On the bench · Amps
Class-D modules that do not fight your layout
On the bench notes for boards that leave room for the PSU, the speaker terminals, and a sane grounding story.
Sep 11, 2026 · 7 min · Editorial
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A module can measure fine on a lab PSU and still be a pain in a chassis. This note is about layout, not THD leaderboards.
Look at the connector farm first. If the speaker outputs, the DC input, and the signal in all want the same 40 mm of panel, you will spend more time on brackets than on listening. Boards that put DC on one edge and speakers on the opposite edge save an evening of sheet-metal regret.
Grounding is the other silent killer. Star the chassis at one screw, keep the input RCA/XLR return short, and do not let the speaker return share that path if the module already has a power ground. If the vendor’s PDF is silent on this, treat the board as a prototype until you prove it is quiet.
PSU headroom matters more than the wattage sticker. A 300 W module on a 150 W brick will clip the rail before the speaker asks for it. Match continuous current, not peak marketing watts.
We are not calling any of this “reference.” It is what you notice when you actually drill the lid.
On the card
Example parts links. Affiliate. We may earn a commission if you buy.
- Sure / Wondom class-D amp module (example)parts-express · 325-162