The "Coupling Effect"...

Discussion in 'Tone Zone' started by EpiDemic, Oct 27, 2017.

  1. EpiDemic

    EpiDemic Member

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    ''
    Tonewood: To be or not to be, that is the question...

    I believe there is a phenomenon that I (a mere commoner) will perilously refer to as the "coupling effect".

    As it pertains to the Laws of Physics, the ultimate question isn't whether this quirk of nature does or does not exist (I think it most certainly does) but rather: To what degree does it affect anything or everything?

    I happen to believe there is a profound effect, but that's just me...

    Hence:

    The strings are attached to the guitar (obviously); At one end they go over the nut and are anchored to the tuning posts, at the other end they are either attached to the bridge/tailpiece itself or anchored directly to the body.

    Anyway, as the strings vibrate, this vibration resonates through the body. In turn, these resonant frequencies are transferred back to the strings and the resulting fundamental frequencies, along with many complex overtones, are ultimately captured by the pickups.

    So, yes, the pickups are just picking up the string vibrations, but the overtones born from being coupled to the body are all part of what makes a particular guitar sound like it does - and I just so happen to believe that this transfer of energy contributes to what we call the instrument's "timbre".

    Need proof of this transfer? Place your ear against the back of the neck whilst strumming.

    The pickups themselves are also "coupled" to the guitar, since they are attached to it (either directly or indirectly), thus picking up some of these resonant frequencies, although probably to a much smaller degree.

    Some pickups are apt to be more sensitive to this than others. Tapping on them (and the body) with your pick (amp cranked) should provide an idea of how much.

    This effect can also be applied to amplifiers - while sitting on a stage floor for instance - where they can be "coupled" to the stage, in turn affecting their perceived tone (bass amps in particular).

    Of course, the only way to truly demonstrate this phenomenon (or lack there of) is to have the strings and pickups suspended in mid-air with neither of them coupled to anything and see how that sounds going though an amplifier...

    IMG_4100.JPG

    ...then instantaneously transfer everything over to an appropriate guitar assembly - using some sort of Star Trek level of technology of course - so we can compare the two sounds in real time!

    Anyway, should anyone decide to take on this noble challenge, be sure to Youtube it using your smartphone so we can all witness the amazing results...

    ...ok, now all you "nay-sayers" can trash me if you wish...

    '
     
    Last edited: Oct 28, 2017
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  2. IGRocker

    IGRocker Well-Known Member

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    I think I pretty much agree with everything you’ve said, including the bit about pickups. More sensitive pickups tend to be the ones that unfortunately feed back and pick up the “unwanted” frequencies as well. The benefit is the added harmonic range available.

    My Wizz PAF humbuckers are a perfect example of that when compared to a cheap set of stock import pickups. They have the clarity of a bell with great harmonics, but don’t you dare stand at the wrong angle to your amp or let your strap lock squeak!!
     
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  3. EpiDemic

    EpiDemic Member

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    '
    I used to "fine tune" the metal pickup covers on my Les Paul so they were "almost" on the verge of causing microphonic feedback when cranking the gain, which gave me a very lively, harmonically active edge.

    This worked great for a while, but over time the metal covers must have deformed just enough to allow the less desirable, uncontrollably shrill, microphonic squeal to take over. So I eventually had to redo them so they were firmly seated, since I couldn't risk having them shrieking at some in-opportune moment...

    '
     
    Last edited: Nov 2, 2017
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  4. Jeffytune

    Jeffytune Member

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    While you have brought up some good points, I (And I am no expert, but I have worked for some) believe it is more that wood can absorb and cancel some frequency's while resonate with other in a sympathetic manor.
    I know that at the Fender custom shop, they will use tuning forks on the necks and body blanks to match them to the same frequency.
    This is why some guitars play with allot of feel and are alive, while other play dead.

    I would also point out that how much this means as a player to your overall tone depends on the type of music your playing. The quieter the more it comes into play.
    Country, classic rock and blues players need it more then a death metal player with EMG's.

    Lastly, you can use a turning fork to find the the resonance point of your guitar. You hit the fork and place it first on the nut, then the bridge and the strap button.
    Why on these spots? Well a vibrating tuning fork with dig into and mar your painted finish....I don't think you would like that. That an checking the points that the string connect to the guitar will show how the strings will influence the wood if at all.
     
  5. Biddlin

    Biddlin Active Member

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    Belief is always the foundation of error.
     
  6. Biddlin

    Biddlin Active Member

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    I do not mean to imply that I am settled on a conclusive view of the effects of wood on a solid body electric guitar or that I would not enjoy a well done experiment. I stand ready to be convinced.
     
  7. duceditor

    duceditor Active Member

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    This question of the importance of "tone wood" is right on up there with "why does evil exist" and maybe even, for a few, "what's for dinner." As an intellectual exercise it has stood the test of time. And like the best such questions (apart from the one above about dinner) it will likely never see a widely accepted "right" answer.

    To me the reason for that has nothing to do with the "truth" of the argument, but on the answer's overall and practical lack of importance.

    Does the construction and materials of an instrument create, modify, augment and decrease overtones initially created by the strings? Yes, it seems --measurably.

    But does the degree that it does so make a practical difference -- one actually heard at the end of the long chain of variables with far greater affect of the overall timbre of guitar's sound. Distortions. compressions, additions and subtractions to the original tone created by the vibrating string.

    I.e., what matters is not what can be measured, but what can be heard and felt. Repeatedly and consistently.

    That said I like maple above the mahogany.

    You got a problem with that? ;)

    -don
     
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