Reverse-engineering my speakers' API to get reasonable volume control

Original Article ↗ Hacker News Discussion ↗

Reverse‑engineering the HTTP API of a networked speaker system to build a custom volume controller sparks broader debate about how badly most hardware and apps handle volume scaling, especially at low listening levels. Commenters dig into digital vs analog attenuation, logarithmic vs linear controls, “loudness” compensation, and why 24‑bit internal audio helps preserve quality when software scales signals. Many also highlight the security and longevity problems of internet‑connected “smart” speakers, arguing for simpler passive speakers with external amps or modular streaming fronts to reduce e‑waste and avoid insecure, unauthenticated device APIs.

Digital vs analog volume, loudness, and quality

  • Several comments dig into how digital volume control likely scales samples before the DAC; with 24‑bit outputs, moderate attenuation is fine, but very low volumes may risk quantization artifacts.
  • Others argue excessive digital attenuation plus high post‑DAC gain is worse for SNR than setting a sensible analog gain and using more of the digital range.
  • There’s praise for designs that adjust the DAC reference level instead of scaling samples.
  • Discussion of “loudness” controls: one amp’s recommended workflow (set a fixed max volume, then use a loudness knob) is seen as close to ideal, matching human perception better than flat gain changes.
  • Logarithmic volume curves and loudness compensation are repeatedly cited as generally mishandled in consumer products.

UX of volume controls (Spotify, iOS, Sonos, etc.)

  • iOS has a finer volume slider via long‑press in Control Center, including for Spotify Connect; this helps but still leaves only ~10% of slider travel usable for some setups.
  • People complain about coarse steps on phones, TVs, and smart speakers; even the lowest levels can be too loud.
  • Sonos is praised for allowing per‑speaker max volume limits, effectively increasing slider resolution.

Networked speakers and API / security issues

  • Many are surprised the speakers expose an unauthenticated HTTP API with filesystem and firmware access; this is viewed as a serious IoT security failure.
  • Some recommend network segmentation; the broader IoT ecosystem is criticized for weak or absent security.

Physical knobs and DIY hardware

  • Strong enthusiasm for standalone rotary controllers (ESP32‑based dials, open‑source haptic “smart knobs,” keyboard knobs, DIY SpaceMouse projects).
  • Several readers want mass‑market, programmable multi‑knob devices; others note current DIY designs are complex and expensive to productize.

Active vs passive speakers, headroom, and longevity

  • Debate over buying powerful active speakers vs passive speakers plus separate amp.
  • Pro‑passive side: amps and “smart” features die first; passive speakers last decades and are repairable, reducing e‑waste.
  • Pro‑active side: matched amps, active crossovers, built‑in EQ, protection limiters, and very long life in quality studio brands.
  • Headroom is defended: large speakers with ample power sound better at normal levels and avoid underpowered distortion.

General audio frustrations and tips

  • Complaints about low maximum gain and poor speakers in many laptops and Bluetooth devices; some see this as bad design, others as protection against damage and annoyance.
  • Tips shared: macOS Option+Shift for finer volume steps; Linux PulseAudio for per‑app gain; Chromecast‑/AirPlay‑style receivers or Raspberry Pi images (e.g., balena‑sound) as smarter, replaceable front‑ends for “dumb” amps and speakers.