Bow pressure changing string pitch

[polkat]

Bill, what strings are those and how long have they been on the instrument? I've found a few synthetic and gut brands that have a rather long strech-in time, and will do that for a while. Also sounds like a lot of bow pressure.

[Wm. Johnston]

Have you ever read about playing 'subharmonics' on a violin? I think what you are hearing might be related to them. Essentially, if you bow the strings with just the right speed and pressure you can get them to vibrate at lower than normal pitches. Perhaps you are bowing in a way that is almost causing them but not quite?

[Bill Yacey]

The E A and D are Thomastic Super Flexible, and the G is A Helicore. The problem is even more pronounced with Dominants, although I didn't use them for more than a month or so before removing them and putting steel strings back on.

[gabi]

the ear perceives sounds with rich higher partials as lower in pitch , and sounds with strong fundamentals and less partials as higher in pitch , for the same given frequency.

play a note on a piano and listen all the way until the sound decay complatly; towards the end when only the fundamental remains the pitch will seam to go higher

[Casey Jefferson]

This is probably what La Folia referred to, when the bow speed up a lot and the pitch will go up:

(around 3:39)

And this is what Bill referred to:

when the pressure is pushed further:

No idea what's happening with all these phenomenon though. Usually pressing the strings and with slow or decent bow speed, the pitch will go down, particularly easy when playing near the fingerboard. When speed the bow up a lot, the pitch will go up, and easiest to do it on G string.

I must agree with the comment about steel strings easy to achieve the pitching raising phenomenon.

[Flyboy]

I have noticed when using gut or perlon wound strings that some strings are more pitch sensitive to bow pressure and position of the bow hair on the string. The truest tone and pitch seem to occur when bowed closer to the bridge.

Is this a normal side effect of using low tension strings (compared to steel)? Steel strings don't seem to exhibit this effect. Is it perhaps out of phase reflections back through the bridge that are creating this detuning from the natural pitch of the string?

Assuming you aren't putting us on, the symptoms you describe correspond to torsional vibration mode of the string. The closer you are to the bridge the less susceptible the string is to rotating upon itself (torsion). Since gut and perlon are generally thicker than corresponding steel strings, they are also more susceptible to torsional vibration.

I'd try another bow to check if it makes matters better or worse.

[Bill Yacey]

I would be ashamed to waste the valuable time of members kidding around about something like this.

I have tried other bows but didn't really pay attention to this being a possible factor. I'm working out of town for a few days, but when I get back I'll report back what I find with different bows.