DIY Bass Amplifier

Written by simon foden Google
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DIY Bass Amplifier
Most circuit boards will arrive pre-assembled. (circuit board with capacitors 1 image by Mograph from

Making your own bass amplifier is a good way to save money and create a unique piece of equipment to your own specs. There are three main components in any bass amp: the speaker, the preamp and the power amp. Bass amps have larger speakers for greater bass frequency response. This is why bass amps are heavier and larger than guitar amps. You can salvage the necessary parts from old or damaged bass amps or you can use a self-assembly amplifier kit.

Skill level:
Moderately Challenging

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Things you need

  • Pre-amp
  • Wiring schematic
  • Power amp
  • Volt meter
  • Speaker
  • Cabinet
  • Soldering iron
  • Screwdriver
  • Shaving brush

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  1. 1

    Source your parts. Decide on what type of bass amp you want and source the parts accordingly. Search second-hand guitar shops for salvageable parts. To save time, it's smart to salvage an oversized bass amp cabinet rather than building your own. A completely non-functioning bass amp will still have a serviceable cabinet. If this is your first project, use an amplifier kit. The parts come pre-assembled and are all compatible. Your kit will come with a wiring schematic and assembly instructions.

  2. 2

    Set up a work space. This must be well lit and well ventilated. You need a power source for your soldering iron. Inspect your parts for damage before you begin assembling them. Pay particular attention to the printed circuit board. Remove and reattach any loose surface-mounted parts.

    DIY Bass Amplifier
    Warm up your iron while you inspect the parts. (soldering image by Bube from
  3. 3

    Assemble the printed circuit board. Amp kit circuit boards come pre-drilled. Follow the schematic and mount the various resistors, capacitors and filters in order. Salvaged preamps will include a pre-assembled board.

  4. 4

    Test the circuit. Refer to the schematic for correct plate resistor and transistor values. Place the legs of your voltmeter on the circuit board. If the voltmeter gives a zero reading, the circuit is incorrectly assembled. Refer back to the schematic.

    DIY Bass Amplifier
    Calibrate the voltmeter on a working circuit to ensure it is accurate. (multimeter image by Aleksey Bakaleev from
  5. 5

    Mount the circuit board in the preamp chassis. Solder the input jack to the input terminal on the circuit board.

  6. 6

    Install the completed preamp. The preamp takes the guitar's signal and converts it into an electrical current. This sits on the shelf inside the cabinet. Slot it in with the dials facing out of the front. Don't wire it.

  7. 7

    Load the power amp. The power amp adds voltage to the preamp signal before sending it to the speaker. Depending on the model, the power amp will either sit alongside the preamp or below it on a second shelf.

  8. 8

    Fit the speaker. There will be a series of screw holes around the circumference of the speaker. This is where you screw in the speaker. There are normally four screw holes. Make sure that the speaker is firmly screwed in. A loose speaker will generate an unpleasant flapping sound at high volume.

    DIY Bass Amplifier
    Use a dry cloth to clean the speaker if you salvaged it. (speaker image by CraterValley Photo from
  9. 9

    Wire the components. Solder a wire between the output terminal of the preamp to the input terminal of the power amp. This connects the two signal processing components. The preamp circuit board processes the signal and influences the tone, the power amp adds volume. Solder a wire running from the output terminal on the power amp to the speaker. Test the amp and enclose the rear.

Tips and warnings

  • Use a shaving brush to remove any solder residue. Wait for the joint to dry then wipe it with the brush.
  • If you are salvaging your components, you can get a manufacturer's wiring schematic from the Free Schematics website.
  • If you are building a tube bass amp, always wear latex gloves to handle the tubes. Oil from your skin can create hot spots on the glass. The hot spots draw heat from the filament and can cause the tube to shatter.

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