#474 – An Interview with Nash Reilly

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Welcome, Nash Reilly of Sonos!

• Chris and Nash met at OSHWA 2018
• Nash is from Montana and went to engineering school at Montana State University.
• His first job out of school was at Micron over in Boise, doing SO DIMM testing for large scale customers.
• He actually tested for things like Cosmic Ray strikes, discussed many times on this show.
• Interned at Sonos when it was 100 people
• Watching how the vendors change their tune as you get volume up
• His role at Sonos started in sustaining engineering
• Making sure supply chain is stable
• Spent 4-5 weeks per year in China, even had to leave vacation to fly to China.
• “Type 2 fun”
• Smoke jumpers for Intel
• Hank Zumbahlen episode
• Staying well grounded
• Lee Hill’s Silent Solutions
• I2S clocks hurt emissions, are often a problem during testing.
• Blog post about emissions
• Solutions for I2S clocks
  • Changing the output impedance of your driver
  • Put a small external RC filter
• Howard Johnson on the podcast
• First 20 pages of the Black Magic book
• Most DACs/ADCs aren’t as finicky as they used to be
• I2S is just SPI in one direction
• Sigma Delta DACs
• Oversampling and modulating in the reverse direction
• THD is like a noise measure, but also has distortion
• Audio Precision test equipment
• Analog Dialogue
• Charty Party
• 30 ms for it to be instantaneous to a human
• Humans are more sensitive to phase delta
• Latency is constant for digital signals
• 3rd edition of AoE
• ADI AN-283
• The Way Things Work
• How do you maintain quality over low quality speakers that are out there?
• Clicks and pops
• “A class D amplifier is just a motor driver with an LC on the output”
• Layout starts to impact things
• Chapter 8 of AoE for low noise design
• Sonos Port
• 20 people in his group, including digital, analog, layout
• Current project has 10 people in total or so
• 1600 total people working at Sonos
• Sonos Amp
• Had to do a custom class D amplifier
• Needed to design in real time control
• Sonos use Linux computers internally for the high level control
• Microcontrollers for controlling other elements of the design faster
• Nash is in charge of making sure the digital section is put together well and writing test plans
• An example schedule: December start (talking with vendors), April schematic, June testing
• For the Sonos Move, Nash worked on an earlier incarnation.
• Nash’s main site/blog
• Find him on reddit
• Nash is @cushychicken