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Mono Audio Power Meter

20 Watt Monaural Audio Amplifier Kit

by Galak Electronics
Part No. VG-503
Shipping Weight: 3.0 ounces (85 grams)

Go Live with this compact and powerful audio amplifier. Incorporating state-of-the-art bridged technology, this amp delivers a wide dynamic range with a combined tone and bass boost control. With 20 watts* of power at your fingertips, the Mono Audio Amplifier Kit fits neatly into a standard footpedal enclosure. Features include thermal** and short circuit protection, volume control, power meter, and standard 1/4" phono jacks.

The Mono Audio Amp kit comes with instructions (including schematic and parts placement) and all the components to build one complete unit. You will need a soldering iron, solder and a pair of cutters for assembly. Check out our custom enclosures under Accessories.

Mono Audio Power Amp Kit:



Mono Audio Power Amp Kit
(Built and Tested):




  • 20 Watts at 4 Ohms with a effective frequency response of 40 Hz-20 kHz.
  • Bridged outputs means higher power with lower supply voltages - will operate down to 9 VDC*.
  • High efficiency amplifier with an average power loss of only 37% at full output power.
  • Wide input supply voltage from 9 VDC to 16 VDC with a maximum supply current of 3.5A at 14.4 VDC.
  • Integrated 4 LED power meter, input volume and combined Tone/Bass boost controls.
  • Fully connectorized with 1/4" input and output jacks and 2.1mm DC power input connector.
      * To achieve maximum output power of 20 Watts, a minumum of 14.4 VDC supply voltage is required. Total output current is limited to 3.5 Amps max.         Total output power @ 9 VDC is 8 watts with 4 Ohm load; Total output power @ 12 VDC is 14 watts with 4 Ohm load.

      **If the unit is purchased without optional enclosure, heatsinking is required to obtain power levels greater than 4 watts.


  • Supply Voltage and current: 9VDC to 16VDC @ 3.5A max
  • Maximum Power: 20 watts @ 4 ohms with 14.4V supply (current limited to 3.5 A total output current)
  • Frequency response: 40 Hz - 20 kHz with less than 0.3% total harmonic distortion at full power
  • Input/Output Connectors: Power In - 2.1mm barrel tip-positive; Audio in/out - 1/4" phono jack
  • Board Dimensions: 3.94" x 1.96" (10.0 cm x 5.0 cm)
  • Board Material: 0.062" (1.6 mm) FR-4, with green solder mask and top layer silk screen
  • Finished Weight: 3.0 ounces (85 grams)

Please feel free to contact us if you have any question about this project or any othe Galak Electronics Projects.

Copyright 2013 by Galak Electronics. All rights reserved.