User`s manual

6. PREAMP MODIFICATION (ALL PREAMPS)

6.1. Overview

The mod is basically the same for all preamp types. Differences are only in respect to the coupler connection

points and the mounting of the D-Sub connector. In this chapter is described only what is common to all

preamps. For detailed instructions about your particular preamp model see the corresponding section.

6.2. Modded device behavior

The stock gain potentiometer continues to function as before if the remote gain controller is not connected or if

it's switched off. To experience remote control magic, turn all knobs to the leftmost (minimum position) and

switch on the remote gain controller – now you are able to adjust the gains from everywhere, using common

MIDI controllers.

Limitations

 You cannot mix local and remote control, but you can switch between both modes.

 The maximum gain which is achievable in in remote-control mode is a few dB lower than with the original pot,

because the couplers don't reach 0 ohms minimum resistance.

6.3. Prerequisites

 Screwdrivers for opening your preamp

 Wire cutter

 Solder iron and wire

Additionally, if you decide to mount the D-Sub jack into the preamp:

 Saw and/or fretsaw, or preferably a mini-grinder tool (e.g. DREMEL with cut-off wheel)

 Small flat file for smoothening of the cutout edges

 3mm drill

 5mm wrench

 Bench vise for press-fitting the connector

6.4. Circuit

The optocoupler's outputs are installed in parallel to the potentiometers. The input (LED) terminals are connected

to the D-Sub connector, with common anode on pin 1 and cathodes on pins 2 to 9.