This question was originally geared toward the guitar, but considering it's one of many stringed instruments, I decided to enlarge the scope of my question to include stringed instruments in general. Here is my slightly reworded question:

I want to compensate for the seemingly usually uneven magnitude of force exerted between any two fingers on any string(s) or in any concentration of strings and frets by devising a mathematical, formulaic method that will yield the exact placement (x, y) of the thumb behind the neck of a stringed instrument in relation to any finger currently in use that would act as a perfect 'center of force' for all fingers to draw on while forming chords or moving from one note to the next, and would enable a perfect and equal magnitude of force to be exerted between each finger on any string(s) held at any point in time.

(I'm not quite sure how to go about explaining just what concept it is that I'm trying to develop, but hopefully this will be adequate.)

Has anyone else pursued/is pursuing this technical concept?

I let my thumb sit on the low E usually. If not, I rest it in the center on the stripe. I also play with my thumb, rather than a pick. I just feel it helps me control the depth of the sound better and it's more comfortable.

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1984 Squier Contemporary Stratocaster
1986 Peavey Envoy 110
1967 Kingston Acoustic

I'm sorry, I don't work for NASA, I just play guitar a little bit.

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Good Vibes To Y'all!



Screamin' Armadillos
Texas Roadhouse Music
Guitar/Slide Guitar/Harp/Vocals

i play with my thumb is strange locations sometimes so depending on the player you are going to have allot of variables you have hand rotation and hand angle that affects thumb location not to mention placement changes for every chord. also neck contours and type of guitar. hell i even change my thumb location based on the chord i anticipate moving to sometimes. if i am going from c to d or c to f I use a different thumb placement on the c chord depending on what my next chord will be. this will be a challenge, your are going to need help from rain man lol

ADD{ also string gauge different tensions and turnings fret height and radius. the angle change in bends hammer on's and Pull offs. this is a really long list of varibles you would have to add into the equation l

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maybe if you had a way to install pressure sensors on a guitar neck to monitor the force applied in each location. you could simply adjusted your thumb until you had an equal amount of pressure per finger. then you could map out the placement. but even that data will be different between individuals. each finger having different levels of strength per person will be another variable. or you could have allot of people play each chord and use an average for a good starting point. could even sell an adhesive backed grid to attach to the neck with the book

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Ha. Well that's different than the average Forum fare.

Hi Chrono_G_Xay: for starters you are going to need a mathematician such as Forum user OrvilleOwner to help with that. Dunno about anyone else but the three dimensional geometry of the thing is way beyond my pay grade, for sure.

However:

Well in a purely empirical way we all have. What I'm getting at is that I think you have left out some of the factors at work here; things we all do whether consciously or not.

Thumb and fingers are not merely balancing one another in isolation from anything else. For example, it is possible to hold a note, perhaps while performing strong vibrato, without the thumb or palm of the left hand touching the back of the neck at all. In that instance the pressure of fretting finger is balanced across the fulcrum of the player's body by pressure from the right forearm somewhere around the lower bout of the guitar.

Forum user ZZDoc once gave a very excellent description of Eric Clapton's finger vibrato technique, pointing out how he does that very thing; and so do many of the rest of us. I seem to recall that Archimdedes had something to say about the geometry for that part of the issue, which will obviously be in constant flux only partly due to where on the neck one is fretting.

So in addition to the mathematics of the placement of fingers and thumb you need to build in the forward force of the torso on the back of the instrument and the pressure of the right arm on the front. Fingers, thumb and palm of the left hand are working with those forces too, in addition to themselves. And all of these forces change from instant to instant as the flow of notes requires.

I can't begin to think how you'd create a formula to describe all of that - but that only indicates my own low limitations. I'm sure it can be done: go to!

And when you're there kindly publish it here first. Your Nobel Prize will follow.

Cheers - C

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I personally don't adhere to the theory that the thumb should be the center of force or the fulcrum point to generate the pressure needed to fret a chord. So I don't really think there would be a point (x,y) worked out mathematically that would be ideal. Rather, I try to think of how my left hand acts when I'm playing violin. In violin, the thumb rests almost parallel next to the fingerboard, and when playing the force exerted on the strings is generated by the fingers and the forearm down to the elbow. It's not a force generated by grip, it's more or less gravity, if you try and put too much muscle into it you'll just cause tension. My violin teacher explains it as if you fret a note, you should be able to wiggle your thumb freely without cutting out.

Now with guitar, you could play single notes this way, but bar chords would be a bear. You can still apply the same theory though, just now you factor in the thumb. I like to put my thumb usually right under the middle finger or between middle and ring, I got that from Pumping Nylon by Scott Tenant (Good book if one wants to learn some classical). That is also the same type of thumb placement one does when gripping a violin bow. When barring a chord, try to only put pressure on the strings that need barred rather than all of them. Basically, I always try to limit the amount of force that it generated from my thumb, all that economy of motion stuff. I wish I had a picture of what I'm trying to say, but I don't >_>

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I traded my car in for a microphone.

Dude! Thats some heavy stuff.

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OK, I'll hum a little bit, got it now?

I agree. the little time I have been thinking about it, I have realized this is something way beyond what am capable of doing

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