Optimal tuning of classical guitar
by Dr Tom Chalko

Have you ever noticed that your guitar is "out of tune" at higher fingerboard positions, even if all strings seem in tune in lower positions?

My approach to this problem in the past was to aim for a "tuning compromise" so that all notes on the fingerboard were "equally badly off".

This "long tuning" procedure was very frustrating, because it caused nearly all notes to be compromised with only a few of them good.

Playing on ever-so-slightly out of tune guitar is annoying, but when such a music is recorded it becomes "permanently annoying" to anyone with a reasonable music sensitivity...

Hence, I decided to modify my guitar to achieve perfectly tempered tuning by means of optimizing the bridge support point for each string individually.

In theory, the XII fret should be exactly in the middle of the string. However, when the string is pushed toward the fingerboard, the tension in the string increases and this (of course) changes the pitch.

My method of finding the optimal string support point on the guitar bridge relies on matching the pitch of the 1-st octave (half-string) harmonic with the pitch of the string when pressed down in XII position.

If they are matched, and fingerboard is of a reasonable quality, all notes played on this string anywhere on the fingerboard are tuned in the best way possible along the tempered scale.

Optimal bridge support point can be different not only for each string in a set, but also can depend on the choice of strings and their tension ratings.

Simultaneous holograms of the vibration modes of front an back of the violin.

Fig.1 Individual bridge supports for each string enable perfect tuning of a classical guitar in a tempered scale

In addition, the position can change in time due to wear of the string and/or the fingerboard.

For this reason I made my system fully adjustable for each string individually.

Fig. 1 depicts my solution. I made 6 tiny blocks from ebony timber, each with a slot for a string.

To prevent these tiny blocks from moving around on a slipery surface of the bridge I equipped the bottom of each block with a layer of 1200 grit sandpaper, by glueing the sandpaper with an epoxy resin.

As you can see in the Fig 1. every string is supported at a different length and none of the supports are where the instrument maker (Rudolf Klier, Germany) designed them ~34 years ago...

For the first time in my life I was able to tune my guitar perfectly and confirm the tuning with spectrum analyzer.

I was greatly surprised how much this perfect tuning increased my joy of playing. All octaves and cords are in perfect tune up to XIX position...

Hologram of the 1-st vibration mode of classical guitar.