Update: The author of the review has now added an initial paragraph to his very long text, pointing out that, well, maybe, just perhaps, his measurements aren’t worth much.
EDIT: before you read any further, please read /u/edechamps excellent reply to this post and then read this excellent discussion between him and /u/Ilkless about measuring, conventions, some of the mistakes I’ve made, and how the data should be interpreted. His conclusion, if I’m reading it right, is that these measurements are largely inconclusive, since the measurements were not done in an anechoic chamber. Since I dont have one of those handy, these measurements should be taken with a brick of salt. I still hope that some of the information in here, the discussion, the guesses, and more are useful to everyone. This really is a new type of speaker (again see the discussion) and evaluating it accurately is bloody difficult.
He still doesn’t address the question of DSP affecting the sound differently when music is playing rather than a sine wave. But I think it’s clear that this whole thing is, well, a waste of time.
I wonder if Phil Schiller is going to tweet about this addendum…
HomePod reviews from the tech press came thick and fast last week, and while the smart speaker’s sound quality was consistently praised, most reviews were based on subjective assessments and didn’t take into account professional-grade output measurements. Early on Monday, however, Reddit user WinterCharm posted exhaustive audio performance testing results for HomePod to the Reddit audiophile community.
Using specialized equipment and a controlled testing environment, the review features in-depth analysis of the smart speaker’s output when compared to a pair of KEF X300A digital hi-fi monitors, representing a “meticulously set up audiophile grade speaker versus a tiny little HomePod that claims to do room correction on its own”.
I’ve been following this Reddit thread and its published results. It’s amazing that in a world of audiophiles who obsess over which USB cable makes their music sound better, that this person performed all of these measurements, and forgot to mention that the HomePod uses digital signal processing to alter all music that it plays. In other words, it is far from neutral, and audiophiles make a big deal about their equipment being neutral. The frequency response may be excellent, but the equalization alters the music from what it should sound like.
In fact, I think it’s highly possible that this reviewer has based the conclusions of his testing on false assumptions. The HomePod has dynamic digital signal processing; it alters the music based on the music. In other words, it’s not a fixed EQ setting, but one that changes as music is played (and according to the room where it’s played). As such, sending single frequency sine waves, or whatever he did, won’t show the results of the EQ.
You can easily hear this by playing some music you know well first on a stereo, then on the HomePod. For some music, the EQ is gentle; for other tracks, it’s aggressive, very bass-heavy. My speculation is that there’s some sort of algorithm that allows certain types of music – with, say, a close balance between bass and treble – to not have such a drastic effect on the bass, and others – more bass-heavy music to start with – to be more greatly affected.
In other words, this person measured the trees, but not the forests.