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Read Me First!
Installation of this product is a simple procedure,
but we recommend this job only if you are an
experienced repair technician.
Requirements
Saddle slot
Minimum saddle slot length: 2.775” (70.4mm)
Maximum E to E spacing at saddle: 2.5” (63.5mm)
The Prefix Pro Series preamp will only fit in guitars
with a clearance of at least 1
11⁄16” (42.86mm) be-
tween the top and back braces, at the point where
the preamp chassis swings inside the instrument.
This path is defined as a 1
5⁄8“ radius, with the hinge
point on the bezel being the center of the circle.
Installation
Preliminary
1. Widen the endpin hole to 15⁄32” (11.9mm) to
accommodate the endpin jack.
2. Drill a 3⁄32” hole (2.4mm) in the saddle slot for the
pickup wire, no less than .100” (2.5mm) from the
nearest string. Install the pickup per Acoustic Matrix
installation instructions.
Cut out the preamp cavity
Please note: For instruments with solid wood sides
(especially maple), we strongly recommend that you
glue 2.5” (63.5mm) x .5” (12.7mm) plywood patches
in the areas inside the guitar where the screw holes
will be drilled. Doing so will prevent the area around
the mounting holes from cracking or splintering
and will strengthen the side of the instrument at
the cutout.
1. Choose the flattest possible location for the pre-
amp on the side of the instrument. The flattest and
most comfortable location for the player is often at
the upper bout, just above the instrument’s waist
and well below the shoulder. Note that the bezel has
a limited ability to bend just enough to conform to
the curved sides of most standard sized instruments.
Caution! When mounting the Prefix Pro Series
preamp on solid wood instruments with highly
curved sides (such as small bodied acoustic-
electrics), exercise extreme caution when choosing
the preamp location.
A highly curved mounting surface may cause the
preamp to bind against the mounting bezel or in
worst cases may cause the wood to crack around the
preamp mounting holes.
2. Attach the enclosed cutout template at the de-
sired location and cut out the cavity for the preamp.
3. Drill the preamp mounting holes with a #45 drill
(.082”/2.08mm).
Output cable / endpin jack wiring
Important note: To ensure full pivot action for the
preamp, remember to leave an extra 3” (76.2mm)
of slack when you decide the output cable’s
final length.
Solder the wire connections
1. Determine the proper length for the cable, then, if
necessary, strip and tin the output wires.
2. To gain better access to the terminals on the
endpin jack, gently bend back the Strain Relief/
Sleeve tab before you begin to solder.
Jack connections
• Red wire to Tip (short terminal)
• Black wire to Switch (longest terminal)
• Shield wire to Sleeve (strain relief)
• Ring is not connected (middle terminal)
PREFIX PRO SERIES PREAMP
INSTALLATION GUIDE
Shield to
Sleeve
Red Wire
to Tip
Black Wire
to Switch
GUITAR BODY
PREAMP
15
/8”
