myth-busting: Resonance is not synonymous with Vibration

[BassJuju]

So, I like a bass that produces a pleasant and somewhat loud tone when played acoustically. I’ve found ones that make little to no sounds when played acoustically to be, um, not good.

So, what is the proper term for that quality?

 

[Dr. Keebs]

So, I like a bass that produces a pleasant and somewhat loud tone when played acoustically. I’ve found ones that make little to no sounds when played acoustically to be, um, not good.

So, what is the proper term for that quality?

I have no bearing to comment, because I'm probably a dunce with this stuff. But, if I may, I'd say that quality is structural stability. Or something like that. I'm ok being flamed if I'm wrong, because I might be able to learn a thing or two here.

 

[Killed_by_Death]

if only I'd read tb before studying Acoustics.

I hope I don't end up repeating myself like this too many times.
This is NOT about Acoustic instruments!

 

[bobyoung53]

For any physics majors here, great article, I'm not one and only skimmed it but this is what causes dead spots, they even use a Strat and guess where the dead spot was found on the Strat, yup, 4th fret G string. There are also live spots on a guitar or bass where the note vibrates for an unusually long time. Normally the higher up on the neck you go the shorter the sustain, any thing not in line with that is either a dead spot or a live spot, very interesting article.

From the article:

"A dead spot, defined by an abnormally fast decay of the fundamental tone, is caused by damping due to energy transfer from the string to the instrument body. ."


"Why is the "sustain" generally better for an electric guitar or bass than for an acoustic one?

The musical signal of an electric guitar or bass originates from string vibrations. In contrast to comparable acoustic instruments, the electric ones do not radiate the sound themselves. Since there is no need to transfer energy from the strings via the bridge, the body may be made from solid material. The string supports are relatively immobile and the strings vibrations, consequently, do not decay as rapidly as for a self-radiating instrument. That means that the "sustain", which is considered as a quality attribute, generally lasts longer for an electric guitar or bass than for acoustic models.

What are "dead spots"?

However, this long decay is not observed for each fret at which the player fingers a string. There are particular locations on the fingerboard where the sustain of a string is considerably shorter than for adjacent frets. This irregularity is well-known among players of electric basses and guitars; they call it a "dead spot". An electric guitar of the well-known Stratocaster type is chosen as an example to illustrate the effect and its diagnosis.

How can dead spots be quantified?

The sustain is quantified by the decay time (in our investigation: defined by a 30 dB level difference) of the total signal at the output socket of the neck pick-up. In the normal case, the decay time decreases steadily with increasing fret number. As an exception to this rule, the decay proves as uncommonly short e.g. at the 4th fret of the D string of the Stratocaster indicating a dead spot. At the same string the contrary ("live spot") holds for the 11th fret. An additional study has revealed that the decay of the total signal is ruled by the fundamental tone of the complex string signal."

The string may induce body vibrations via the neck rather than via the bridge. Energy is transferred to the instrument and gets lost for the string vibration. The "vibration willingness" of the neck is the cause for additional damping of the strings, i.e. for dead spots.


ASA/EAA/DAGA '99 - Dead Spots of Electric Guitars and Basses.

 

[BarfanyShart]

This discussion makes me think about the problem of wolf notes on DB. That is essentially over-resonance at certain frequencies that interferes with the string's vibration on certain notes. A bad wolf tone is crazy when you are bowing, because the string suddenly become hard to bow, you apply more force to produce the note, and then that force kind of releases in a vibration throughout the entire instrument that is like a percussion instrument - like a drum head's vibration, as opposed to a pitched string. People add mass or tension to their strings to shift the wolf up or down a little, so as to avoid it while playing in tune. I had a crazy wolf on my EUB on low A (they are usually an octave higher on a real DB) that magically disappeared when I switched to fifths tuning. The wolf probably moved to a different note somewhere, but I haven't found it.

 

[bobyoung53]

This discussion makes me think about the problem of wolf notes on DB. That is essentially over-resonance at certain frequencies that interferes with the string's vibration on certain notes. A bad wolf tone is crazy when you are bowing, because the string suddenly become hard to bow, you apply more force to produce the note, and then that force kind of releases in a vibration throughout the entire instrument that is like a percussion instrument - like a drum head's vibration, as opposed to a pitched string. People add mass or tension to their strings to shift the wolf up or down a little, so as to avoid it while playing in tune. I had a crazy wolf on my EUB on low A (they are usually an octave higher on a real DB) that magically disappeared when I switched to fifths tuning. The wolf probably moved to a different note somewhere, but I haven't found it.

In the above article I just reference they call Wolf tones a "live spot" as opposed to a dead spot. I had just the opposite of you, I had a dead A on my upright. Really bad place for a dead spot.

 

[Honkey tonk]

if something never vibrates how would you know its resonate

 

[micguy]

Gosh, if only I'd read tb before studying Acoustics... my loss

I studied Acoustics first, myself, and yes, it can be frustrating. ;-)


Dead spots on an electric instrument are a result of resonant modes of the neck (a neck has several resonant modes). For any given mode, there are places that move a lot (antinodes), and places that don't (nodes). Having a resonance in a neck is not inherently a bad thing, but when the antinodes of a specific mode line up with a fret location of that note, the neck (since it moves easily at that point) will steal energy from the string quickly, resulting in the dreaded "dead spot".

On any neck, there will always be areas of diminished sustain - that's unavoidable. By changing stiffness and mass distribution on a neck, you affect the locations, frequencies, and severities of places with diminished sustain. If you succeed, or get lucky, and your areas of diminished sustain are not very noticeable, you have avoided "dead spots".

The idea of having resonance, while trying to make it relatively even across different notes, is an issue for electric and acoustic instruments. For an acoustic to project, it has to steal energy from the string, but if the sustain of different notes is vastly different, that's also a problem. An acoustic has both ends of the string stealing energy - the body end using vibration to produce output. On an electric, the body is relatively fixed; it's the neck end of the string that needs the most attention in terms of evening things out..

A roasted neck, because the roasting crystallizes the resins in the neck, has less damping than a normal wood neck. Hence it has more "resonance". I have a few necks that are roasted, graphite reinforced, thick cross section (p width rather than J), and that have light weight tuners on the neck. The first 3 factors add stiffness, the last reduces mass loading. All of those 4 factors move the neck resonances up in frequency, changing the location and frequency of the most obvious neck mode (that one on the G string of a Fender or similar design), reducing the dead spot to a more benign form of reduced sustain area. So, despite reduced damping/more resonance (which would tend to make dead spots more of a problem), the thing has less problems with dead spots

Still, the reduced damping in the neck is quite noticeable - you tap the back of the neck, and the thing rings like a bell. That enhanced resonance adds to the joy in playing the thing. The instrument feels alive, yet avoids dead spots.

 

[bobyoung53]

I studied Acoustics first, myself, and yes, it can be frustrating. ;-)


Dead spots on an electric instrument are a result of resonant modes of the neck (a neck has several resonant modes). For any given mode, there are places that move a lot (antinodes), and places that don't (nodes). Having a resonance in a neck is not inherently a bad thing, but when the antinodes of a specific mode line up with a fret location of that note, the neck (since it moves easily at that point) will steal energy from the string quickly, resulting in the dreaded "dead spot".

On any neck, there will always be areas of diminished sustain - that's unavoidable. By changing stiffness and mass distribution on a neck, you affect the locations, frequencies, and severities of places with diminished sustain. If you succeed, or get lucky, and your areas of diminished sustain are not very noticeable, you have avoided "dead spots".

A roasted neck, because the roasting crystallizes the resins in the neck, has less damping than a normal wood neck. Hence it has more "resonance". I have a few necks that are roasted, graphite reinforced, thick cross section (p width rather than J), and that have light weight tuners on the neck. The first 3 factors add stiffness, the last reduces mass loading. All of those 4 factors move the neck resonances up in frequency, changing the location and frequency of the most obvious neck mode (that one on the G string of a Fender or similar design), reducing the dead spot to a more benign form of reduced sustain area. So, despite reduced damping/more resonance (which would tend to make dead spots more of a problem), the thing has less problems with dead spots

Still, the reduced damping in the neck is quite noticeable - you tap the back of the neck, and the thing rings like a bell. That enhanced resonance adds to the joy in playing the thing. The instrument feels alive, yet avoids dead spots.

I'm going to ask the mods to combine this post and my post above as a sticky with the bottom article link as it could stop many arguments that happen here over and over again. The article I referenced didn't explain how to get rid of them just explained why there are live and dead spots. I just asked a mod about it, we'll see because this keeps coming up over and over again.

ASA/EAA/DAGA '99 - Dead Spots of Electric Guitars and Basses.

 

[micguy]

In the above article I just reference they call Wolf tones a "live spot" as opposed to a dead spot. I had just the opposite of you, I had a dead A on my upright. Really bad place for a dead spot.

Open A string is a dead spot that also shows up on some headless instruments. The worst dead spot I ever ran across was a headless travel bass - the open A string was just a thud - no real semblance of a note. The neck shook violently for a tiny bit when you plucked the string, then it was over - the neck literally stole that note's energy before it got started when you tried to play it. You can also run into this resonance on a regular bass if you tune the A string down - one of my basses, when I tuned it to D standard (the A string becomes a G string), it had a relatively obvious dead spot on the open G. The solution there was more mass on the headstock, which moved the resonance down in frequency - off the neck, so to speak.

 

[James Collins]

The less the instrument resonates, the better for the sound coming out of the pickups. It's not a matter of resonating well or poorly.

That's fine, but your original post uses the phrase "resonates well". I think your original post is the type of post that doesn't define terms that leads to more misinformation. "Resonates well" could mean a number of things. Just trying to point out the opacity so you can have a better conversation.

 

[jamro217]

The basic concept is that in order for the maximum sustain and response from the strings the rest of the instrument should be rigid. The more flexibility the instrument has the less the strings will resonate. The movement in the instrument cancels out the movement of the strings.

 

[bobyoung53]

Open A string is a dead spot that also shows up on some headless instruments. The worst dead spot I ever ran across was a headless travel bass - the open A string was just a thud - no real semblance of a note. The neck shook violently for a tiny bit when you plucked the string, then it was over - the neck literally stole that note's energy before it got started when you tried to play it. You can also run into this resonance on a regular bass if you tune the A string down - one of my basses, when I tuned it to D standard (the A string becomes a G string), it had a relatively obvious dead spot on the open G. The solution there was more mass on the headstock, which moved the resonance down in frequency - off the neck, so to speak.

That is about the worst place to have a dead spot, mine was pretty bad too, I finally got rid of it.

 

[Killed_by_Death]

original post uses the phrase "resonates well"

I think almost everyone reading will understand that the myth of resonating is a good thing is shown right there in the opening post.
You're the only one who misunderstood & continued with the myth.

 

[bobyoung53]

So, I like a bass that produces a pleasant and somewhat loud tone when played acoustically. I’ve found ones that make little to no sounds when played acoustically to be, um, not good.

So, what is the proper term for that quality?

I don't know but that's different than what we're talking about, ever blow on a empty bottle top and get a note out of it? That's the resonant frequency of the column of air inside, basses have resonant frequencies too and if you hit that frequency with any certain note it will suck the energy out of the string and make it sound dead. Fenders are famous for dead 4th 5th, and 6th fret dead spots on the G string although the newer ones are much better in that regard.

 

[Killed_by_Death]

The more flexibility the instrument has the less the strings will resonate.

Exactly, & the stiffer the neck & body, the better the strings can vibrate, which is why necks with reinforcement (graphite/Ti) generally don't have dead-spots. (or at least less often than non-reinforced)

 

[James Collins]

You are over generalizing all resonance as bad. A hofner or a starfire doesn't have a bunch of dead notes just because the bass is more resonant than a precision bass. Good night man.

 

[micguy]

That is about the worst place to have a dead spot, mine was pretty bad too, I finally got rid of it.

I ran across that travel bass in a GC, took it down off the wall, and didn't even plug it in - it was sooo bad that there was no point. I had been thinking about ordering one, but was lucky that I found out about the issue without having to shell out any cash.

 

[Kro]

Gosh, if only I'd read tb before studying Acoustics... my loss

Is he wrong? If so, feel free to actually contribute.

Certainly somebody with your pedigree could help forward the discussion.

 

[Killed_by_Death]

A hofner or a starfire doesn't have a bunch of dead notes just because the bass is more resonant

Again, you're confounding Resonance with Vibration. They are NOT synonymous!
I'm begging you to open your mind & learn instead of just arguing your 'opinion'.