Teardown: Sonos One

The Sonos One speaker is the flagship smart Alexa-enabled speaker. Sonos is hoping it will boost the the trajectory of the 15-year-old speaker company. With an MSRP of $199, it’s $50 more expensive than the Echo Plus. Some might think the price differential is due to more expensive components or better sound quality, but I have another take: I believe it’s a sign of a struggling speaker company in an impossible war.

🎵I like big bottoms, and I cannot lie

Carefully removing the bottom cover, we see the first signs of a speaker company: part numbers and careful coding everywhere. There are different part numbers for black and white parts in the tool, shot date of September 2017, Revision D of this part, and a “PC,” which means this polymer is 100% polycarbonate (a somewhat rare and more expensive choice). This level of detail shows a company that runs an extensive supply chain.

🎵It’s getting hot in here, so take off all your casings.

Digging a bit deeper, we see traditional design and manufacturing processes for pretty much everything. As an example, the speaker grill is a flat sheet of steel that’s stamped, rolled into a rounded square, welded, seams ground smooth, and then powder coated black. While the part does look nice, there’s no innovation going on here.

🎵You spin me right, round, baby, right round. Like a speaker, baby, right round!

After removing all the speaker components, the complexity of the main body comes into view. This is actually two separate parts that are glued together and the seam ground smooth. This is a design we used to call a “block and chisel,” where you start with one big shape and “cut away” plastic to make components fit. It would be impossible to mold this part as a single piece. It’s possible this is a common manufacturing process to increase sound quality while still remaining cost-competitive with higher-end speaker cabinets. The polymer used is ABS + 10% glass fiber, which is quite unusual for traditional consumer electronic products but is a likely addition to improve sound quality. Glass fibers cost more, are harder to design tooling for, and create poor surface finishes (but provide great mechanical properties in exchange).

🎵Your traces bring all the boys to the yard.

Turning our attention to the main circuit board, there’s more evidence of a speaker company tacking on some technology. The power supply (electronically dirty, analog circuitry) is on the same board as the communications, MCU, and audio output (digital, clean circuitry). In most products I’ve worked on, these are often separated into to two separate boards. While it’s always dangerous to guess, this is likely common in all Sonos speaker hardware to minimize the number of circuit boards that must be manufactured and installed into the cabinet.

You’ll also notice all the communications are on a separate PCI Express module (which is made by Sonos but designed around Atheros’ AR9580-AR1A chipset). Putting communications on a separate module is a commonly used technique with large companies to standardize radios across a broad number of products and simplifying the FCC certification process. Another supply chain trick and symptom of a company with a broad array of similar products.

🎵I’m hopelessly devoted to you.

Taking a careful look at the heaviest part in the product: the rear panel is die cast zinc and serves as the primary heat sink for the product. Notice the lineup of the primary processors on the circuit board (blue arrow) and their matching surfaces on the zinc part (red arrow). This means lots of heat is being generated by the microprocessors and flash. We see:

· Freescale NXP SoM SC667517EYM10AE

· Cypress NAND Flash 8Gb S34ML08G101TFI000

· Micron DDR3 Memory 4Gb (2x) MT41K256M16TW-107-P

If you are familiar with consumer electronics, you’ll note these are some sophisticated — and expensive — parts for a speaker. This is common with smart speakers because they need to store lots of data on the device and quickly process complex audio signals.

🎵Oh it’s such a shame for us to part

Looking upwards to the top of the speaker, we find the microphone array, audio processing circuitry, and all related buttons and LEDs for the UI. This board looks to be designed by a very different team/person (possibly even outsourced) from the power and communications board. There are 6x MEMs microphones equally spaced joined by 2x TI PCM1864 audio 4-channel front-end ADCs. The digitized audio information is then beamed down a ribbon cable to the power and processor board we looked at earlier, eventually to make its way to Amazon’s Alexa backend.

Now that our shiny new Sonos One is in pieces on the table, let’s turn our attention to Amazon’s flagship competing product.