I'm thinking about building a class D amp, and would like to use this thread as a means of collecting various bits of info in one place and hopefully fostering useful discussion :-)

We have a quiet time at work right now, so I spent the last week reading diyaudio.com and figuring out what class-D boards/modules would be most appropriate for my needs.

What I want in an amplifier:

  • audiophile quality;
  • enough power to drive my current speakers (Usher S520; their sensitivity is just 84.5 dB and apparently they need quite a bit of juice to make them sing);
  • reasonable requirements in terms of power consumption / heatsinks / size and weight;
  • it should be relatively straightforward to hook up and configure.


I think the following three options (mostly) meet my needs:

1. Eastern Audio Technology (Hifimediy) T4: https://hifimediy.com/amplifiers/diy...dorf-amplifier

This board is based on TK2050/STA516 combo.

Pros:

  • very well-reviewed;
  • uses high quality components (capacitors, inductors, etc);
  • this board is basically self-contained and only a handful of components are needed to build a functional amplifier (a case, a transformer, connectors and wiring).


What I don't like about this board is the lack of info and technical documentation. For example, the manufacturer states that it provides 2x180W @ 8 Ohm, but doesn't provide THD at full power. I suspect that the rated output power is at 10% THD. It means that it probably outputs about 50-70 Wpc while keeping distortion reasonable.

2. Connex IRS2092 Stereo: http://connexelectronic.com/product/...reo-amplifier/

This board is based on the IRS2092 controller chip and IR power MOSFETs.

Pros:

  • well-reviewed;
  • uses high quality components;
  • provides all the power I will ever need;
  • very low parts count if used with its matching power supply;
  • excellent documentation;
  • best in class protection against fault conditions if used with its matching power supply.


However, there are some things that I don't like about this board. First of all, I'm a bit suspicious about IRS2092 which was initially pitched for PA and automotive applications. On this particular board the output filter, apparently, is not included in the feedback loop, which means that some loads could interact with the filter and adversely affect the sound. The input impedance is very low, so a buffer is needed to provide maximum compatibility with different sources.

3. Hypex UcD180HG-HxR: https://www.diyclassd.com/product/ucd180hg-with-hxr/5

This board is produced by Hypex and uses their proprietary technology. Two boards are needed to build a stereo amp.

Pros:
  • widely considered to be among the best class-D amps available at the moment;
  • uses high-quality components;
  • low parts count if used with its matching power supply;
  • excellent protection if used with its matching power supply;
  • balanced input;
  • excellent documentation.


What I don't like about this board: rated power output at 8 Ohm is 120 W at 1% THD and just 60 W at 0.1% THD (similar to Hifimediy T4). Expensive. No single-ended inputs.


At this point I'm inclined to go with the Hypex simply because it's guaranteed to be good, even if the resulting amplifier would be rather expensive.