Project Report: Ahmad Saad 5-14-04
The Electric Washboard Report
The aim was to turn an old fashioned washboard into an electronic instrument that sends midi to create sounds and program changes. The initial goals were:
-Make each ridge on the washboard send a note on when 5v is applied to the ridge.
-Change the interval spacing between notes on adjacent ridges.
-Allow the user to press buttons that select from preprogrammed templates to decide on the interval spacings between the ridges (choosing the tuning of the instrument).
-Include a pitch slider that allows 12 keys in one octave.
-Make a handheld device which can precisely apply 5v to one or more ridges.
Goals added later:
-Include a controller to move the release slider of the amp envelope in reason.
-Flush held notes when changing pitch.
-Pitch bend up/down
The first step was to create a circuit on each ridge, and connect the ridges to the Doepfer box. The surface of the ridges had to be coated with caulk to prevent it from conducting electricity. A strip of conductive copper tape was then placed along each ridge. The strips all cover the wooden edge of the washboard as well. At the edge of the washboard, screws were put through each strip of copper. By placing wires between the screws and the copper and tightening the screws, wires were attached to each ridge, which could be connected to the Doepfer box. It was then confirmed that when 5 volts was applied to a ridge (completing the circuit) the Doepfer box would send a note on with velocity of 127 and the corresponding note number, and a velocity of 0 when the circuit is not complete. At this point, we were able to play notes on all 18 ridges of the washboard, by completing the circuits with the bare end of a wire plugged into 5v.
With the notes wired, the tuning template and pitch functions were created in MAX before any of the supporting hardware was installed. Bang buttons selected from 9 tunings, and a slider selected from 13 pitches across one octave (including low and high C) for the pitch. Once the programming was complete, 12 buttons and a slide potentiometer were installed and connected as controllers. Each button when pressed would activate a different bang to choose a different tuning. 3 additional tunings were designed at this time to make use of all the buttons. The slide potentiometer controlled the slider in MAX which affects pitch. The slide has to be set up so that specific values selected specific pitches. A range of slide values had to be specified for each of the 13 pitches on the pitch slider. This is the time when we connected a flush to the slider to flush notes when changing the pitch. Another slide pot was installed to be a controller for the release slider in reason. Finally 2 more buttons were attached as controllers, and wired to the pitch bend wheel in reason. 1 button to bend up, 1 button to bend down.
The original intention was to play the washboard with a spoon connected to 5v. However, this proved difficult to play. Therefore the last hardware created for this project was a special 5v glove. A wire is attached to the Doepfer box 5v output. The wire runs into the glove and splits 5 ways at the heel of the palm. Each split runs to a thimble to which it is soldered. The thimbles are at the finger tips. The player can wear the glove and put their fingers in the thimbles. They can then play notes by touching any thimble to any ridge.
The final step was to select a different channel for each of the 12 tunings, and create a patch in reason on each of 12 channels. This was so that each tuning has its own unique sound.
One problem we came across was that the pitch slide pot was not
selecting pitches consistently. This was because too few possible slide values
were assigned to select each pitch. Once more values were assigned to select
each pitch, the pitch slide worked consistently and smoothly.
The other problem was that even with the glove, it was still difficult to precisely play the washboard because of mistakenly hitting adjacent notes. Doing things over again, we would have made the copper strips just a little bit thinner, or bought a washboard with wider grooves. However, we were not able to do anything to help this problem except make the glove, which is more precise than the spoon.
The washboard's input devices are:
-The 18 copper strips for 18 notes
-12 buttons to choose the tuning
-2 sliders (pitch and release)
-2 buttons to affect pitch bend in real time
There was also the 5 volts glove.
The washboard is played by strumming/tapping the ridges with the fingertips of the glove. Single or multiple notes can be played, and it is easy so sweep across all the ridges.
select boxes are used for note 0-17 so that each ridge would have a corresponding box to pass on its note, and only that note. The note numbers pass through the select boxes and then through 2 boxes which add numbers, then to the note out. Note velocity runs directly from notein to noteout. Channel number is selected by banging message boxes connected to noteout. 12 bangs apply to the 12 buttons. The bangs serve only to bang message boxes. For each note, there is one message box that sends an argument to the first number adding box. So pressing the bang for 1 tuning sends 18 different arguments to the appropriate addition boxes. The bang also sends a channel number to noteout so that each tuning is on a different channel. The pitch slider sends the same argument to each of the 18 second addition boxes, to affect the overall pitch of the instrument.
The first addition box receives arguments based on the interval spacing
The second box receives arguments based on overall pitch.
The pitch bend buttons activate logic statements to send 0 or 127 to the pitch bend wheel. The logic statement sends 63 to the pitch bend wheel at all other times.
The second slider is present in max simply as a controlin box.
The tuning is based on conventional theory- diatonic, melodic, harmonic, diminished, whole tone, pentatonic, chromatic and blues scales- as well common intervals: major arpeggio, minor arpeggio, diminished 7 arpeggio. There is also one setting in which all notes are a diatonic third apart.
11 subtractor patches and 1 Malstrom patch are set up over the 12 channels. Each patch has been modified so that the second slider controls the release slider on the amp envelope, and so that max controls the pitch bend wheel. The patches are all fairly similar, with the exception of whole tone and harmonic, which have no polyphony, and lots of portamento. These two patches were created to have the option of being able to play smoother sounding notes. The subtractor patches are all relatively the same. They all have 2 waves, spaced 2 octaves apart. Doubling the notes accommodates the wide range of notes in some of the tunings (for example the higher notes on the arpeggio tunings become too thin). •
see Todd Ryan's report