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Hello!
I think every guitar has one or two dead spots (I read that somewhere). My archtop has two of them. At fret
10 and 11 on string d the tone just fades out more quickly than on any other fret.
Can I do something to improve the tone? It has nothing to do with the strings, it stays the same when I change them.
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06-15-2015 11:47 AM
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probably a bad fret - but it might just need some dressing, not necessarily a refret or anything crazy. A competent lutheir should be able to sort that out.
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yeah I guess it has something to do with a specific frequency of the guitar itself.
Easy to diagnose by making contact with the headstock on a wall and playing the note, the dead spot very often vanish.
I have got such an obvious dead spot on the G string on 12th fret of my Gibson SG.
Some people add little weight to their headstock, but it is not something I would do on an already neck heavy guitar.
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My 125 and epi emp reg both have one.. (I forget where exactly.. it has been a while.) but i think on the emp reg it was A or D at the 12th fret. when I put a pickup in the top it moved to the 11th fret.
I never noticed one on my 165 (may have been there but I didnt notice tho) high E string 8th Fret (C).. it became noticable after I changed the heavy gibson branded grovers with lighter kluson style.
It COULD be a bad fret but I would be surprised.. a bit of weight on the headstock (like vinlander suggested) would work.. also try tuning up half a step your d string.. if it is the fret it should still be the 10/11 fret.. if it moves or changes in any way it is a dead spot.
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The Fender "Fat Finger" is a clamp designed to add additional mass to the headstock. They claim it adds sustain, and can be placed in different positions on the headstock to eliminate dead spots.
Fatfinger? Guitar | Fatfinger Accessories | Fender® Accessories
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Back in the mid '90's, the local Guitar Center had a free live concert by a local, somewhat renown, fusion guitarist and group in a large rear storage room. The guitarist was a PRS endorser and played at the time one of the McCarty hollow bodied guitars that he made sing like a bird from heaven. After the show, I was wandering around and found a small store room that was empty except for about 50 PRS hollow bodies that looked to be excess inventory. I started picking them up and picking chromatically up the fretboards from the first fret to the nut. The first ten I played all had a bunch of dead spots from around the 5th fret up to the 13th or 14th fret. After trying those ten, I figured they were all like that. Damned if I'd pay four grand for a bunch of dead spots or have to try a Fat Fingers to make them play OK.
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By tuning the d-string half a step up, I notice that the dead spot moves also. So thanks for that tipp! It seems to be a resonance thing with the guitar...
Just an idea: what about recording the frequency on a looper, play it through an amp and place the guitar in front? I heard that some people do this to "break-in" their guitars, that is, improve the response.
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It's called a wolf tone. Usually this is due to the instrument's self-resonance at a particular frequency (note). Essentially, the guitar body vibrates so efficiently at that frequency that it absorbs or "steals" the string energy, leaving a quickly decaying sound. There is not much that can be done - as you noticed, tuning things differently just moves the fretted note. The pitch itself remains the same and has the same effect.
This is more true the lighter and more acoustically responsive the instrument is. Classical guitars are often guilty of it. Years of breaking in do help to smooth out the effect, but it never totally goes away.
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As I understand it, a wolf note is the opposite of a dead spot - a note sounding significantly more forceful and often with a different timbre than the rest of the notes. The wolf note is caused by the note hitting the instruments self resonance, wheras the dead spot is the note hitting a frequency in the instrument which is in counter phase with the note so the two more or less cancel each other out. Wolf notes are well known - and hard to avoid completely - in bowed string instruments where they are heard more clearly than on plucked instruments. For bowed instruments there are small "tubes" available which can be clamped to the string in question between the bridge and the tailpiece in an attempt to tame the wolf note.
Originally Posted by rpguitar
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You dont mention if the guitar is solid or laminated top. There is a device called a tonerite (?) that will break in the top a little quicker. I remember as a kid fiddlers hanging their violins near the stereo speakers to break them in faster.. didnt really give it much thought.. then I heard of the tonerite and though of those old time fiddler but still dismissed it as a gimmick.. then saw Bob Benedetto doing ads for tonerite and though "he is a very very good businessman" I just dont want to believe it ... but I am a dick LOL Originally Posted by lapideusvir
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In bowed instruments those notes appears as a warbling tone. In a plucked instrument such as a guitar where the sustain isn't has long, they can sound like dead spots or where the note dies quickly. I own a classical guitar where the builder attempted to eliminate "wolf" tones or dead spots by affixing small ebony knobs or buttons to the underside of the top bracing thereby shifting the resonance of the top. Definitely a trial an error type of thing. There are no dead spots on that guitar so either it works or there were none prior but I'm not going to remove the buttons to find out.
I own another lightly braced flat top acoustic that has one dead spot at the F# at the 11th fret G string. Since on this guitar I don't spend a lot of time in that area and if I do it's a quick note, the effect isn't noticed by anyone except for me.
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>>Dead spots on fretboard… Can I do something to improve the tone?<<
This gets to be a complicated subject.
The short answer is: try a small amount of poster putty on the antinode of the mode that’s causing the problem.
Maybe some players or guitar techs want to learn how a few known luthiers and acoustic researchers put it straight:
The poster child of this is the 'cello wolf note'. The geometry yields a fairly low impedance at the bridge top, and when there's a strong resonance that can move the top and the bridge at a played pitch the bridge impedance can match that of the string very closely. At that frequency there is not enough energy reflected from the bridge back into the string to maintain the stick-slip Helmholtz action with the rosined bow that keeps the string going, but ONLY at that frequency. This is normally the fundamental of the string tone; the second partial an octave higher still 'sees' the bridge as a good termination. The string thus shifts up an octave in pitch. When that happens the body resonance is no longer being fed, and the vibration at that frequency dies out. When it does the bridge top is no longer moving, and the string'sees' it as a termination at the fundamental frequency, so that starts up again, and the pitch shifts back down. It's the pitch shift, several times per second, that gives the 'cello wolf' its growl.
Though less common to notice, it's possible to hear the same thing on the guitar at the pitch of the 'main air' or 'main top' resonant modes. The usual outcome on the guitar is simply a note that's twice as loud for half as long as the one next to it. A guitar has 'low impedance to energy transfer' (= high admittance) at some very specific frequencies, namely its modal resonant frequencies, so energy from a vibrating string will tend to transfer rapidly from the string to the guitar top at those frequencies, resulting in a short duration, initially loud tone, frequently referred to as the guitar wolf tone. When the mechanical impedance of the string and the mechanical impedance of the top are the same, maximum rate of transfer occurs.The higher the impedance mismatch, the lower the rate of transfer. A wave traveling down a guitar string hitting a perfect impedance match just travels on as if the string was infinite in length and the energy in the wave dissipates into infinity. The more normal situation is that an impedance mismatch occurs (e.g. at the bridge) and some of the wave is reflected and some is transmitted across the interface. The reflected part of the wave in the string interferes with the oncoming waves to produce standing waves in the string, which happens at specific frequencies and we see it as a"normal" string vibrating at its resonant frequency. So managing impedance mismatches is critical to guitar design, as this determines whether or how much of a wave is transmitted from one part of a guitar to another, which subsequently determines"volume and tone".
1. On instruments of the violin family a wolf is usually reduced or eliminated with a dynamic attenuator known as 'wolf tone eliminator'.
2. Occasionally, switching to a heavier or lighter string gauge, can mitigate the problem by providing a larger mismatch of impedance, even if the pitch of the resonance is not changed.
3. As dead spots follow the pitch, not the fret, there are other possible solutions. The pitch on 10th fret4th string is C4 at 262 Hz; the pitch on 11th fret 4thstring is C#4 at 277 Hz. At least in theory (only less perceivable), these frequencies are also compromised by the 'wolf' on the corresponding frets 3rdand 2nd string. Chance is that the problem is around the 'main top resonance' (MTR) of this archtop guitar (a smaller one?). So adding mass to its antinode, here at the centre of the bridge, might help - try a heavier bridge! If the MTR drops to about 255 Hz, all should be good.
4. If you don’t like to reduce the acoustic power of this guitar by adversely adding some mass to the bridge, you can go a different route (though take care not to be messing with the static stiffness of the top). Violin makers have a useful rule of thumb (applicable also to archtop guitars): if you get the frequency reduction you want by adding a gram of mass, you’ll need to take off three grams of wood in the same spot to get the same frequency drop. Once you knew exactly where to work, you could remove wood from the top plate (and/or brace). Ok, this should be of more interest to the builder from the outset…
5. Some guitar builders know at least one effect of the guitar neck on tone, respective on dead spots: when the lowest resonant mode of the whole body/neck system is high enough in pitch to match the 'main air' resonant frequency, the two can couple. The result is that the 'main air' peak is lower than it would have been, and split into two peaks with a dip in between. The power can actually be greater than it would be without the coupling, and there is also less chance of a 'wolf' note at the 'air' pitch.
Since the headstock moves a lot in this 'neck' mode, the mass out there is a big factor. This is why some guitars get a big change in the tone when the tuners are swapped out, and others don’t. The closer the construction of archtop guitars is to pure electric guitars (most mass-fabricated "archtops" will fall in this range, regardless of their actual price range, and nearly all semi-acoustic guitars - the latter are just a special sort of solid body guitars), the more the neck will be the most flexible and moving part of the instrument, and in doing so it alters the way the strings work and what the pickup ‘hears‘.
6. A sound post can be tried on the more electrically intended archtops; some will be surprised how little it will change the overall tone.
7. Some players don’t care at all even about multiple dead spots of their archtop guitars - they call it "character".
Yes, all physical objects have resonances and dead frequencies, though the difference in consistent quality, including the dead spot issue, among archtop guitar (and violin-related instruments) manufacturers was always huge - the more it is presently!Last edited by Ol' Fret; 06-15-2015 at 07:53 PM.
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If you are going to quote luthier Alan Carruth at least give him credit. If you are Alan Carruth. I apologize.
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LOL, no apology necessary! I hope this forum is not a scientific peer review community, so I don't have to quote any source used! If it is: I'm never afraid of swimming in shark pools, though it's usually a waste of time - time rolls on steadily and eludes us as it steals past (quote: Ovid).
Yes, Alan Carruth is absolutely worthy of honor when it comes to music acoustics of stringed instruments. Wish he would address more archtop-related topics!
Much above, among some other luthiers, is quoted from his statements. Nobody, IMO, can put it more precise in words at the moment. He has answered so many coherences. If people would only read and/or believe - the guitar world could easily be a better one, though we all know that some sketchy global players would try to intervene instantly!
Actually, I'm quite pleased that at least one member here has heard about Alan - even through his implementations!
Now we can discuss about the work and research of generous luthiers, past or present, or try to give the OP something on hand how he can educate himself and fix the problem of his axe.
The question remains... why so little deep insights from really knowledgeable guitar (and violin) builders seem to arrive (not only) in this gear corner. If customers don't make every effort in getting self-educated, they'll end up as guinea pigs for fewer and fewer, but ever more powerful multinational corporations.
This excuse would be expected: time is money, and only the high and mighty get heard (or are worthy to be cited). Sure, it has always been so! Already Seneca talked about the man who is very busy, but has no time for the nitty-gritty of life: homo occupatus.Last edited by Ol' Fret; 06-15-2015 at 10:18 PM.
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Thanks a lot!! I learned quite a bit and will try out these different things. When all doesnt work I will call it "character" of my guitar! :-) btw, it is a laminated 15" archtop (Peerless MT).
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I thought I had a pretty good understanding of what wolf tones / dead spots are, but I realize that there are much more to it. Thanks for providing additional (and partly corrective) information.
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Talking about fiddlers dangling their violins in front of stereo speakers it does work for solid topped acoustics...
This is a renovation I did a while back. This guitar (Fender Japanese, 70's) needed to be rehydrated as it was seriously abused.
After everything was fixed I looped harmonised scales in G, C, D and E and left it for 8 hours. The result was amazing. You could feel the body fighting against itself with some notes/frequencies before the looped scales but after it was as if it was 'played in'.
Stradivarious violins that are locked away in collections have to be played in before concert season.
As for dead spots heavier or lighter tuners can help. Hollowing the underside of the wooden bridge or a different wood is an idea. Changing a wooden bridge to a metal tune-o-matic would help, you could put nylon saddles on to soften the string tone.
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A wolf note is from a note that matches the guitars own resonance frequency.All guitars have there own resonance frequency or f0. This type of resonance is found when a guitar is in equilibrium with acting forces (plucked string). Changing a guitars f0 after construction is not always easy. The f0 belongs to the guitar as a unit and not just the top or back or neck or bridge but the entire guitar. That is why so many things can influence the f0. The best f0 is one that is in between 2 notes from the musical scale.
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Tonerite...I took a pair of those Nakamichi-branded My Mini Plus speakers. With an adaptor I hooked them up to the 3.5mm socket of a smartphone, MP3 or portable CD player. Then I placed the mini-speakers on the top of the guitar lying supine, one on the bass side, the other on the treble side, next to the bridge. Originally Posted by SamBooka
And let them rip with whatever music you wish to hear. Like some Gary Karr, for instance. Or Yo Yo Ma. Works the top a treat. The batteries last 5 hours so I have them tethered to an USB charger on a power strip.
I don't know if they work as well as Tonerite but at least, these things blast music and are useful for something else. Music sounds better too tonally coloured by the wooden top and augmented by the body cavity of the guitar. Recorded stringed instruments sound more "real" with better bass response. Voices sound more "life-like".
Oh yeah, when no-one is home try looping this: http://www.amazon.com/XLO-Reference-...ds=xlo+cd+disc . You could balance the mini-speaker on the strings over the bridge and then it works like a Tonerite.
PS I don't think anyone would be crazy enough to do it like I do. But if you are, please protect the nitrocellulose surface of the guitar top with a sheet of thin paper each under the mini-speakers.Last edited by Jabberwocky; 06-16-2015 at 03:42 PM.
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Ok.. so off topic but whatever.. something that DOES break in are speakers.. I bought a cheap monoprice sub for my computer and was a little disappointed in the sound but hey.. it was cheap..EQ it as best I could and then forgot about it...
The next day i was doing cleaning in the basement with my daughter and she wanted to hear Katy Perry.. sigh...
The day after THAT I tried the speaker again without thinking of it and woah.. the bass was wwwwwaaay off (much to loud).. duh.. new speaker.. break in period etc etc.
Ted Weber charges to break in speakers.. I think they do like 100 hrs or something. And for the nuts like me you can carefully
break them in using a variac .. provided your wife doesnt go nuts from the noise.
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Originally Posted by lapideusvir
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Without going through all contributions: the problem may be either a neck or body resonance or a badly seated fret.
In the latter case, if you tune half step down, the bad frets will stay, sounding notes half step deeper with the same problem. If it's a resonance, it will shift to wherever the same frequencies then are (roughly, because with changed tuning and thus string tension the whole system of resonances also moves in a difficult to predict way).
I have used lead pieces from fishing supply store and attached them to the heads of guitars - that shifts effectively the resonance frequencies. You can experiment incrementally with different weights. When you have found a good weight, you can think od a more permanent solution with that weight. Sometimes not much is necessary.
This is more extreme example for testing purposes:
Also changing the string tension shifts the resonances a bit and that can be sufficient for the problem at hand.
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I know that acoustically, changing Stop Tailpieces on semi-hollow guitars causes changes in tone, and loudness. When plugged in ??? Difficult to gauge.
I bought a guitar that had a very lightweight aluminum TP. It weighed almost nothing. And the tones were not working for me. I put a heavy TP on. That evened things out quite a bit.
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