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Is the 12th fret harmonic an independant...

property of the strings?

Those of you who read the thread 'A couple of questions about tuning...' will know there seems to be some disagreement about whether the 12th fret harmonic is part of the intonation process or an independant property of the strings.

In that thread I claimed the harmonic is an independant property and offered a way to prove it somewhat scientifically. Well I went ahead and did the experiment myself and I belive it strongly supports my position. You are welcome to perform it yourself and see.

First, I used my P-Lyte since the strings were well broken in. I checked the intonation which was as accurate as I can get it.

Then I twisted a 3/4 inch piece of wire around the 'A' string at the 6th fret.

SAM_0011.JPG

Next, I retuned the open 'A', necessary because the mass 'defect' made the string out of tune.

Open A.JPG

Then I checked the 12th fret and found it was still in tune. This is to be expected since the mass 'defect' is below the 12th fret.

12th Fret  A.JPG

At this point the string can be considered intonated (to at least the level most of us would accept). That is the open 'A' is in tune and the 12th fret is an octave higher.

So what about the harmonic, the harmonic that was exactly 1 octave higher than the open 'A'? It's 10 cents flat.

12th Fret Harmonic.JPG

I think that shows pretty conclusively that a string can be intonated and yet the harmonic can be out. A simple mass defect in the string can cause this condition.

I welcome your comments.
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Re: Is the 12th fret harmonic an independant...

6/28/2010 1:26 PM

Barney Brazitis (17673) wrote:

Well, the harmonic is a property of the node that divides the string into 2 equal parts, which is physics. And some do use the harmonic for intonation purposes. I believe that folks who "set up" instruments do tune a string to itself using the harmonic and then stretching the string or shrinking it to tune the harmonic to the string. Am I correct?



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Re: Is the 12th fret harmonic an independant...

6/28/2010 2:07 PM

Paul Warren (14577) wrote:

Well, the harmonic is a property of the node that divides the string into 2 equal parts, which is physics

It's probably more correct to say the harmonic is the point around which the two ends of the string vibrate at the same frequency. Since the frequency is dependant on length and mass the harmonic is at the center of mass of the string. Assuming the string is defect free the center and the center of mass should coincide.

And some do use the harmonic for intonation purposes

Yes, it seems so. And there's nothing wrong with that. The only trouble is that to do so assumes there is no mass defect in the string. If there is then the open string will be out of tune. If you then re-tune the open string the 12th fret and the harmonic will be out.

I suggest that it's better to tune the open string first then set the saddle so that the 12th fret is 1 octave higher. If you then check the harmonic it should also be in tune. If it isn't then you have clearly identified a defect with the string (or something else).

I believe that folks who "set up" instruments do tune a string to itself using the harmonic and then stretching the string or shrinking it to tune the harmonic to the string. Am I correct?

Apparently some do. I'm not saying it's wrong either. I'm just pointing out that there is an underlying assumption involved which may not always be true.



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Re: Is the 12th fret harmonic an independant...

6/28/2010 9:35 PM

Barney Brazitis (17673) wrote:

The node is the midpoint and the harmonic is a property of the node? Interesting non the less..

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Re: Is the 12th fret harmonic an independant...

6/28/2010 4:16 PM

Clifton Jackson (35274) wrote:

Yo Paul,
This is very interesting!! Great work, I appreciate it. :^D
Black Hawk
leer

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Re: Is the 12th fret harmonic an independant...

6/28/2010 11:09 PM

WAYNE ELLIOTT (21617) wrote:

I think that shows pretty conclusively that a string can be intonated and yet the harmonic can be out.


I think this demonstrates that the string
HAS NOT BEEN INTONATED!

If the 12th fret tone ...
and the 12th harmonic tone
are not spot on, or a few
cents off ... then the string
has NOT BEEN INTONATED!

If you were to get the 12th
fret tone ... and the 12th
harmonic tone to be no more
than a few cents apart ...
you will find that the notes
from the 6th fret to the 20th
will play fairly well in tune.
Where as the notes on frets
1 through 5, will be out!




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Re: Is the 12th fret harmonic an independant...

6/29/2010 11:23 AM

Paul Warren (14577) wrote:

I think this demonstrates that the string
HAS NOT BEEN INTONATED!


We'll just have to agree to disagree then. I checked the notes all the way up the string and they were all in tune to the extent you'd expect from any properly setup bass. ONLY the 12 fret harmonic was significantly out of tune. I suspect some of the other harmonics would be too, but I didn't bother to check.






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Re: Is the 12th fret harmonic an independant...

6/30/2010 10:24 PM

Todd Ingram (16004) wrote:

i agree with wayne. i don't know about this mass stuff but when i did my bass i had the same trouble as paul. i kept adjusting the bridge until everything was the same on the tuner. if i play an open note and then fret 2 octaves higer past the 12th fret i'm still in tune with the open string. if there's a problem with mass cof a string throw the thing in the trash and get a string that's not screwed up. my 2 cents or 7.





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Re: Is the 12th fret harmonic an independant...

6/30/2010 10:39 PM

Paul Warren (14577) wrote:

i agree with wayne

That's fine Todd. I haven't been telling anyone what they should believe.

The only point I've been trying to make is that if a string has a mass defect somwhere along it's length it can still be intonated. This procedure, which you can easily try yourself, demonstrates that.

Of course, if the string is too defective, or if you play the harmonics and need them to be in tune, then I'd chuck it in the trash too.



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Re: Is the 12th fret harmonic an independant...

6/30/2010 9:50 PM

Roger Gumbs (29626) wrote:

Couldn't a number of things factor into some inconsistencies in intonating a bass. Bridge placement, the heel, the neck...if any of it is even slightly off...say even a millimeter...wouldn't this affect it?

I think perfect intonation is overrated anyway...an audience can't hear if a basses intonation is slightly off.

I've only read some of the posts, so don't throw rocks at me if I sound like I don't know what I'm talking about!! :)



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Re: Is the 12th fret harmonic an independant...

6/30/2010 10:11 PM

Paul Warren (14577) wrote:

Couldn't a number of things factor into some inconsistencies in intonating a bass. Bridge placement, the heel, the neck...if any of it is even slightly off...say even a millimeter...wouldn't this affect it?

Absolutely Roger. This point was brought up and discussed. For the experiment I used my P-Lyte which was properly set up and had seasoned strings. This way the only issue was the mass defect I added.

I think perfect intonation is overrated anyway...an audience can't hear if a basses intonation is slightly off

I couldn't agree more. I made this same point myself. All I wanted to demonstrate is you can get your bass well intonated even if a string or two are less than perfect. If you don't play the harmonic it won't matter at all.

...so don't throw rocks at me...

I'd toss a beer your way, not rocks. lol





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Re: Is the 12th fret harmonic an independant...

7/1/2010 1:40 PM

Roger Gumbs (29626) wrote:

Thanks for the clarrification Paul!

I'd have a beer with you any day brother!



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Re: Is the 12th fret harmonic an independant...

7/1/2010 2:57 PM

WAYNE ELLIOTT (21617) wrote:

Couldn't a number of things factor into some inconsistencies in intonating a bass. Bridge placement, the heel, the neck...if any of it is even slightly off...say even a millimeter...wouldn't this affect it?
...............................
Yes, but this is a qoute from Paul.
...............................

@@@@@@@@@@@@
The point I was making is that when a difference
between the 12th fret and 12th fret harmonic is
observer the most likely culprit is the string.

@@@@@@@@@@@@



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Re: Is the 12th fret harmonic an independant...

7/1/2010 5:38 PM

Paul Warren (14577) wrote:

I'd appreciate it if you'd stop taking my quotes out of context Wayne. That's called 'quote mining' and it's misleading.

How about you state your position clearly and provide some support for it as I have done.



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Re: Is the 12th fret harmonic an independant...

7/2/2010 9:17 PM

Roger Gumbs (29626) wrote:

Oh...Well Paul is Crazy cause he's from Canada...if you don't believe me....just ask Todd! haha


After reading some more of your posts, you both have made good points...I'm sticking in the middle...I like both of you guys!!!

PLAY NICE!!!!! :)

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