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Saddle setback for a 640mm scale classica
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Author:  Michael McBroom [ Fri Apr 21, 2006 3:56 pm ]
Post subject: 
I'm working on a classical with a 640mm scale for a client and it's about time to glue down the bridge.

I have had good luck with the "modified" Gilbert method of compensation for 650mm scale classicals, which is where 1/32" is cut from the nut end of the fingerboard and the saddle is set back 0.060". I'm thinking, though, that with a 640mm scale instrument, the setback should be less because the sharping of the string will be less, not only because of the shorter scale, but because any given set of strings will be at a lower tension than a longer scale when tuned up to pitch.

I'm thinking that a setback of 0.40" would probably work fine. But I'd be interested in reading your thoughts on the matter.

Best,

Michael
Michael McBroom38829.0473263889
Author:  Martin Turner [ Fri Apr 21, 2006 4:34 pm ]
Post subject: 
Michael,

Im no expert on this matter since Ive never deviated from a 650mm scale length with my classicals.

My understanding of compensation is you're primarily compensating for the physical change in string length as the string is pushed onto the fret. I would think that if finger pressure is the same then the extra string tension that comes with a 10mm shorter scale length wouldnt really have much of an effect on the change in string length caused by fretting the string.

Others in here with more experience in such matters will no doubt respond to your query.

[QUOTE=Michael McBroom] I'm working on a classical with a 640mm scale for a client and it's about time to glue down the bridge.

I have had good luck with the "modified" Gilbert method of compensation for 650mm scale classicals, which is where 1/32" is cut from the nut end of the fingerboard and the saddle is set back 0.060". I'm thinking, though, that with a 640mm scale instrument, the setback should be less because the sharping of the string will be less, not only because of the shorter scale, but because any given set of strings will be at a lower tension than a longer scale when tuned up to pitch.

I'm thinking that a setback of 0.40" would probably work fine. But I'd be interested in reading your thoughts on the matter.

Best,

Michael
[/QUOTE]
Author:  Joe Beaver [ Sun Apr 23, 2006 4:13 am ]
Post subject: 
Let me tell you first I'm no authority on the suject but, I use a 660 scale on my classical guitars. I don't compensate at the nut end but do compensate the saddle .10" Since the difference between 660 & 640 is about 3% I'm wondering is .04 is enough?
Author:  Michael McBroom [ Sun Apr 23, 2006 6:55 am ]
Post subject: 
Joe,

I also posted a request for info over at the (mumble-mumble) forum, and got a couple of responses that claimed that a short scale needs more compensation than a longer one.    Now I'm really confused.

Okay, if you just look at the geometry of the string as it's being depressed, I can see how a shorter string length will increase the depression angle, which might mean that the string get's stretched more. But looking at the triangles that are formed when a string is fretted, the hypotenuse, which runs from from saddle height to fret height, while maybe disproportionately longer because of the greater angle, is still shorter because the scale is shorter. I'm gonna have to crunch some numbers, but even after I do, I bet I'm still not gonna understand why a shorter scale needs more compensation.

Best,

MichaelMichael McBroom38830.6674305556
Author:  RCoates [ Sun Apr 23, 2006 7:09 am ]
Post subject: 
[QUOTE=Michael McBroom] Joe,

I also posted a request for info over at the (mumble-mumble) forum, and got a couple of responses that claimed that a short scale needs more compensation than a longer one.    Now I'm really confused.

Best,

Michael[/QUOTE]

If you consider that the movement caused by fingering is the same, then the distance moved as a percentage of scale lenth is greater on a short scale.

Consider a scale of 10mm and a fingering movement of 3mm. that equals a huge change in string length. Instead consider a scale of 1 million mm and a fingering movement of 3 mm. There you would have an insignificant change in scale length.

What that buys you? I don't know, but kind of give you an idea of what's happening.
Author:  Joe Beaver [ Sun Apr 23, 2006 7:12 am ]
Post subject: 
Micheal,

I know what you mean. There is a lot of info out there, some good and some, well... not so good. It just seems to me that the differences between say a 650 & 640 scale are pretty darn small. I'm thinking that if you have used 650, compenstated it by whatever, and you like the way it came out then I would only make small, small, small changes with a similar scale instrument.
Author:  CarltonM [ Mon Apr 24, 2006 5:26 am ]
Post subject: 
[QUOTE=RCoates] If you consider that the movement caused by fingering is the same, then the distance moved as a percentage of scale lenth is greater on a short scale.[/QUOTE]
Ronn, that just makes too much sense. It's too intuitively correct. That means it can't be right, can it?
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