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Synthcube has made available Roman Sowa’s MIDImplant for addition to the TTSH. This is a small postage
stamp sized board that seems to punch above its size category. Because it is so small, it does not have
any mounting holes. You can hot glue it down, build a bracket to hold it, or use its ten-point connection
pads as a mounting.
Features:
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Runs on DC power +6-17 Volts.
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2 CV outputs
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2 Gate outputs
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Basic configuration can be performed by way of a pushbutton switch (optional)
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More configuration options are via MIDI Sysex messages (preferred).
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Decent accuracy.
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CV range is 0V to +5V (five octaves).
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Starting MIDI note (for 0V) is configurable.
Older examples of the MIDImplant provided gate signals in the form of a pass-through (S or V gates) from
the input power. On these units, the amplitude of the gate signal was equal to the input power voltage.
A new version of the MIDImplant was produced for Synthcube that has gate amplitude fixed at +5V. You
can identify these by the Synthcube name on the back of the PCB. These newer units require the inclusion
of the Gate Booster.
The problems the builder must solve to add a MIDImplant to the TTSH are:
1.
The original TTSH circuit for the KBD CV Bus does not support connection of an internal pitch CV
source. There is a header for it, but it does not work correctly. A fix for this is suggested below.
2.
It is not easy to reliably mount the tiny MIDImplant board directly. There are no screw holes, and
the manufacturer suggests hot melt glue, which I find undesirable. An alternate mounting is
suggested below.
Improved Routing for KBD CV Bus.
The KBD CV bus is common to both the tip of the KBD CV Output jack, and the “CV” pin on the header
next to this jack. If it was just this, it would be identical to an ARP 2600, where the 3620 was connected
to the CV bus, and the panel jack provided an output for that signal. However, on the TTSH, the tip-
switched contact of the KBD CV Output jack is connected to GND in the middle layer of the PCB, where its
pin connection goes through the board. This effectively makes the jack an input. In a standard build, the
only way to modulate pitch via the CV bus is to introduce a CV to the panel jack. There is no way to select
between CVs coming into the main board header versus the jack. So, there is no option, in the standard
build, to connect a CV that is coming from something inside the case.
Method 1.
A very simple solution is to snip off the tip-switched pin of the KBD CV Input jack, and solder on an
insulated wire jumper in its place. The insulation should come all the way up to the jack housing. This
jumper is routed through the hole on the PCB to avoid contact with the solder pad at that location. An
internal pitch CV source is then connected to this jumper.
Behavior
