April 9, 2020

Tailpieces with Volume and Tone Controls

I have been installing volume and tone pots below tailpieces since long ago, but my latest versions are much improved. Until now, I used the thumbwheel potentiometers that you see on many archtops, usually below the pickguard:

The grounding of the strings was also done reliably without needing heavy metal pieces, as you can see.

The new version, below, has different potentiometers and grounding.

These are the fittings: two pots, two thumbwheels and two pieces that adapt the pots to the cavities in the tailpiece. These pieces are made of FR4 fiber glass. They are very strong, durable and can be bonded easily. There is also a small PCB that will tidy up the connections.

At the other side, the elevated area that contains the potentiometers is a little higher, but not much. This tailpiece is exclusive of my Berlin II models, and its pointed design matches the shape of their pickguards and cutaways, so I had to maintain the look despite the internal differences. I have other tailpiece designs for other models, and I’ll have to implement these same improvements for them.

The grounding is now done with brass pieces that are epoxied inside the cavities for the string ends:

These are the thumbwheels. The new pots feel smoother and, above all, their rotational life is much better. The old pots had an expected life of 15.000 rotations; these other, 100.000. That’s some improvement!

The printed circuit board has SMD components. It has a treble bleed circuit. The two capacitors use C0G dielectric, to avoid piezoelectric effects.

A view of the tailpiece before installing the fittings: