speaking of intonation

[Bbach1]

I just adjusted the truss rod on my Hamer (not the one I pound nails with) and whilst in the middle of that, I thot I may check the intonation. Just to be clear, the harmonic pitch of a string means playing it open correct? I would then compare that on my tuner to the fretted note on the 12th fret and both should read the same. Do I have that correct?

[Dak Lander]

The tuned open string, say the "B", should tune the same as the harmonic of that string at the 12th fret. It is also a good idea to fret that string at the 12th too and check it. All three should tune the same, with the 12th, both fretted and harmonic, an octave above the open.

To get the harmonic, very lightly touch the string right over the 12th fret and, as you pluck the string, remove the finger touching the string at the fret. With some practice you will become adept and you will hear the difference in the ring of the string.

The easiest harmonics to get, on most guitars, are on the 12th, 9th, 7th and 5th frets though all notes will have a corresponding harmonic, at least to my recollection.

[Bbach1]

That was the thing that I was questioning. How do you get the harmonic. Thanks for answering that. But how the heck does that create the harmonic? I guess I don't quite understand what the harmonic of one string is.

[PBBPaul]

I've forgotten the technical lingo but what happens is you create a kind of virtual bridge. The 12th fret is the halfway point between the nut and bridge. By lightly touching the string at this point, you get two sets of vibrations - one below the 12th fret and one above. If you fret the string at the 12th fret, you get just the vibration above the 12th fret. The "harmonic" gives you both. The 5th fret represents one fourth of the distance between the nut and bridge so when you lightly touch the string at that point, you get 4 sets of vibrations. This probably doesn't make a lot of sense. It's a lot easier to understand when you see pictures.

[NMcGuitar]

There was a lesson on this in (I believe) last month's Guitar Player mag. I'll see if I can dig it up...

[NMcGuitar]

Found it!!!

[Steevo]

Originally posted by cwfno:

....I would then compare that on my tuner to the fretted note on the 12th fret and both should read the same. Do I have that correct?

Here's how I would explain it. When a string is plucked open, it vibrates like a jumprope held by two children on a playground ... held at both ends with the big swing in the middle. When the string is touched lightly at the 12th fret and plucked, it vibrates in halves with a null, or no movement, at the 12th fret. This null has to be placed precisely over the 12th fret for the guitar to play with proper intonation. To move the null point of the harmonic, you adjust the saddle of the string either toward or away from the nut. Use your tuner to match the pitch of the harmonic at the 12th fret and the fretted 12th pitch. Don't push too hard when fretting because you don't want to pull it sharp ... just enough pressure to make the note clear.

 

Anyway, that's the way I do it...

[A String]

Originally posted by cwfno:

That was the thing that I was questioning. How do you get the harmonic. Thanks for answering that. But how the heck does that create the harmonic? I guess I don't quite understand what the harmonic of one string is.

This is some great info guys! Just to help out in the actual harmonic department...

touch the string just above the 12th fret. (Do not push the string) Then pick the string the way you normally would. Just after you strike the string (We're talking less then a second here...), remove your finger. It may take a few practice shots, but you'll get it!

[Billster]

Originally posted by cwfno:

But how the heck does that create the harmonic?

Ask your physics teacher.

 

Is it legit to link to Harmony-Central from MusicPlayer? all about harmonics

 

Since the harmonic rings out from the true halfway point of the string, it is a guide to the frequency required for the fretted note to be in tune, since the 12th fret is supposed to be halfway between the nut and the bridge.

[fantasticsound]

Harmonics are resonant frequencies. When you pick a note on the guitar, the fundamental frequency (the specific note you're playing) creates resonances at multiples of that frequency. For example:

 

The A string of a guitar is tuned to 220Hz. But when you pluck or pick the string, you're actually hearing varying amounts of 220Hz, 440Hz, 660Hz, 880Hz, and other frequencies. The relative volumes of these harmonics, along with the attack of each note determines much of what we use to identify a guitar playing middle C from a piano, from a flute, etc.

 

On a string, you can isolate specific harmonics by lightly touching the string at an exact multiple, half the length, one third, one fourth, etc. The first harmonic, located half the length of the string (the 12th fret) is twice the fundamental frequency. So the first harmonic of the A string is 440Hz.

 

But strings have mass and tension. We vary the thickness (and, hence, the mass) of the strings so the high strings don't have incredible amounts of tension and the bass strings don't flap in the wind. But this difference in mass creates a problem when setting an absolute scale length.

 

To counteract this issue, we adjust the scale length at the bridge so that the first harmonic is properly tuned to the identical note on the 12th fret.

 

Does that clarify or confuse you more??

[Shoes]

My mind always drifts away to Fragile and Roundabout when I think of guitar harmonics. It's a pleasant place.

 

Great work at explaining that... I've never actually thought about what was happening there beyond thinking I was establishing a fret or what ever. Likely some complementary sideband frequency effect that acts as a carrier for the harmonic given they have would have corresponding wave points...

 

er... something like that... yer right... easier to see than smell.

[PBBPaul]

I knew that Neil would show up sooner or later and articulate it properly.

[Bbach1]

Well that is fantastic advice from all of you. I don't just like to know "how" to do things, I like to know why also. Knowing why helps me retain the information. Tanks a bunnnnnnch!!!

[Guitarzan]

i don't want to pee in anyones cornflakes but, for intonation purposes don't use the harmonic. use the 12 fret note compared to the open string.

i believe i remember our buddy Earlybird mentioning that in one of his GP articles.

[Bbach1]

Guitarzan, I would very much hesitate to argue with you. My owners manuel however, says to compare the intonation and the fretted note at the 12th fret and they should read the same on the meter with A=440hz. With all the above tips, I'm happy to say my intonation is doing very well. Now the rest of me just has to catch up.

[Guitarzan]

from Guitarplayer december 2000..

REPAIRS

setting intonation, by Dan Erlewine

 

Don't make this mistake:

a lot of people set intonation by chiming the open string harmonic at the 12th and tuning the fretted note to match the chimed harmonic. Most experts agree that this is not an accurate way of setting intonation.

 

it pays to hang onto all those old Guitarplayer mags.

[Bbach1]

Originally posted by Guitarzan:

from Guitarplayer december 2000..

REPAIRS

setting intonation, by Dan Erlewine

 

Don't make this mistake:

a lot of people set intonation by chiming the open string harmonic at the 12th and tuning the fretted note to match the chimed harmonic. Most experts agree that this is not an accurate way of setting intonation.

 

it pays to hang onto all those old Guitarplayer mags.

Just when I thot I was starten ta unerstand.

[Steevo]

Originally posted by Guitarzan:

from Guitarplayer december 2000..

REPAIRS

setting intonation, by Dan Erlewine

 

Don't make this mistake:

a lot of people set intonation by chiming the open string harmonic at the 12th and tuning the fretted note to match the chimed harmonic. Most experts agree that this is not an accurate way of setting intonation.

 

it pays to hang onto all those old Guitarplayer mags.

Exactly ... you must tune the harmonic (via the saddles) to the fretted note .. not the other way around. The fretted note is fixed ... the harmonic can be adjusted.

[Guitarzan]

the 12 fret note isn't fixed, in fact it needs to be compensated to match the open string note. how much depends on many things, string guage, action and (if you are real serious) even the players touch and attack.

also all strings should be in tune when checking the intonation of any paticular string, to make sure there is no difference in tension on the neck. and the actual checking should be done in playing position with no hand pressure on the tuning keys while actually checking the notes on the tuner.

 

[KHAN]

Originally posted by Guitarzan:

from Guitarplayer december 2000..

REPAIRS

setting intonation, by Dan Erlewine

 

Don't make this mistake:

a lot of people set intonation by chiming the open string harmonic at the 12th and tuning the fretted note to match the chimed harmonic. Most experts agree that this is not an accurate way of setting intonation.

 

it pays to hang onto all those old Guitarplayer mags.

[fantasticsound]

I'm predictable, eh, Neil? Thanks.

 

I'd be a fool to argue with Dan Erlewine about guitar setup and repair! I'm that guy who's has just enough information to be dangerous.

 

 

Seriously, I see Dan's point... But I'm not certain why matching the harmonic and 12th fret note wouldn't automatically put the 12th fret and open note in tune with one another.

 

Using Dan's method, you're essentially setting the harmonic of the open string (which should be the same as isolating the harmonic at the 12th fret) to the octave note at the 12th fret.

 

Or is Dan conceding that the harmonics on a guitar string will be inherently out of tune with their fundamental even at the 1st, 2nd, and 3rd orders. {That would be octave (at the 12th fret), octave + a fifth (at the 7th fret) and two octaves up (at the 5th fret). The most commonly used harmonics.}

 

Interesting....

[Werewolf by Night]

Quick 'n' dirty, simple short answer on the question of "how the heck does that create the harmonic?"

 

When you lightly touch an open string over the twelfth-fret, pick it, and release, it creates a little dead-spot, or "node", where you touched it that is not vibrating as much as the rest of the string, and the two halves on either side of that dead-spot are vibrating as if they were two strings, each about half the length of the whole open string.

 

Same if you quarter it, eighth it, etc... and "artificial" harmonics are the same process applied to a fretted string. Count twelve frets above any fretted note, and with a finger of your picking-hand rapidly hit the string directly above that fret, hitting the string against that fret, with a quick, sharp typewriter-striking like motion. A chiming note an octave above the fretted one will ring out.

[A String]

Originally posted by fantasticsound:

A string is tuned to 220Hz.

[Dak Lander]

Well, getting back to this to somewhat clarify... What I do when checking intonation is to check the open note against the fretted note and then, if all is good, verify with the harmonic.

Works for me because, as stated above, the harmonic spot can move.

For me, using the harmonic as the last test verifies that all is in conjuction.