GM 16 Instructions
DESCRIPTION
Amplifying the acoustic sound of an
instrument over a sound system has been
difficult. Microphones feed back, and pickups
don't deliver a natural frequency response. By
mixing the two, the advantages of each come
through. The pickup supplies the gain and low
end, and the mic supplies the clarity and high
end to deliver the best combination of clear
sound and gain before feedback.
The Rane GM 16 is designed to be
mounted inside acoustic instruments such as a
guitar. It is a uni-directional condenser which
can be positioned for the best sound within the
instrument. It requires a special 6 volt 2-wire
phantom power supply to operate, supplied on
Rane's AP 13 Acoustic Preamplifier (for
which the GM 16 is intended to be used). A
second pair of leads are provided to connect to
an existing pickup. Output is derived from a
¼" TRS jack at the base of the gooseneck that
wires the pickup to the tip and the microphone
to the ring. This jack replaces the existing jack
or endpin on the instrument body. If a ¼" TRS
cable is used, both pickup and mic signals are
kept separate on a single stereo cable. If using
a mono ¼" cable, only the pickup is active.
INSTALLATION
1. Remove the strings. Enlarge the hole for the
GM 16 with a ½" tapered reamer if needed.
2. If the instument has a pickup, disconnect
the wires from the existing jack and solder
those leads to the loose set of wires
protruding from the middle of the GM 16.
Separate and cover the connections with
electrical tape.
3. Insert the microphone assembly through the
soundhole and tighten the strap button/
locknut from outside the instrument.
4. Replace the strings and tune the guitar. Set
the phantom power on the AP 13 to 6 volts.
Connect a quality ¼" TRS to TRS cable
from the instrument to the preamp. Set the
front panel switch to TIP=PZO/
RING=MIC. Consult the AP 13 owners
manual for further instructions.
MICROPHONE PLACEMENT
Position the microphone approximately
¼" beneath the soundboard near the treble side
of the soundhole, with the active black face of
the microphone towards the interior of the
instrument (approximately towards the chest
of the player). Rotating the active face of the
mic towards the back of the guitar often tends
to reduce excessive bass response.
Every instrument is different, and may
require a different mic position. You are
encouraged to experiment with positioning the
mic until the best combination of tone and
volume is produced. Like any microphone, the
GM 16 can feedback if not properly used.
Most pickups that sound 'midrangey' are
better with the 630 Hz slider pulled down in
the AP 13’s Piezo equalizer section. The mic
will be less boomy with it's Low Cut filter
raised. Experiment with combinations of mic
position and equalization for best results.
