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    I agree that the mocrophonic activity s minimal, but have to say, it is
present and is functional in solid bodied electric guitars. I undertand that
we can't generate tone that's very musical when we remove the srings
from our electric guitars, but there is another very simple test that you
can do to see my point while your strings are off and you're strumming
between thos two humbuckers trying to generate tone to no avail.

   Just take your Les Paul and plug it in and trun the amp up. Begin
tapping on the body...anywhere you'd like....or along the length of the
neck for that matter. What is it that inevitably happens with any electric
guitar with magnetic pickups when you do it?

    The tapping can be heard through the amp...no strings...no interaction
between magnets and ferrous metals....no warping of magnetic flux
lines....just plain old acoustic tapping being pickep up and sent to the
amp via the microphonic behavior of the magnetic pickups.

    Do the same with several guitars of the same model made with
different body woods and you'll hear the different resonant qualities of
those woods being communicated to your amp....still with no strings on
the guitars.

    This is much easier to prove than to disprove since every guitar will
exhibit this ability to ring when tapped with no strings present. It's on of
the quirky things that I always read and document when I build electrics. I
listen to the tone of the tapped body through the pickups.

   This has just been my experience so feel free to disregard it.

Regards.


   

Rick,
   i agree with you on your feelings about neck stiffness and the integrity
of its joint to the body when it comes to transferring vibration back to the
body. I wasn't as clear as I should have been earlier and should have
spent another minute saying that those vibrations are sent back into the
body through the strings as the stiff neck provides an anchor of sorts at
the nut end of the string forcing the strings to releae their energy into the
body at the bridge end as much as possible.

    The vibration isn't sent through the neck, but away frm it and back into
the body because of this combination of stiffness and solid foundation at
the joint. The body and neck are working together as a tone creating
system while the neck's part in the operation is to force the body to do as
much of the work as possible.

Thanks,
Kevin Gallagher/Omega Guitars

Kevin, I wasn't disregarding your experience in the least. Please re-read my post to see how I stated myself. It was not in any way a dismissal. I actually agree with you for the most part and understand your experiment completely.

My only point is that this microphonic effect while present is minimal at best. I have heard the exact results you have but at barely audible levels. To understand what I am saying try tapping your guitar while playing some chords to see how much of it you still hear through the amp. Do the same thing with some high gain settings. It becomes obvious that the microphonic effect is minimal in practice. That is all I am saying.

I also agree with Rick on the neck (and neck joint). In my long winded post above I tried to say the same thing: that the neck's role in tone is quite significant but only because it couples with the strings directly. I don't believe the neck sends much energy into the body at all. The analogy I use to think about this is a diving board. If the end of the diving board is plucked it starts to vibrate. It does not sit still while the rest of the pool vibrates.

~David

David,
   Agreed...it is a minimal contribution. I wasn't offended at all by your post.
I like to hear what other people have experienced and will always listen in
my effort to learn. I've had a thousand teachers and most them don't even
know they've contributed to my education.

Thanks,
Kevin Gallagher/Omega Guitars

Kevin, thank you, and likewise. Thank you also for the clarification. My next question was going to be what pickups you use for such a large microphonic effect, but I understand and agree with you completely now.
~David

The microphonics of a pickup without strings is explained in several ways:

1) If the pickup is spring or foam suspended, it's going to move differently from the body itself when the guitar is tapped.   With two or more pickups, the magnetic fields of the pickups will be disturbed by any differential movement or vibration.

2) If there are any ferrous metal parts on the guitar...for instance the bridges of Teles or Strats, you'll have differential movement and vibration between the pickup(s) and the hardware.   This includes any ferrous pickup mounting screws.

3) If the pickups are not potted solid, you'll get rattling and movement of the coil turns, the bobbins themselves (think humbuckers...), etc.

To test pickup microphonics, plug an unmounted pickup straight into an amp and tap on it.   To then test for interaction with metal guitar hardware, test in the guitar without strings.

To take this whole thing even further out, consider this: the material a coil is potted with affects the tone of the pickup.   Potting with superglue, as I did for a while, makes a pickup sound harsher than if you pot it with wax.

Thanks Rick,

   That make alot of sense. Were you actually "potting" the pickups in
super glue or were you brushing or pouring the super glue onto them?

   I wouldn't want to stand too close to the pot full of CA. That stuff is
pretty noxious in an open format. I used to do my pore filling under the
UV cure poly finish using CA glue and it was pretty nasty once it was
spread over a surface like a back. I had to do it on a downdraft table and
vent it out of the shop.

    I'm going to try clipping a lead onto a few new and old pickups here to
get an idea of their microphonic qualities before they're installed in a
guitar. We're getting blasted by a snow storm here today, so I'll be able to
spend a little time tinkering with some things.

Thanks again,
Kevin Gallagher/Omega Guitars

Warren, Excellent thread you have started! I have learned a ton so far about electrics and electronics and their relationship to wood and tone. Great stuff. I'll go back to my desk now.

Kevin, I just dropped thin CA into them; it does penetrate quite well.   I just don't like the sound it develops in the pickups.   

If you're going to wax them, then a great way is to use a crock pot, but you really should do it under vacuum and release.   I currently use a laboratory vacuum oven and put the crock pot in, pull down about 26" of mercury, and then release the vacuum which then forces the wax all the way through the coils.   I'm going to change that over to putting a vacuum line into the lid of the crockpot, right where the handle is screwed in, and putting a bit of closed cell gasketing around the lid.   The crockpot and lid are plenty strong enough to become a vacuum chamber.   I can hook this up to my CNC vacuum pump.