Best practices for a floating bridge

[Helmholtz]

At what volume level? Acoustic energy depends on the physical movement of air.

In his book "Physics of the Electric Guitar" Zollner shows plots of the relative decay times ("sustain") of string harmonics up to 8kHz. Bridge resonances show as shorter decay/sustain at the associated harmonics/frequencies. Measurements are standardized and thus results don't depend on level. No air movement involved.

As the bridges didn't show any signs of vibration up to 700Hz, no significant vibration is transferred to the guitar body via the bridge. In other words, the direct vibrational coupling between strings and body of the analyzed solid body guitars tends to zero (acoustic guitars are a completely different matter). And this is good as otherwise sustain would strongly suffer. Vibrational energy that is once transferred from the strings to any other part of guitar practically has no chance to re-enter the string and thus is lacking from the electric signal.

It could be shown that vibrational energy is indeed transferred from the strings to the neck especially at a number of neck resonances. From this it seems that the sustain is primarily influenced via the neck. As the guitar body is rigidly coupled to the neck, it becomes part of the vibrational modes of the neck, thus considerably influencing neck resonances and damping. So the body's stiffness, shape (including type of neck joint) and mass matter.

It also could be shown that the guitar players hands (and belly) influence neck resonances and damping/sustain.

As there is little chance to excite string vibrations via body > bridge > string, acoustic feedback most probably works by the moving air "shaking" the neck or directly exciting the string.

Appearance aside, would you really consider subbing your strat body for one made of rubber or steel to have insignificant tonal affects?

No, see above. But I am conservative .

I'd be interested in seeing it if you have a link.

My little summary above is based on long time studies of relevant literature. Especially many papers and academic theses from Prof. Fleischer and others - and above all Prof. Zollner's books as well as private "conversations" with Zollner. Unfortunately most of the material is in German. And yes it's rather "scientific". Zollners chapter on "String Dynamics" comprises 68 pages.

You might inquire at https://www.gitec-forum-eng.de/landi...-news/contact/ to see if Zollner's book "Physics of the Electric Guitar" is available in English meanwhile, or ask them specific questions.

[Helmholtz]

I often read statements like "the guitar bridge needs to transfer the string vibration to the body". At least for solid bodies this is completely wrong. Rather the main purpose of the bridge (as well as nut and frets) is to reflect the travelling string wave back into the string to produce a standing wave without losing energy - just like a rigid wall "reflects" a ball (a thin or soft, yielding wall would steal energy from the ball).
With acoustic guitars it's somewhat different as the light weight bridge must transfer (a small) part of the string vibration to the vibratory guitar top to produce sound. Consequence is reduced sustain.

[Leo_Gnardo]

It also could be shown that the guitar players hands (and belly) influence neck resonances and damping/sustain.

So, skinny electric guitarists get more sustain, the guitar body vibrations would be damped by pressing against a mound of flesh - how about that ! ! !

And yes it's rather "scientific"

Those of us who aren't "science deniers" will have to accept the facts. Watch your diets, dial down the beer consumption, and plenty of situps folks! Arrrrgh...

[Helmholtz]

So, skinny electric guitarists get more sustain, the guitar body vibrations would be damped by pressing against a mound of flesh - how about that ! ! !

Maybe, but a strong, round belly might have less contact area...

Actually the influence of the fretting hand is stronger as the vibration amplitudes at the neck are much larger than at the body and it's easier to damp a lower vibrating mass.

Both effects are relatively small but interesting. And they do support the underlying theory.

[Fluoroscope 5000]

I would definitely consider swapping a wood body for something like a urethane foam body (of which one guitar I have is made). It has the virtually same damping characteristics as a medium weight wood like Mahogany, Alder, etc. probably with less high end damping.

One thing about the thick metal bridge damping factor the tests may not show is the movement of the entire bridge (rather than resonance) with regard to the material it's anchored to. Surely, picking and strumming is enough to move the total bridge mass significantly. Imagine how much it would move when strumming if it were just hanging freely. It then becomes a matter of how much the body allows for bridge movement -- how it ends up damping some portion of the string attack. Softer/lighter-weight bodies do tend to have a softer/rounder attack in my experience. I also think raising a hard tail style bridge off the body with Steel washers would reduce damping in some ways.

[Helmholtz]

One thing about the thick metal bridge damping factor the tests may not show is the movement of the entire bridge

Agree that the transient movement of the bridge during attack wouldn't show in these decay time measurements.

As the bridge always returns to its original position, it can be assumed that the bridge movement is resonant as well but presumably at a frequency below the lowest string fundamental. This kind of bridge resonance would show as a frequency modulation (vibrato) of the guitar signal for a fraction of a second. It would steal some of the attack energy.

[Helmholtz]

Retrieved these:

https://acoustics.org/pressroom/http...fleischer.html
https://www.researchgate.net/publica...ectric_guitars
https://www.unibw.de/lrt4/veroeffent...-diagnosis.pdf
http://www.luteria.ufpr.br/portal/wp...mechanical.pdf

Just a small part of my resources.

[Fluoroscope 5000]

Agree that the transient movement of the bridge during attack wouldn't show in these decay time measurements.

As the bridge always returns to its original position, it can be assumed that the bridge movement is resonant as well but presumably at a frequency below the lowest string fundamental. This kind of bridge resonance would show as a frequency modulation (vibrato) of the guitar signal for a fraction of a second. It would steal some of the attack energy.

Makes sense...and the frequency at which it modulates would be a product of the entire guitar. There may also be other higher frequencies excited within the body and the neck. Seems too complicated to calculate, so just try some guitars and pick those you like the response of.

[Chuck H]

... so just try some guitars and pick those you like the response of.

Funny how it comes down to the same way it's always been done

[Chuck H]

It's mentioned in the bottom link (which I found fairly comprehensive for my laymans understanding) that "Both instruments had an adjustable bridge without vibrato mechanism."

I think this could be significant relative to what Flouroscope 5000 indicated regarding momentary reaction in the bridge. But not just momentary in the case of floating bridges. And especially in the case of the lighter framed vintage strat type vibrato.

I have the bridge on my own strat "decked" as it were. That is, pulled tight enough to the body so that there is no movement on heavy string bends and with the front screws down low. I had to readjust my bridge for my recent vibrato experiment. Fortunately it didn't take long because I have a lot of experience adjusting floating bridges. But on this strat I much prefer the bridge decked and I don't use the vibrato.

Thank you Helmholtz for taking time to locate references that support the discussion.

[Helmholtz]

It's mentioned in the bottom link (which I found fairly comprehensive for my laymans understanding) that "Both instruments had an adjustable bridge without vibrato mechanism."

Yes, Fleischer's main focus is on neck resonances/dead spots which appear to be strongest sustain killers in typical solidbodies. It makes sense to treat different potential influences separately.

My main point above was that with solid bodies string vibrations typically do not penetrate the bridge and reach the body.

Zollner also analyzed e.g. an American Standard Strat with a floating 2-point bridge. He essentially found additional string damping at 3 discrete frequencies between 2 kHz and around 7 kHz. He could relate them to longitudinal/extensional string wave resonances. Such longitudinal string vibrations will involve movement of the bridge as a whole and certainly are influenced by the bridge-system resonance/compliance.
As in this case the bridge moves a whole and does not vibrate in itself, Zollner doesn't call it bridge resonance.

There may also be other higher frequencies excited within the body and the neck.

Yes, but higher frequency bridge-guitar-system resonances within the guitar's signal spectrum that couple to normal transversal string vibration will show in the decay time/frequency plot. If they don't show they don't influence sustain.


I have not yet seen separate (transient) analyses of string attack induced phenomena with different bridges/mounting types. Would be most interesting as I think that attack response is very important with musical instruments. And I would love to be able to relate my extensive experimenting with different bridges, saddles, blocks, springs, string angle, tilt angle etc. to real measurement.

[Helmholtz]

And especially in the case of the lighter framed vintage strat type vibrato.

Are you sure that a vintage strat vibrato with the large steel block is substantially lighter than a Floyd Rose? Vintage type weighs 390g/13.8oz without springs and mounting hardware.

[Chuck H]

Are you sure that a vintage strat vibrato with the large steel block is substantially lighter than a Floyd Rose? Vintage type weighs 390g/13.8oz without springs and mounting hardware.

Well it may be. The Floyd also uses a block, but as I recall the block doesn't have as much mass as the vintage Fender type. On that note, not all vintage "style" bridges have the heavy block either. The Floyd is a pretty substantial hunk of metal. Quality, machined steel in the best models. I'll see if I can determine an average weight for such bridges with a little searching and re post.

[Chuck H]

Well I'm finding vaguely definitive sources that put such bridges between 1.25 and 1.5 POUNDS!!! (567 to 680 grams) With a titanium version indicated as being "amazingly light" at only 14 ounces (397 grams). For the standard Floyd Rose Amazon indicates the shipping weight as 1.5lbs. for the bridge and 1.65lbs. for the bridge with the nut.

And, of course, they make heavier "sustain" blocks too if you wanted to add another three ounces

[Helmholtz]

For the standard Floyd Rose Amazon indicates the shipping weight as 1.5lbs. for the bridge

The complete shipping weight of a Fender Vintage vibrato (including springs, clamp and mounting screws) is 1.4lbs. Not much difference here.

Anyway I don't like Floyd Roses, probably because of the spongy attack and somewhat rubbery feel.

With 2 of my strats the vintage type vibrato is decked/blocked (mainly for 2-note bends and to allow finishing a song in tune if a string breaks) but I don't notice a difference in sustain and attack compared to the floating ones.


I preferably use Fender Vintage (best "sounding", brightest saddles IMO), but also Callaham and Gotoh.