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.

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

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.

Component Sorting Sheet top

To identify and keep track of every part in the kit, download and print the Component Sorting Sheet (PDF).

Resistors top

Since channels 1 and 2 of the MB2 are identical, the steps below are written for just one channel. It’s up to you whether you want to build one channel at a time or both at the same time.

Bend Resistors top

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

R1, R2
10k resistor (x2)

R3, R4
68R resistor (x2)

R5, R6
2.7k resistor (x2)

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 BC337 Transistors top

Place the transistors that do have a silver marking in the positions with a filled-in shape. Check that they are all oriented according to the shape on the PCB, then solder and trim.

T1, T2
BC337 transistor (x2)

Populate LSK389 Transistors top

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

Imporant: 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.

LSK389 transistor

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 (x2)

0.22u cap (x2)

Quick Question top

Are you using the component sorting sheet?

Yes No

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.

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. This is to hold the jacks in place for soldering.

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

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

XLR screw (x8)

Solder Middle Pad of XLR top

It's rather difficult to get the PCB to sit on top of the XLR jack long enough to solder it. So we'll take a different approach: adding solder to the PCB first and then heating that solder while inserting the jack. To start, add a small amount of solder to the middle pad of one of the XLR footprints.

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)

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: Do all of the resistor positions correspond the chart and/or sorting sheet?
  • 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?

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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