harmonics question

[geoff douglas]

Hi guy's and gal's,

A quick question please before i go to bed,,,could someone explain for me why when plucking harmonic notes does the pitch of the notes decrease when climbing up the neck on any given string, the opposite to strumming the string where the pitch goes up when climbing up the neck. The same result happens even when past the 12th fret.
I think its going to mess my sleep up tonight just thinking about it, lol
Thanks
Geoff

[GeorgeB]

Wikipedia offers a good explanation, hope this helps to de-confuse

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http://en.wikipedia.org/wiki/Guitar_harmonics

[link deemed unsafe by URLVoid so clickable link removed by Admin]

[KenC]

The shorter the vibrating length of string, the higher the pitch. Each position that gives you a harmonic divides the string into a number of equal segments. A 12th fret harmonic divides the string in half (i.e., the longest possible segment). As you move from the 12th fret toward the nut, each position gives a shorter vibrating length, and therefore a higher pitch. Keep in mind that unlike a fretted note which allows the string to vibrate between that fret and the bridge, with a harmonic up through the 12th fret the length of the vibration is measured from the fingertip to the nut. Of course, all of the harmonics you can find as you get closer to the nut also show up at equal distances along the string so it's possible to get a relatively high harmonic between a pair of lower ones. I have no luck trying that on guitar, but with a hot enough bass and amp they are easier to find. The classic example is Jaco playing Portrait of Tracy:

[youtube]LEs5sKDXZuk[/youtube]

Ken

[geoff douglas]

Thank you George and Ken,

I will check the site out an try to get my head around it, im still a bit confused why the pitch still decreases after the 12th fret, i sort of imagined it might go up after it.

Cheers all and have a great weekend
Geoff

[KenC]

im still a bit confused why the pitch still decreases after the 12th fret, i sort of imagined it might go up after it.

You're into the other half of the string after the 12th fret, so everything is a mirror image of what happens between the nut and the 12 fret. Measure the distance from the nut to the fifth fret, for example, and then try touching the string that exact same distance away from the bridge. You will get the same harmonic you hear at the fifth fret.

Ken

[geoff douglas]

Hi guys, i think i get it now.
Fret 7 and 19 have the same string length ratio, just mirrored, they are the same distance from the center of the string , fret 7 and 19 have the same harmonic note. Fret 8 and 17 too have their same mirrored ratio and are also their same distance from the center of the string, 8 and 17 have their same respective harmonic note also.
The thing that i had trouble with was why was fret 7 low and fret 8 high,, why was fret 16 low and fret 17 high, why was there this sawtooth pattern of harmonics as you progress up the neck.
I understand now that it is the interaction of both frequencies produced by the different string length ratios that results in the strings final frequency, whether the two waves where in phase or out of phase, whether they were constructive to producing a higher frequency, in phase so to speak, or destructive, out of phase that results in a lower frequency.. Like two ripples in a pond colliding, the resultant wave is never the same as either ripple was before they collided, but depending on the ripples frequencies and time in the cycle of their collisions, the resultant ripple might be high, low, wide or sharp. At fret 7 the collision of the two frequencies results in a stretched waveform, a destructive effect, hence lower frequency, the bottom of the sawtooth. At fret 8 though the collision of the two frequencies have become constructive to produce a higher frequency, the peak of the next sawtooth, and so it goes on.
Its been interesting for me and i thank you George and Ken for your input.
I will sleep better tonight im sure,
Cheers all
Geoff

[geoff douglas]

Thanks Ken for your second reply,
I was writing my findings when you posted your message is seems. Its interesting isnt it, i only realized the phenomenon of the harmonics going low when playing up the neck last night when a mate of mine was playing a tune totally with harmoic notes, It wasnt till i got home from work today that i actually played around with my guitar and looked at the whole harmonics thing. Thats when i found this sawtooth pattern, even though it is an erratic sawtooth, it is a sawtooth. It turns out that every harmonic position low on the neck has its mirrored harmonic up the neck with exactly, well as good as exactly, mirrored note.
By the way i have 5 songs completed now, Tears in heaven, I'm a believer, Horse with no name, Lola, and almost mastered Wonderwall, and i can even sing while playing now, woo hooo, lol, it took a while but im off and running now. This guy called Justin on utube is great in my opinion at teaching songs, i cant recommend him highly enough.
Have a great weekend all
Geoff