Overview

The Buchla 700 was a synthesizer released in 1987. It was conceived and built by Donald Buchla together with Lynx Crow, who wrote the firmware for the 700. Some years ago Lynx kindly allowed Aaron Lanterman to release the source code on his website: ​http://lanterman.ece.gatech.edu/buchla700/. While our modifications are in the public domain, Lynx's request still applies to the underlying original code. Please respect that.

The Buchla 700 was a 12-Voice polyphonic synthesizer using frequency modulation, wave shaping and wave shape interpolation to create its sounds. In contrast to many instruments of its time it did not use a traditional keyboard as input, but an array of touch sensitive membrane keys.

In addition to the inbuilt LCD display, an external monitor could be connected for editing of sounds.

Overview of key shortcuts

The emulator is usable via a combination of mouse and keyboard. It was possible to connect an actual mouse to the 700’s serial port, so even if it might be somewhat unusual by modern standards we have kept it. Approached from a modern perspective the interface of the 700 needs some adjustment. Certain keys have different values in different situations and sometimes even function differently depending on which area the mouse is hovering over.

The keyboard Layout is as follows:

Emulator	700
Keys 0 - 9	Data entry keys 0 - 9
Keys 'a' - 'n'	Move fader 1 - 14 up
Shift + keys 'a' - 'n'	Mover fader 1 - 14 down

The mouse functions as follows:

Emulator	700
Left mouse button	Select
Right mouse button	Escape to main menu

The 700 hundred had 10 data entry keys counting from 0 - 9. These are used whenever numerical data needs to entered. Keys 8 and 9 have the additional function of being able to increment/decrement numbers and at other times toggle functions. We have emulated these using the numbers on your computer keyboard, 0 - 9 being mapped to the corresponding data keys, with 8 and 9 being used for incrementing and decrementing.

The membrane faders on the top half of the keyboard were used for direct manipulation of parameters. Each fader has a corresponding segment in the LCD display containing the name of the assigned parameter and a vertical bar representing the amount applied.

In future releases, a midi mapping to the faders will be possible, but at present they are emulated by keyboard alone. Keys ‘a’ to ’n’ are assigned to the faders, where a normal keypress emulates the fader being pushed upwards and a keypress with shift emulates it being pressed down

The layout of the membrane keys is as following:

[Image of membrane key layout]

Midi Configuration

It is possible to control the Emulator with a midi keyboard. Currently, it must be started from the command line with the extra argument ‘-m’ and desired midi channel. An example command for using it with MIDI channel 1 is:

./buchla -m 1

Librarian

Patch Editor

Score Editor

Sequence Editor

Instrument Designer

Waveshape Editor

The Waveshape Editor allows you to edit the transform function for the oscillator. What looks like a waveform is in fact an array of 254 values which are scanned by the wave generated by the frequency modulation setting. To understand this better, imagine a sine wave oscillating between 0 and 253, it will count from 0 until 253, back down again and repeat. Instead of playing the actual waveform directly a value is used to lookup the value stored in the waveshape table. In our example the sine wave would look up all values from 0 until 253 and then from 253 until 0 and repeat. This way, if you draw a diagonal line from bottom left until top right, the scanning waveform will be played unaltered.

The Waveshape Editor shows you the current wave shape being used. Click on a point in the wave or hover over a point and press ‘e’, this will toggle the edit mode. If you move the mouse up or down and wait a second or two for the screen to refresh you will see you have changed the value of single point. To exit the edit mode click or press ‘e’ a second time.

Most of the time you will of course want to manipulate more than a single point. For this, move the mouse cursor over the wave shape and press + (9) or - (8). This will change the “Width” setting in the control part of the screen. You can select "Width 0" until "Width 7" and another option "Interp". The "Width" options allow you to “bend” multiple points, 0 being only one point and 7 being the entire wave shape. "Interp" lets you draw the wave shape free hand.

Tuning Tables

Assignment Tables