User manual

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the DAC in the standard TB-303) which causes any pitch difference between the notes to
be audibly slewed. (Normally, without Slide, C35 is driven by the IC11B op-amp, which
follows the DAC voltage directly.)
In MIDI there is no formal concept of a slide. It is possible to use pitch-bend on a single
note, but that does not relate to the musical notion of tying two note events into one over
time, and it has technical problems including: the need to return at some stage to zero
pitch-bend, the lack of reliable control of the amount of pitch bend the slave device
implements and the typical inability to arrive at a precise final pitch. Also, smooth slides
of pitch are impossible with MIDI pitch-bend, since these are discrete commands.
Since musicians typically conceive of slide as something added to two or more pre-
existing note events, rather than slide being a conversion of two or more static note
events into one longer note event with a complex pitch variation over time, it is natural
that a single control voltage be used to turn on Slide. Prior to version 2.1D, the Devil
Fish Slide In turned on the slew circuit, but did not affect the Gate of the synthesiser.
This provided maximum flexibility, since there are musically useful reasons for slewing
the oscillator’s control voltage with respect to the input CV (or the internal sequencer’s
DAC) without at the same time turning on the Gate. However, in version 2.1D I
implemented a system which can still work in this “isolated” way – turning on the slew
circuit only – or which could also turn on the Gate.
The most usual concept of Slide is that when such an input is on, the synthesiser’s Gate is
also on, and that all changes to CV are slewed. This is the “combined” slew and gate
mode.
The Slide In voltage of version 2.1D has two thresholds:
1. +2.3 volts and above – turns on the slew circuit. (As for all previous versions.)
2. +4.0 volts and above – turns on the Gate of the synthesiser, if it was not already
turned on via the Gate In or the internal sequencer.
Therefore, for ordinary Slide operation, simply have your external MIDI to CV converter
(or whatever you are using to control the Devil Fish) provide more than +4.0 volts. 5
volts to any other value, say as high as 30 volts, is fine.
To turn on the slew circuit, without turning on the synthesiser’s Gate, use a voltage such
as 3.0 volts. If you have only an on/off Gate signal and you want to provide 3.0 volts to
the Slide In, then you will need to experiment with external resistors in series, or as a
divider, to create this voltage.
Also, with version 2.1D, I changed the Gate In threshold voltage from +1.5 volts to +3.5
volts. This should not have any practical impact, since all MIDI to CV converters can be
assumed to put out at least 5 volts for their Gate signal. As before, there is no hard upper
limit to the Gate In voltage – up to 30 volts is fine.