MB2 Assembly Guide

Safety Precautions, Warranty, and Disclaimer Improper soldering and handling of electricity can cause serious injury and damage to your property. Read and understand the instructions below before beginning your project. Follow the instructions, build carefully, and use the appropriate tools. Build at your own risk. DIY Recording Equipment, LLC is not responsible for any damage or injury resulting from the assembly or use of your kit. You are the manufacturer of your kit. It is your responsibility to turn this group of parts into a working piece of recording equipment. DIY Recording Equipment, LLC does not guarantee the success of your project and disclaims any Implied Warranty of Merchantability. Please visit the support forum for assembly support.
Damaged or Missing Parts All kits and parts are checked before being shipped to you. If something arrives damaged or if your kit is missing a part, please open a support ticket to inquire about a replacement. Missing parts will be replaced at our expense. Damaged parts should be returned for verification. If the part shows signs of use beyond what was necessary to determine that it was damaged, DIY Recording Equipment, LLC reserves the right not to replace the part.
Welcome to the MB2 assembly guide.

Thank you for purchasing a MB2

If this is your first DIY project ever, we recommend reading our Getting Started Guide.

Required Tools top

Soldering Iron
We recommend an adjustable-temperature station, such as the Weller WLC100.

Solder
You can use 60/40 "leaded" solder or lead-free. We recommend 60/40 because it flows better and is easier for beginners to use.

Wire Cutters
You'll need a pair of good "snips" for cutting of the excess leads after soldering.

Phillips Head Screwdriver
A #1 Phillips head screwdriver.

Optional Tools top

Multi-meter
If a problem needs solving, a multimeter can come in handy. You can also use it to sort resistors.

Desoldering Pump
If you accidentally solder something in the wrong place, a desoldering pump can save the day.

Resistors top

Bend Resistors top

Bend the resistor leads 90 degrees at the body so they can be inserted into the PCB.

R1, R2
10k resistor (x4)

R3, R4
68R resistor (x4)

R5, R6
2.7k resistor (x4)

R7, R8
470k resistor (x4)

Sort Resistors top

Resistor sorting made easy! Enter a value to find the color bands, or enter your color bands to find the resistor’s value. Type in the value of the resistor you need and this tool will show you the corresponding color code.

Place Resistors top

Place the resistors into their respective positions on the PCB. As you place each resistor, bend its leads against the bottom of the PCB so that it stays in place during soldering.

Solder Resistors top

Solder the resistors to the PCB. Observe good soldering technique: heat the pad and lead for 2-3 seconds, apply a small bit of solder, and continue to heat the pad for another 2-3 seconds. The finished joints should be shiny and should have just enough solder to cover the pad entirely.

Trim Resistors top

Use clippers to trim away the excess leads. Clip as closely as possible to the joint without clipping the joint itself.

Transistors top

Populate BC327 Transistors top

Note that there are two different types of transistors in this bag: some with silver markings on top and some without. Those without a marking are the BC327s. Place them in the positions that have an outline of the transistor instead of a filled-in shape. Make sure the transistors are aligned so the flat edge matches that of the outline on the board. Then solder and trim.

T1, T2
BC327 transistor (x4)

Populate LSK389 Transistors top

Spread out the pins of the two LSK389 transistors so that they will fit in the T1 pads. Then place the transistors, making sure to align the tab on the body with the tab on the PCB.

Important: Double check the orientation of these transistors before soldering. These parts are expensive and difficult to remove once they're soldered in. Once you are positive that the tab on the transistor and on the PCB line up, solder and trim the leads.

These components are the functional core of the MB2. Their job is to provide 26dB gain for both the positive and negative halves of the balanced signal at the same time. This is a very delicate task, as any noise or distortion introduced in one half of the signal will not be canceled out, and will be amplified by the following mic preamp. So each LSK389 contains two matched, low-noise transistors (one for each half of the balanced signal), which are thermally coupled in the same case.

T3
LSK389 transistor (x2)

Capacitors top

Populate Small Capacitors top

Place the smaller capacitors in their respective places. These capacitors are not polarized and therefore can be placed in either direction. Solder then trim the leads.

C1, C2
1n cap (x4)

C3, C4
0.22u cap (x4)

Populate Large Capacitors top

These capacitors are polarized, so they must be placed in a certain direction. The positive lead is slightly longer, while the negative lead is marked with a stripe on the body of the capacitor. Place the capacitors with the positive lead in the pad next to the "+" marking on the PCB. Double check their orientation, then solder and trim.

C5
100u cap

Jacks and Case top

Screw Panels to XLRs top

Screw the input and output panels to the XLR jacks with the longer, thread-cutting screws. Leave the screws loose for now so that the XLRs have a bit of room to move.

J2, J6
3-pin XLR male jack (x2)

J4, J8
3-pin XLR female jack (x2)

XLR screw (x8)

Populate XLR Jacks top

Place the XLR jacks. Once all the leads including the plastic mounting tabs have snapped into place, tighten the screws on the panel. Solder the jacks but do not trim the leads.

Slide PCB Into Case top

Unscrew and remove one of the panels. Then slide the assembly into the lower channel in the case. The input panel should be on the side closest to the "M" in "MB2."

Screw in Panels top

Re-attach the remaining panel to the XLRs. Then fasten the panels to the case with the shorter screws.

PCB bracket screw (x8)

Apply Foam Pad top

Remove the backing from the foam pad and apply it to the bottom of the case.

Final Checks and Testing top

    Before you wrap up, check the following things:

  • Capacitor orientation: Is the stripe on the cap on the opposite side from the "+" marking on the PCB?
  • Transistor orientation: Does the shape of the transistor match the outline on the PCB?
  • Resistors: Are all the resistors in the correct positions?
  • Soldering: Is every solder joint shiny and clean? If one is cloudy or misshapen, try reheating it for 8 seconds and adding a tiny bit more solder.
  • Trimming: Are all of the excess leads trimmed down as close to the joint as possible?

Connect Mic to MB2 top

Connect a dynamic or ribbon microphone to MIC INPUT 1. Do the following steps with channel 1 and then connect the mic to MIC INPUT 2 and repeat the steps.

Connect the MB2 to an Audio Interface top

Run an XLR cable from MIC OUTPUT 1 to a microphone input on your audio interface. Turn the gain knob on the interface down all the way, then engage +48 phantom power. The phantom power is what powers the MB2; it does not pass through to the microphone.

Next, set a channel in your DAW to record the channel you plugged the MB2 into. Sing, hum, or make some noise into the mic and set the gain on the interface accordingly. Make a short recording to check that the signal is passing cleanly from the MB2. Now repeat these steps for channel 2.

Finished! top

All good? Congrats on finishing your build! Have a question or problem? Drop us a line.

Help Us Improve top


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