Sony WH-1000XM4C FCC Teardown

With the Sony WH-1000XM4C announcement, my question is, how close is the new model to the original WH-1000XM4 from 2020?

From the press release and product pages, there are some differences in specifications, like a lower battery life, absence of NFC, and Bluetooth 6.0 support. But how similar are the old and new models on the inside? Are components interchangeable? Or did Sony re-engineer the new model completely? I dig into the FCC teardown to find out.

For the original WH-1000XM4 teardown, check out my teardown post.

We begin with the earpads removed, revealing the foam covering the driver. The original WH-1000XM4 foam has no cutouts, but I recall seeing a post on reddit of a WH-1000XM4 with similar cutouts. Perhaps later versions of the WH-1000XM4 used similar foam inserts.

There are no photos in the filing showing the driver, but the appearance will be identical to the WH-1000XM4.

Moving on, we have the interior of the earcups. First the right side.

Everything looks pretty much the same as in the original WH-1000XM4, except for the plastic cover on top of the battery, and a few small changes covered further down. Why Sony has added a cover for the battery, I do not know, but Sony’s recent models like WH-CH530, WH-CH730N, WH-1000XM6, and WH-1000XX, have their batteries in compartments.

Moving to the left side, an identical layout to the WH-1000XM4, except the NFC PCB and its connections, have been removed.

The first change on the right side is the removal of the battery thermistor connector on the SUB PCB. The small photo insert is from the original WH-1000XM4 with the connection still in place (red box).

I checked the rest of the SUB PCB, and there is no connection elsewhere on the board for any thermistor.

The second change in the new model, is the presence of 3 contacts on the battery connector. Previously the WH-1000XM4 only had 2.

There are a few small differences on one side of the SUB PCB, with some small components rearranged due to the addition of the new 3 pong battery connector.

The reverse side of the SUB PCB is the same, minus the trace to the thermistor port.