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Topic: Mechanics of Split tuning |
John Hyland
From:
South Australia
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Posted 28 Oct 2022 10:54 pm |
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I’m trying understand the mechanics of split tuning.
For instance, without rod or screw adjusters;
I can set the B string raise to C# ( A pedal) and a B to Bb lever to arrive at C yet if I use pedal C it is a long way off. I would have thought they are the same relative movements so I would end up with the same note. I should note using the lever only ends up somewhere near A.
Is this the same for others. In other words you can only split tune one set of pedals/levers?
And
Why are some strings better at being balanced?
And
Is it do do with the finger proportions?
Btw I understand how rod or the set screws adjustment works. |
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richard burton
From:
Britain
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Posted 30 Oct 2022 1:04 pm
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| If the C pedal cross-shaft has more flex than the A pedal cross-shaft, then there may be a different resultant note when the split is activated. |
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John Hyland
From:
South Australia
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Posted 31 Oct 2022 12:22 am
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| richard burton wrote: |
| If the C pedal cross-shaft has more flex than the A pedal cross-shaft, then there may be a different resultant note when the split is activated. |
That’s a good thought as pedal c has all its load in the centre of the cross rod. The b note lower goes further on the pedal C than the pedal A so that is counter intuitive. So maybe that’s not the reason.
So as.
A general rules the movement should be the same? |
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Tony Glassman
From:
The Great Northwest
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Posted 31 Oct 2022 4:59 am
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Since you have no split changer devices (changer split screws) , you’re relying on opposing leverages to balance a split “C” note in either pedal lever combo.
It seems to me that you must use different leverage points at the bell crank and/or the changer for both 5th string raises on the A & C pedals to yield that same B—>C# change. That means, the B—> C#. change occurs at different rates for each pedal which in turn produces different travel lengths on each pedal.
So, the finely tuned “C-note split that you’ve dialed in to split the A pedal and Bb lever under one set of circumstances , may not hold true with the different rate & travel length conditions of the C-pedal when adding in that same Bb lever. |
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Ian Worley
From:
Sacramento, CA
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Posted 31 Oct 2022 1:03 pm
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You haven't said what brand/model/year guitar you're discussing here. Changer geometry varies quite a bit over time and from builder to builder. Assuming all else being equal and properly adjusted, the position of the raise scissor to achieve the C# raise alone in a typical all-pull changer should be identical for either the A or C pedal when fully engaged regardless of which changer hole they're using respectively, therefore the effect of the lower should be the same too in the resulting split. I would suspect there is something else going on. An under-tightened lower return spring is always a possible culprit for imbalance issues. This wouldn't likely affect the split note, but it could affect the tuning of one or both of the C# raises by themselves, which could skew the tuning of the split the way you're describing. Possibly some flexing somewhere as Richard suggested. Most guitars have some cabinet drop too, if your pedals are Emmons the C pedal being closer to the middle of the guitar will likely produce more drop, if the B>A# is on a vertical lever this could counter that effect a little. Could also be just some good old fashioned binding somewhere in the works.
_________________
All lies and jest, still a man hears what he wants to hear and disregards the rest - Paul Simon |
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John Hyland
From:
South Australia
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Posted 31 Oct 2022 1:16 pm
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| Tony Glassman wrote: |
So, the finely tuned “C-note split that you’ve dialed in to split the A pedal and Bb lever under one set of circumstances , may not hold true with the different rate & travel length conditions of the C-pedal when adding in that same Bb lever. |
That makes some sense. My pedal A and C travel is very similar but not set up to be identical. Maybe I will play with that. The 5 string B is a little unique as few setups move the same string the same note. |
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John Hyland
From:
South Australia
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Posted 31 Oct 2022 1:39 pm
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| Ian Worley wrote: |
| You haven't said what brand/model/year guitar you're discussing here. Changer geometry varies quite a bit over time and from builder to builder. Assuming all else being equal and properly adjusted, the position of the raise scissor to achieve the C# raise alone in a typical all-pull changer should be identical for either the A or C pedal when fully engaged regardless of which changer hole they're using respectively, therefore the effect of the lower should be the same too in the resulting split. I would suspect there is something else going on. An under-tightened lower return spring is always a possible culprit for imbalance issues. This wouldn't likely affect the split note, but it could affect the tuning of one or both of the C# raises by themselves, which could skew the tuning of the split the way you're describing. Possibly some flexing somewhere as Richard suggested. Most guitars have some cabinet drop too, if your pedals are Emmons the C pedal being closer to the middle of the guitar will likely produce more drop, if the B>A# is on a vertical lever this could counter that effect a little. Could also be just some good old fashioned binding somewhere in the works. |
Hi Ian. This is getting to the crux of my query as to whether the finger design can affect the amount the natural balance of the split.
I am making this guitar so most options are still possible. It is all pull and designed for split tuning but I haven’t gotten around to drilling the holes.
I don’t believe binding, tight springs nor over tuning are the issue but cabinet drop is a good thought. But I think the difference in two “C” tunings is more than cabinet drop values. But I will look more closely.
My copendent of RKL B<<Bb is not very common but I love the combination with A+B PEDALS for the minor and pedal A+RKL+LKR (E<<Eb)
My next iteration of fingers will reduce the required travel of the lowers and this may or may not have a positive effect on the split lower. I just don’t know.
My 1975 sho bud (without split tuners) does this split pull reasonably well.
Thanks John |
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Ian Worley
From:
Sacramento, CA
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Posted 31 Oct 2022 2:13 pm
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Are you copying a certain changer design for your build? On the later '70s Sho-Bud changers with the two piece scissor (2/2, 3/2) the position of the raise scissor does actually change slightly when a lower is added because the upper pivot is actually offset from the axle. The movement of the finger itself alters the angle of the raise scissor slightly. It would be minimal, but the pull rod closer to the axle would produce a slightly sharper note when split because of this extra pivot point. That would be an exception to what I said above. The earlier '70s Bud three-piece scissor design, similar to '60s ZBs and some others, wouldn't do this, nor would most modern all pull changer designs where the upper pivot of the scissor is on the axle so the C# produced by the rod and the relative position of the raise scissor is consistent regardless. Maybe you can post some pics of your finger/scissor design to see their geometry?
_________________
All lies and jest, still a man hears what he wants to hear and disregards the rest - Paul Simon |
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John Hyland
From:
South Australia
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Posted 1 Nov 2022 12:09 am
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| Ian Worley wrote: |
| . Maybe you can post some pics of your finger/scissor design to see their geometry? |
As you can see the design means no matter which hole is used the movement is the same. This is why I’m struggling to understand why the lowers end up different between the two pedals.
I did think the pedal travel might have something to do with it but regardless of the travel the finger movement is identical.
Last edited by John Hyland on 1 Nov 2022 12:56 pm; edited 3 times in total |
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Shorty Rogers
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Posted 1 Nov 2022 6:23 am
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Unless I missed it, no one has mentioned the fact that the amount of travel an octave pair needs to make depends in part on the diameter of the core wire of any wound string. For example, if your 10th string B is a 36 wound and your fifth string is an 18 plain, they will pull evenly if the core wire of the 10th string is also an 18 gauge. You can check with a micrometer on both the plain and a bit of exposed core wire on the wound string. If they are not the same gauge, you can change the guage up or down slightly with either string and perhaps get closer to an even pull.
Please be aware this technique only helps to time the octave pair. You can also do this with the G# pair if you use a wound third. You still may have difficulty timing the results of pulling both octave pairs together. Likewise, the splits can be adjusted slightly by adjusting core wire sizes, but it’s all trial and error. Different manufacturers will use different core wire/wrap wire pairings. When you find a pairing that works better for your ears, stick with that brand for that pair. You are still likely to want to add the ability of tuning the splits with an adjustable stop to the middle position of one or both of the octave pair. Also note that on the 6th string pull, the core wire may be too thin to allow the changer to achieve a full 1.5 step pull between the lower and the raise. For my string setup, using a wound 24 for my 6th string requires a 12 for my 3rd string. Not all 24 wound strings have a 12 for a core wire. D’Adarrios seem to consistently use that combination in my experience. |
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John Hyland
From:
South Australia
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Posted 1 Nov 2022 12:06 pm
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| Shorty Rogers wrote: |
Unless I missed it, no one has mentioned the fact that the amount of travel an octave pair needs to make depends in part on the diameter of the core wire of any wound string. For example, if your 10th string B is a 36 wound and your fifth string is an 18 plain, they will pull evenly if the core wire of the 10th string is also an 18 gauge. You can check with a micrometer on both the plain and a bit of exposed core wire on the wound string. If they are not the same gauge, you can change the guage up or down slightly with either string and perhaps get closer to an even pull.
Please be aware this technique only helps to time the octave pair. You can also do this with the G# pair if you use a wound third. You still may have difficulty timing the results of pulling both octave pairs together. Likewise, the splits can be adjusted slightly by adjusting core wire sizes, but it’s all trial and error. Different manufacturers will use different core wire/wrap wire pairings. When you find a pairing that works better for your ears, stick with that brand for that pair. You are still likely to want to add the ability of tuning the splits with an adjustable stop to the middle position of one or both of the octave pair. Also note that on the 6th string pull, the core wire may be too thin to allow the changer to achieve a full 1.5 step pull between the lower and the raise. For my string setup, using a wound 24 for my 6th string requires a 12 for my 3rd string. Not all 24 wound strings have a 12 for a core wire. D’Adarrios seem to consistently use that combination in my experience. |
That’s good information shorty and thanks.
My query relates to the action on the same string. Ie 5th in this instance. A and C pedal raises to C# |
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J D Sauser
From:
Wellington, Florida
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Posted 2 Nov 2022 2:47 pm Re: Mechanics of Split tuning
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| John Hyland wrote: |
I’m trying understand the mechanics of split tuning.
For instance, without rod or screw adjusters;
I can set the B string raise to C# ( A pedal) and a B to Bb lever to arrive at C yet if I use pedal C it is a long way off. I would have thought they are the same relative movements so I would end up with the same note. I should note using the lever only ends up somewhere near A.
Is this the same for others. In other words you can only split tune one set of pedals/levers?
And
Why are some strings better at being balanced?
And
Is it do do with the finger proportions?
Btw I understand how rod or the set screws adjustment works. |
BASICS:
The more a string is being pulled (raised) the slower it changes pitch... until it becomes near breaking point, or past it..
So, when you raise a string a 2 half tones, the travel to go from the first to the second half tone, will be longer than going from unaltered to the first half tone raise.
Counter-Likewise, or in an inverted way, when you lower a string half tone from it's unaltered pitch, the string slacks and it becomes more sensitive to tension change (decrease in this case). So it takes LESS travel to lower the same string a half tone than it took it to raise it only even from unaltered to the first half tone and much less than raising it to the second half tone.
This is why, when you raise a string two half tones and then lower against that with only the mechanical travel it took to lower it from unaltered down a half tone, that travel will fall short of the top half tone raise, and thus "out of tune".... UNLESS you tune Just Intonation, and the desired pitch would happen have to be "somewhat" sharp... like minor thirds are tuned in JI. But we're unlikely to be THAT lucky
There are 3 ways of applying "Split Tuning" on ALL-Pull guitars:
1-The "old" way as still found typically on a Carter PSG would be with an additional pull rod added to the the lower lever but slightly raising the same string. One would tune the full tone raise with the normal raise hex nylon nut, then tune the lever's SPLIT half tone lower against that raise with the basic lowering hex nylon nut and finally the the simple half tone lower by tuning the additional "correction" RAISE hex nylon nut on the lower lever. The thinking is, that they lower is tuned with enough excess mechanical travel so to overcome the excess tension from the full tone raised string. Evidently, then the lower is excessive when used alone off the more relaxed unaltered string (lower only) and requires some counter-raising with the helper pull.
This system can be applied to most ANY all-pull PSG which does not otherwise have split tuning ability, as long as you have on more raise available at the changer end and have the needed hardware.
2- Split tuning at the changer finger (most All Pull PSG today)"
The lower only (off the unaltered pitch) is tuned as a bottom out screw against the changer finger stops. Then the pull is tuned at the hex nylon tuner against the full tone raise. When the lower is actuated as lower only, the lower scissor is over-pulled but the changer finger cannot lower further than hitting the split screw.
3- The Anapeg way:
Anapeg PSG had a changer design which could be considered and evolution from the Harlin Bros. changer, then re-interpreted on the Fender PS210 by Gene Fields (founder of GFI) and now also seen in some further variations by Excel and the new Sierra Co. These guitars' changer are basically free of the traditional actuator scissors (even though, one could argue that the Excel interpretation has scissors, it doesn't really). The system consists of two fingers sitting behind each other... the raise and visible pitch changing finger riding on the lower finger. On some of those guitars, The lower finger has a slacked micro-pull rod to the raise finger. Similar to the first example, the lower can be tuned to drag-along a little the raise finger. When a superior raise is engaged, that micro raise is over-ridden by the superior raise and the full mechanical travel of the lower brings the pitch down from a full tone raise a half tone.
Interestingly, the Excel Superb PSG which uses in ESSENCE an Harlin-PS210-Anapeg Evolution changer, where the lowering rather occurs by horizontal motion (vs. radial), they have a max-bottom-out split screw similar to the typical design described in pos. 2, but in front of the fingers (as they instead of tilting, move horizontally towards the pickup.
... J-D.
_________________
__________________________________________________________
Was it JFK who said: Ask Not What TAB Can Do For You - Rather Ask Yourself "What Would B.B. King Do?"
A Little Mental Health Warning:
Tablature KILLS SKILLS.
The uses of Tablature is addictive and has been linked to reduced musical fertility.
Those who produce Tablature did never use it.
I say it humorously, but I mean it. |
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John Hyland
From:
South Australia
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Posted 3 Nov 2022 12:52 pm Re: Mechanics of Split tuning
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| J D Sauser wrote: |
So, when you raise a string a 2 half tones, the travel to go from the first to the second half tone, will be longer than going from unaltered to the first half tone raise.
Counter-Likewise, or in an inverted way, when you lower a string half tone from it's unaltered pitch, the string slacks and it becomes more sensitive to tension change (decrease in this case). So it takes LESS travel to lower the same string a half tone than it took it to raise it only even from unaltered to the first half tone and much less than raising it to the second half tone.
... J-D. |
I wonder if anyone designs a finger set which accommodates this. |
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J D Sauser
From:
Wellington, Florida
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Posted 3 Nov 2022 11:58 pm
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A cam-shaped “vari-radius” or excentric hung finger, would seem a possible line of thought but in THEORY only, as in reality mechanical movement is too short and each string gauge (and even moreso wound vs. plain) react differently in pitch to tension change.
PLUS each of us has different tuning preferences.
So, we have to adjust for what phisics puts onto our laps to play with mechanically.
Afterall, the problem can solved and has been solved in various ways.
I remeber that about 25 years ago Mike Cass (if I remember right) even came up with a split tining solution on Push-Pull guitars.
I would like to think, that the problem ought to resolvable even on a Pull-Release, even though I never wrapped my head around that for the lack of nececity.
… JD.
_________________
__________________________________________________________
Was it JFK who said: Ask Not What TAB Can Do For You - Rather Ask Yourself "What Would B.B. King Do?"
A Little Mental Health Warning:
Tablature KILLS SKILLS.
The uses of Tablature is addictive and has been linked to reduced musical fertility.
Those who produce Tablature did never use it.
I say it humorously, but I mean it. |
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