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Friday, December 12, 2008

Sequential Circuits Multi-Trak

via this auction
"Here are some features:
The velocity-sensitive, multi-timbral MULTI-TRAK combines the superior expressiveness of velocity touch sensitivity with the compositional flexibility of multi-timbral sound, as pioneered by Sequential with the Six-Trak and MAX synthesizers. Other features of the MULTI_TRAK include a built-in multi-track sequencer, a chorus effect for richer sounds, a split keyboard, individual audio outputs for each voice, a cassette interface for program and sequence storage, and, of course, MIDI (Musical Instrument Digital Interface).

The block diagram (page vii) shows the main sub-sections: keyboard, sequencer, sound memory, voices, and MIDI. Using this as a basis for discussion, we trace backwards from the audio output, to see how the sub-sections, work together. There are two types of audio outputs, the Mix outputs and the Track outputs. The Mix outputs, A and B, provide a psuedo-stereo effect from the chorus. Stereo headphones can be plugged into either Mix output. The Track outputs are useful in studio situations, where each voice can be run through its own channel of the main mixer board. If a Track output is used, its voice is removed from the MULTI-TRAK's Mix outputs.

These audio outputs come from the six independent synthesizer voices. In contrast to homophonic synthesizers, which program each voice with the same sound, each of the MULTI-TRAK's voices can have a different sound (multi-timbre). Each voice has a multi-waveform oscillator (or noise) as the principal sound source. The oscillator drives a resonant low-pass filter which contours the timbre, and an amplifier which contours the dynamics. There are three attack-decay-sustain-release (ADSR) envelope generators: one for oscillator frequency, one for filter cutoff frequency, and one for amplifier gain. (The polarity of the first two can be inverted.) A triangle- or square-wave low frequency oscillator (LFO) can modulate oscillator frequency, pulse width, or filter frequency. The amount of LFO modulation can be controlled with the Mod wheel. A second modulation route runs from the oscillator triangle output to the filter frequency, for frequency modulation (FM). Frequency glide ("portamento") and voice volume are programmable. A Pitch wheel is provided for bending notes. Non-programmable master volume and tuning controls are provided. The TUNE switch has been eliminated by fully-automatic oscillator tuning, although a manual tune command is still available.

A voice has two types of inputs. First are the sound parameters from the sound memory. These operate on the synthesizer voices to define the track's timbre-in other words, the instrumental sound. The synthesizer program memory stores 100 sound programs, each consisting of 40 voice parameters. 100 instrumental sounds and effects are factory-programmed, but the player can modify (edit) these as desired. Light-emitting diodes (LEDs) clearly indicate the selected program, and if the program is being edited, they also display the parameter value and indicate which parameter is being edited. You use a single knob to change all parameter values. Programs can be copied. And the non-volatile memory is retained when power is off, thanks to a long-life backup batter. To permanently back-up programs and sequences, provision is made for storing them on audio cassette

The second type of input to a voice are notes. Notes tell the voice to play and what pitch to play. A voice can be played by notes coming from three sources: the keyboard, the sequencer, and MIDI. The MULTI-TRAK has a five-octave keyboard which you can use to overdub tracks, to play one or more voices live along with recorded sequences, or to play six voices live with either one sound (polyphonic or unison), or multiple timbres (in Stack or Split modes). The velocity with which a key is played can affect the loudness or brightness of the note, or the amount of LFO modulation applied. Other keyboard modes include voice stacking (for fatter sounds), a programmable split point, and a flexible arpeggiator.

When playing the MULTI-TRAK keyboard "live," each key played has the same sound (homophonic mode), except in Split mode, where the keyboard can be divided into two parts, each with its own timbre. When playing live, more complex multi-timbres are not possible because the MULTI-TRAK cannot know which keystrokes you intend for which timbres.

But the sequencer can record whatever you play on the keyboard as a separate track using its own voice. So each track can be overdubbed with a different sound. The sequencer allows overdubbing and editing without re-recording, splicing, or accumulating noise and distortion by "mixing-down" and "bouncing" audio tape tracks
The 1600-note memory can be allocated to four sequences. Sequencer functions include overdubbing, programmable playback speed, programmable track volume, track erase, warning of memory-full, built-in metronome and autocorrect, an append function (which adds sequences together), and sync-to-tape.

Thirdly, the voices can play notes coming in from MIDI, which may be from another synthesizer or an external sequencer.

The MULTI-TRAK can send live notes, recorded notes, or sounds out to MIDI. For example, Sequential's Model 242 MIDI Interface Cartridge for the Commodore 64, and associated 900- series software, offers increased sequencer storage (up to 4000 notes), program and sequence storage on cassette or disc, and song transposition, as well as forthcoming music display and editing functions.

Finally, if you use a MIDI rhythm unit (such as the Sequential Model 400 Drumtraks), it sends a MIDI clock to the MULTI-TRAK sequencer, which synchronizes the MULTI-TRAK song to the drum song (or pattern).

Note: For more information on MIDI applications and use with Sequential's Drumtraks, please see the MULTI-TRAK MIDIGUIDE.

In order to get the most from the wealth of features found in your new MULTI-TRAK, we hope you will study this manual and the MIDIGUIDE thoroughly, and keep the reference card on hand while performing. You will find the MULTI-TRAK to be a most versatile music tool, both in itself and with its powers of MIDI expandability."

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