
38
The
2600/TTSH EG’s
gate inputs are not gate detectors, they are g
ain stages. If you don’t drive them with
a full +10V gate signal, the EGs will never rise to a full +10V on their outputs, leading to reduced signal
gain from the VCA outward. Many devices in the modern studio will 5V gate signals, which will
not fully drive the EGs. The Gate Booster uses a comparator on its input to detect gate signals of varying
amplitude (threshold is +2.7V), and then generates a cons10V gate on its output. It then uses its
own generated gate to produce a +10V trigger impulse for the ADSR. The trigger represents a momentary
impulse at the leading edge of a detected gate.
Note 1: if you drive your TTSH using MIDI-to-CV converter, program it for multiple trigger mode.
This function will allow you to overlap notes on a MIDI keyboard and the ADSR will reset and make
a new note event for each new overlapping note. This mimics the behavior of an ARP 3600 series
keyboard. You do not need to connect a trigger CV from the converter, just gate. The Booster
takes care of the rest.
Note 2: ARP user manuals refer to the Gate and Trigger jacks as outputs. This installation converts
the function of the Gate jack to
an input
. The Trigger jack still functions as an output for the
Booster’s generated trigger signal. There is no external output for the Booster’s genera
ted gate
signal.
For installation, make sure you have cut the trace running from the tip of the Gate jack to pin 1 of the
Gate Switch (see Figure 1). Then, refer to the photograph. The Booster is installed in the span between
the tip of the Gate jack and pin 1 of the Gate switch, where the trace was previously cut (the cut is
obscured in Figure 10). In the photo, the polarity of the power connector is indicated, and power jumper
connectors cross over (here Red = +15V, Green = 0V and Black = -15V). If you install the locking header
on the main PCB the other way around, your power jumper should not cross over.