Adam Machin

Tech Blog

HomePod Audio Post Listening Analysis

This is not an attempt to educate you, but please let me know if there is anything technically incorrect.

A personal opinion is that music, like computing science, largely adheres to “Garbage in Garbage out” – Audio, like visual, is unforgiving in nature.

Amplifiers I do believe work best when they receive a “Line In Level” https://en.wikipedia.org/wiki/Line_level

Own Audio Equipment Observations:

 

  • ”My Amplifier is expecting “Consumer Line Level”
  • Vinyl records typically have double the Dynamic Range than Digital Music.
  • My Vinyl Pre-Amp is active. I have a further “Passive Pre-Amp set to 100% for Vinyl”.
  • My CD player produces “Line Out Level” – it is noticeably “louder” – so much so I purchased a passive Pre-Amp from Schiit Audio in the USA. I set this to roughly 70-80% for the CD Player to make it quieter.

 

Music is Louder now than it used to be:

http://www.bbc.co.uk/news/entertainment-arts-35250557

 

  1. Older or Complex Apple Music iPhone (Sound Check [off]) -> HomePod | Flat, Quiet
  2. Older or Complex Apple Music HomePod (Sound Check [on]) -> | OK
  3. HiFi Older or Complex Apple Music (Sound Check [off] (Volume 100%) -> OK
  4. Hifi Older or Complex Apple Music (Sound Check [off] (Volume 50%) -> Flat – (I reckon it’s because the Amplifier is expecting a “Line Level” Signal. If you provide it with a weak signal, it’s going to struggle to make it sound OK.

(I have noticed Apple TV does not allow Volume Adjustment on “AirPlay” but strangely Airport Express seems to allow volume adjustment.

Thoughts on HomePod

  • HomePod has 7 “horn tweeters + a woofer” sound is crisp bass is un-distorted.
  • HomePod works to make 3 virtual sound stages (left, right and centre) through a combination of direct and acoustic reflective – processing.
  • I believe it is this very “virtualisation” that causes older or complex music to sound flat or confused, but why?
  • It’s trying to work out which sounds it needs to amplify for directional i.e. Vocal, Lead Instruments/Left/Right/Centre. Provided with a “Quieter source” -> things get lost, given an older recording that originally intended greater dynamic range and little compression. Those “quieter parts of a song, HomePod sees as “un-important” and pushes them to the back.

 

I think in conclusion given the amount of digital processing happening on HomePod on what started out as a digital music file, with a digital system, then you might as well turn on “Sound Check”. I still like it. It will receive software updates.

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