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Posted: Wed Aug 13, 2008 8:12 am
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ThatGuitarGuyAL wrote:
Ceri wrote:
How interesting. That is presumably the effect of moving metal parts within the magnetic field of the pickups inducing current in the coils. Strangely, my divers' watches don't do that - perhaps they are shielded by the thick pressure casing?

And we all know that tapping / scratching on the pickups is audible, without any need to crank the amp.

The issue here is pups reproducing sound without the strings there to act as a diaphragm. Because of the bearing of that on the popular notion that pickups can collect sound directly from the body wood, as well as from the main source, the strings.

From the accumulating evidence, it seems it can happen, however miniscule the effect. So the next question is - how?

Presumably, a strong direct sound source is causing the poles to vibrate and so induce a tiny current into the coil. Remember, there has to be interference in the magnetic field to create a signal: these are not piezos. Given the microscopic movements involved - wow!

In the end, we need to remember that, if it occurs at all, this is never the less an absolutely tiny effect, and will be utterly lost beneath the main source, string vibration. So timber cannot be influencing tone by direct contact with pickups to any significant degree. That happens because different timbers absorb certain frequencies faster than others, and the reciprocal relationship of that to the decay of the vibrating string. As discussed on the previous page, that is how wood colors tone.

Excellent contributions from everyone on this fascinating thread! It's great when we all put our heads together on something, isn't it?

:D - C


I have to ask, just to make sure you didn't overlook it, how does the second hand on your divers watch function? Is it a pop-pop movement, or is it a sweep motion?


Sweep. Which as you say, may be the explanation. Though when I hold it to my ear I can hear ticking of moving parts. To be fair, I haven't shoved my watch right up against the magnetised pole pieces to see if they can pick up the movement - and I'm not going to try that one, for obvious reasons!!

Cheers - C


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Posted: Wed Aug 13, 2008 8:45 am
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I actually don't put them right against the pole pieces, it's more of while we're on stage, if I'm grabbing a drink from my girl, or the pretty bartender, I grab it with my right hand, so my left hand kind of rests across the body of the guitar, and occasionally my watch rotates around so the face is on the inside of my wrist, therefore, facing the guitar. So there is a little bit of spacing between the watch and the pickup, about the same as the spacing between strings and pickups.

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Posted: Wed Aug 13, 2008 9:11 am
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Ceri wrote:
Excellent contributions from everyone on this fascinating thread! It's great when we all put our heads together on something, isn't it?

:D - C

I'll second that! This tread is a good example of how broad the knowledge base is on this forum. It also shows that if all else fails, someone will probably be willing to take their guitar apart in the name of science! :D


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Posted: Wed Aug 13, 2008 9:15 am
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something i find interesting is that if you take a mobile phone wich is playing a song and hold it close to the guitar pickup you can hear the song coming out of your amp!!

how does that happen?

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Posted: Wed Aug 13, 2008 10:00 am
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[quote="Synkronized"][size=14][color=darkred]

Hey....this is one helluva technician; Maybe I can get him to wire up and animate a cadaver I have sitting in a freezer out back in the shed!! :P

Square business!!I am VERY impressed with the body of knowledge being disseminated herein. ('wonder if the censors are gonna bleep that one :? )

Doc :wink:

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Post subject: Re: Strat physics question
Posted: Wed Aug 13, 2008 2:53 pm
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bluesgrass wrote:
We all accept that the wood used to make a solid body electric guitar has a significant impact on the tone of the guitar (otherwise strats might be made out of plywood or at least mahogany vs. alder vs. ash wouldn't matter), but can anyone explain how the vibration of the body is transferred to the pickups? Does it create a more complex string vibration or something like that?

Extra credit if you can explain how the maple / rosewood discussion factors into this.

I'm an engineer, so these are the things I torture myself about all day. :wink:

Thanks!



Take it to the source. Post this to a DiMarzio, EMG, Duncan website and see how they respond. :wink:

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Posted: Thu Aug 14, 2008 9:33 am
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You could experiment and play w/ and w/o a pickguard and try to listen to any difference in tone.
("Compressive tension" makes no sense. Compression is the exact opposite of tension.)
The reflective amplitude of the sound wave will vary depending on what the guitar is made of. I don't know what type of volume each pickup pole covers (how far it reaches, etc.).
Robin Trower says that he can hear a difference in tone when he plays with the tremolo backplate removed. But he plays at massive volume.


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Posted: Thu Aug 14, 2008 4:49 pm
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cool9 wrote:
("Compressive tension" makes no sense. Compression is the exact opposite of tension.)


You're right, it was an ill-chosen phrase. I should have said compressive force. I'll go back and edit it.

These ideas are tricky enough, without speaking clumsily!

Cheers - C


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Posted: Mon Aug 18, 2008 6:09 pm
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zzdoc wrote:
Synkronized wrote:
[size=14][color=darkred]

Hey....this is one helluva technician; Maybe I can get him to wire up and animate a cadaver I have sitting in a freezer out back in the shed!! :P

Square business!!I am VERY impressed with the body of knowledge being disseminated herein. ('wonder if the censors are gonna bleep that one :? )

Doc :wink:


LOL maybe ...send a picture of the cadaver and I'll make you a quote lol


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Posted: Tue Aug 19, 2008 9:18 am
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OK. So if a pickup just picks up the effect of metal strings vibrating across a magnetic field, wouldn't an acoustic with a pickup basically just sound like an electric instead of a loud acoustic? I've used the stick on pickups that you just stick to the body and the kind that fits in the hole just under the strings - both just amplify the acoustic sound. For that matter, how do nylon strings effect the magnetic field at all?


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Posted: Tue Aug 19, 2008 9:27 am
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E-e-e-er...

Just when I thought we'd tied the whole thing up.

You are right. I've seen nice footage of Antonio Forcione playing a Yamaha with a magnetic soundhole pickup, and that reproduces all the wacks and bumps that he inflicts on his soundboard.

Back to the drawing board. How does that work? Is it all transmitted via the strings? It sure doesn't sound like it. It is the technological mechanism that we need explained - any actual scientists round here...?

:? - C


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Posted: Wed Aug 20, 2008 9:41 pm
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I always thought that the warmer, "woodyer" sound of my Stagemaster was due to the different pickups, and maybe the different neck and bridge. After reading this post, I'm starting to think that maybe it is because the Stagemaster doesn't have a pickguard and the pups are screwed right into the body. Having a sheet of plastic separating the pickups from the body is bound to affect the way vibration transfers. Was thinking about tearing the Strat down, screwing the pups down direct and recording a before and after, but know I'm not going to want to put the same old strings back on and new ones would defeat the purpose of the test. Has anyone tried it before?


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Posted: Thu Aug 21, 2008 6:54 am
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stagemasterplayer wrote:
I always thought that the warmer, "woodyer" sound of my Stagemaster was due to the different pickups, and maybe the different neck and bridge. After reading this post, I'm starting to think that maybe it is because the Stagemaster doesn't have a pickguard and the pups are screwed right into the body. Having a sheet of plastic separating the pickups from the body is bound to affect the way vibration transfers. Was thinking about tearing the Strat down, screwing the pups down direct and recording a before and after, but know I'm not going to want to put the same old strings back on and new ones would defeat the purpose of the test. Has anyone tried it before?

There's a good question. It seems like the pickguard wouldn't affect the vibration of the strings, but that having the pickup attached to the body would add another dimension of moving pieces. The same might be true of this strat:
http://www.fender.com/products//search.php?partno=0101570852

bss just got one of these, maybe he will weigh in on whether he notices a difference...

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