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Re: A "parasite" tone

PostPosted: Tue Sep 13, 2016 9:30 pm
by Alain Lambert
Could a compensated nut help to ged rid of that problem?
After all it does change the scale length by a small amount.
This would be easy to try

Re: A "parasite" tone

PostPosted: Wed Sep 14, 2016 2:13 pm
by Alan Carruth
It would be worth a try; almost anything would.

Re: A "parasite" tone

PostPosted: Wed Sep 14, 2016 5:34 pm
by Massimo Milan
Here's an audio clip of sounds taken from 4th and 5th string on 2nd fret
First tone = fingertip right close to the fretwire --> then in the middle of the fret
https://soundcloud.com/memyguitar/zip-tone

Re: A "parasite" tone

PostPosted: Thu Sep 15, 2016 5:16 am
by Massimo Milan
and here a video clip of a spectrogram and waveform of the tones; i could not in any way couple the audio really don't know why, so i put some captions under the waveforms I hope itis clear enough
https://vimeo.com/182827085

Re: A "parasite" tone

PostPosted: Thu Sep 15, 2016 1:29 pm
by Alan Carruth
There sure is some beating going on there!

I'll try to run a spectrum, rather than a spectrogram, and see what I can see.

Re: A "parasite" tone

PostPosted: Thu Sep 15, 2016 5:48 pm
by Massimo Milan
Alan Carruth wrote:"I. On future instruments you'd want to avoid using a really tall saddle, ....


That tall saddle comes from the original project where a one of a kind suspended Bridge had enough room from the top to let the strings pass under and climb from behind to make the knots, but it was unsuccessful and had to be substituted by a differently shaped Bridge.

Re: A "parasite" tone

PostPosted: Fri Sep 16, 2016 9:49 pm
by Alan Carruth
I could not get the sound file off the web site and into the FFT program I've got. Sorry.

Re: A "parasite" tone

PostPosted: Sat Sep 17, 2016 3:22 am
by Massimo Milan
Alan Carruth wrote:I could not get the sound file off the web site and into the FFT program I've got. Sorry.


Please be so kind to try this:
https://dl.dropboxusercontent.com/u/881 ... 20TONE.mp3

(see also my PM)

Re: A "parasite" tone

PostPosted: Sun Sep 18, 2016 10:09 am
by Massimo Milan
Here video and audio coupled, with captions:

Vimeo:
https://vimeo.com/183188346"]https://vimeo.com/183188346

YouTube:
https://youtu.be/t9USFNMDs2I

Re: A "parasite" tone

PostPosted: Thu Sep 07, 2017 11:37 am
by Eirikur Blodax
Hi all,

I stumbled onto this old topic looking for a solution to exactly the phenomenon you're describing here.
Recently I bought a new guitar, an all solid classical that came with extra hard tension nylon strings,
and I found many of the individual strings in a chord chiming...

After restringing and winding/unwinding strings there was no change, but then it struck me: it's all my own fault and has to do with tension changes directional forces!
Plucking up with my thumb or pick I hear a lot of additional tones like in the uploaded video, but striking down far less so. In addition to that, the pressure on the strings (again, self-inflicted) makes a huge difference on this new guitar - remember it is an all solid with the high tension strings that do ring out substantially.

So: forming the chords with just enough string pressure gives me a well-sounding tone every time, plucking up or down makes no difference. Pressing down hard away from the fret gives significant under- and overtones when played individually, especially when plucking up.

Maybe my experience and explanation makes sense and helps someone (I couldn't sleep, thought my guitar was faulty!),
Cheers,
Eirikur

PS: Striking the entire chord makes the additional tones quite pleasing actually...

Re: A "parasite" tone

PostPosted: Sat Oct 21, 2017 7:06 pm
by Tom Anderson
Its been a long time since I've browsed MIMF...I just got way too busy. But this thread intrigued me because this exact problem nearly drove me mad when I was working as a repair guy at a local guitar shop.
Here's what I think is going on. The demon sound and the beating is caused by the little bit of string in between your fretting finger and the fret, when you fret the string back from the fret. For example, if you're fretting on the third fret of the fifth string (C) and place your finger further and further back toward the second fret you reach a point where the little bit of sting (maybe 1" long) begins to vibrate and presto..the demon sound. I can reproduce this sound on many/most nylon string instruments, and never on steel (differences in tension and flexibility, I assume). If you fret with your index finger and use your middle finger to lightly touch that little bit of string before the third fret, you can feel this unwanted vibration. Press just a little harder with your middle finger and its gone (damped out).

Why does this happen?..I think its because the fret starts acting like a fulcrum rather than a "stop" once the little bit of string gets long enough. So when the main vibrating length (3rd fret to saddle) goes up, the little demon bit goes down. In effect, you have two vibrating lengths...the main one, and the main one plus that pesky little bit. Just a guess!
How to stop it (other than fretting close to the fret) ?...I don't know...but not pressing down so hard helps (higher damping), and I'll bet that if you had a scalloped fingerboard you never have this problem as long as you didn't "bottom" the string onto the fingerboard when fretting.

Comments?