DIGITAL GUITAR AUTO-TUNER PROJECT

No, I think you'll find that it does _not_ prove the converse. ;-)

--
  Keith

someinteresting reading about harmonics and overtones

harmonics overtones modes inhamonicity

You mean that proving the converse doesn't prove anything? Oh, I get it!

The converse of something is nothing.

Proving the converse of something proves nothing.

Ah, so!

Jerry

--
Engineering is the art of making what you want from things you can get.
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I read in sci.electronics.design that Ben Bradley wrote (in ) about 'DIGITAL GUITAR AUTO-TUNER PROJECT', on Thu, 28 Apr 2005:

If one or both of the outer strings shifts phase, in such a way that the bridge can twist, the decay is different from the case where the middle string shifts (relatively).

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
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That's funny! All the ideas are smart.

What's funny? What ideas?

Usenet messages need to stand by themselves. There is no guarantee that any older messages are available to the receipient. That is why we quote the relevant portions, and post replies after (or intermixed with) the quoted portion. The google usenet interfact is seriously broken, but you can live with it if you follow the instructins below in my sig.

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And now for something completely off-the-scale:

While I'm barely at the "hacker" stage in my DSP knowledge (I'm still working out how modulating a reflected mm-wavelength signal can yield accurate distance measurement over thousands of mm), I have been following the threads in this Subject-line with great interest.

I'm particularly fascinated with the complexity of obtaining a "useful" or "pleasing" tuning for a musical instrument. I hadn't realized that there were multiple "standard" ways of tuning a piano, for example. Thank you all for giving me an excuse to renew my Usenet Lurker's License.

I'd like to ask one question, though, regarding the tuning process for instruments involving mechanical vibration -- not just the ones someone referred to as "plucked" but also percussion instruments and probably others. If, as some have mentioned, the tuning of stringed instruments is made more difficult because people pluck the strings differently (is this the same as "attack". or is that a "keyboard only" term?) and the sound changes over time (decay), why not add a feedback loop into the process?

That is, why not have the "tuning instrument" induce the vibration as well as analyze the resulting sound. A PWM-speed-controlled motor with a _gentle_ off-center cam is probably not the only approach. but it doesn't seem very difficult to do (certainly no more difficult than analyzing the pure sine wave coming from a guitar string ).

Is there a reason that "tuning instruments" (at least, the ones I've seen and the ones discussed here) only analyze sounds and don't attempt to apply controlled signal stimulation? Or is it that such already exist and are simply too expensive for everyday use?

(Whoops! I think I just violated my ULL! Time to re-cloak... er, re-Lurk. )

Frank McKenney, McKenney Associates Richmond, Virginia / (804) 320-4887 Munged E-mail: frank uscore mckenney ayut minds pring dawt cahm (y'all)

-- "Very few things happen at the right time, and the rest do not happen at all. The conscientious historian will correct these defects." -- Herodotus

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Ha! Another bit of usenet wisdom for my sig file!

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Frnak McKenney wrote: ...

My guess: generating the sound is usually something that comes so easily to a musician that it's not worth automating. Something was published on a piano tuning device that both excited the string -- I forget how -- and turned the tuning peg with a geared servo motor. A human had to place the string-isolating wedges and move the servo from peg to peg.

Jerry

P.S. Is your name really Frank?

--
Engineering is the art of making what you want from things you can get.
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You can demonstrate this energy transfer with a really fun demo: Take three pieces of string, two weights (maybe a large hex nut, or fishing weight) - suspend one string horizontally, like in a door frame, or between two chairs. Make pendulums out of the other two pieces of string and weights, both the same length, and tie them at about 1/3 and 2/3 length on the horizontal string:

X---------+-----------+----------X X = support, + = knot | | | | - = horizontal string | | | = vertical string | | O O O = pendulum bob

Start _just one_ of these pendulums (pendula?) swinging, and watch what happens. See also

Activity 2.

Cheers! Rich

I wish I had thought of that! (You're welcome.)

Jerry

--
Engineering is the art of making what you want from things you can get.
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...

Can a piano bridge really twist? One is a long strip glued to the sound board, the other is part of the cast-iron frame. It astonishes me that twist has a significant affect.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

I read in sci.electronics.design that Jerry Avins wrote (in ) about 'DIGITAL GUITAR AUTO-TUNER PROJECT', on Thu, 28 Apr 2005:

I don't know if it's significant. The sound board bends in all sorts of ways, so the bridge might be moved by notes other than the one under consideration.

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

I read something about a self-tuning piano. It used a magnetic pickup (as for an electric guitar) to sense the frequency. Presumably they excite the string the same way, by driving a current through the pickup coil.

I think that was the piano where all the strings were tuned sharp and to tune a string a current was allowed to flow through the string, heating, lengthening and flattening it. If they used a pickup instead of a microphone then they could tune multiple strings at once without them bleeding into each other. Very clever.

Jonathan

Maybe it would make sense for something like piano, but consider that guitar tuners cost about 20 bucks and can fit in a back pocket. Adding some for stimulation is going to be pretty expensive compared to that, plus as Jerry said, musicians are pretty good at plucking their own strings! Plus, I don't many people that would trust a machine "banging on" their expensive instruments.

I was wondering the same thing.

instruments.

Somewhere in the attic, I have an oak box with a tuning fork mounted on it. One tine of the fork is driven by a coil and the other drives the button of a diaphragmless carbon microphone that modulates the coil current. Coil voltage is available on binding posts. At one time, it was General Radio's premier 1 KHz frequency standard. Feeding back to a mechanical resonator has been done for a long time.

Jerry

--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

A guitar already has a mag pickup, so it should be possible to just plug it into a tuner (with vol and tone right up) and have the tuner search for the slight narrow-band impedance resonances at each string pitch, then use that to sustain continuous oscillation. Of course it would probably also pick up harmonics of other strings if they weren't damped (ideally need access to a hex pickup as well, I guess). A practical design would be tricky, but still quite cheap.

Tony (remove the "_" to reply by email)

Because the whole point is to get the instrument in tune *as played* by the performer. It is a good thing that the tuning analysis is as passive as possible.

A surprising number of musicians, as well as nonmusicians don't seem to get this: An instrument that's in "perfect tune" can be played out of tune by a bad player (or deliberately by a good player), and a badly-tuned instrument can be played in-tune by a good player. The quality of the overall performance depends a lot more on the player than on the instrument.

I happen to play trombone, which is an extreme example of this, but it applies to all wind instruments and most stringed instruments. A piano (and electronic synthesizer), which I also play, is at the other extreme, being one of the instruments on which the performer has almost no real-time control over the pitch.

-- Dave Tweed

I read in sci.electronics.design that David Tweed wrote (in ) about 'DIGITAL GUITAR AUTO-TUNER PROJECT', on Fri, 29 Apr 2005:

My colleague, John Bowsher (a physicist as well as a trombonist) demonstrated this to an AES British Section meeting many years ago. Two demos:

- producing a constant pitch note while collapsing the slide.

- producing a swept pitch note with the slide stationary.

I don't really believe it, and I was there!

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk