New guitars and unbalanced tones

bluetrain

Hi!

I have a new guitar (quite expensive one from France) and couple of notes play a bit louder than others on the neck. I'm trying figure out how I could balance the sound if it's possible at all. Especially on the A-string and on the 11th fret the note really makes the guitar body resonate and it's loud but it dies also really quickly. It's quite irritating and something I would not expect to have on this expensive guitar. Is this something I would expect to balance out with time when the guitar breaks in naturally?

My older guitar had also some unbalanced notes and actually they balanced out quite a bit after I refinished the guitar.

Jazzaferri

Sounds a bit like its a "wolf" tone thing happening.....hopefully one of the luthiers will jump on this one

I am not clearly understanding if it is one pitch in different parts of the guitar or different pitches....if it is different pitches...less likely to be a wolf note if it is a couple of different pitches.

bluetrain

It's one pitch that dies out very quickly and especially on the a-string. On d-string the same effect is less pronounced. This guitar has a low air resonance tuned to low E-string (around 82hz). My old guitar had the air resonance between G and G# (around 100hz) and this same "wolf note" effect on d-string on 10th fret.

noodlenot

sorry, what is the note that gives you the wolf? is it A string, 11th fret : G#? i don´t have much experience with selmer tops (unfortunately), but that´s close enough to the generic main top resonance on a classical guitar.
How new is the guitar? if it´s really new and underplayed you might get lucky in the long run. have you tried changing strings to a different tension ones? what about sticking some putty around the bridge area - does it lessens the phenomenon?
maybe someone with more experience can help. i do wish you luck, wolf notes can get tricky to pinpoint.

best,
Miguel.

Craig Bumgarner

Diagnosing something like this via text can be tricky, but I'll take a stab at it. And before going further, I bet the builder would be interested in having the first shot at solving the problem for you.

What you describe sounds like what is commonly called a "wolf note". If the frequency of any of the predominant peak resonances of the guitar land on a scale note, that note will be louder initially but decay quicker than other notes.

G# on the 11th fret of the A string is 207.65hz (at A=440 Concert Pitch). This is lower than the 220-235hz main top resonance I've found on most Selmer style guitars I've looked at but not unheard of.

There are couple ways of testing a wolf note. Be SURE your guitar is in tune to concert pitch. If this is not A=440, the tests below still work, but the note frequencies are not the same. G#, for instance will not be 207.65hz. Again, this does not matter in the tests below. Just tune to the concert pitch you usually use, but be sure it is accurate, i.e. use a tuner.

1) tune the offending string(s) down or up a quarter step and see if the problem goes away. Tune down a half step and see if the problem moves to the 12th fret.

2) add a little weight to the bridge area as Miguel suggests. Blue poster putty works well enough for this. 10 grams should be enough, though you can try various amounts. The added weight will lower the top resonance some and again, the problem will go away or move elsewhere. Try moving the putty to various locations on the top (and the back if you are curious) to see what effect this has.

3) does the same G# on the D string, 6th fret or 1st fret on the G string react the same way? It should in theory, but sometimes there are other elements at play. Again, be sure all strings are perfectly tuned.

If these tests confirm the wolf note, what is to be done? The solution, besides tuning a quarter step down all the time, is to shift the offending peak resonance off the scale note. There are a variety of ways from easy to seriously serious, but things get complicated fast, and unintended results can occur, so probably best not to offer DIY advise here. Better to take the guitar to a luthier who understands these things for advise and consult. And again, the builder would be the first expert to check in with.

If you prefer DIY, suggest reading Gore & Gillet's Contemporary Acoustic Guitar Design first.

Craig Bumgarner

bluetrain wrote:

My older guitar had also some unbalanced notes and actually they balanced out quite a bit after I refinished the guitar.

Yes, this would make sense in that refinishing most likely changes the mass of the top which in turn shifts the peak resonant frequencies, presumably away from the offending scale note in your case.

Mandobart

When you mention "unbalanced tones" - could this be from sympathetic vibration of the strings between the tailpiece and bridge (aka the "afterlength")? This is something most mandolin players deal with by something to physically dampen this part of the strings, like a piece of leather woven between and around the strings between the bridge and tailpiece. On bowed instruments, the design of the instrument is such that the afterlength is 1/6th of the free vibrating length (nut to bridge distance) and for some reason this prevents such problems.

A "wolf tone" is usually only found in bowed instruments, due to constant string vibration with the bow. It sounds like a wavering tone, like a siren. In an un-amplified picked instrument like a guitar, you can't sustain a long enough note to get a wolf tone, even if there was a potential to develop one.

Jazzaferri

The concept of wolf notes is something that all luthiers of acoustic acoustic electric instruments have to understand and work around.

bluetrain

Thanks for your replies guys!

Now that I know the right term "wolf note" I did some googling and found out some discussion especially on classical guitarists trying to figure out how to tackle their "wolf notes". Even John Williams had these problems and he get's the best guitars in the world! It's surprising to me that "wolf notes" do not appear that much on factory made cheaper guitars as much as they do appear on more expensive hand made guitars. I'm wondering if this is because hand made guitars are usually more responsive than factory made guitars? Here's the link: http://www.classicalguitardelcamp.com/v ... 43&t=13814

Craig, It is definately a "wolf note" that I'm dealing with. The G# on A-string plays really loud and dies really quickly and tuning the string does not change this. If I tune half step lower then the "wolf note" appears on 12th fret which is still G#. On D- and G-strings the effect is similar but the notes have more sustain to a degree that it doesn't bother me. On A-string however the notes die very quickly and of course in this area of the fretboard with A-string there's not much sustain anyway so maybe that's one reason the effect is so pronounced. I haven't tried adjusting the weight of the bridge yet but I'll take a look at that at some point. Right now I got idea that I try to lower the humidity in my room from 50% to 35% and see how it affects. The luthier (Jean Barault) who built this guitar said that in his shop there's air humidity of 20-25% all around the year so maybe the big humidity difference might be one reason for this. Actually it was a huge suprise to me that the humidity is so low in his shop. Jean said that I should try 30% humidity. The guitar is three weeks old and Jean also said that I just should give the guitar more time but it hasn't changed during the three weeks so... maybe I'm just over critical.

Sadly when I got this fantastic guitar there was a trussrod issue right away and I have to send the guitar soon back to Jean. I don't see that the trussrod would affect how top vibrates.

Craig Bumgarner

bluetrain wrote:

I'm wondering if this is because hand made guitars are usually more responsive than factory made guitars?

Oh yeah, for sure. The more responsive an instrument gets, the harder it is to control. Channeling a high performance guitar is a large part of a luthier's job, but it is also partially the player's responsibility too. Just a like it takes both the mechanic and the driver to get the best out of a high performance race car.

One of the rewards of a responsive guitar is it is capable of more voices and nuances than a less responsive instrument. It is the player's job to tease these out in the fashion desired. Not that controlling a wolf tone is necessarily a player's responsibility.

I can't quite see the humidity connection, but this kind of thing is complicated and I would be interested to hear how this experiment turns out. The humidity level affects the arch of the top among other things and the degree of arch alone may be vary the top stiffness alone enough to shift the offending peak resonance.

20-25% seems low to me, but the climate where I am is damper than northern Europe where indoor humidity levels can get very low. Drying out is usually more harmful physically to a guitar than humidification, so the builder is probably anticipating the very dry environments of heated northern homes to prevent cracking, etc.

What was the truss rod issue if you don't mind me asking? Did the wolf note problem change before and after?

If you want to get a little deeper into this, you might want to take a frequency response curve of the guitar. There are several good software apps for this. Visual Analyzer (free) for PC and FFT (~$10) for smartphones. Either will give you a curve like the picture below just by tapping the guitar top. Visual Analyzer in particular will allow for very accurate determination of peak resonant frequencies. FFT is good enough though and easier to set up. If you are interested, PM or email me, and I'll help you get set up. With this, you can quantitatively see where the peaks are and more importantly how they are changing with efforts to shift them. In the screen shot below, the first peak around 100hz is the main air resonance and the 2nd peak is the main top around 238hz. Again, this stuff is complicated, so not recommending major surgery based on something like this. It is just one tool among many to understand what is going on.

bluetrain

The more responsive an instrument gets, the harder it is to control. Channeling a high performance guitar is a large part of a luthier's job, but it is also partially the player's responsibility too. Just a like it takes both the mechanic and the driver to get the best out of a high performance race car.

That's well said!

What was the truss rod issue if you don't mind me asking? Did the wolf note problem change before and after?

The trussrod issue came immediately when the guitar arrived to me so I can't say did it have any effect on the wolf note. There's a tiny crack in the neck close to the zero fret (the side where the hand touches the neck) so apparently the trussrod cracked it at some point.. maybe a fault in the wood or something.

I'll write more on this topic when I get the guitar back. Thanks for your replies this far!