The Apple HomePod arrives in stores this Friday, February 9. You can read my review of it on Forbes here. You can also choose ‘Follow on Forbes’, which appears when you click FULL BIO next to my name at the top of this page if you’d like to be alerted when further posts from me appear.
Now updated to add another under-reported detail, the reasons Apple set up the Audio Lab and the kinds of audio it tests.
‘Things Nobody Has Told You...' is my occasional column touching on tangential, but interesting, details that have been lost or gone under-reported. Sometimes it’s a ground-breaker, sometimes it’s a piece of trivia that might enliven a dinner party conversation…
I’ve talked in depth to several senior Apple execs to get the skinny on what was behind the HomePod.
1 It’s been in development for longer than you might think
Something that’s only come to light recently is how long Apple has been working on it smart hi-fi speaker – more than six years, it seems. Apple has its own audio labs, working on everything from telephony radio to microphones and beyond.
Gary Geaves, Apple’s Senior Director, Audio Design and Engineering, told me, ‘Over the years we've massively expanded the team. We believe we have the biggest acoustics team on the planet. We've drawn experts from many of the audio brands and from universities. And, really, the reason that we wanted to create this team was to deliver on products like HomePod but also to double down on audio in all of our products. We have been developing HomePod for six years so it's fully battle-hardened by now.’
2 It ain’t a mono speaker. But stereo… ?
The HomePod has lots of speakers inside it. Seven tweeters and one big woofer. These are beam-forming tweeters, that is, they can push particular sounds in specific directions, creating a wide soundstage as they do so. This is not a mono speaker, where the music is mixed down to a mono track. It does pay attention to the distinct left and right channels of a stereo track and uses them as part of the sound it creates. I suspect Apple doesn’t refer to it as stereo partly because audiophiles have strong opinions about what qualifies as stereo in terms of separation of speakers, whether they’re two independent speakers and so on. And perhaps because it feels that it’s irrelevant to most listeners, that when they hear HomePod they’ll feel such distinctions are academic. Certainly, the sound that a single HomePod produces is wide and persuasive.
3 It’s a solid, hefty machine
Pick it up and you notice two things. It’s a pleasing, tactile experience thanks to the soft-touch mesh which covers it. And it’s heavy. It weighs 5.5lbs (2.5kg) which is more than you expect, again because that acoustically transparent mesh gives the HomePod an appearance that’s almost delicate, especially in the white finish. In fact, it’s pretty robust. The weight is reassuring, and a lot of it is down to the woofer which sits in the middle.
4 The woofer moves like you wouldn’t believe
Kate Bergeron, Apple’s Vice President, Hardware Engineering told me about the woofer.
‘It's actually a lot heavier than it looks,’ she said. ‘It’s a pretty impressive magnet inside the enclosure, mounted on dampers so that the intended vibration from the sound that comes out of it isn't transmitted into the final product which would cause unwanted rubs and buzzes and maybe the product moving across the table. Our subwoofer, which is high excursion, travels 20mm. It's an amazing performance in a very small package.’
Now, 20mm may not sound much but it’s 0.79in, which considering that’s inside a machine less than seven inches tall is a big proportion. Unusually, because the seven tweeters are in a 360-degree array near the base, the only place for the woofer is in the middle, upward-facing towards the top. Bass is non-directional, so it can work in this orientation.
5 It’s performing smart analysis of the music as you play it. Non-stop.
Those seven tweeters are putting out different sounds. The HomePod analyzes music on the fly to work out what’s the main vocal, what’s background noise and so on. It then puts the background noise into the tweeters facing the wall and pumps the main sound directly out to the room. This continuous analysis happens because there’s a powerful processor in the HomePod, the Apple A8 chip, first seen in the iPhone 6. As Apple points out, this speaker has a full iOS computer inside it.
6 The tone HomePod is going for isn’t neutral, it’s faithful
Tuning to taste is a part of designing a speaker. Some companies, like Sonos, for instance, aim for an entirely neutral sound. Apple seems to have gone for something subtly different, partly made possible by that A8 chip again. Apple talks about staying true to the original recording, rather than neutral. By analyzing every song as it plays, the idea is to divine what the intention of the particular mix in each track is and then trying to reproduce it as faithfully as possible. Added to this is the facility to bounce background elements off the back wall to create ambiance and throw the main vocals into greater relief.
7 You won’t hear a scrap of electronic noise from HomePod, thanks to the Noise and Vibration team
Yes, there really is such a thing at Apple. Gary Geaves revealed, ‘The Noise and Vibration team was set up around 15 years ago and joined the acoustic team around seven years ago. Their initial kind of responsibility was to look at fan noise and disk noise for Macs. More recently they've expanded into the area of audio products. So electronic noise is important in those products and also unwanted vibrations. In HomePod, the vibration isolation system built in is inherently part of the design. So the Noise and Vibration team were key in developing that and also testing to see whether the design worked as we intended.’
8 Apple extended its Audio Labs and built listening chambers for HomePod
The audio lab already had several anechoic chambers before HomePod came along, but built its biggest chamber six years ago specifically for the development of this product. These are not minor commitments. Some are buried in the ground, with isolating areas to preclude sound from seeping in – even the pipes carrying cables into the chamber have breaks in them to prevent vibrations. One, designed to spot those electronic noises, was built to fearsome specs. Gary Geaves explained: ‘When you use HomePod in a very quiet circumstance, say it's idle and it's just plugged into the into the mains on your nightstand, you don't want an annoying noise coming from it. This chamber has a hard floor and it's extremely quiet inside.’
In terms of isolation from the external world, this chamber is very carefully engineered. ‘It is built on a slab of concrete that weighs 28 tons and is a foot thick. The metal walls of the chamber are a foot thick and weigh a further a 27 tons. The chamber is on 80 isolating mounts.’
In other words, the chamber is basically silent. As a guide, a well-engineered recording studio would have acoustics measured at around 20 decibels. The threshold of human hearing is 0 decibels. So, if you measure a sound at that level you can't hear it. That chamber, I’m told, is at -2 decibels!
9 Hundreds of Apple employees had the reverberations in their living rooms measured
If you’re a company like Apple which is known for its secrecy, how do you do your testing? Answer: turn to your staff. Real rooms are not the same as anechoic chambers as there’s no reverberation.
Apple constructed a room described as typical. Then, to model what the right reverberation for a room is, they went out into hundreds of employees’ rooms and in each room did ‘literally thousands of measurements’ to characterize the reverberation. After figuring out what the average was from a special room was tuned to have the same reverberation as an average room. Apple says this was ‘only a starting point because Siri needs to work everywhere.’
10 Design is based on performance as well as aesthetics
Gary Geaves again: ‘With an audio product that buzzes, particularly on the bass notes, you get this edge to the sound, it sounds very nasty. One of the things we found was traditional measurements were telling us something but there wasn't a really good correlation between what you would measure and what you would actually hear. So the team had to develop their own measurements and metrics that had a better match with what you would actually hear when you measured something. So that combination of upfront design and inherent vibration control in the system, plus the testing, means that when you get to the end of the product development you are not caught out: you don't have to add things like pucks or feet on the bottom kind of as an afterthought.’
11 Apple’s interest in speakers predates HomePod and includes Psycho Acoustics
This interest in audio testing makes sense when you think about it. Lots of Apple products have speakers in them. As Gary Geaves explained: ‘Around seven years ago we started to create a centralized and expanded audio and acoustics team. You may know that acoustics in audio is a very broad ranging science. It takes in everything from telephony audio, which is a very specialized form of acoustics in audio, to microphone testing and development, speaker transducer engineering, simulation engineering, you need experts in psycho acoustics - the science of how people perceive sound - tuning experts and so on.’
Philip Schiller, Apple’s Senior VP of Worldwide Marketing, added, ‘We're really proud of the engineering team we’ve built, because we think they are world class. It's amazing the resources that have been developed and grown here. This is among the most unique facilities for audio engineering certainly in the country if not the world. And we all benefit. This is what contributes to why the speakers are sounding better and better on iPhone and iPad and why people are loving their AirPods. and hopefully people are going to love their HomePods.’
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