A sound is defined by three basic elements: pitch, timbre and volume. In a synthesizer
you have control over these three elements. A voltage controlled oscillator (the pitch) is
treated using a voltage controlled filter (the timbre) and then finally articulated using a
voltage controlled amplifier (the volume). In the DB9 the control of these elements has
been limited to specifically assist the user produce bass sounds.

The Pitch

The Voltage Controlled Oscillator (VCO) is an oscillator which generates a pitch based
on a voltage. The DB9 uses the original 1 volt per octave pre-MIDI standard. The DB9’s
MIDI interface generates this voltage and it is then used to control the DB9’s synthesizer
board. The tuning knob will let you adjust the fine tuning range.

The Timbre

The voltage controlled filter will adjust the sound of the machine quite dramatically but
you can also select the harmonic content of the basic waveforms using the waveform knob
on the front of the DB9. There are two wavforms to choose from giving two harmoni-
cally diffrent sound sources. These are sawtooth and square. The sawtooth waveform
produces a thin "brassy" sound. The square wave is much more aggressive, more syn-
thetic sound.

The Voltage Controlled Filter (VCF) adjusts the sound of the basic waveforms by reduc-
ing or emphasising certain harmonics. These are adjusted on the DB9 using the following
knobs. The cut-off frequency know (Cut Off Freq.) adjusts the cut-off frequency of the
voltage controlled filter. As you turn the knob anti-clockwise the higher harmonics are
reduced, eventually the waveform will approach a sine wave. The filter resonance knob
(Resonance) adjusts the harmonic emphasis of the VCF. As you turn the knob clockwise
the harmonics become more emphasised. When the resonance knob is turned fully clock-
wise the filter will produce the classic "acid" sound, which has been used on so many suc-
cessful recordings.

Use the envelope modulation know (Env Mod) to control the amount of envelope signal
used to bias the filter. The further clockwise the know is rotated the greater amount of
envelope modulation applied to the filter and the brighter the sound will be. The enve-
lope decay knob (Decay) controls the lenght of time the sound takes to decay away.
Turned fully anti-clockwise the decay time is very short. Turned fully clockwise the decay
time is very long.