Violin Making: Setting the Bass Bar in Fiona

One of the mysterious steps in violin making is setting the bass bar. There is much discussion about the bar tension, placement, and thickness; all factors that affect the tone of the final instrument. Also all factors that can not be changed after the top is glued on. Today I shaped, glued, and trimmed the bass bar in Fiona. Oh all the questions? The wondering? The acoustical samples and science. Every article I’ve read on “What makes the sound of a good violin?” Now I see and measure the details, someday I’ll understand or get a ‘feeling’ for the effects and results.

Tap Tone Test

I took tap frequency readings and weighed the plates prior to cutting the F-Holes, after cutting the F-Holes, after setting the bass bar, and now again after trimming the bass bar. After trimming the plate resonance frequency is at the same point as prior to cutting the F-Holes. The removal of wood for the F-Holes, the additional stiffness and trimming of the bass bare canceled each other the F-Holes to resolve to the same acoustical values.

Fiona, #6, is a bit lower frequency than Diana, #4. Diana had an F for the front plate and F# for the back plate. Fiona is 1/2 step lower with D# for the front and F for the back. This is also what Claude, #3, measured at. Fiona also weighs a bit less for each plate, with equivalent dimensions, which is expected with the lower frequencies. The wood has a little bit less density.

Continual Learning

As I build each instrument and record the resonate frequencies and plate weights. I can observe the effects as the building process progresses, as well as the final tonal effects on the instruments. The more I build, the more I understand. Right now I’m hypothesizing and observing.

There is a violin maker in the Maestronet blogs who used to work at the Jet Propulsion Laboratory, a Mr Don Noon. His tag line reads, “Making fiddles ain’t rocket science…  it’s much more complicated.”

Everyday, new lessons, more progress; the path to mastery

 Photos journey of setting the bass bar

Fiona with a fitted bass bar. The plexiglass brackets hold the bass bar in position while checking the fit. Chalk is spread under the bass bar, and then the bar is pressed into place, removed, and inspected for even chalk on the bar. Where its not even, the chalk and a little wood is removed until the bar fits perfectly.
Fiona with a fitted bass bar. The plexiglass brackets hold the bass bar in position while checking the fit. Chalk is spread under the bass bar, and then the bar is pressed into place, removed, and inspected for even chalk on the bar. Where its not even, the chalk and a little wood is removed until the bar fits perfectly.
Top view of Fiona's bass bar. The bar is placed in proportion to the center line of the top plate. The placement is close to the line of the G string, the lowest string on the violin. The purpose of the bass bar is to transmit the lower frequencies down to the larger 'bass' end of the violin's vibrating top plate.
Top view of Fiona’s bass bar. The bar is placed in proportion to the center line of the top plate. The placement is close to the line of the G string, the lowest string on the violin. The purpose of the bass bar is to transmit the lower frequencies down to the larger ‘bass’ end of the violin’s vibrating top plate.
High Tech bass bar clamps :-) You can purchase cast iron C clamps to span perfectly over the bass bar. I like to use the simplest technology that works. Stradivarius did not have cast iron spanner clamps, but then he probably didn't have rubber bands either....
High Tech bass bar clamps 🙂 You can purchase cast iron C clamps to span perfectly over the bass bar. I like to use the simplest technology that works. Stradivarius did not have cast iron spanner clamps, but then he probably didn’t have rubber bands either….
The under side of my bass bar clamps, wine corks. The corks are cut in half and line up with the bass bar. Without them you don't get even pressure, also the cork (or modern plastic corks in this case) provide a nice pliable surface to avoid denting the soft spruce.  Once done with the process, I celebrate by finding a new wine cork :-)
The under side of my bass bar clamps, wine corks. The corks are cut in half and line up with the bass bar. Without them you don’t get even pressure, also the cork (or modern plastic corks in this case) provide a nice pliable surface to avoid denting the soft spruce. Once done with the process, I celebrate by finding a new wine cork 🙂