Mechanics of split tuning ??

Michael Dene · From: Gippsland,Victoria, Australia

In Winnie Winston's book there were a couple of very educational, simplified drawings of an all pull mechanism and a push/pull mechanism.

I'm playin a LeGrande II with the little Hex screws at the end and am very appreciative of being able to split tune several notes on both necks.

However I am finding it impossible to visualise what is actually happening ... ie:
the physical action of each component of the split tuning arrangement. Has anyone got, or can draw, a diagram that might explain it?

Thanks Michael

LeGrande II D10
Fender Artiste S10
Peavey Session 500

Ricky Davis · From: Bertram, Texas USA

Basically here's what happens.
Take the 6th string lower a whole tone. Ok you have a single finger with pivot points on it...>a Raise section when pulled and a lower section when pulled> so they go opposite directions. When you raise that string; the raise section is pulled....and with it raised, now you are going to lower it a whole tone....>so you need a certain distance to lower it a whole tone from the raised finger pivot. So now that you have that in tune from the right distance and leverage of the lower activation of the knee lever.....>When you lower it by itself without the raise section be activated....; because of the new pivot position;....It will now lower too far with the same distance and leverage of that lower activation of the knee lever.....So you need to stop that distance with either a screw behind the lower section or a extra rod on the raise section on that knee lever pulling point to raise it back up in time.
Ok how's that for an explaination??ha....totally confused?? Well I am

Ricky

Michael Dene · From: Gippsland,Victoria, Australia

Wow !!! Thanks Ricky, and while I'm trying to absorb that without hurting my brain too much, I'll still accept a drawing!!

Thanks, Michael

Richard Sinkler · From: aka: Rusty Strings -- Missoula, Montana

Oh Ricky. My brains are oozing out my ears and on to the floor.

C Dixon · From: Duluth, GA USA

As usual Ricky is correct.

Here is another way of looking at why a split usually comes out sharp, before you tune it. Follow along:

1. look at the travel on the 3rd sring pull rod when you engage the B pedal.

2. Look at the traved on the 6th string pull rod when you engage the B pedal.

Why is the travel sooooooo much different, yet both strings are only being raised a half tone? Ok, the answer is, the higher the pitch the more travel required to get the same amount of change in pitch.

Now carrying this a step further. When you raised the G# to A you have "X" amount of travel. When you lower the A to G with the knee lever, you have "Y" amount of travel.

Because of the above physics the amount of Y travel is less than twice X travel. So it is not enough to lower the A fully to G. So you have to flatten it with the "lower" nylon tuner at the end plate.

This then makes the G# to F# too flat. Thus the reason you have to pull it back up with the allen screw; or extra raise rod on some guitars.

Further physical evidence of the phenomena is to look at the fret separation between ANY three contiguous frets. The middle fret is never exactly half way between the outer two frets.

carl

[This message was edited by C Dixon on 31 March 2004 at 10:07 AM.]

Michael Dene · From: Gippsland,Victoria, Australia

Thanks Carl for your reply. I'm still getting my head around some of the physics associated with the PSG. I've been involved with stringed instruments for over 50 years but only after taking up Pedal Steel have I had to explore string guages,tensions compounds etc and all that goes with it!!

------------------
Michael
Emmons LeGrande II D10 8&5
'75 Fender Sho-Bud S10
3&4
Session 500

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