M0070 Professional Preamp User Guide 1.0 5 ©2009 Microlynx Systems Ltd.
If the LED remains completely off, you might want to try increasing the gain by turning the Gain
potentiometer clockwise. The gain is adjusted to 0 dB at the factory. The noise level of the M0070 is
very low, so for most applications it’s better to have a smaller output level than to have distortion.
Selecting the input impedance
For minimum noise and best transient response, we recommend using the low impedance setting
(switch in the “IN” position). Some piezo transducers will lose low frequency response with this setting,
so if you find that the low end is weak you might get better performance with the switch in the high
impedance setting. Experiment to see what works best for you.
Adjusting the volume
Turn the volume knob fully counter clockwise to completely mute the preamp. When setting up, we
suggest setting it to about ¾ clockwise and adjusting the gain and/or volume on your amp for the
desired volume; this will allow you to fine tune the volume while playing.
Using the phase switch
The amplified signal coming from your amp will interact with the acoustic signal coming from your
instrument. Depending on the location of the listener, this interaction can be in phase, causing
constructive interference, or out of phase, causing destructive interference or cancellation. Destructive
interference can be particularly noticeable. It is typically worst when the two signals are at similar levels
and is most noticeable at lower frequencies, causing the sound to be “thin”.
The Phase switch reverses the phase of the amplified signal and can greatly mitigate the effect of this
cancellation. Be aware that the effect strongly depends on the location of the listener, so what sounds
good to you might be bad for the audience. It’s therefore best if someone on the floor can tell you how
you sound.
Using the rumble control (high-pass filter)
Infrasonic frequencies (below the lowest frequencies generated by your instrument) can cause all kinds
of problems, including possible damage to your amplifier and speaker. The M0070 has an adjustable
high pass filter (Rumble Cut) that can cut these low frequencies without affecting the tone of the
instrument.
Turn the Rumble control counter clockwise to increase the amount of subsonic attenuation, and
clockwise to decrease the subsonic attenuation.
For instruments with a low‐E string, the lowest frequency generated is about 41 Hz. We recommend
that you start with the control fully counter clockwise, and then adjust it slightly clockwise if you find
you are losing bottom end.
For instruments with a low‐B string, the lowest frequency generated is about 31 Hz. We recommend
that you start with the control about mid position, and then adjust it slightly if needed.
Using the tone controls
The M0070 has a three‐band equalizer that can be used to adjust your amplified tone. This can be used
to compensate for idiosyncrasies of your instrument/transducer, or to create effects.
