For those of you who were holding your breath, sorry the column didn’t make it into last issue, but we did give you that massive musical instrument supplement to chomp on in the meantime. Anyway, at long last, breathholders, here is part two of the CREEM Synthesizer Lesson begun in October.

It might make everything a bit more understandable if you referred back to the previous column, but to briefly refresh your memories, I explained last time that with just an oscillator, a mixer, a filter, and an amplifier you pretty much have yourself a synthesizer. I discussed those basic components in detail but added that there were lots more fun things to be had. So let us plunge ahead.

ENVELOPE GENERATOR This acts to shape the sound by governing the attack and decay of the tone, Thdre are several different kinds of waves (attack and decay sequences) in a synthesizer. For instance, the oscillator produces even, continuous waves. The envelope generator, however, produces a single wave for every sound event (note) that determines how the tones build up and die down. Any wave that shapes a sound is called a control signql. Some of the most comfrionly heard control signals in urban spaceland are:

Sine wave — Characterized by symmetrical, even rising and falling, like a vibrato effect.

Sawtooth wave - —"t A long rise or “ramp” with ap abrupt, immediate cut-off. Sounds like one of those eerie new police sirens.

Square wave-r"'— Has an immediate rise and fall, resembling a trill.

RING MODULATOR For this one., go back to those waves mentioned in the Envelope Generator explanation . What the Ring Modulator does is take two oscillator-oroduced sounds (to get an effect, each tone must have a different wave form) and superimposes one on the other1. What ypu get is a “sum and difference” pitch. That is, the pitch that is produced is only that portion of each sound which intersects the other when their two waves are superimposed. It’s sort of like a filter for wave forms.

FREQUENCY SHIFTER This is a rather esoteric component not found on most synthesizers. But even if it’s not all that relevant, it’s kind of cute. The frequency shifter shifts a frequency (pitch) up and either compresses or spreads out the partials of that frequem cy, depending, on which action you select. (Partials are “odd vibrations at non-specific places,” explains my instructor Roger Powell. Something like irregularly placed harmonics.)

WHITE and PINK NOISE -Simple. The switch labelled “white noise” turns on white noise — that is, a' hissing or vacuum cleaner sound that results when a very large number of frequencies are played simultaneously. The switch labelled “pink noise” also, turns on a lot of frequencies, but these are somewhat concentrated in the bass range and, when played simultaneously (via the switch), produce a deeper — someone thinks “pinker” — hissing vacuum cleaner. You can use these two switches for all sorts of whooshing or explosion effects by imposing on them some of

your other controls. You can also use the white noise to check out whether your sound jsystem is responding properly to the whole range of frequencies.

SEQUENTIAL CONTROLLER (sequencers) - This hefty component here is almost a fellow musician. Each of the eight vertical rows of dials controls a segment in a sequence pre-programmed ]by you. This sequencer can control a sequence of volume changes or whatever you want, but is most often used to control a sequence of frequency changes. For example, you take each row of knobs and set them up so they will produce a certain pitch — each row a different pitch, so the eight rows make up, say a scale. Program'the speed you want this sequence (here, a,scale) played at, punch on the sequencer and watch it go. It will play this scale you have programmed into it unendingly with perfect timing. If you want to you can program it to skip a note or two in the scale or do it backwards or inside-out, whatever. And very slow or fast. With a simple twist of the wrist you can change the key up or down. If you like, set each row to a very low frequency and have the sequencer do a percussion-like part. In tbe meanwhile, you can be doing your own lead part over the sequencer’s backup. Amaze your friends by leaving your synthesizer alone in the room playing the opening to “Baba O’Riley” from Who’s Next. There’s lots of fun to be had with this new electronic buddy, the sequential controller.

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And that’s pretty much all there is to the modules — pretty much all there is to a synthesizer. But for the sake of convenience and efficiency for the player, the original designers included a conventional keyboard. Aha — conventional on the outside, but go on...

KEYBOARD - On this synthesizer there’s two, of four octaves each. Two, because each one can be patched into separate and different combinations and permutations of filters, oscillators, etc. Basically, the extra one allows for more flexibility in your sound. The keyboard on a synthesizer is actually just a series of switches regulating voltage. When a key is pressed the voltage into the synthesizer is altered. An octave on the keyboard equals one volt. Middle C is zero volts, so it goes down to -2 volts at the far end of the bass and up above middle C to a high of 2 volts. The synthesizer modules respond to instructions that are given to them by your increasing or decreasing the ' voltage — playing up or down the keys. It may be misleading to call the reference point on the keyboard “middle C,” better to icall it the “midpoint.” Because, although these look like conventional keyboards, the fact is that they aren’t necessarily programmed to th? diatonic scale. Adjacent notes on these keyboards might be a third or a fifth apart. And really the keyboard doesn’t have to be set up to control pitch at all. Each key could be set to produce the same pitch but with a different volume — the one note would get louder, not higher as you went up the keyboard. Each keyboard s just a set of 32 switches regulating voltage, and each keyboard can be patched into almost anything you want it to control.

That’s just about it, except for a few goodies that Roger has on or attached to the keyboard unit. Briefly, they are:

RIBBON CONTROLLER A ribbon stretched the length of a long rectangle. It’s a voltage regulator, too, just a different physical configuration and a bit more flexible. Run your finger up and down the ribbon to continuously alter voltage and, so, change pitch, volume, whatever you’ve chosen. Similar soupd to the theramin in “Good Vibrations.”

BEND CONTROL - Used to bend notes like on a guitar. A wheel set into the keyboard unit that alters voltage up to one volt. Just roll the wheel (it will spring back by itself) and, provided your keyboard is set up to control frequency, the note you are playing on the keys will “bend” up. Roger uses this when playing harmony “guitar” parts with Todd.

PRE-SET SWITCH You’ve patched it all up beforehand and so all you do is throw this switch to change from one module to another — to give your sound a fast costume change.

And that, spacemen, is that. Drive carefully.