MIMF

Hi all,

I'm building a Ramirez style classical guitar using plans from Scott Antes. On the plans it says "26.125 string length" but the nut-to-12th fret distance is given as 13.0625, exactly half of the string length. Some time ago I build a classical ala Cumpiano & Natelson; on that one the nut-to-saddle distance is a little more than twice the nut-to-12th. Not as much compensation as a steel-string, but some.

I could use some guidance. Is there a way to calculate compensation for a classical, or should I just place the saddle back a little? Or place it dead-on according to the plans?

Thanks,
Phil

Here's a quote from French's book, Engineering the Guitar:

"Note that classical guitars typically have very little compensation in the saddle. A typical instrument may have the saddle set perpendicular to the strings and set 0.090 in (2.29mm) back from its nominal position. This is possible because the elastic modulus of nylon is about 1/30 that of steel. The pitch error due to stretching the strings is very small. Even though the unwound strings have larger diameters than comparable steel strings, the large difference in elastic modulus makes the pitch increase due to bending small."

In your case, I don't know if the actual string length is meant to be 26.125", or whether this is meant to be the scale length, in which case the nut to 12th fret distance is correct, and some added compensation (as above) would be needed at the bridge.

Don't build it without an allowance for saddle compensation (if you're not doing nut compensation). I've just fixed a guitar that had the front of the saddle at nominal scale length and not enough room on the saddle to do decent saddle-only compensation.

For a standard 650mm scale length you should allow at least 1.5mm for compensation and at least 0.5mm for "roll-forward" of the bridge/saddle. Some string sets/set-ups need more than that.

Phil Walsh wrote:Is there a way to calculate compensation for a classical

Yes, but I suspect you won't like it. It starts with measuring the longitudinal stiffness of the string after it has stabilised under tension at pitch...(yes, it's different for each of the six strings and different again if you change brand/gauge).

Thanks, guys. This is pretty much I what I was thinking.

That is a pretty long scale for a classical built today - just converting the numbers give 664 rounded up to the nearest mm and 665-666 with compensation. While longer scales were popular in the 60's-70's they have gone out of favor and 650 (plus compensation) is pretty much the standard. Personally I would shorten the scale unless you really want the longer one.

Phil, for classical building get in the habit of using metric as the world of classical guitar making uses it universally. There is a strong argument that back in the 19th c. an inch based system was used, but that won't help you now.

That Ramirez guitar isn't so popular these days. the scale is long and the body is large. If you look at contemporary builders you will be very hard pressed to find anyone building like that now. Aside from having the plans, is there a particular reason why you are building that one?