unmounted from a guitar body, will cause nasty clicks in the same way tapping a microphone does. In fact, I used to have fun shouting through the pickups in my old guitar when using high gain settings. Had the pickups been wax-potted, that would have virtually nixed that.