Audio Amplifier Kit - STA540 (KIT-09612)

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This is a stereo amplifier kit designed to make use of the STA540 power amplifier IC. Once this kit is completed you have a fully functional, two-channel audio amplifier, complete with a standby switch, volume control and indicator LEDs. The kit also includes a 6400BG heatsink for the STA540 to dissipate any damaging heat.

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I was hoping someone may be able answer a couple of questions for me regarding the STA540 audio amplifier kit (SKU: KIT-09612). I am aiming to build an amplifier/monitor for my Roland electronic drum kit. The usage would only be for home/personal use NOT for live gigs. I am also not after perfect audio, just something that will tolerate the attack of a drum hit and the frequency range from a bass drum to a cymbal. I would house it in a cabinet (I will construct) and a single speaker.

My questions are:

  1. Are the 2x 10k Giant Trimpots in the kit that are designated Left and Right on the PCB to control the volume of the left and right output channels? I was wanting to have 2 inputs – electronic drums (mono) in one, and external music source (mp3 player mono) in the other so I can play along with music. Given the output is to be mono, I was thinking I could use the left/right channels for these 2 inputs and use the volume controls to level the drums against the music.
  2. Is the power source DC? If so can a generic DC adapter be used?
  3. Would a cooling fan be required or are the cooling fins enough?
  4. Can the stereo outputs be wired to a single speaker as simply as the left and right positive wired to the speaker hot terminal and the left/right negative to the speaker negative terminal or is some sort of mixing component required between to achieve this?

    I hope this all makes some sort of sense!



Hi Stuart

I wouldn’t do tat at the speaker level.
You might have to do a bit more research but I think you may be able to link JP13 pins 1 and 2 to achieve a mono output (albeit on 2 speakers).

Someone else may be more up on this amplifier but this is the level I would be looking at combining the 2 channels.
Cheers Bob

  1. Yes - the volume controls operate separately on each channel.
  2. Yes - according to the specs power is 8v to 22v DC. The generic adapter will need to be able to supply sufficient power for the volume you intend to operate at.
  3. Depends on your application. Consistent loud volumes in a small or badly ventilated box with high ambient will require a fan. If those conditions don’t apply you would get by without a fan.


Sorry I missed this bit.
It may be possible to operate this amplifier with a single speaker in “Bridge” mode. Some do support this, some don’t. Do NOT attempt to connect the two outputs in parallel. You will still have to combine the 2 channels somewhere as I suggested above.
Cheers Bob


Thanks Bob and Jeff for your replies. It has helped me a lot.