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M0070 Professional Preamp User Guide 1.0 

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©2009 Microlynx Systems Ltd. 

Each of the controls and connectors is described in detail below. 

Volume Control 

Having the volume control at your fingertips is probably the single most useful feature of the M0070.  
When the preamp is mounted behind the tailpiece you can change the volume or mute the signal 
without having to precariously balance your instrument while trying to reach over to your main amp.  
The volume knob is separate from the other knobs and easy to find.   

Phase Switch 

Phase differences between the natural sound of the bass and the amplified sound coming from the 
amplifier can cause the total perceived sound to be either thin or boomy.  The easy to reach Phase 
switch on the M0070 inverts the signal to the amplifier and can greatly improve the overall sound.   

Variable Rumble Cut 

Sub

audible acoustic energy cannot be heard but can stress the power amplifier and in extreme cases 

cause permanent damage to the amplifier or speaker.  The Rumble Cut is a high

pass filter that 

attenuates these sub

sonic signals.  The cut

off frequency can be adjusted to suit the instrument and 

application. 

Three Band Tone Control 

The M0070 has a high

performance three band tone control circuit to cut or boost the low, mid and high 

frequencies by up to 12 dB.  The cut

off frequencies for each of the controls were carefully selected to 

be of most use for acoustic bass applications.   

The tone control knobs have a center detent to provide a quick tactile indication that they are in their 
“flat” position. 

Impedance Select Switch 

Most modern piezo transducers can operate nicely into a 1 Mohm input impedance.  The Impedance 
Select switch gives the option to provide a 10 Mohm input impedance when required. 

Direct Out with Phantom Power 

The M0070 has an XLR Direct Out to connect it to a PA or recording consol using a balanced microphone 
cable. 

The M0070 will automatically switch to operate off 48 V phantom power if available.   A green LED on 
the side of the preamp indicates if phantom power is being used. 

Ground Lift Switch 

This switch can be used to reduce hum caused by ground loops when you simultaneously use the XLR 
and phone outputs. 

Pre/Post EQ Switch for Direct Out 

This switch allows you to select either the raw or equalized signal for the Direct Out. 

Summary of Contents for M0070

Page 1: ...iding a fairly strong output signal so why do you need a preamp There are two reasons performance and convenience Performance and sound quality Piezo transducers are sensitive to capacitive loading Since instrument cables have a capacitance of about 25 pF ft the longer the cable the more loading the transducer sees Increased loading negatively affects both the level of the signal and the frequency...

Page 2: ... Hi Z EQ Post Pre Gain The front panel has the most commonly used controls and adjustments It looks like Microlynx M0070 Professional Preamp Volume Phase Rumble Bass Mid Treble The rear panel has the input and outputs as well as the controls that are less frequently used It looks like Out GND Lift Phant Power In EQ Post Pre Lo Z Hi Z Direct Out The left side panel is visible when the preamp is mou...

Page 3: ... sub sonic signals The cut off frequency can be adjusted to suit the instrument and application Three Band Tone Control The M0070 has a high performance three band tone control circuit to cut or boost the low mid and high frequencies by up to 12 dB The cut off frequencies for each of the controls were carefully selected to be of most use for acoustic bass applications The tone control knobs have a...

Page 4: ...observe the correct polarity Slide the battery forward until it engages in the holder Replace the top cover with the serial number sticker at the bottom Carefully insert and tighten the screws Do not over tighten Installing the Preamp on your instrument For ease of use we strongly recommend mounting the preamp under the tailpiece of your instrument To protect your instrument and avoid rattling pla...

Page 5: ...arly 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 audienc...

Page 6: ...ges in the signal chain If phantom power is available the M0070 will automatically cut over to it eliminating drain to the battery The green LED will illuminate to indicate that the preamp is running off phantom power Note that if you are only using the Direct Out and no phantom power is available you will need to plug a patch chord into the phone output to enable the battery Using the Post Pre EQ...

Page 7: ...lanced Distortion at 1 kHz 0 03 at 14 dBu output level Residual noise level 25 µV C msg weighted Headroom At least 3 dB from when Clipping LED comes on Input gain tone controls flat 6 to 6 dB Frequency response 3 dB 10 Hz to 20 kHz tone controls flat Rumble Cut fully CW Rumble cut range 3 dB 10 Hz clockwise to 37 Hz counter clockwise Bass adjust range 12 dB shelving 6 dB at 70 Hz Mid adjust range ...

Page 8: ...is found not to be defective Microlynx retains the right to charge the buyer for testing expenses at Microlynx standard hourly rates in effect at that time This product contains no user serviceable parts This warranty shall be void if the product is opened This warranty does not cover damages or losses resulting from physical abuse neglect misuse shipping improper installation improper environment...

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