Purpose of the Bass Bar?

November 19, 2018, 7:42 AM · I am just curious, what is the purpose of the bass bar?

I was reading about violin as an instrument (history, construction, etc). While most components in a violin was well explained, I only find info on how to fit but not what it is for.

I suspect it has to do with tone production, but based on what I read about, the violin mechanics is we draw the bow over the string, the rosin in the bow grabs the string and create a vibration. The vibration triggers down to the bridge then to the top, the sound post then to the back. It doesn't seem the bass bar inside is doing anything?

Replies (16)

November 19, 2018, 9:08 AM · According to the A Dictionary of Music and Musicians by George Grove:

"BASS-BAR, an oblong piece of wood, fixed lengthwise inside the belly of the various instruments belonging to the violin-tribe, running in the same direction with the strings, below the lowest string , and acting as a beam or girder to strengthen the belly against the pressure of the left foot of the bridge , as the sound-post does against that of the right foot (in a right handed instrument). It is the only essential part of the instrument which, owing to the gradual elevation of the pitch, has had to undergo an alteration since Stradivari's time. Tartini states, in the year 1734, that the tension of the strings on a violin was equal to a weight of 63 lb (29 kg), while nowadays it is calculated at more than 80 lb (36 kg). (Other modern value: c. 22 kg / 220 N according to string manufacturers' data.) This enormous increase in pressure requires for the belly a proportionate addition of bearing-power, and this could only be given by strengthening the bass-bar, which has been done by giving it a slight additional depth at the centre, and adding considerably to its length. In consequence of this we hardly ever find in an old instrument the original bass-bar of the maker, just as rarely as the original sound-post or bridge, all of which however can be made as well by any experienced living violin-maker as by the original Stradivari or Amati."


Edited: November 19, 2018, 2:49 PM · Start here:

The search some more.

James Beament's book "The Violin Explained" goes into it further in his chapter
"The Violin Body."


November 19, 2018, 1:55 PM · Many thanks for both of you! Now I learn more!
November 19, 2018, 4:56 PM · Most modern strings give a total tension between 45 and 55 lbf, a lot less than the 80 stated and also less than Tartini’s claim of 63 lbf, so increased tension is not the reason for changes in bass bar design.
I thought for a while it migyt help dampen the sometimes shriller sound of steel e-strings, but since old German violins with integral bass bar still sound fine, that can’t be the reason either.

Length and (more) weight og the bass bar DOES make a difference in the sound, though.

Edited: November 20, 2018, 8:00 AM · In addition to the structural support due to string force, there is a another function of the bass bar. When making a violin, you strive to create a front plate with a full and strong tap ring tone, and at a specific frequency, prior to cutting in the ff holes. When you cut the ff holes, the plate goes from a acceptable ring, to a dull thud. The bass bar, assuming installed and tuned properly, restores the ring tone of the free plate. This is not something that is apparent unless you have spent significant time creating a beautiful plate, only to be disappointed when you cut in the ff's! No problem, once the bass bar is in and proper, all returns to good!
Edited: November 20, 2018, 8:16 AM · All other things being equal, there's far less tension in a synthetic string than in a steel string. And also nylon would seem to have less tension than gut, too.
Edited: November 20, 2018, 8:48 AM · I recently restored as a baroque set up violin, an original circa 1800 Hopf stamped violin that had no original bass bar, and clearly never had one. The wood was quite thick in the bass bar region, 4-5mm. Checking with an expert it was decided to string it up just as it was built, with no bass bar. The result a not very loud violin with good tone but a little bit weak G string, so it would seem that the bass bar does indeed help the bass response and possibly the volume.
November 20, 2018, 9:04 AM · One of the things ignored so far in all this discussion (and misstated by Beament in his book) is that the "tension" in the strings is translated to a downward "force" vector on the bridge (not "tension") and since the angle of fingerboards and thus the height of bridges and the force vector (apparently called "pressure" by many) through the bridge into the violin top was increased because of that after the Baroque period, that is another reason for subsequent changes to the bass bar.

What Andrew F. wrote above is probably sorta true, based on the relative densities of the core materials. However strings of all core materials, as produced these days, are fairly close in tension as strung because of the addition of winding materials to increase the mass per unit length of the low density nylon and gut cores (which are of almost the same density (or mass per unit length). Also nylon stretches a little more than gut so that needs to be accounted for since it effectively reduces the "density" of an installed nylon-core string compared to gut-core.

In any event many of us may test the gut-stretching phenomenon in a few days - so take note and HAPPY THANKSGIVING!

November 20, 2018, 9:21 AM · Actually modern scholarships refutes the idea that average baroque tension and downward force were any less than modern set up, the angle over the bridge has remained pretty much the same, and the tension of gut strings in the 1700s is often thought to be higher than modern strings if not equal.
November 20, 2018, 10:14 AM · Certainly seems to be some very interesting "reverse engineering" research going on re. this subject. Thanks, Lyndon, for that input.
Edited: November 21, 2018, 8:07 AM · I am reluctant to believe some of the figures in that Grove Dictionary quote. A violin strung to 80 lb tension - really? I would not want to play or even handle such a violin, or be anywhere near it for that matter!

The tension of 63 lb (for violin gut strings?!) attributed to Tartini in 1734 makes me wonder if the definition of the pound weight in Tartini's time and location was different to what it is now. In those days, long before today's global standardisation, weight and length units tended to vary from country to country, and possibly even locally within a country.

Edited: November 21, 2018, 8:34 AM · Those figures for tension aren't high, Trevor.
A ukulele has 8 or 9LB per string, and a CG has a total of about 100LB.
I bought a tenor guitar on EBay and it was strung in fifths (steel), and I played around with it for a while. I quite like fifths tuning, but I under-used it. Then my dad gave me a micrometer, and I measured the widths of those strings and realised that they were DGBE strings, tuned up to CGDA, so I very quickly tuned it back down again!
I'll leave someone else to calculate how much tension that thing's bridge was experiencing.
November 21, 2018, 8:44 AM · If the linked graph for tensions of many string sets is to believe, the total tension of a set of modern violin strings ranges from 48 to 57 lbs. The actual downward force on the bridge will be considerably less (a simple trigonometric calculation based on the string bend angle at the bridge).


Edited: November 21, 2018, 8:55 AM · One mustn't forget the more direct tension loading on the tailpiece cord and in particular the end button. I've known end buttons fail in orchestras, and it even happened with a professional solo violist in a concerto once.

@Andrew, I think the tension loading of guitars and uke's is naturally higher than in the violin, and those instruments are designed for it.

Edited: November 21, 2018, 9:52 AM · I think the bass bar is less for structural support and more for keeping any undesirable nodes from forming...

I'm not too savvy in violin acoustics, but I know a fiddle without a bass bar will be very shrill and have poor response in the bass end.

November 21, 2018, 4:29 PM · The bass bar serves several purposes.

A significant one is to cause the top plate to vibrate asymmetrically from side to side. This causes a more dramatic pumping action of the air through the f-holes, giving a more powerful sound in the lower frequency range of the instrument.

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