Within its hallowed but modest expanse lies scores of dusty devices strange and wondrous, patiently awaiting the day when some knowing hand will once again awaken them to perform their magic.
What follows is a list of equipment that Timara majors can sign out from the Timara Technician's office. Some of this equipment, like the portable DAT player, is used quite often but most of it rarely sees the light of day, probably because nobody knows about it. Hopefully, this issue of Tech Notes will remedy this situation.
Sony TC158SD Portable Cassette
Old, and losing some of its high frequency response, but still operable. Has both line level and mic level inputs.
Sony PCM-F1
Converts two audio signals into a standard video signal which can then be recorded onto any video deck (VHS or BETA) in place of the video signal. If you have a video deck with hifi stereo inputs you can record two more audio signals to make it a quad recorder.
Sharp VL-L63U VHS Camcorder
With Battery Pack, remote, and tripod.
Quad Microphone Preamp
Midi Horn
Another Midi Wind Controller built with brass instrument fingerings. This was designed and built here in Oberlin by John Talbert and Gary Nelson. Gary has used it extensively in his concerts and compositional work.
Media Master - Midi Slide Projector Controller
This device accepts Midi KeyOn signals to control 4 slide projectors and two AC power switches. Here is a way to control your slide projectors through a Midi sequencer program or even a Midi keyboard.
Roland CP40 Pitch to Midi Converter
Converts the pitch and amplitude of a microphone level signal into Midi control signals.
Roland Pad-80
The Roland Pad-80 has eight percussion pads which send out Midi Note On/Off signals when struck. Each pad has programmable settings for Midi Channel, key number, sound length, sensitivity, velocity curve, and various ways of layering of up to 3 key sounds per pad. There is also an external pedal control for Modulation, Pitch Bend, or Aftertouch effects.
When eight is not enough, there are jacks for 6 'satellite' pads with the same programmable features as the built in pads. I've tried out our home-built dual pads with these external inputs and they work just fine.
You can also build your own sensors without much difficulty. Go out to Radio Shack and buy a piezoelectric disk for about a dollar. Connect the two leads to a simple 1/4" plug that will connect to the Roland external inputs, and then go ahead and stomp, slam, shoot, drop, or whatever. It is that simple.
Midi Micro
This is an Oberlin built microcomputer that will send out Midi control signals based on what the micro reads at the control inputs. (If you are familiar with the Clarity Retro in Studio 4, this does the opposite direction.)
The control inputs can be any of 8 panel switches, 8 switch input jacks, or 8 continuous control voltages. Audio signals inserted into the control voltage jacks are automatically sent to Envelope Detector circuits which transform each signal into an envelope control voltage that follows the signal's amplitude.
The control inputs can be connected to a wide variety of sensors such as pedals, pressure sensors, light sensors, motion detectors, and so on. Some of these are described later.
Each particular application requires that you program the micro using its own internal operating system language called Forth. This system includes a library (or, in Forth terms, a dictionary) of subroutines (words) which deal with the Midi outputs and control inputs among other things.
Programming the micro involves connecting it to a Macintosh serial port and running a terminal emulation program to load your programs and test them. Materials for learning Forth language are available along with documentation of all the "words" that make up this machine's Forth "dictionary". Most application programs are simple, involving only about ten lines of code. John Talbert is available to help you develop your code.
Midi microcomputers are showing up everywhere these days being used in a wild variety of performance situations. The Oberlin Timara department was among the first places to develop and use such devices.
PortaMod
A home-built box with 5 microphone inputs and 4 outputs. Each input signal is ring modulated with its own VCO (Voltage Controlled Oscillator). The VCO's have adjustments for frequency and amplitude.
Portafilt
Another home-built box with three Voltage Controlled Filters. Each filter has separate Low Pass, High Pass, Band Pass, and Notch Filter outputs. Each filter has two control voltage inputs, one for Resonance and one for Cutoff Frequency along with pots for setting the range and offsets of the control voltages.
Pulse Generator
Has six pulse generators, each of which outputs a pulse with a variable pulse-width (0.1 sec. to 1.0 sec.) whenever the amplitude of an input signal goes above a set threshold.
The sensors described here fall into one of two categories: an on/off switch action such as in a sustain pedal, or a continuous controller such as in a control voltage pedal.
If the sensor output is a voltage, it can usually connect easily to any control voltage input of an analog synthesizer. Most equipment these days, however, are more apt to use Midi signals than control voltages. What you need, therefore, is a way to convert a voltage or a switch action to a Midi command. Most keyboard synthesizers provide just such converters in the form of a Continuous Controller pedal input and a Sustain switch pedal input. Be aware, however, that the two functions are different: the control pedal requires a voltage and the sustain pedal requires a switch type device.
Before connecting a sensor to a keyboard pedal input make sure the sensor action matches that of the pedal and check with the Timara technician to make sure the plug is wired correctly for the particular synth being used. Finally, if you are using more than one or two sensors, look into the Midi Micro described earlier.
Here, now, are some of our sensors:
Floor Pedal Unit
This is a one-piece unit with 2 continuous controller pedals, 6 continuous controller wheels, and 5 push button switches.
Light Sensors
Up to six small boxes with light sensors connect to a central power supply box. The outputs are continuous control voltages.
Light Wand
This is a small wand with light sensors at each end working in opposition to each other. Its full continuous voltage range occurs when one end is rotated from light to dark while the opposite is happening at the other end.
Pressure Pads
These are built from a pressure sensitive foam material sandwiched between two metal plates. They put out a rising voltage when squeezed.
Piezo Drum Pads
Piezoelectric sensors output a voltage which is sensitive to changes in pressure. These work well with the Roland Octapad.
Foot Switch Pads
We have various flat pads which can fit inconspicuously under rugs or mats. When stepped on its internal switch is closed.
Mercury Switch Wand
This is somewhat like a conductor's wand. A switch is closed when the top end is tilted down.
Infrared Power Switch
A 60Hz AC power receptacle is switched on and off by means of a tiny hand-held infrared transmitter working in a push-on/push-off mode. The Transmitter's range is about 50 feet.
Triple Electronic Switch
This box contains 3 electronic switches, each with one output, two signal inputs and one control input. The output connects to one of the two inputs depending on whether the control voltage is high or low. The signals being switched can be audio or video; though, for video signals, you may experience a momentary loss of sync when switching.
The switching can be extremely fast. A type complex modulation occurs when the switching control signal is a square or pulse wave within the audio range.
Color Video Monitor This is a small Color Monitor (12 inch diagonal) with a standard NTSC video input. It also has a small, tinny-sounding internal speaker for your audio.
TOA SM-25M Floor Monitor
Small 25 Watt wedge monitor.
Sound Effect CD's
Ten CD's of sound effects with everything from John Glenn's heartbeat to your favorite animal sound. A copy of the list should be in each studio.