Justin Guitar Community

Tools of the Trade => Guitar Maintenance [fixing, cleaning, setup, action, intonation, playablility, buzz etc] => Topic started by: Styrr on August 08, 2018, 06:23:47 pm

Title: Sustain dying out
Post by: Styrr on August 08, 2018, 06:23:47 pm
Not sure if anyone can answer this but here goes.
Problem – sustain dying out on B string fretted at 12th fret.  i.e an octave above natural B. It also happens playing at the 13th fret  [C].
Also happens with G string at 12th fret, but to a lesser extent.
Doesn’t happen with any other string or those strings at any open or fretted positions.
Tried it on all my guitars (electric) and it varies on most to some extent. It is most noticeable on 2 of my guitars that sustain the most. That may be because they normally ring forever  which makes it more noticeable. Seems that those with trems are less of a problem.  On my Strat there is hardly any difference, it is there but only because I am listening for it.
My guitars are quite a mixture from hard tails to trems and even a bigsby, and different string gauges and manufacturers. 9-42s, 9-46s, 10-46s and 11-49s.

It isn’t a high fret(s) issue and I don’t think it’s a pick up height issue either (as it happens no matter which pick up combination I use).. All guitars are set up to factory specs, so they are not set up for low action. Intonation pretty good too.

Done quite a lot of research and not come up with a reason or solution. Could it be just that those frequencies don’t quite line up for the nodes ( fret to saddle) ?. I would have thought that intonation would have sorted that. And it doesn’t happen with the high E at 7th fret.
Only noticed this because I was learning the guitar solo for Mark Knopfler’s  Wild theme/ Local Hero. Now I wish I hadn’t entered this particular rabbit hole.

Anyone offer any thoughts ? or at least a rabbit hole extraction machine?

Take Care
Title: Re: Sustain dying out
Post by: Dan Graves on August 10, 2018, 07:33:51 pm
Have someone check the setup, I can't replicate this issue on either my Les Paul, my PRS C24 or my Annihilator (hardtail, floating trem and floyd rose respectively).
The topnut and bridge would be my first places to check, then neck curvature and intonation.

I'd also like to point out that 'factory spec' setups tend to be mostly uniform, and relatively high, because they're meant to be a fairly safe 'middle ground' sort of thing.
If you'd want them low, (learn to) set them up yourself, or have someone else do it.
Title: Re: Sustain dying out
Post by: Styrr on August 11, 2018, 05:48:31 pm
Thanks for the reply Dan,
I know you are pointing out the usual suspects; so here is my thought process:-
Nut and saddles are Ok – besides if there was a problem with the nut; fretting at the 12th fret would surely have eliminated that?. And as the sustain is good on the open string that should indicate that the saddles isn’t the issue either ?
Intonation is good (or as good as it can be depending on the saddle type)

Yes that’s why I said the guitars were set up to factory specs; to make sure that sure that too low an action wasn’t the problem. I didn’t have any fret buzz or choking etc when bending with the action slightly lower as I like it. From all my research that choking on the bends is normally due to a high frets (not that the bending was my problem). I checked with a fret rocker and no the frets are fine too.
 I actually don’t mind the action being a little high and set them up myself. I will lower them a touch if and when I find a solution.
Neck relief is about 10 tho on all of the guitars, so should be good.

It happens to some extent on all 8 of my electric guitars, just some worse than others.
The 3 that is most noticeable are: a PRS Pauls guitar; a Gretsch G5422T hollow body; and a Gibson SG. Then comes the Gibson Les Paul; and a Fender Tele. Least noticeable are on the trem guitars: Fender Strat; PRs custom 24 and a James Tyler JTV69 (Line 6 Variax).

As a measure of how much sustain I am losing I did some timing on the PRS.
On a clean channel, with a minimal amount of gain but the Volume full on and the master set about half way (but attenuated down):-
Open B string; full sustain for about 5 secs, gradually reducing down until about 15 secs.
B string fretted at the 12th Fret; full sustain for about 3 secs; quickly reducing down to 6 max.

I did take one of my guitars in to get it checked out and to confirm I wasn’t just imagining it. Two people played it and confirmed that yes the sustain was dying out quicker when fretted and couldn’t find anything wrong with the set up. The only suggestions were to a) try adjusting the pickup heights and b) if it was still under warranty to take it back to the store I bought it to see what they could do. As it’s a PRS Pauls guitar , it has a limited lifetime warranty – i.e. it’s under warranty as long as the original owner has it. Which is me. That may or may not get the PRS sorted, but won’t do much for the others unless I know what was done.
Title: Re: Sustain dying out
Post by: Dan Graves on August 11, 2018, 08:17:10 pm
Well, sometimes life is stranger than fiction; I've handled guitars that would not properly fret or intonate higher up, and the nut was usually the culprit, be it that the groove was either too shallow or too deep, sometimes too narrow.
The reason I mentioned factory spec being middle of the road is because it could also be it's slightly too high for what your guitar can handle.
It would be odd that it would kill sustain that far up, but like I said, life can be stranger than fiction.

But in any case, since it's a PRS, I'd have the store take a look, if it's a deep(er) issue the warranty will cover it, if not, they can fix it for you.
They can be a bit finnicky to get right sometimes ...
I can tell you I've struggled with my SE's at times.
Title: Re: Sustain dying out
Post by: simon3142 on August 12, 2018, 09:48:38 am
A slightly off the wall suggestion, If it is problem exists on several guitars, were you always using the same amp/speaker?
Is it possible the the effect is being created after the signal has left the guitar?
Title: Re: Sustain dying out
Post by: Dan Graves on August 12, 2018, 01:43:47 pm
It would take a rather weird constellation of faults, or some weird mix of effects pedals and compression/filtering...
Certainly worth a try, should be less effort than having the guitar checked at the store.
Title: Re: Sustain dying out
Post by: Styrr on August 12, 2018, 07:41:29 pm
Not necessarily too much of the wall. Something I didn’t consider and an interesting point to test anyway.
So we tried.
Into 2 other different amps, so a tube amp; modelling amp; solid state amp. All combos with different speakers; different speaker sizes; clean channels; and no /pedals/effects  -  essentially the same result. Timings on the normal sustain length varied a little. Interestingly the cut off was the same at 3 secs. So we can probably assume that it is the guitar(s) ?? just to make sure; I did try different cables, various lengths and manufacturers (Cable guys; FenderCustom Shop; and Planet Waves).

Whilst I was doing this testing, I thought I’d try to eliminate the nut issue so I detuned the B string to A. Fretted at the 12th the sustain wasn’t as long as the open string; but no way near as dramatic i.e instead of 3-6 secs it lasted for about 11 secs. So, significantly better.
Which leads me back to the frequencies (and nodal points). To test that; I tried fretting the high E string at the 7th fret. Contrary to my original statement that it was fine; it wasn’t. It wasn’t quite as bad at about 5-7 secs.
Frequency of open B string is approx 494 hertz, fretted (so an octave higher) it is approx 988hz. Beginning to make me think that some guitars might just have a dead(ish) frequency range for resonance. ???

As an aside; yesterday I took the guitar into another shop where I have bought a number of guitars and equipment and frequently visit when passing. He tried it unplugged and we could hear a buzz at that frequency (and only at that frequency). He thought it was a truss rod that was slightly loose as he had had that before and it wasn’t fret buzz etc. Funny thing is I can’t make it happen at all. I can only get a twang as it hits the frets if I pluck very hard.

So looks like it’s back to the place I bought it to see what they (or PRS) can do. That won’t be this week as it’s holidays and we have grandkids to look after.
Take care all
Title: Re: Sustain dying out
Post by: Dan Graves on August 13, 2018, 04:31:53 pm
Ye gods, you went into these calculations so deeply we've almost left the land of setups and waltzed into the world of mathematics and algebra  :o
Respect for being so unbelievably thorough though, you've pretty much eliminated all of the usual suspects.
Do keep us posted, because I'd genuinly like to know how they'll solve it.
Title: Re: Sustain dying out
Post by: Styrr on August 13, 2018, 07:59:30 pm
Ye gods, you went into these calculations so deeply we've almost left the land of setups and waltzed into the world of mathematics and algebra  :o
Respect for being so unbelievably thorough though, you've pretty much eliminated all of the usual suspects.
Do keep us posted, because I'd genuinly like to know how they'll solve it.

Not surprising really. Background of Electrical and electronic engineering; plus 20 years  of software engineering. Degree in maths/physics /computing along with a lifetime career in resolution of problems.
All of this taught me to beware of making assumptions and to try and get to the core of the problem.

Which leads me on to my research assumption failure. Of course I tried with “sustain dying out”. This just led me mainly to problems of choking out on bending. When I tried a different approach :- dead notes it seems that I am not alone in having this problem and one of the solutions is a loose truss rod (another is a fret not seated fully).


Not sure I am convinced that those solutions are reasonable and viable. And to be honest not even going to try sticking fishing weights on the B string. Even if it fixed the issue it’s not a long term solution on a £3000+ guitar.

A loose truss rod is about the only thing I could try (giving that it was also pointed to by a friendly guitar shop owner). I rechecked the neck relief (always do the carpenters maxim – check twice, cut once). It was 12 thou not 10 as it was when I bought it (it’s one of the first things I do when I get a guitar home). I could adjust it and that ‘may’  tighten the truss rod. It’s not a difficult thing to do; but I am now at the stage that bo*;^!ks, let’s see what the PRS dealer comes up with. I will try and go to see them sooner than next week. Will certainly let you know how it turns out.
Take care
Title: Re: Sustain dying out
Post by: Styrr on August 25, 2018, 04:38:19 pm
Ok. The guitar has been back to the PRS dealer. Tech spent about 45 mins checking it over  making sure the set up was ok (and reducing the neck relief).  No, he couldn’t find anything wrong. No lifted fret or high fret; nut and tuners were all good; and action wasn’t too low. He tried a different B string and still the dead note was there. The only thing left to would be to return to PRS Tech centre.
I declined that option for the following reason:-
Before taking it back to retailer I did a lot more research.  In the PRS forums there are quite a few (loads) of pages about this issue. A lot of it is nonsense spouted by the usual ill-informed forum idiots. But amongst the other posts there are some incites to what’s happening and that I am by no means  alone in noticing this problem.

To summarise what I have understood:-
All guitars (stringed instruments) suffer to some extent from this.  to quote a quote from one posting

"John Suhr did leave an interesting comment:"

'All guitars will have a dead spot some place unless they are made out of concrete.

The more alive the guitar is the more dead spots you will have. PRS are not exempt either and even had a kit they would ship you to try and move the dead spot to an area that doesn't bug you as much. Changing mass in the headstock will move it like even different tuning gear buttons

A good finger vibrato would go a long way in letting the note regenerate itself as well !'

My understanding of the major reason it happens is due to the neck having one or more resonate frequencies. If that coincides with the frequency of the note being played we can get a cancelling of the sustain if it is out of phase and an increase in the sustain if it’s in phase. 
The best analogy to this hypothesis is if you have two waves on the water approaching each other where the peaks and troughs coincide (in phase) we get  heightened  peaks and lowered troughs. Where they are 90degrees out of phase we get a cancellation.  Of course this isn’t quite what happens with the water as the waves will carry on after meeting with more or less the same energy and in their original direction. With the guitar the note loses energy much more quickly. Which is a function of the fact that higher frequencies require much more energy to continue (sustain) unless there is some external energy causing resonance. Phew!

An alternative explanation could be just that if the note frequency is the same as a resonant frequency of the neck; then that’s what is ‘stealing’ more of the energy from the note. A much simpler reason to understand;  but not necessarily correct.

All this (at least in my mind) is why some people have this problem and some don’t. i.e. if the guitars resonant frequencies don’t correspond to a node point (fret) then it not as noticeable.

Other  references.
http://www.logosfoundation.org/kursus/The Science of String Instruments.pdf


My final test to check this out was to add mass to the headstock (via 2 Shubb capos). The dead note disappeared from that B string 12 th fret. I didn’t check to see where it moved to.

I will just have to play that Mark Knopfler solo on my strat.
Take care
Title: Re: Sustain dying out
Post by: Dan Graves on August 26, 2018, 10:38:22 pm
If that's THE John Suhr, then I'd say he would know, he's built plenty of guitars over the years.
Personally haven't run into true dead spots, but if John's correct when he says it's somewhere on the guitar (AKA not just the neck), my customers were a lucky bunch.

And again, wow, that research.
Also, thanks for that first link, that's one interesting paper, and one hell of a list of Physicists that worked on it  :o

One thing though, if adding weight to the headstock helps, why not just do that instead of using the Fender ?
If the PRS is comfortable enough to use...
Title: Re: Sustain dying out
Post by: Styrr on August 27, 2018, 03:12:14 pm
Yes, I believe it was THE john Suhr.

The general consensus is that the whole construction of the guitar contributes, but in these issues it is the neck that is primary culprit. The body has much more mass and is therefore harder to promote these *‘eigenfrequencies’. Adding mass to the neck seems to shift them; as attested by my experiment of adding weight to the headstock. A sample of 1 doesn’t prove this to be true but at least it doesn’t rule out the hypothesis.

The PRS is lovely to play and one of the two guitars I own for their playability and not just for their tone. All the others I have for are for particular genres or songs I like. I mostly still try rhythm and not lead. As such it doesn’t really matter that much about the dead note on the PRS.  The videos I have watched of Mr Knopfler playing wild theme/local hero, he is playing mostly a Strat or a Les Paul. So once I have the long (50+ bars) solo committed to my brain and fingers it’s then trying to get the tone right – so Strat anyway.

Just wish I could play and sound like the promo/ad for a  McNull guitar:-
If you are a Mark Knopfler fan, I recommend listening to it. Almost heresy, but it might even be better than the original.

Justin get a song lesson up on it for me  :)

*Eigenfrequency is just science terminology for saying self oscillation:- the frequencies  at which a body will naturally want to oscillate. (my definition:- which isn’t absolutely correct, but near enough I think).  If engineers get this wrong it can and has led to tragedy with some bridges oscillating to destruction.

Take care
Title: Re: Sustain dying out
Post by: close2u on August 27, 2018, 05:49:31 pm
Oh boy.
That Macmull


I did this a few years ago ... not even in the same ballpark truth be told

Title: Re: Sustain dying out
Post by: Styrr on August 28, 2018, 02:39:17 pm

that's not too shabby  ;D It is a long solo and to get it all down is a triumph in itself.
That's almost note for note for the sheet music I have for that song.

As for tone, yeah it's not going to match the ad, but they are using high quality gear not recording it with a camcorder/smart phone. If it wasn't as amazing, it wouldn't be much of advert  ;)

I get a passable tone using the bridge and middle pickup into a clean channel with a electro-harmonix soul food pedal set as a boost but with the highs rolled of a touch. (suppose you could do similar with the tone roll off slightly on the guitar and the gain up a bit on the amp)
I am having trouble with the rakes and volume swells. The rakes because it alters my timing and I find the volume swells  too fiddly with the volume knob and I am too slow with it anyway.

But we have now gone off topic

I enjoyed your version and well done
Take care