This is the Cellomobo. What's with that name? Well, it belongs to the
same family of instruments as the Saxomophone and the Tubamaba. It
started out as an attempt to bow a computer model of a plucked string.
I got interested in this idea while using the Karplus-Strong
model with live sound input from the radio tape knife. I found that
when the input from the knife was resonant with the string model, the
sound was rich and satisfyingly complex. It was almost impossible to
get the knife to resonate however, and it occurred to me that a bow on
a vibrating string gets some feedback from the string that
gives it a
cue of when to stick and when to slip, and that was entirely missing on
the tape knife. So I used a shaker (now a speaker driver) to move the
input piezo up and down
(orthogonal to its direction of sensitivity) with the output of the
string model. If that sounds like a recipe for feedback, well, it is.
And that is good. Actually, I use a few tricks to keep it from getting
excited when it is not being played, but it is a very lively instrument
to play. I find it very interesting to take a sound out of the the
digital domain, and physically handle it and shape it and feed it back
into the computer. This is what human-computer interaction is all
about! Besides the vibrating playing surface, the interface includes a
knob that controls the feedback gain in the string model, a knob for
the gain to the shaker's amplifier, a button that I use for various
things and a ribbon controller for pitch control. There is also a force
sensing resistor under the ribbon that is mapped to a low pass filter
inside the model's feedback loop. These knobs and sensors talk to pd on
my laptop via an Arduino microcontroller board. Here's my pd patch, and here's my Arduino sketch. And here is a
video
of me demonstrating the prototype to the 250a class at Stanford in
Winter 2006. Here are some tunes I recorded with Anne Wellmer
last summer (2006): first second third fourth
Here's a link to a radio piece by Gideon D'Arcangelo
about Bill Verplank and interaction design that features the
cellomobo: Studio
360
August 22, 2007:
I have a portable version using an aura bass shaker rather than a
woofer, that I built for a gig at the Stone in
NYC. Come see us October 4, 2007, at 8pm! Here is a duet: cmobo2.mp3
September 26, 2007: and a duet with the tape knife (which is now a
trowel!) bedone.mp3 bedtwo.mp3
Ed Berdahl, Hans-Christoph Steiner and I submitted a paper to NIME
2008, which includes the cellomobo. NIME2008BerdahlSteiner.pdf
a plucked string.
I got interested in this idea while using the Karplus-Strong
model with live sound input from the radio tape knife. I found that
when the input from the knife was resonant with the string model, the
sound was rich and satisfyingly complex. It was almost impossible to
get the knife to resonate however, and it occurred to me that a bow on
a vibrating string gets some feedback from the string that
gives it a
cue of when to stick and when to slip, and that was entirely missing on
the tape knife. So I used a shaker (now a speaker driver) to move the
input piezo up and down
(orthogonal to its direction of sensitivity) with the output of the
string model. If that sounds like a recipe for feedback, well, it is.
And that is good. Actually, I use a few tricks to keep it from getting
excited when it is not being played, but it is a very lively instrument
to play. I find it very interesting to take a sound out of the the
digital domain, and physically handle it and shape it and feed it back
into the computer. This is what human-computer interaction is all
about! Besides the vibrating playing surface, the interface includes a
knob that controls the feedback gain in the string model, a knob for
the gain to the shaker's amplifier, a button that I use for various
things and a ribbon controller for pitch control. There is also a force
sensing resistor under the ribbon that is mapped to a low pass filter
inside the model's feedback loop. These knobs and sensors talk to pd on
my laptop via an Arduino microcontroller board. Here's my pd patch, and here's my Arduino sketch. And here is a
video
of me demonstrating the prototype to the 250a class at Stanford in
Winter 2006. Here are some tunes I recorded with Anne Wellmer
last summer (2006):