Specifications

6/18/2009 5
3. User instructions
3.1 Audio Mixer
The audio mixer functions are very straight-forward.
 Connect desired number of microphones and/or line level input signals to the XLR
sockets INPUT1 - 4 on the back panel.
 If required, connect the output signal from the XLR sockets OUTPUT LEFT and RIGHT.
 If required, connect a headphone to the phones socket.
 If required connect the digital output to an external unit with a suitable digital input.
 If available, use mains power supply through the mains adapter/charger unit.
 Set the 48V switch to off, mid position.
 Power-on the mixer by the toggle switch POWER.
 Check battery status by setting TEST switch to BAT position. The lower meter will
indicate the battery status between 0% and 100%.
 Turn gain control knobs 1 – 4 fully down, anti-clockwise.
 Set MASTER knob to 0 dB.
 Switch on the 1 kHz TEST tone, left position. The test tone is a highly stable and very
low-distortion sine wave.
 The output signal on the XLR sockets is 12 dB higher than what is indicated by the PPM
meter. This is because MM-4220 is basically a digital mixer/recorder with a maximum
signal level = 0 dB. At this maximum level the maximum output level on the XLR line
outputs is +12 dBu.
 Calibrate the gain in external analog equipment that is connected to the XLR line output
sockets. (Equipment connected to the digital output needs no gain calibration.)
MM-4220 is now ready to be used as an ordinary mixer.
 Select 48V phantom power for microphone inputs 1 and 2 or 1, 2, 3 and 4 if required.
Note that the sum of all phantom currents used must not exceed 5 mA. Also note that
phantom power does drain the battery more.
 Adjust gain for each input by turning the knob and setting the 3-way gain switch in
0/24/48 dB position, as required.
 Adjust panning by turning the PAN pot.
 Select low-cut HPF filter if required. This may be useful for cutting wind noise.
 Adjust the phones knob for a good listening level with headphones.
The MASTER knob may be used for adjusting the sum of all inputs. However, it is advised that
it is left in the range close to 0 dBu.
Setting master knob to a low value while any of the inputs has too much gain will result in
distortion. On the other hand, setting the master knob to a high value while the inputs are set to
low gain may increase the noise level.
Use of the input knobs at the lower range, below -12 dB, is not recommended with high level
signals. In that case, reduce pre-gain by the gain switch. If this is already set to 0 dB then the
signal level is too high and external attenuation is required.
Maximum input level is + 12 dBu (3 V
rms
).
Good audio mixing is a matter of balance between noise floor and
clipping level, for maximum dynamic range.