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Google Nest Audio Spinorama and Measurements

napilopez

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Hi! I published my review of the Google Nest Audio today. You can read that here. It's written for a more mainstream tech audience, but most of the same information is there, so I'll try to keep this post relatively light on the non-measurement-related text.

As I note in my review, when Google gave journalists a more in-depth look at the speaker after its announcement, I felt it deserved a deeper look than a simple quick impression of the sound quality.

The presentation had the usual phrases along the lines of "deep lows and crystal clear highs" and how the speaker will let you hear music "aS tHe ArTiSt InTenDeD," the most annoying phrase in audio marketing. But then the device's product manager said, unlike the original Google Home, this speaker had been designed via "double-blind testing." That made my ears perk up -- that phrase carries some weight around here.

He also talked about maximizing dynamics, increasing thermal dissipation, waveguides, dispersion, minimizing resonances, and internal cabinet volume. All from a top-level overview tailored to mainstream tech coverage, but still, just hearing those things made me feel Google had put some real effort into this design.

And it shows. Here's the spin as measured at 62 percent volume at a distance of 2 ft/0.6m via Bluetooth:

Google Nest Audio Spinorama.png


I mean, wow. This is a $99 speaker -- for each unit, but still; we've seen much worse spins from speakers far more expensive. The only 'real' issue here is the high-Q dip at 9 kHz, and it's largely balanced out off-axis. Below this, directivity control is excellent, with no visible crossover dip and a listening window that is ±1.5dB from 200Hz to 8kHz. There are no obvious significant resonances. It's quite wide directivity, too.

Someone buy the engineers a pizza.

The response does drop precipitously after 13kHz. I should note that as I used Bluetooth for these tests, I wasn't sure of the sample rate being used, so that might affect the highest frequencies slightly (I got slightly different results for 44kHz vs 48kHz, for example). But this should not be an audible issue for most people. I can hear up to 19kHz fine and though maybe the speakers lacked a little 'air,' at this point that might just be the bias of knowing the measurements.

The elevated bass is not a problem; it is due to some purposeful loudness compensation, and it is subjectively appreciated. At this SPL (admittedly not very loud) you're getting useful in-room bass down to the 40s. More on this later.

I think any way you cut it, this is pretty darn good performance given the price and size. I should also note the speaker is a lot smaller than I had assumed from photos -- its face smaller than a paperback book. It's 6.9 x 4.9 x 3.1 inches (17.5 x 12.4 x 7.8 cm), which makes the unit even smaller than the iLoud Micro Monitor (7.1 x 5.3 x 3.5 in / 18 x 13.5 x 8.9 cm). The woofer is just 3 in (75mm) and the tweeter is 3/4" (19mm).

Here's an image provided by Google of the unit without its cover:

1601926530791.png


You can see that unlike some of the smart speakers out there, this is a pretty traditional design. A woofer, a tweeter, and a waveguide in a sealed enclosure. No fancy weird drivers and layouts, just the good ol' basics. Not that I mind more inventive designs, but only if they contribute something useful.

Let's look at horizontal directivity. First the ER curves:

Nest Audio Horizontal ER.png


Again, 9kHz and above 13 kHz aside, it doesn't get much better than that.

Here are the raw horizontal curves.
Nest Audio Horizontal 0-90.png

This is extremely good for the most part. Among the best I've seen below 8 kHz, frankly. To be fair, having a small woofer for easier integration with the tweeter helps, but still: $99 speaker.

Note the bumps below 500Hz were artifacts of an impromptu measurement setup; I just moved so I have not yet figured out my permanent measurement setup. These bumps are not present in several other measurements of the speaker.

Just to make sure though, I performed a few measurements with the speaker about 8 feet up, further from reflecting surfaces other than some leaves from the trees. Here is one such measurement with a 9ms gate. Note I might've been slightly off axis here as the speaker was too high up for me to confirm alignment, but the point was confirming the lack of resonances below 1kHz.

Google Nest audio 9 ms gate.png


Back to directivity, here are the horizontals normalized to the on-axis.

1601927064405.png

No significant anomalies other than the obvious one.

And the normalized polar map telling us the same thing:
1601927479138.png


The speaker is also well controlled within its vertical listening window, though it is better below the tweeter axis than above it. I feel this should be the other way around, as this is the type of speaker you are more likely to hear while standing up. ± 0/5/15 vertical:

Nest Audio Vertical LW.png


Ceiling and floor reflections are pretty typical for a 2-way, which is to say fairly messy:
1601928206167.png


Which you can see as well in the polar map:

1601928233433.png


Luckily evidence suggests that if the verticals don't show up much in the ER and PIR curve, they shouldn't hurt much in terms of tonality.

Lastly, we look at the woofer's behavior at different SPLs. The top curve is 90% volume, the bottom curve is 30%. White is the 62 percent volume the speakers were tested at, which equates to about 71 dB at 1m. I've applied baffle step compensation to each of the measurements, although note this will necessarily be a little bit off; I could not get as close to the woofer as ideal because I couldn't take off the fabric cover. Actual results might be slightly different, but this is good enough for this evaluation:

Nest Audio Compression Baffle compensated.png
I have no idea what the notch at 150Hz is about. The Nest Audio does not have built-in room EQ like the Google Home Max, so it's not trying to fix a room node or anything. Perhaps it is a notch to minimize distortion artifacts that might arise at high SPLs.

Nest Audio deconstructed.jpg


Some of you know I usually care little about distortion if it's not audible in a pejorative way. In this case, I was a little surprised it wasn't audible at high SPLs, given how small the thing is; other small speakers I've tested tend to show more signs of strain at high volumes.

Granted, I'm not sure how useful distortion measurements of the woofer alone are, but at the very least we can see Google took care to make sure distortion does not rise above the fundamental at high SPLs, as many cheap speakers do. Here's the woofer at the SPL level of the spin:

Nest 62 distortion.png

(Note that I could note apply baffle step compensation to distortion, hence the droop)

And here it is at 90:

Nest 90 distortion.png


Again, still not crazy loud at 90%. I believe this translates to about 84-85 dB @ 1m. But still, distortion in the bass remains well below the fundamental.

So there you have it. It's a small speaker and it won't get crazy loud or crazy low, but what's there is designed very well considering the low price and design constraints -- not to mention all the other features packed into the speaker. Easy peasy recommendation if you don't need high SPLs and can live without the option for a sub (Amazon added a wireless sub for the echo, so who knows, maybe Google will do the same).
 
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Looks like an excellent cheap speaker. Thanks for posting :)

Inferring absolute levels from the info you gave, it seems that 90% volume would give us about 85dB/1m - is that about right?
 
Looks like an excellent cheap speaker. Thanks for posting :)

Inferring absolute levels from the info you gave, it seems that 90% volume would give us about 85dB/1m - is that about right?

Hah, I just edited the post to say precisely that. Yes, obviously not incredibly loud, but still I appreciate that Google worked to offer reasonable performance within its limitations.

The company rates the speaker as "86 dB max loudness" and "77 dB max bass" (whatever that means) so this seems about right. I could not measure 100% because my poor little umik was already on the edge of clipping at 90%, so close to the woofer.
 
By the way, here's a look at the in-house software Google is using to "simulate over 2,500 listening positions."

Snag_3ff0d0f.png


Unfortunately the image is low res so can't make out too many specifics.

I'm not sure if that means they are simulating the response completely, or using a klippel-esque machine, or whatever. They do have an anechoic chamber for testing. But pretty cool to see the 3D directivity balloon.

Nest Audio in anechoic chamber without enclosure (1).jpg
Still cool, to see.

And here's a screengrab of the software used by double-blind test participants:

Snag_4010ab4.png


So I think there's a clear Harman/TooleSchool influence. Again, I'm just happy to see they're actually putting in the effort to use their massive resources and make something good at this price point. If only there were better inputs...
 
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Thanks for the review @napilopez!
Great performance for US$200/pair.
Studio monitors alternative, perhaps....for those wanting super clean look.

I see 2 ways of connecting to PC:
- Bluetooth (requires bluetooth dongle on desktop, or built-in to all laptops/tablets)
- Cast music from PC to speaker, using Google Chrome browser (or other chromecast compatible players like Spotify Connect [premium feature]). (PC must on same subnet as speakers)

update: I'm not sure whether this will play mono signal in both or there's actually channel separation when used with 2 speakers?
 
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Perhaps we're starting to see the influence of Genelec and Devialet trickling down with manufacturers paying special attention to the structural rigidity of the cabinet design.

 
Great performance for US$200/pair.
Studio monitors alternative, perhaps....for those wanting super clean look.

I see 2 ways of connecting to PC:
- Bluetooth (requires bluetooth dongle on desktop, or built-in to most laptops/tablets)
- Cast music from PC to speaker, using Google Chrome browser (or other chromecast compatible players like Spotify). (PC must on same network subnet as speakers)

Yeah. Though I can't speak to the reliability of stereo performance for sure, not having tried that myself. But with a single speaker at least, latency doesn't seem too bad on a PC (I can watch videos without being annoyed at the delay), and the speaker does support AAC if your on an Apple device or Android (AFAIK Windows 10 doesn't support AAC)

For audio enthusiasts, the ideal use case seems to be for playback in a small room or at low SPLs. They'd make great speakers for a bedroom or other secondary system. As a primary system, the inability to add a subwoofer would definitely get to me, so I hope Google comes up with a solution for that.
 
Perhaps we're starting to see the influence of Genelec and Devialet trickling down with manufacturers paying special attention to the structural rigidity of the cabinet design.

Don't we just love a good cut-away speaker to peer at the insides? :)
 

Yes, they definitely can, and I confirmed with Google stereo works over Bluetooth as well. I believe you just have to set up an audio group first. However, I believe this will introduce some significant delay as the speakers are not using any fancy wireless tech for stereo like some other systems. So a stereo pair is best for music only. Shame about the connectivity!
 
Yes, they definitely can, and I confirmed with Google stereo works over Bluetooth as well. I believe you just have to set up an audio group first. However, I believe this will introduce some significant delay as the speakers are not using any fancy wireless tech for stereo like some other systems. So a stereo pair is best for music only. Shame about the connectivity!

I wonder also how well synced the two speakers would be with each other. Very small inter-channel differences can be problematic in terms of imaging.
 
I wonder also how well synced the two speakers would be with each other. Very small inter-channel differences can be problematic in terms of imaging.

A legitimate concern. I haven't noticed issues with prior Google Home speakers I've listened to, but there are few things more annoying than wireless speakers cutting out during music playback, so I hope that's not the case here.
 
A legitimate concern. I haven't noticed issues with prior Google Home speakers I've listened to, but there are few things more annoying than wireless speakers cutting out during music playback, so I hope that's not the case here.
Not only that, but in terms of delay between speakers. Seems like it wouldn't take much for that to become audible, as opposed to the less-noticeable low frequency delay you might find between a soundbar and subwoofer connected by Bluetooth.
 
Not only that, but in terms of delay between speakers. Seems like it wouldn't take much for that to become audible, as opposed to the less-noticeable low frequency delay you might find between a soundbar and subwoofer connected by Bluetooth.

Yep. I had that issue with the devialet phantom reactor, actually. Occasionally the center image started drifting towards one speaker, and I thought there was a weird volume issue at first, but adjusting the volume wouldn't fix it. Until I realized I was actually experiencing the precedence effect. One speaker had started to lag behind the other, so even though clarity hadn't changed much, I heard the sound being biased towards the earlier speaker. I had to restart the speakers to fix it everytime, and it was supremely annoying. Luckily a firmware update seemed to help, but I would definitely just hardwire those.
 
What do you guys suspect is causing the issue between 8Khz and 10Khz? And to a lesser extent, 900Hz -1Khz? I'm surprised it's a traditional 2-way design underneath the housing.
 
Very nice review. Impressive performance.

Anyone seen measurements for the Google home max, I tried searching for some but found only it's physical dimensions and links to this review. :)

If it wasn't made in similar way to this I wonder if the next version will be, seems potential for something pretty impressive in a Google nest audio max.
 
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