So, does the Feiten system work?
Imagine being a citizen of the US and having someone turn up at immigration with no knowledge of the explorations of John Cabot, Christopher Columbus or Ponce de Léon.
"Crumbs" cries the visitor "there's a whole country here! How come no-one's ever heard of this? I must be the first one here..."
That's a little bit how I feel about the Feiten System; not so much that it "doesn't work" but that it works because it is basically equal temperament with some window dressing thrown in to distract people from getting hung up on the harmonic intervals. Nut compensation, as employed by the Feiten system achieves little and the rationale for it is absurd. However for a guitar with an incorrectly cut and dressed nut it may well provide an element of intonation relief. To me, cutting the nut correctly is a better solution...
The intonation offsets, on the other hand, may have some merit in countering the effects of inharmonicity and the effect of arc relief which probably has a far more significant effect on our perception of intonation accuracy than the compromise necessary to accommodate equal temperament tuning, particularly in the higher reaches of the fingerboard.
However any person who is not clinically tone deaf can learn to intonate a conventionally built guitar in such a way as to average out the error between the 12th fret and the 19th caused by arc relief without the need for any expensive modifications.
Perhaps we should be asking "is the Feiten system necessary?" to which my answer would be a resounding "no". Far better, and cheaper, to learn how to tune your guitar to equal temperament which for centuries has been the successful working solution to resolving the insistent push towards natural harmonic intervals with the need for fixed pitch values.
The guitarist really needs to take a leaf out of the keyboard player's book. Because the keyboardist, whether they play synthesiser or grand piano simply accepts with Zen like rationality the equal temperament intonation that they are handed. There is really no need for guitarists to feel they need their instruments to play any more "in tune" than any of the other equal temperament instruments and there is certainly no need for them to feel the need for instruments that exactly reproduce the natural harmonic intervals since these have little place outside of the rarified atmosphere of the Early Music special interest groups.
What many guitarists have, sadly, is the overwhelming urge to buy the latest gimmick that promises to make them sound better without them having to put in any actual work, so devices which offer seemingly magical solutions are sought where they should be developing skills. I've often commented that the person who invents the guitar that not only tunes itself but strings and plays itself as well will be laughing all the way to the bank...
