DIY Balanced Microphone Preamplifier

Written by jason parnell
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DIY Balanced Microphone Preamplifier
Balanced microphone preamplifier (circuit board image by Michael Shake from

A balanced input allows you to use a very long cord to record or perform without having to deal with external noise affecting the final output. However, many common preamps are designed for line-level, not mic-level, recording. A proper microphone-gain-level balanced preamp is an important part of any artist's or recording enthusiast's arsenal. Building a DIY balanced microphone preamplifier is a simple electronics project that will add noticeable quality to any recording.

Skill level:

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Things you need

  • 25-watt soldering iron
  • Rosin-core solder
  • Blank circuit board
  • Resistors
  • Capacitors
  • Transistors
  • Integrated circuit
  • Audio pins
  • Wire cutters
  • Wiring pencil
  • Project box
  • Hand-held rotary tool

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  1. 1

    Download a balanced microphone preamp schematic from an Internet resource. A schematic represents electronic components and how they are connected by a series of symbols. Each symbol informs you of both the type of electronic component (such as resistor, capacitor, transistor) and its specifications technical specifications.

  2. 2

    Use your balanced microphone preamp schematic to determine the parts you'll need for construction. Write down each element represented in the schematic, typically resistors, capacitors, audio pins, transistors, a power supply and at least one IC, or integrated circuit. Order the parts from an Internet retailer. When ordering resistors, 1 per cent metal film is best to achieve a balanced output.

  3. 3

    Arrange the electronic components on a blank circuit board by inserting the connecting pins into the circuit board. Bend the pins at 90-degree angles to lock the components in place. Arrange the components as the symbols on your schematic are oriented.

  4. 4

    Solder the electronic components to the circuit board using a 25-watt soldering iron. Place rosin-core solder against the joint of each electronic component's connection pin and the circuit board. Melt a small amount of rosin-core solder by placing the heated tip of the soldering iron against the solder. Allow the molten solder to cool before snipping the excess connector pin off with wire cutters.

  5. 5

    Wire the electronic components together with a wiring pencil by following the wire scheme represented in your schematic. Simply melt a line of the conductive copper coming from the tip of the wiring pencil directly onto the circuit board. Connect each individual component from left to right to avoid burns and smears.

  6. 6

    Modify your project box with a hand-held rotary tool by cutting holes for the audio-in, audio-out and external power supply. Enclose the balanced microphone preamp in the project box and seal it shut with the supplied screws.

Tips and warnings

  • Experiment with different resistor types and integrated circuit specifications, as most circuit designs are flexible and always leave room for improvement. Consider combining your DIY preamp with a DIY microphone for a unique sound.
  • Always use a soldering iron and wiring pencil in a clean and ventilated area due to toxic fumes resulting from molten metals.
  • Always wear eye protection when working with electronics.
  • Never attempt to power up or use exposed circuits, due to risk of electric shock.
  • Always package your circuit in a project box before use.

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