Why unusual harmonics on string pairs on the higher frets?

James Holland · Post by **James Holland** » 22 Sep 2015 1:41 am

I'm definitely getting a "third" note at higher volumes. For example on string 4/5, I get a low E note combined with E/B at fret 24. And I get another really low E with the B/G# on strings 5/6 at the 24th. Its a lot worse above the 19th fret than below. I get it on any amp (SS, tube, 100W, bass, etc) when mildly cranked and hitting the strings hard. I put a Wallace True Tone in it, and same thing (but nice single coil sound!). So the question, is this normal? If not, what can it be if its not the amp and not the pickup? I've checked/damped the other strings, the afterlength, etc. to try and find a cause unsuccessfully. Or, is this just some high freq distortion that has to be managed/avoided when going really high?

Lane Gray · Post by **Lane Gray** » 22 Sep 2015 2:37 am

Lower the pickup.

Pete Burak · Post by **Pete Burak** » 22 Sep 2015 5:49 am

Did you try the same test with a different amp?... This would be to rule out amp circuitry or speaker issue.

Jamie Mitchell · Post by **Jamie Mitchell** » 22 Sep 2015 6:29 am

it's not an amp/pickup issue. those are combinations tones. totally normal. if you're in tune, they'll be in tune!

https://en.m.wikipedia.org/wiki/Combination_tone

Donny Hinson · Post by **Donny Hinson** » 22 Sep 2015 7:22 am

As I understand it, when two musical tones of different frequencies are produced together, the frequencies interact, and they will produce two new musical tones (harmonics). One of them is the sum of the frequencies of the two tones, and the other is the difference in frequency of the two tones. Normally, these two new tones are much lower in volume, and are masked by the original tones. But under certain conditions (such as playing them through a fuzztone, or an amp with distortion) they can be quite noticeable.

Lane Gray · Post by **Lane Gray** » 22 Sep 2015 8:23 am

If they're loud enough to be noticed, it might be an indication of something not right. IM distortion is more prominent once waves aren't sine anymore.

James Holland · Post by **James Holland** » 22 Sep 2015 8:53 am

I started to suspect combination tones, but its odd they are so loud. Some amps are worse than others, my tube amps being the best. I can't say I've ever heard these in recordings? Perhaps the good steelers avoid them with dynamics?

admin · Post by **b0b** » 22 Sep 2015 9:09 am

If you are not damping the strings behind the bar with your left hand, you will hear very strong harmonics from the back of the string at the 24th fret.

Also, on the high frets the string length is often very close to the keyhead string length. It could be setting up a strong sympathetic vibration in the keyhead. I mute the keyhead on my Desert Rose with rubber grommets:

James Holland · Post by **James Holland** » 22 Sep 2015 6:34 pm

It appears to be IMD (intermodulation distortion). Good reading on Wiki, looking into "intermodulation distortion", "power chord", "combination tone" and "resultant tone". This effect is actually used in pipe organs, to produce a sub-harmonic, when space and cost prohibit the longest pipes for the lowest notes that would otherwise be used.

It appears to require a lot of sustain to generate. I was able to simulate it on a telecaster, when I used my solid bar at highest frets. I couldn't generate it with my fingers, nor a regular hollow slide.

I still feel that its undesirable for pedal steel, and confused why I'm getting it, but don't hear it on recordings, or during live performances. I haven't had a live gig loud enough to hit the levels where it happens yet, but that's coming. Maybe it gets covered up in a full band situation at stage levels?

Lane Gray · Post by **Lane Gray** » 22 Sep 2015 11:05 pm

Have you tried my suggestion? I've found it helps. Like helps a lot.

Dan Robinson · Post by **Dan Robinson** » 22 Sep 2015 11:34 pm

I'm with Lane on lowering the pickup, and strongly agree with his emphatic "helps a lot."

With pickup too high my guitars sound "brittle," and harmonic (IM) distortion is worse. Have noticed the same on 6 string electric guitars, too. Lowering your pickup might do the trick.

Dan Robinson · Post by **Dan Robinson** » 22 Sep 2015 11:41 pm

b0b wrote:I mute the keyhead on my Desert Rose with rubber grommets.

B0b, that's ingenious! Love it. "Simplicity is the ultimate elegance."

James Holland · Post by **James Holland** » 23 Sep 2015 3:17 am

Yes, I've adjusted the height - kind of hard not to, when replacing a pickup LOL! Its probably 3/16"+ clearance right now. And correct, it does help. Like on a tele, I think it helps smooth out the transient from a heavy attack, like compression.

In the OP I stated I tried muting the afterlength - that's what Bob is doing with his snubbers. Afterlength noise is usually really high harmonics, due to the short string length. I had this issue too, but it was resolved and not a contributor.

I appreciate all the input. I learned to look at these things from this forum. Its quite possible a lot of folks can't hear these tones. As Jamie indicated, they can be manipulated to be on pitch with the intended notes, but, its gnarly hearing them as you "smear" into these really high positions.

Dave Hepworth · Post by **Dave Hepworth** » 23 Sep 2015 11:30 am

Hi James,
I can hear these notes you mention .I first heard these when at fret 15 and when playing strings 4&5 and raising string 4 up one semitone ,(e to f lever). I can hear the 4 string go down a semi tone !
Yes it's not loud but listening carefully they are there.
More apparent the more unclean your sound.However you can sometimes here it acoustically as well .
The more you listen the more you hear them .I turn off to them now ,and they are not a problem anymore.
They are called Tartinni Tones and are a the summation of frequency differences in 2 notes ,you hear the difference ,like beats when tuning strings only in this case the result is not a couple of beats a second but hundreds or thousands a second ands so now you hear a note rather than a beat.
Regards Dave

Alan W. Black · Post by **Alan W. Black** » 30 Sep 2015 4:08 am

Is it accurate to say, one could tune these intermodulation tones away completely, but only for those strings at that fret with this one pedal/lever position. But you'd suffer for that tuning change. I'm a newb at this instrument, but tuning is a compromise averaged out over the whole neck and all pedal/lever positions. This IM tone you've got, as said before, is the same as those beat frequencies you hear when tuning by ear, but up in the audio range.
Since you mention yours, I've tried this on my tele, mostly for an experiment - if you adjust your own intonation, forget the octave. Adjust your intonation by tuning the 5th fret note to the 5th fret octave. You're making that area of the neck more accurate. If you only play down there- 5th fret and below, like Dylan(?) for lack of a better example- there are less beat frequencies in your chords. It is very significant. Magnificent, really. You can play full chords with a little distortion like never before. It's also at the expense of the higher chords and pairings. Nature of the beast. I haven't left that intonation on the guitar for long, but I may.

Jamie Mitchell · Post by **Jamie Mitchell** » 30 Sep 2015 6:43 am

Alan W. Black wrote:Is it accurate to say, one could tune these intermodulation tones away completely, but only for those strings at that fret with this one pedal/lever position. But you'd suffer for that tuning change.

it would not be accurate to say that.
you can't 'tune them away'. there always going to be there, it's just a physical reality of multiple pitches being sounded. but, if you're in tune (just, fwiw), they'll be in tune.

do you sing harmony vocals at all?
if you have, you've probably experienced singing in a trio of voices, and sometimes, if you're really killing it, it gets fat. heavy, a lower fundamental than anyone is singing appears. that's combination tones. they appear, usefully, when you're doing something right...

j

Alan W. Black · Post by **Alan W. Black** » 30 Sep 2015 12:31 pm

Right, that's what I mean. The enharmonic, unwanted ones. When your two notes are perfectly in tune these "undertones" aren't perceived as a problem. When two notes are a little out of tune there is a beat frequency. The beat frequency can slow to a stop, or increase into the audio range. Very high up on the neck, where the notes are sooo close together, the slightest microscopic angle on the bar can certainly result in beat frequencies that get into the audio range.

chris ivey · Post by **chris ivey** » 30 Sep 2015 2:06 pm

this all seems like a lot of fancy words and theories for something that will probably be
unnoticeable once your technique improves. bar pressure, accuracy, damping, solid clean picking, etc.
playing at the 24th fret much would take some precise skill. i rarely go there.
play regularly in a band situation for a year and see if you still hear it. or if you even go near the 24th fret much.
unseasoned players seem to have lots of questions which will work themselves out in time if you don't dwell on them.

Tim Russell · Post by **Tim Russell** » 30 Sep 2015 4:09 pm

chris ivey wrote:this all seems like a lot of fancy words and theories for something that will probably be
unnoticeable once your technique improves. bar pressure, accuracy, damping, solid clean picking, etc.
playing at the 24th fret much would take some precise skill. i rarely go there.
play regularly in a band situation for a year and see if you still hear it. or if you even go near the 24th fret much.
unseasoned players seem to have lots of questions which will work themselves out in time if you don't dwell on them.

Great post.

Alan W. Black · Post by **Alan W. Black** » 1 Oct 2015 4:26 am

Can't argue with that.