Mandolins with no tone bars / bracing?

[dcoventry]

Brent,

Yah. I was looking through old threads on this sight and came across this one and thought, "Wow, this question never really got continued much and it seems important." Being new to this sight, and Mandos in general, I had a purely educational interest in the topic "dovetailed" into the fact I am wanting to purchase not only a PacRim, but one with out tone bars. The dreaded double whammy I have come to see

Learning about the mandolin has been exceptionally fun and interesting. I wish more folks posted more often. I truly am excited over learning more.

[Fran]

My violin has a bass bar on one side and a soundpost on the other. Both serve to stiffen the top.

Nope! The tone bar is there to distribute sound vibrations across the top, and the soundpost transmits the vibrations from the top to the bottom of the instrument. The location of the soundpost is crucial and will make or break the sound of your violin. Luthiers usually install it using a trial and error procedure, until the optimal sound is achieved.

[Rick Cadger]

To be fair, he said they serve to stiffen the top, not that that was their intended purpose. Many violin resources discourage keeping a fiddle at full string tension with no post in place for fear of damage occurring from the lack of the support it provides (whether that was its design function or not).

A few questions come to mind as a result of posts here:

1) Does a refret (even professionally done) other than one done by Weber invalidate a Weber warranty?
2) Does a refret (even professionally done) other than one done by Gibson, Eastman etc invalidate Gibson, Eastman etc's warranties?
3) Not a question per se, but a puzzled observation: an endpin mod for a jack does NOT invalidate a Weber Warranty, but I seem to recall Sean from Eastman implying in another thread that a similar mod WOULD invalidate an Eastman warranty.

[Stephen Perry]

Warranty service to some extent hinges on the specifics of each case. Sometimes on how the retail customer treats the dealer and how the dealer treats the supplier.

I can't see why irrelevant modifications should impact warranty service. Should a mod impact something and that thing fails, that's a different matter. Certainly putting in an endpin jack shouldn't logically invalidate a warranty issue with the neck joint, and so on. Although the presence of modifications may cause difficulties in swapping out or repair, these can be addressed by polite discussion.

But we're on bars, and apparently, posts. Bars, in my experience, have an impact on structure, on general response by overall shape, and on detailed response/balance/clarity through the very last bit of detailing, once the instrument is assembled. Unbarred tops prove interesting to work on, but exhibit many of the same patterns seen in barred tops.

Interesting subject.

[dcoventry]

Stephen,

As a newbie, I find this subject fascinating. I'm a fairly quick study, but th edepth of knowledge found on this sight is amazing. I think mando people are better informed on their instruments than other groups.

I wonder if the industry would consider the concept of "authorized" repair people much like the auto industry does. Or could you get a specific process approved? Or has this been addressed? Sorry if it has.


D.

[Stephen Perry]

If something simple on a line I carry can be fixed by me, I get authorization, and then fix it. I end up with credit against instruments I'm purchasing. I think that's authorization enough!

[dcoventry]

Stephen,

I see. Thanks for that info. I always wondered how that works.

[Big Joe]

We have two different issues here. On one hand, we have a company simply stating the policy of the warranty. He is not responsible for the warranty wording, only pointing out what is required. He cannot simply say we will overlook this but not that. If one states he will make an exception to that warranty it becomes a legal issue that can lead to issues certainly not wanted by any company. As a Lawyer you can understand that Stephen.

On the other hand is a customer service driven person trying to state he can improve an instrument with minor, unnoticeable alterations to the instrument. The company cannot give blanket permission for this, but if it is not detected then it is not an issue. When in charge of warranty issues for Gibson we would have to make similar statements. That does not mean things would not be done as an accommodation but we did have a form that we required the consumer to sign stating it was an accommodation and not a warranty service and did not extend or alter the warranty whatsoever. This covered our legal behind and still allowed us to handle an issue with the consumer.

While there are certain similarities between mandolins and violins, they are completely different and what can apply to one does not apply to the other. The tops are carved in a completely different manner, and the rims and scroll also differ the way in which they are structurally strengthened. The strings put a LOT more pressure on the top on a mandolin than on a violin. This requires a bit different carving and thicknesses and the arch of the top of a properly carved mandolin provide sufficient support for the bridge and strings. The "braces" do not brace anything, merely alter the response of the top. Removing these do not make the mandolin muddy or give any negative response. Actually, there is not a large difference from the tone bar and non bar instruments. On the whole, the tone bars give a little more emphasis in the mids, but not substantial. How this would apply to any other brand I cannot say since they don't make a model like that. It would be interesting to try and I may do that. We hope to have some mandolins out this year. We have a few we have done in the past to compare and I would like to try one with tone bars, one with no tone bars, and one with a X brace system I came up with a few years ago and got to build into one mandolin.

These are interesting discussions but are better if we are on topic and understand manufacturers have to state what they do about warranty issues. What is done in practice is not always what can be stated in a public forum.

[Jesse Harmon]

I would propose a thought experiment...

Assume we took the 50 "most competent judges" of mandolin tone we could find. Say a panel of 50 experienced builders, players and long-time enthusiasts each of whom had universally respected opinions regarding mandolin tone.

Now, assume we asked them to each list the 20 best sounding mandolins they had ever heard. Finally, assume we combined those 50 lists into a single Master List of great sounding mandolins.

I'm guessing our 'Master List' would consist of a few hundred mandolins (since many individual mandolins [such as Monroe's, Marshall's, Grisman's & Reichman's Loars] would be on multiple,or even all! of the lists).

My guess is that 100% (or very close to 100%) of all the mandolins on the list would have some form of bracing built into the design.

(Actually, my guess is that a disproportionately high percentage of all the mandolins on our master list would be F-hole mandolins, with Red or Adirondack Spruce tops, Sugar maple back/sides, tone bar bracing, and a varnish finish, but this is a topic for a different thread entirely ).

Things are built the way they are built for a reason.

I'm hangin on to that handcrank on my car window.

[Stephen Perry]

Generally the warranty issues I see are unambiguous and clearly a result of defect in construction or materials. Back coming off. Binding coming loose. Crack. Or are minor. Tuner failing. Bridge cracked. I doubt the major problems (which are surprisingly rare) get much inspection at the importer or maker's shop. Of course, if an instrument has been obviously wet and it's coming apart, that doesn't get back to the maker. I'll pass my observations along, the answer comes back, and the culprit who left the thing in the rain buys a replacement. And the minor problems I just fix.

I don't see tops collapsing or anything like that very much at all on warrantied instruments of any quality. Not that I can recall.

So the warranty issue isn't much of an issue. The big problems are obviously big, and I doubt any company would deny a claim for structural failure because the instrument has different tuners than stock and has been refretted, fitted with a pickup, and has a non-stock bridge. But it's nice to have the original stuff around, and refit that before shipping back. And let's the owner keep his upgraded stuff.

These things are made to be used, and the users like to get the things the way they like. Just as with cars. Putting fancy wheels on isn't going to impact a power train warranty.

[pops1]

My Brentrup has tone bars, but they are very minimal. Only a couple of inches long and not very big. Mandolin sounds GREAT and my guess is that Hans only put them there for sound and not for strength as the carving of the top gives it it's strength.

[fscotte]

Sorry to bump this thread, but it's interesting that no one brought up John Monteleone's take on the tone bar. He said that vibrations from the bridge travel quicker towards the neck and tail, and slower towards the f-holes. The purpose of the tonebar was to help distribute those vibrations more efficiently and equal. I assume the direction of the grain certainly has a role in how well sound travels through the wood.

[Marty Henrickson]

I'm glad this got brought back up, as I didn't see it the first time through. It's also relevant to me, as I'm thinking my next instrument purchase (not sure when, mind you) may very well be an F-style "The Loar" to complement my A-style Gibson (which I think has tone bars). Of course, I would also like to justify this purchase to my better half by explaining the different tonal characteristics of tone-bar vs. no tone-bar construction.

I'm wondering if some informed person could tell me which of The Loar F-style mandos do and do not have tone bars. As of now, I believe they offer the following F-style models:

1) LM-700 VS (no tone bars)
2) LM-600 VS (tone bars)
3) LM-520 VS (?)
4) LM-500 VS (?)

Thanks in advance!

[dcoventry]

The LM700(F Style) and LM400(A Style) have no tone bars.

[sunburst]

...it's interesting that no one brought up John Monteleone's take on the tone bar. He said that vibrations from the bridge travel quicker towards the neck and tail, and slower towards the f-holes. The purpose of the tonebar was to help distribute those vibrations more efficiently and equal.

John Monteleone is one of the greatest living builders and a friend of mine, but that is not correct. Vibrations do not "travel" along the tone bars. Tone bars adjust the stiffness of the top, and to a lesser extent, the mass of the top. The combination of stiffness and mass in the top, and where it is concentrated, affects the frequencies of the top modes, but braces do not change the physics of the top plate in any fundamental way. The speed of sound through the wood is not changed by tone bars.
Luthiers often speak in ways that express their visualization of what is going on in instruments, and such visualizations are often not based in physics.

[fscotte]

John Monteleone is one of the greatest living builders and a friend of mine, but that is not correct. Vibrations do not "travel" along the tone bars. Tone bars adjust the stiffness of the top, and to a lesser extent, the mass of the top. The combination of stiffness and mass in the top, and where it is concentrated, affects the frequencies of the top modes, but braces do not change the physics of the top plate in any fundamental way. The speed of sound through the wood is not changed by tone bars.
Luthiers often speak in ways that express their visualization of what is going on in instruments, and such visualizations are often not based in physics.

Isn't there 'some' truth to his suggestion? Sound does travel at a certain speed depending upon the stuff it's traveling through. Does grain direction affect the speed of sound? It would be neat if there were more information on what Mr. Monteleone was saying, or if he would expound on his thoughts some. I dunno maybe he's just trying to sound cool for the Master video series..

[draino]

Isn't there 'some' truth to his suggestion? Sound does travel at a certain speed depending upon the stuff it's traveling through. Does grain direction affect the speed of sound? It would be neat if there were more information on what Mr. Monteleone was saying, or if he would expound on his thoughts some. I dunno maybe he's just trying to sound cool for the Master video series..

Sound doesn't travel through the top plate, the top plate produces sound. An image of tiny little waves from the string traveling through the bridge as tiny little waves and then entering into the top out of the bridge as tiny little "sound waves" or "resonances" is not what happens. The bridge excites the top into vibration, and the top will vibrate in various ways (modes). i.e., whole top bouncing in and out; whole top rocking back and forth; whole top twisting along its length, etc.

The vibration of the top then creates compression waves in the air, which we hear.

[Nonprophet]

It does, and in almost all cases it voids the manufacturers warranty.

That's a very interesting statement Brett. I'd not heard that before, but it's certainly worth remembering!


NP

[Chris Baird]

The "speed of sound" is faster along the grain than across it. The waves do actually move around at the "speed of sound"... within the strings first, then they hit the nut and bridge where an impedance mismatch occurs, some of that wave energy is transferred and some reflects back into the string. As the waves bounce back and forth they encounter one another in a regular way, sometimes constructively and sometimes destructively. This creates patterns which we can either study all together, as operational deflection shapes, or, try to separate into modal shapes. The modal shapes, however, are not the actual waves, but, rather the patterns the waves make as they interact.

I don't know what tone bars have to do with the speed of sound, but, they add stiffness and mass and will affect the instrument accordingly.

[draino]

The "speed of sound" is faster along the grain than across it. The waves do actually move around at the "speed of sound"... within the strings first, then they hit the nut and bridge where an impedance mismatch occurs, some of that wave energy is transferred and some reflects back into the string. As the waves bounce back and forth they encounter one another in a regular way, sometimes constructively and sometimes destructively. This creates patterns which we can either study all together, as operational deflection shapes, or, try to separate into modal shapes. The modal shapes, however, are not the actual waves, but, rather the patterns the waves make as they interact.

I don't know what tone bars have to do with the speed of sound, but, they add stiffness and mass and will affect the instrument accordingly.

Hmm, this kind of makes sense, but kind of doesn't. Admittedly, I need to read and study more on the topic, but the description of waves moving "within" parts of the mandolin doesn't really make a lot of sense to me. The entire component (sticking with the top here) is set into harmonic motion -- there's no sound or wave or vibration traveling "through" the top like an electric current or something. Its a coherent motion which is defined by the tops weight, stiffness, etc., and the force being applied at the bridge. So I don't really see how "the speed of sound" (whatever that is) relates here.

Edit: I removed part of the post because, after hitting post, I realize that I might be, somewhat, understanding what is meant by "the speed of sound". Should post when in a somewhat hurry...

[sunburst]

...The entire component (sticking with the top here) is set into harmonic motion...

Plates have numerous modes, "partials", if you will, but they are not harmonic. Strings have harmonic partials, plates do not.

The wave lengths of sound at the frequencies important in plate and air modes in mandolins are generally longer than the structure of the mandolin itself, so there is no actual "traveling" of sound waves through mandolin parts, but there are standing waves that occur.

[Chris Baird]

Standing waves, aka mode shapes, occur whether the bending wave length of the frequency in question is longer or shorted than any part of the mandolin. The "critical frequency" (as coined in the violin world) is about 950 hz, This is where the bending wave length in wood begins to get equal to or greater than the wave length in air (for a particular frequency). Above this frequency the impedance match between the plate and the air is great and there is much improved sound radiation.

The "speed of sound" is a term used in the acoustic engineering world to indicate the speed that mechanical disturbances travel through any medium (gas, liquid, or solid). Admittedly, "sound" probably isn't the best term when discussing musical ideas and structural acoustics. In wood those waves are both compression and transverse. The speed that the energy is transferred is very fast (20,000 ft/s in steel, and 10,000+ ft/s in wood), faster than the movement of the plates/strings themselves. When I say "waves" I'm talking about the movement of that energy, at the speed of sound, through the medium. Shear motion from transverse waves (which is what vibrates the air) of the plates and strings is what we see when we view or model the modes. The transverse wave, of course, travels, but, for resonant structures, reflects back off the boundaries in a regular way creating areas of greater and lesser shear motion depending on the phase relationship with other waves/energy in the same place. The speed of shear displacement of the medium (i.e. the vibrating plate in the direction perpendicular to the surface) is slower than the transverse wave's propagation across the medium.

[dcoventry]

CHRIS!! You got some splaynin' to do!!............

[Fstpicker]

So, six months later how is the instrument performing. Any top issues??

I need to do some research into bracing in general. If the top is arched correctly, it should have the necessary integrity? Why brace at all? Adding weight to the top hampers the vibrations, doesn't it?

dave

My Loar LM-400VS was the first production 400 made by Loar...serial #2. Serial #1 was a prototype. I believe it was made in February of 2010 according to the number inside, and it was sold in April or May of 2010. Accordingly, as of this month it is 16 months old. There is absolutely no sinking of the top in the least. It has held up beautifully in every way, structurally, asthetically, and tonally!

So...I guess the "no-tone-bar" thing can be made to work after all!

Jeff

[Stephen Perry]

Writing and thinking about "sound" in solids is pretty interesting. There's the distinction between pressure waves and shear waves, for one thing. Regardless, a wave front or energy front moves from the string through the bridge. The basic character of an instrument type doesn't really vary much from one specific instrument to another. The specific timbre of instruments seems to lie in the details of how they deal with sound.

Seems compelling to me that bars are about 8" long. That corresponds to a half wavelength of about 3500 Hz in spruce, with a speed of "sound" of about 4000 ft/s. The potential for substantially influencing an important area of the sound spectrum seems pretty clear.

One thing I notice in working on mandolins is that the mandolins are a lot happier when the components are happy with themselves and happy working with the other parts. Tone bars are especially sensitive to this. Tone bars fighting the top really make for an uncomfortable situation. Not having bars removes this problem. The top only has to work with itself, the bridge, the F holes, the rim, and the back. All those can be made pretty happy without as much effort as when bars are there.

The bars clearly add something. One thing is that production mandolins with bars don't seem to have the sudden "light up" of the barless ones. They have a more integrated (that doesn't really capture what I'm getting) response to begin with, but that sometimes sounds forced to me. The barless ones typically seem a little fat and dull to my ears, but once the top especially is happy the response time improves greatly. With a bit of work, the brilliance comes in very sweetly. I like the barless model.

Not that the barred models aren't rather nice, especially when the bars and the top like each other.