User manual

15
current could upset the Devil Fish / TB-303, but will not cause damage. This is a high
gate voltage. If you need to drive a Moog or Korg active low gate, you will need a little
circuit comprising of two resistors and a transistor to invert the polarity of the signal. (In
my experience, Mini-Moogs are entirely unsuitable for driving from external CV and
Gate, unless they are extensively modified.)
CV Out
The standard TB-303 CV Out is connected directly to the output of an op-amp – this
ensures an accurate voltage even when it is driving a lower impedance device. The output
can handle being shorted to ground but the Devil Fish / TB-303 machine will not like it.
You should ensure that it never gets connected to a signal which tries to drive it below
ground or to any other voltage – since this could damage the op-amp. The CV Out carries
the voltage of the internal DAC, after it has passed through the slide circuit. If an external
CV is driving the machine through CV In, then the internal DAC is ignored and the input
CV is passed through the slide circuit to drive the internal synthesizer and the CV Out.
The Tuning knob only affects the tuning of the oscillator of the internal synthesizer. The
Tuning knob has no effect on CV Out, Filter Frequency or Filter Tracking.
The range of the CV Out is 1 to 5 volts when driven by the internal sequencer. It may
range a little above or below this when an external CV is used. The internal sequencer
produces a voltage in the range of 1 to 5 volts. This represents the 3 octave range of a
pattern which can be transposed by up to an octave. 2 Volts is the normal C at the left of
the keyboard, 1 volt is the C an octave below. 3 Volts is the C at the right of the
“keyboard” and 4 volts is that C transposed up an octave. In pattern play mode, you can
press “Pitch” and one of the 12 keys to transpose the pattern up by 0 to 12 semitones, so
the normal 1 to 4 volt range can be transposed to as high as 2 to 5 volts.
When the internal DAC is driven by the MIDI In system, it can go 3 semitones below and
above this range: 0.75 volts to 5.25 volts. These extra semitones at the top of the range
may not be entirely in tune, since the Devil Fish has a clipping circuit to limit excessive
CV inputs and that circuit begins to be activated above about 5.0 volts.
CV In
The CV may be usable somewhat below 1 volt. Do not put voltages below 0 or above
+5.25 volts into the CV input. The Devil Fish has a protection circuit to guard against
these voltages, but it is best that you avoid them nonetheless. Many MIDI to CV
converters are capable of going below 0 volts or above 5 volts.