Intonation training on a fretless?

[RJVB]

As a former violinist I still have a kind of prejudice against looking at my fretting hand, and that's not helped by the fact that I seem to be aiming for the centre point between 2 frets when I play under visual control. I guess that's kind of intuitive - and indeed in French we talk about cases ("boxes") rather than what *fret* to play.

I have been playing with the idea of getting a wider fretboard on my nylon-strung resonator, and leaving it fretless for starters just to see if that helps me in mapping tone heights to finger positions on the fretboard. That mapping, and maintaining it, is an important part of the regular practice on violin and family.

But there's a difference - I think. On a fretless instrument your fingertip has to stop the string instead of a fret, but on fretted instrument it (probably) shouldn't stop the string at that exact location in order to get a clear sound. That would imply you need to add a fixed (but poorly defined) offset to location, and that can't make learning that mapping any easier.

Anyone here who has significant experience with fretless guitars who can comment on this?

[Bob_Ross]

I'm not sure I understand the question.

I have a lot of experience playing fretless bass, and a tiny bit of experience playing fretless guitar, and I can authoritatively say that where you stop the string on the fingerboard in order to play a note in tune depends on how your instrument is set up.

Some instruments intonate properly when your finger presses the string down just a hair behind where a fret would be; other instruments intonate properly when your finger presses the string down precisely where a fret would be. And usually -- but not always -- you can make an instrument behave either way just by adjusting the bridge saddles.

The important thing is to recognize which way the instrument is setup, and then calibrate your muscle memory to that paradigm so that you're not relying on visual cues, before you get on the bandstand!

[RJVB]

Well, of course I'm talking about properly set up instruments, and even about identical instruments that differ only in whether or not they have frets.

If you're implying that a fretted instrument can only be perfectly intonated at the octaves on a single string then yeah, that doesn't help either unless your brain is already calibrated to equal temperament

[RJVB]

But it's interesting to know that fretless guitars are also compensated at the bridge. I'm not certain if I've ever seen "misaligned" bridges on viols (i.e. bowed instruments with frets) but I'm quite positive that violin family bridges are supposed to be perpendicular to be aligned with the centre notches in the f-holes (i.e. "straight"). I don't see any reason why the physical principles that underly the need for compensation on a guitar don't apply to violins & family so I presume players simply learn to adjust their fingering accordingly (and viols have adjustable frets of course).

[Jimmy blue note]

I play fretless 7 string guitar. It's a much more textural experience, the technique is very different, the use of fingertips controls so much and I use the portion of the left hand fingertip that I don't use when playing fretted.
As far as the contact point, I set the nut height quite low, just on the verge of sitar-ing; that keeps my string deformation and intonation issues at a minimum. I DO compensate at the bridge, personally. I have fret markers on the fingerboard because my guitar originally had frets, since pulled and filled with epoxy and wood dust. I moved the side markers to the actual fret line. I do look at my fingers for placement but the note doesn't really necessarily coincide with the note being played. It'a sometimes a little behind and sometimes a little in front of it. That's because when playing melody, the strength of the notes on a scale have the luxury of NOT being just intoned. In other words, I'm not bound to the "slight offness" we're indoctrinated into accepting but rather I find the overtone note that sounds more beautiful and natural to my ear.
Yes that means that there's a lot of muscle memory that my left hand has learned to play natural scales. So for me, it's a lot of muscle memory, guided by my eye to keep my perception of the fingerboard but not the actual contact point of the string to the fingerboard.

Does this make any sense? Also where on the fingertip I feel the string effects the sound I get. I don't really play straight "exact" notes a lot, even when I'm playing faster passages. There's so much nuance required in fretless guitar playing. I've been playing fretless for more than 25 years and it's still a learning process that changes the way I play fretted guitar.