A C O U S T I C B L E N D E R S Y S T E M
20
USING OTHER MICROPHONES
The BLENDER is also compatible with other manufacturers’ mini-electret micro-
phones. Consult the manufacturer for specific minimum power requirements,
wiring configuration and instrument mounting systems (the Fishman microphone
mounts are dedicated to the Crown GLM series).
Dynamic microphones (such as the SM 58) may be used with the BLENDER.
You'll need a low to high impedance adapter in the AUX/MIC IN jack. Turn off the
Phantom Power (switch is in) for this application.
POSITIONING THE MICROPHONE
It’s worth taking the time to experiment with the placement of the Crown
GLM-200. Here are some suggestions to help you get started:
INTERNALLY MOUNTED MICROPHONE
(flat top guitars)
Start with the microphone centered in the
soundhole, slightly below the top. Position the
face of the microphone (marked “FRONT”)
toward the sound chamber of the instrument.
Tilting the microphone as much as 90° may
help reduce boominess.
EXTERNALLY MOUNTED MICROPHONE
(violin, bass, cello, arch-top guitar).
Start with the microphone centered halfway between a bridge foot and F-hole.
Position the face of the microphone (marked FRONT) towards the instrument.
Tilting the microphone as much as 90° may help reduce boominess. Placing the
microphone directly over an F-hole will produce a deep, woody tone. However,
the microphone will feedback at the instrument's cavity resonance. This can be
easily remedied by notching out the feedback with an external equalizer (see
below). Placing the microphone over the soundboard will produce a tight, focused
tone with more midrange emphasis but less overall volume.
ADDRESSING FEEDBACK
LOW FREQUENCY CAVITY RESONANCE
All stringed instruments’ sound chambers are tuned to resonate at an optimum
frequency, in the instrument’s lowest octave. Placing a microphone directly over
the opening of the instrument may result in feedback at this "cavity resonance".
Typical resonances are:
Guitar; 95-105 Hz
Bass; 65-75 Hz
Violin; 275-300 Hz
Cello; 125-135 Hz
To address Cavity Resonance Feedback:
1) POSITION THE MICROPHONE away from the opening on non-flat-top
instruments. This works well in low volume settings.
2) TURN DOWN BASS CONTROL on MICROPHONE channel.
3) PUSH IN BASS CUT SWITCH on MICROPHONE channel.
4) INVERT PHASE SWITCHES on both channels.
(See Pages 8 & 21)
5) OUTBOARD EQUALIZATION: This works well in higher volume settings.
An external equalizer (such as the FISHMAN Dual Parametric D.I.) may be
used through the BLENDER’s MICROPHONE channel EFFECTS LOOP.
See FIG. 1
(See Page 16)
a. PARAMETRIC EQ: We suggest cutting 5 dB at the instrument's cavity
resonance with a .5 octave bandwidth (Q).
b. GRAPHIC EQ (although less precise and much noisier) may also be
used. Cut 5 dB at the instrument's cavity resonance with 1/3 octave
cuts on either side of the center frequency.
HIGH FREQUENCY FEEDBACK
Occurs when the microphone's rising response creates a feedback loop with a
high frequency driver in your speaker system. This feedback usually starts
above 1.5 kHz, peaks at 4 kHz and subsides at 9 kHz. There are several
approaches to minimizing HIGH FREQUENCY FEEDBACK:
1) STRATEGIC POSITIONING: This works best in low to medium volume
settings. The simplest solution for this type of feedback is to keep the
microphone out of the path of the loudspeaker.
You can do this by:
a. Avoid standing directly in front of your amp.
b. Send separate MIX and TRANSDUCER signals to your soundman and
have only the TRANSDUCER signal sent to your stage monitor.
2) TURN DOWN TREBLE CONTROL on MICROPHONE channel.
3) REVERSE PHASE SWITCHES on both channels.
4) OUTBOARD EQUALIZATION: This works well in higher volume settings.
An external equalizer (such as the FISHMAN Dual Parametric D.I.) may be
used through the BLENDER’s MICROPHONE channel EFFECTS LOOP.
See FIG. 2
a. PARAMETRIC EQ: We suggest cutting 5 dB at 4 kHz, with a 1.5 octave
bandwidth (Q).
b. GRAPHIC EQ (although less precise and much noisier) may also be
used. Cut 3 dB at 1.2 kHz. Gradually increase the amount of cut to
-9 dB at 4-5 kHz. Above 5 kHz, gradually decrease the amount of cut to
-3 dB at 10 kHz.
