Friday, July 3, 2015

D02: a simple 80W Bass guitar amplifier built around the TDA7294 IC

As stated by the ST datasheet, the TDA7294 is a monolithic integrated circuit in. Multiwatt15 package, intended for use as audio class AB amplifier in Hi-Fi field applications.

D02, is a simple 80W Bass guitar amplifier.

I've some parts laying around that i decided to assemble in order to build a portable Bass guitar amplifier. I've a nasty 10" speaker, a power transformer, a car amplifier heatsink, and some other parts found in the on a "dumpster dive".
My friend Matteo gives me a speaker case he does not use more, he also cut's the stickers with his cutter plotter machine.

The circuit is really simple. The preamplifier it is build around a TL072 opamp. The first stage amplify the signal, the second does 3-tone balances.

The amplifier stage is pretty much the same of the ST TDA7294 datasheet, with just some value changed.

The circuit can be definitely improved. But just as it is now, it sounds pretty good.
The first improvement for this amplifier will be a better speaker.

  • read risk disclaimer
  • excuse my bad english


  1. Hello Davide,

    Great project, very efficient !
    Two questions :
    - in your schema, alimentation outputs VCC and VCC15 in positive and negative, but you only use VCC. Haven't you used VCC15 for preamp and equalizer ?
    - I see that schema is in Eagle format. Is it possible for you to share it ? Or at least Bill of Materials ?

    Thank you in advance, and keep going, your projects are great !
    Arnaud (from France)

    1. Hello Arnaud, my typo mistake, the preamp is +VCC15, not VCC, i will fix in a few.
      You can download the schematics from here: (link expires in 2 days)

    2. ...and thank you of course for your comment!