Microlynx Systems M0070 User Manual

Microlynx M0070 Professional Double Bass Preamp

‐User Guide‐

Overview

The Microlynx M0070 double bass preamp was designed by a professional electronics engineer and bassist to meet the specific requirements of performing double bassists who need their instrument to be amplified. The design goal was to make the best product on the market today, and we think we have succeeded.

The M0070 has best in class distortion, noise, headroom and transient response. If you want the clean, natural, distortion‐free sound of your bass, you can’t get a better preamp than the M0070.

The M0070 is designed to mount under the tailpiece. Its light weight wood enclosure construction make it acoustically transparent, so it doesn’t alter the natural frequency response of your instrument.

Advantages of a Preamp

Most modern piezo pickups are capable of providing 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 response. The M0070 requires only a 12” patch cable and so has negligible loading on the transducer. With the M0070 you get as close as possible to the natural sound of the instrument and pickup.

Due to the high output impedance of the transducer, the longer the cable, the more prone everything is to picking up hum and noise. The output impedance of the M0070 is much lower than that of a transducer and this greatly reduces the sensitivity to hum and noise pickup.

Convenience

The M0070 is designed to mount inconspicuously under the tailpiece of the bass. All the controls are easily accessible without having to reach over to an external amp or preamp, which may be some distance away to avoid feedback.

Features and Controls

The M0070 is a full‐featured preamp that has everything you need to manage your amplified sound. The following diagram shows the signal chain:

Post

Pre

Direct

Lo-Z

Hi-Z

Out

10 M

1 M

High pass

Gain

0/180

deg

Tone Control

VolumePhaseRumble Bass Mid Treble

OutIn

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

Direct

Out

GND

Lift

Phant Power

Post Pre

Lo-Z

Hi-Z

InEQ

The left side panel is visible when the preamp is mounted under the tailpiece. It has the clipping and low battery LED as well as the gain setting potentiometer. It looks like

Clip

Bat

Gain

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.

Adjustable Input Gain

The input gain control can be used to boost or cut the input signal by up to 6 dB. For best noise performance it should be set to the maximum level that doesn’t cause clipping. If this level is too high for your amplifier, it can be backed off.

Low Battery and Clipping Indicator

The M0070 has an easily visible red LED that flashes if the signal gets close to clipping level. The gain should be set so that the LED only occasionally flashes. There is still at about 3 dB of headroom before clipping actually occurs.

If the LED is constantly illuminated, the battery is low and should be replaced. If you use a quality alkaline battery, there will still be at least three hours of usable life left after the light first comes on.

Operating instructions

Operation of the M0070 professional preamp is simple and intuitive. Please read and follow these instructions to get the most out of your preamp.

Installing and changing the battery

Carefully remove the screws at either end of the preamp and gently lift the top cover. Install the battery in the holder, making sure to 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, place the supplied strips of felt on the top and bottom of the preamp at both ends. Place the preamp under the tailpiece and use two of the tie wraps to attach the preamp to the tailpiece. Tighten the tie wraps until they are snug but do not over tighten.

Use a short phone patch cord to connect the transducer to the input of the preamp.

Powering the preamp

The M0070 only consumes power if a ¼” mono phone plug is inserted in the phone output, or if phantom power is supplied to the Direct Out.

To conserve battery life, always unplug the output when not in use.

Setting the gain

Plug a phone cord into the output of the preamp. The red LED will flash briefly to indicate that the preamp is being powered.

Look at the red LED while playing your instrument as loudly as possible. Ideally the LED should barely flicker.

If the LED is on for extended portions of your playing, reduce the gain by turning the Gain potentiometer counter clockwise using a small screwdriver.

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.

For each control, there is a centre detent at mid position. The control has no effect at this position. Rotating the control clockwise will boost band of frequencies, while rotating it counter clockwise will cut the frequencies.

Be aware that boosting the output, especially the bass control, may cause the output to clip. To check this, make sure the Pre/Post Eq switch is in the Post position (“IN”) and check that the red Clipping LED stays off or only barely flickers when playing loudly. Once you have verified this you can set the switch to the “OUT” position if you desire.

Using the Direct Out

The Direct Out XLR connector provides a 600 ohm balanced output that allows you to connect to a mixing board with a standard microphone cable. This eliminates the need for a separate DI box and minimizes the signal degradation caused by having additional stages 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 switch

This switch allows you to choose whether you send the equalized or unmodified signal to the Direct Out connector. For optimum signal quality we recommend using the Pre EQ setting (“OUT” position).

Using the Ground Lift switch

If you are using both the phone out and the Direct Out it is possible that the two outputs can be tied to different power circuits. This can create a ground loop that causes hum. Setting the ground lift switch to the Lift (“OUT”) position can reduce or eliminate the hum.

If you have any questions or feedback about this product, please contact us at

Microlynx Systems Ltd.

107, 1925 – 18 Ave NE Calgary, AB T2E 7T8 Canada 403‐275‐7346 www.microlynxsystems.com sales@microlynxsystems.com

Specifications

Dimensions (box only) 12.5 x 3.8 x 4.2 cm (4‐7/8 x 1‐1/2 x 1‐5/8 in.)

Depth (including knobs and connectors) 6.5 cm (4‐1/2 inch)

Weight (including 9 V battery) 130 grams (4.6 oz.)

Input impedance Low impedance 1 MΩ

High impedance 10 MΩ

Input overload level +17 dBu (at minimum gain)

Output impedance Phone jack out 10 kΩ

Direct Out (XLR) 600 Ω balanced

Output clipping level (0.5% distortion) Phone jack out +13 dBu

Direct Out (XLR) +8 dBu into 600 ohms balanced

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 +/‐ 12 dB at 500 Hz

Treble adjust range +/‐ 12 dB shelving, (+/‐ 6 dB at 5 kHz)

Power supply 9 V battery (alkaline recommended)

48 V phantom power on XLR input

Current consumption Less than 5 mA, phone jack output only

Less than 15 mA if Direct Out (XLR) output is used

Specifications are typical and are subject to change without notice.

Limited Warranty

Microlynx Systems Ltd. (Microlynx) warrants this product to be free from defects in workmanship or materials under normal use. The period of this warranty is two years from date of purchase, and covers both parts and labor.

Microlynx’ responsibilities under this warranty are, at its sole option, to repair or replace without charge any defective component(s) in the product. This obligation shall not arise until the buyer returns the product to Microlynx.

To obtain warranty service, the purchaser must first contact Microlynx to obtain a Return Merchandise Authorization (RMA). Microlynx will not accept any returns without an RMA.

The buyer shall return the product in an adequate container, with transportation and insurance prepaid. If a defect is found that is covered by this warranty, Microlynx will pay for standard surface return shipping and insurance.

If repairs are required that are not covered by this warranty, Microlynx will notify the purchaser with an estimate of the repair costs, and requires prepayment for the repair, shipping and insurance costs before the product will be repaired. If the product 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, extreme temperature conditions, or power line irregularities.

Microlynx assumes no responsibility for this product being used in a hazardous or dangerous manner, either alone or in conjunction with other equipment.

Except as stated herein, the product is provided as is, without warranty of any kind, express or implied, including but not limited to any implied warranties of merchantability or fitness for a particular purpose. To the maximum extent permitted by law, in no event shall Microlynx be liable for any damages, including, without limitation, lost profits, lost savings, loss of business information, business interruption, or any other incidental or consequential damages arising out of the use, misuse, or inability to use the product. In no event shall Microlynx’ liability exceed the purchase price of the specific product purchased and against which a claim is made.

This warranty gives the buyer specific legal rights, and the buyer may also have other rights which vary by province or state.

Microlynx Systems M0070 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual