Here is a  photo from inside of our labs.

Starting new string instruments from scratch takes way too long and lacks flexibility. This framework provides the ability to re-use components, get to a functional stage faster and bring pieces from past projects into new projects. The concept takes ideas from analog modular synthesizers into the realm of stringed instruments. The module dimensions were based on the frac-rack standard from PAiA electronics which they use for their modular synthesizer kits shown below.

A modular framework for string instruments,  makes it easier to build dulcimers, ukelins, table-top guitars, dan-bau, table top mandolins, keyed monochords, clavichords and veolian harps. Additional a lot of the ideas from our posts on robotic musical instruments could be integrated as modules.

Starting from left to right the modules in our prototype our a basic string tuning unit, a dulcimer tuning pin unit, clavichord module, generic holder (configured as a breadboard module), guitar pickup, dual solenoid plucker, speaker module, generic holder (which is currently being used by an E-bow), soundboard, and (off-screen) another dulcimer tuning pin unit.

The tuning units work well with all types of instrument strings. Violin strings, fishing wire, cable, guitar strings, mandolin strings all work.  The strings can be played by hand, with pics, with a slide, by bow or by some of the mechanical and electro mechanical modules.

This clavichord module is in its second iteration. The plucking action remains weak, but the tuning is pretty good. By using that much horizontal space its possible to cover nearly an octave of keys. The Keyed Monochord module was not available until the end of 2014. That unit provides superior key action.

The pickup unit allows metal strings to enter the electrical signal domain. This makes it easy to route the sounds into a computer or iPhone(via iRig). But getting the vertical height of the pickup inline with the guitar strings remains an outstanding issue. The tone of the instrument through the pickup is surprisingly pleasing.

The generic holder module has been worked well. It was designed to match the size of the a breadboard and the the aurduino. This makes prototyping circuits and working with an  much quicker. Arduino is a generic proto-typing circuit board. The breadboard module is configured as an amplifier based on the 741 op-amp. The other generic holder is being used with an Ebow. The e-Bow provides a fanstatic way to activate the strings and create a great drone sounds. Arduino circuits we used to drive the solenoids in the dual plucker.

Finally, the soundboard provides an acoustic-mechanical way to project the sound. Different materials have yielded different sounds. Balsa woods sounds cheap and tinny. Metallic soundboards were rough and atonal. Thinly sanded and planed hardwoods sound the best but are fragile and time consuming to make. Oaks and pines worked well. But foam-core, sweet foam-core was the biggest surprise. Cheap and easy to work with, its strength to weight ratio is great. The tone is sweet and has a good sustain.

Many of the modules remain in the prototype stage, but initial feedback has been encouraging.