Jeroen's Project Journals

  • Audio amplifier

  • 3-channel audio amplifier. Mains-powered and with digital volume control. Includes a 3D printed enclosure matching the Teensy DSP/DAC, OLED display and rotary click-encoder control

  • Gallery

Carrier board design


I’ve been going back and forth on this carrier-board design for a while now. The current iteration looks like this: Render of the amplifier carrier-board

The pinsockets match the connector pins of the amplifier modules, so there’s room for 3 of them. Volume control is done with a PT2258 dedicated volume control IC. The board accepts 12V power (Green connector, top-right connector) for the amplifiers and creates 5V out of this for the microcontroller etc. The JST XH connectors for the display and encoder knob include a jumper-selectable 3V3/5V Vcc (although I doubt that will be useful, since a 5V Vcc usually implies 5V logic, which the micro cannot do). The 90-degree pinheaders (double-row for mechanical robustness) match their counterparts on the now-much-simpler breakout board that is installed across the rear-connectors:

Render of the connector breakout PCB

And here’s a quick mockup of what this would look like in the end (this shows an earlier iteration of the carrier-board):

Render of the carrier and breakout boards installed in the enclosure

I’m still not sure what I’ll do with this. I really need the volume control, and I like the no-internal-wiring idea, but the size of the carrier and the separate breakout board adds cost and complexity. Leaving the volume control on the breakout board as in the original design would be ideal, but I don’t have room on that board for a power-stage or for the PT2258 (which is much larger than the digital potmeters). Making a separate board just for volume control is also problematic for space-reasons inside the enclosure. Ideally I would design a single, fully custom board that includes power, volume control and the amplifier circuit, but that’s a level of complexity I’m not quite ready to take on right now.

What I should really do is check what happens with the original volume control board and 12V power for the amplifiers. If I’m really lucky this will all go away and I actually already have everything I need to make a usable amplifier out of this.