How does a guitar body affect electromagnetic pickups?

[lingyueqing]

If the pickups are just electromagnets detecting vibrations in metal strings, what effect does the guitar (size, shape, type of wood, solid body, hollow body) have on the pickups?

Most argue that the pickups are similar to microphones. However, direct contact with the pickup by material other than metal does not produce any significant sound from an amplifier.

How can wood vibrations from the body effectively transfer to the electromagnetic pickup to affect tone in a significant way?

 

[Tonart]

If the pickup coils physically move relative to the magnets, even if on a microscopic scale, current will be induced. ‘Self induction’, so to speak.

This can possibly occur if the body is vibrating and causing the pickup to vibrate.

Perhaps this is why hollowbodies sound different, and why feedback occurs.

No matter what, whether through the body vibrating the pickup, or the neck vibrating the string, the guitar itself will inherently affect the amplified sound, and not by a small amount at that.

 

[elvis]

I would argue that the string vibration is very much affected by the resonant frequencies of the body. Listen to any electric guitar unplugged.

Second to that is that the body vibrates, moving the pickup relative to the strings. Mute the strings and tap the body with the guitar plugged in.

Anyone who thinks the wood is not a significant part of the tone should try metal and acrylic body guitars. There are quite a few of the around.

 

[elvis]

Also note that the neck may be the biggest factor, as it has the least mass, so it will vibrate more than the body.

 

[justmund]

https://forums.prsguitars.com/threads/the-subtractive-theory-of-tone.17439/

 

[Tonart]

Also note that the neck may be the biggest factor, as it has the least mass, so it will vibrate more than the body.

Yup fully agree. It’s a suspended slender cantilever.

 

[Dusty Chalk]

Indirectly. If you're familiar with the concept of sympathetic vibrations (hold a chord with one hand on an acoustic piano by playing slowly enough that the hammers don't hit the strings, then play a chord loudly and quickly with the other hand, and the strings will start vibrating due to the sound waves), then the body of the guitar starts vibrating sympathetically due to ... a variety of reasons, including sympathetic vibrations...and then vice versa...and it's frequency dependent...plus the rigidity of the guitar is also frequency dependent...

 

[Tonart]

Actually this thread touches on a very important subject, that is how electric guitars are viewed, the paradigm for electric guitars.

I believe the subject effect is why when you tap on the body, you hear an almost EXACT copy of the acoustic tapping sound coming out of the amplifier. It’s certainly not some warped version coming off the amp, in some electromagnetic language that only a pickup would understand. In a blind fold situation, anyone could plausibly guess that it sounds like wood being tapped. Isn’t it amazing how accurately the pickups translate this? Electromagnetism is so alien to wood, yet it comes out almost perfectly reproduced.

When you play an electric unplugged, why do some guitars sound woody and full of character, yet others sound thin and lifeless? Where is that woody sound coming from? Is it plausible the body is beating the air to such an extent that you can hear the woody tone so clearly in your ears? Maybe so for an acoustic guitar, but solid heavy wood blocks moving air to that magnitude on account of the minuscule energy in a thin metal string?

Therefore I believe it’s the string itself that is causing that woody tone. It’s the string itself whose vibration has been influenced by the vibration of the neck (and perhaps bridge to a much smaller extent). The string vibrates the air, and the air vibration reaches our ears.

That’s also why I believe acoustic tone is the first and foremost barometer of a great electric guitar.

All this will get sensed by the pickups, because it’s the string itself that is behaving in a spooky part-metal part-wood manner, so to speak, plus the body vibrating the pickups directly.

The subject effect is what makes a guitar a guitar. Pickups play their role as sensors and translators. But which is more important: Adele herself or the ultra high-end microphone she uses? You could say both play a part in the final sound, but really which is more meaningful authentic and indispensable? Would you prefer an average vocalist with an Everyman voice paired with space-age electronics? Or a top notch vocalist with unique timbre paired with basic electronics (think 1960’s hit records).

You could post modulate pitching, sustain and all that. But can you ever replicate Steve Perry’s timbre with electronics?

 

[toothace]

How can wood vibrations from the body effectively transfer to the electromagnetic pickup to affect tone in a significant way?

Remember that a pickup is basically a microphone, and will pick up what it "hears". Ever hear those songs where the artist yells into the pickups? Or how about EVH or Paul Gilbert capturing the whirr of their drill with the pickup? Same as an acoustic player knocking on the guitar body and the sound being projected through the sound hole, an electromagnetic pickup will do similarly...

 

[Tone-y]

Or how about EVH or Paul Gilbert capturing the whirr of their drill with the pickup? Same as an acoustic player knocking on the guitar body and the sound being projected through the sound hole, an electromagnetic pickup will do similarly...

The drills work because they put out an electromagnetic field as the internal coils move past the magnets when the motor rotates (same as how your strings are moving past the magnets of the pickup). Not sure about the shouting in to the pickup, but it could be that it makes the strings vibrate at the same frequency and this is what the pickups are picking up

 

[Screamingdaisy]

If the pickups are just electromagnets detecting vibrations in metal strings, what effect does the guitar (size, shape, type of wood, solid body, hollow body) have on the pickups?

Most argue that the pickups are similar to microphones. However, direct contact with the pickup by material other than metal does not produce any significant sound from an amplifier.

How can wood vibrations from the body effectively transfer to the electromagnetic pickup to affect tone in a significant way?

Why does a hardtail sound different from a floating trem?

 

[Tonart]

Why does a hardtail sound different from a floating trem?

Good point about the bridge. I happen to believe the classic Strat tone is achieved by the following main ingredients:
- Maple neck
- Light, thin and partially hollow body (to accentuate body vibration). It’s not oftened thought about, but mounting pickups on a slender pickguard over a cavity probably lends a pronounced hollowbody effect. At a micro level that pickguard must be vibrating like crazy and vibrating the pickup along with it, and it’s really a wonder Strats don’t feedback much more than they do.
- Tremolo
- Singlecoil pickups

There I said it. IMO a Strat is functionally a hollowbody.