MicroPre and MicroPre 2 Instructions
The MicroPre is a single
channel Jfet preamp
providing up to 4 db of gain
and a single mono output.
The Micro Pre 2 is a two
channel Jfet preamp that
provides up to 4 db of gain
per channel and separate
(stereo) outputs.
Rotary Potentiometer:
Shown with the solder lugs
pointing up. To function as a
volume pot, lug 1 is soldered
to ground on the back of the
pot. Lug 2 is the wiper, lug
three is the tap.
Thumbwheel Potentiometer:
Schatten Design
thumbwheel mounted circuit
board shown. Lug 1 is soldered to pad 1 on the circuit board which is ground. Lug 2 is the wiper, lug 3 is the tap.
TRS Stereo Output Jacks: Regular stereo jacks have 3 lugs. On these jacks, Tip is used for the (+) signal, Ring is used as a
switch to turn the battery on when a mono plug is inserted into the jack. The insertion of the mono plug into a stereo jack
creates a connection between the Ring and the Sleeve. Sleeve is used as ground.
Balance Potentiometer: This is a stacked linear pot in which the upper and lower sections are reverse taper to each other.
These pots often have a center detent.
Basic Wiring Configurations: For the single channel MicroPre, figures 1 and 2 show wiring using normal audio taper (log)
potentiometers. Figures 3 and 4 show wiring using Schatten Design circuit board mounted thumbwheel potentiometers.
Note that the ring contact on the jack is being used as the battery switch.
fig 2
figure 3
fig 1
fig 4
