PREFIX SERIES PREAMPINSTALLATION GUIDE

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Read Me First!

1. Choose the flattest possible location for the preamp on the side of the instrument. The flattest andmost 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 tothe curved sides of most standard sized instruments.

Installation of this product is a simple procedure,
but we recommend this job only if you are anexperienced repair technician.

Requirements

Caution! When mounting the Prefix on solid wood
instruments with highly curved sides (such as small
bodied acoustic-electrics), exercise extreme caution
when choosing the preamp location.

Saddle slot
Minimum saddle slot length: 2.775” (70.4mm)
Maximum E to E spacing at saddle: 2.5” (63.5mm)

A highly curved mounting surface may cause thepreamp to bind against the mounting bezel or in
worst cases may cause the wood to crack around thepreamp mounting holes.

The Prefix preamp will only fit in guitars with aclearance of at least 2 ¼” (57.15mm) between the
top and back braces, at the point where the preampchassis swings inside the instrument.

2. Attach the enclosed cutout template at the desired location and cut out the cavity for the preamp.

Soundboard

3. Drill the preamp mounting holes with a #45 drill(.082” / 2.08mm).

Minimum 2.250”(57.15mm)
clearance between
top andback braces

Output cable / endpin jack wiring
Important note: To ensure full pivot action for thepreamp, remember to leave an extra 3” (76.2mm)
of slack when you decide the output cable’s
final length.
Solder the wire connections

Back

1. Determine the proper length for the cable, then, if
necessary, strip and tin the output wires.

Installation

2. To gain better access to the terminals on theendpin jack, gently bend back the Strain Relief/
Sleeve tab before you begin to solder.

Preliminary
1. Widen the endpin hole to 15⁄32” (11.9mm) toaccommodate the endpin jack.

Jack connections for the Prefix Premium
Blend model

2. Drill a 3⁄32” hole (2.4mm) in the saddle slot forthe pickup wire, no less than .100” (2.5mm) fromnearest string. Install the pickup per Acoustic Matrix
installation instructions.

• Red wire to Tip (short terminal)• White wire to Ring (middle terminal)• Black wire to Switch (longest terminal)

Cut out the preamp cavity• Shield wire to Sleeve (strain relief)

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 aroundthe mounting holes from cracking or splintering
and will strengthen the side of the instrument atthe cutout.

Black Wire
to Switch

Shield toSleeve

1White Wire
to Ring

Red Wire
to Tip

Jack connections for Onboard Aura andPrefix Plus-T models• Red wire to Tip (short terminal)• Black wire to Switch (longest terminal)• Shield wire to Sleeve (strain relief)

3. Insert the hot pickup wire (inner conductor) in theleft side of the terminal block, marked “IN,” thepickup ground wire (shield) in the right side of theterminal block, marked “GND,” and tighten down
the screws on the top of the terminal block with a3⁄32” (2.4mm) slot head screwdriver.
4. Snap closed the trap door.
5. Angle the preamp 90° from the bezel and insert
it in the cut-out, then fasten the preamp bezel
using the four self-tapping screws and the twoplastic backing plates.

Black Wire
to Switch

Self-Tapping Screws

Shield toSleeve

Red Wire
to TipSoundboard• Ring is not connected (middle terminal)
Endpin jackInstall the endpin jack per Switchjack Installation
Guide.

Plastic Backing Brackets

Mount the preamp
Complete the installation

1. Insert the pickup in the saddle slot.
2. Carefully pull back the “trap door” on the preamp(located next to the output cable) to expose theInstall a 9V alkaline battery.
To keep the wires inside the guitar from rattling,
secure them with the included adhesive backed
clips. Attach the wire guide clips to the side of theinstrument.

TerminalBlock
Trap Door
Pulled Back

PreampControl Panelterminal block.

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009-087-007 Rev E 5-09