The Amp Hour #560 – High End Audio with Remco Stoutjesdijk

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Welcome Remco Stoutjesdijk of ItsOnlyAudio.com!

• Remco calls himself a “recovering audiophile”
• Why didn’t we stop trying to improve audio setups in the 70s?
• Remco started with vacuum tubes but moved into silicon at Wolfson Micro. He got his first job by writing a letter asking if they needed anyone and his hobby projects helped to place him into special projects group.
• “If you work in hardware you play with simulators. If you work in software, you play with hardware”. This is why he moved into applications.
• For a little while, he worked at Rohm Semi on LEDs
• Back into audio with ASK industries, who make hardware that is used in stereo setups for cars that are branded with Bang & Olafsson and Burmester.
• Differences between car and home
  • Extreme conditions, like Audi running a 36 hour “sun test”
  • Fixed acoustic environment
• One thing they did was to develop a tuning tool for the end brand (ie. B&O) to tweak with their experts
• Big things they were working on was outside noise cancellation and engine noise cancellation
• However, not all sound is bad. “Putting the car in ‘sport mode’ pumps more sound into the cabin”
• They’re really trying to find the acoustic transfer function (of say, the engine) to reverse any impact it has on the listener’s ears.
• Unwanted noise is first put through a filter. Then they have to apply filter before sound arrives.
• An example transform is a Levinson-Durbin recursion
• Active Noise Control (ANC) isn’t really “cancellation”
• It’s important to think about the stability, since it’s a control system
• Often they’re looking for the lambda coefficient
• After going out on his own, Remco and his family moved to Poland. Polish is a difficult language to learn. It’s on a remote branch of the “tree of languages” (which show the inheritance of different languages and the other languages they’re based upon)
• Poland has a growing tech scene
• Past guests Jan Rychter and Michael Gielda from Ant Micro (and most of the team) are based in Poland, though in different areas. “7Sensing” is another dev shop out there.
• Remco is now consulting via ItsOnlyAudio.com and is a member of the Consulting forum (apply here if interested in joining).
• When not working on client projects, he is building up IP library and bringing demos to audio shows
• ADI Sharc DSP
• Shannon Parks episode
• Tools of the trade for doing audio on chips
  • CMSIS DSP library
  • Components of that library
    • Biquad filter
    • DMA buffers
    • Ring buffers
• Loudness war website
• Push to custom silicon are necessary for super phase sensitive items
• PTP – Precision Time Protocol based on UDP
• Chris wondered if Disney World does something like this to synchronize speakers throughout the park? BoingBoing article
• Dunte protocol
• Audio ecosystem is fairly small, though there are some startups now
• Modern audio need to tie into Alexa / Google / Apple for streaming
• OCA – open control alliance (warning: autoplay audio??)
• Signal processing / fidelity is as good as it can get, wow we need to improve playback environment
• Improving noise comfort for loud urban environment
• Chris and Remco have both used binaural beats to try and drown out sound in the past

• Find Remco online