Mediocre measurements for new Sonos Amp



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Userlevel 7
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lahey wrote:

The analog input SNR measurement after he changed the software setting was 87 dB at 5W.


I found nothing in the review that indicated he'd adjusted the Line-In gain in the Sonos app. What I did observe was a general lack of knowledge of how to use Sonos.

So probably you will not hear the noise.


I'm sure that's true 🙂
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pwt wrote:


I found nothing in the review that indicated he'd adjusted the Line-In gain in the Sonos app. What I did observe was a general lack of knowledge of how to use Sonos.


He said he bumped the setting up from 2 to 3 (maybe he clarified this in the comments that folloed the review). He said that anything higher than 3 resulted in clipping when he used his test signal.
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lahey wrote:

He said he bumped the setting up from 2 to 3 (maybe he clarified this in the comments that followed the review). He said that anything higher than 3 resulted in clipping when he used his test signal.


Ah, it's there now, on page 3 of the comments. Thanks. That makes sense: with a 2V signal, that would be at the top end of normal for the Line-Out of an audio separate like a CD player. In fact, I wonder whether he should have left it at '2', and not '3'.
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Or maybe set it to 1.
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lahey wrote:

The analog input SNR measurement after he changed the software setting was 87 dB at 5W. So probably you will not hear the noise.



Sorry, I am wrong on this. The 87 dB is SNR at full power, not @5W, after changing the software setting. I thought he was saying that the software setting made a big difference in noise, but in fact he was saying it didn't matter much. The fact remains that this is a great amp for streaming, but the analog input is a little noisy.
I agree. It appears the line in performance does not measure well but the streaming side of things is fine. The convenience it brings is incredible. There are not many reviews that measure measure the sonos amp so it is nice to have this.
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Call me skeptical because I’m getting great performance from a very good vinyl front end feeding the line input. The amp converts the line in from analog to digital before it hits the digital amplifier so in either case the AMP is amplifying a digital signal. It should operate with the same specs in either case. There is a 70ms delay with the line input, not sure if that has anything to do with measuring the amp, but I’m not too concerned.
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I'm an owner of the Sonos amp but not super defensive about it. Many things weren't measured or done in a methodical way and lots of things unmeasured. Plus the conclusions aren't clear.
What odds that those that measure haven't used one for real life listening to music and those that have one for that end could not be bothered about the measurements?
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Kumar wrote:

What odds that those that measure haven't used one for real life listening to music and those that have one for that end could not be bothered about the measurements?



Yeah its very uneven. I'm not seeing concrete conclusions but it has a negative tinge to it.
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airforceteacher wrote:

I just started reading it, but it reads like someone who knows nothing whatsoever about Sonos - not familiar with daisy chaining Ethernet or using it as a bridge, unaware of several previous Sonos products with inputs. And what’s that crack about the custom power cord? I guess I’ve never tried other cords but I always assumed they were standard figure 8 size. Is the Amp not standard size?



He didn't take the trouble to find out which would have been two seconds of a google search. Seems like he started with bias for some reason.
It’s a pretty typical bias, performance over everything else. Very few folks buy equipment based on this. It’s certainly a valid bias, though. Lots of motorcycles, etc sold for similar reasons.

When you are more interested in music through the house, with great sound, minimal wires and visual impact, simplicity of operation, voice/phone/tablet/PC control, integration of video system audio, excellent support (manufacturer and peer), ... Sonos is still far and away the best choice.

Try getting support from the Chinese maker of those near-perfect DACs some time, lol (and the likelihood of actually hearing a difference in that DAC vs a Sonos device is most likely nil for anyone over 25). Not to mention all the power blocks and interconnects required for all that stuff, and having to manually power them on and off... Yeesh! No thanks. My ears are more than happy, as is the wife. I’ll stick with Sonos.
Userlevel 7
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I see two types of folks looking for sound systems, the ones that want the best system they can afford based on their listening to it and folks that are more impressed by price and specifications and pay little attention to their ears.

I'm firmly in the first group, if I can't hear it I'm not going to be paying for it.
This article confirms that the Amp is using the Qualcomm DDFA chipset, which offers outstanding digital performance. It's certainly possible that the 70ms delay confused the tester's analog input measurements, but who knows...

https://www.cnet.com/reviews/sonos-amp-preview/

The Amp doesn't include the digital-to-analog converter found on most of its kind, instead using a Qualcomm DDFA amplifier, which keeps the signal digital until the last possible moment. The analog input still features an analog-to-digital converter though, and the signal -- say of a record player -- can be streamed to other Sonos units in the home.

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Nice breakdown of the technology here:
https://www.theverge.com/circuitbreaker/2018/8/29/17791754/sonos-amp-new-price-features-release-date-hdmi-arc-tv-audio-speakers

As for the nitty gritty of what’s inside...

The modulator is a DDFA (direct digital feedback amplifier) class D amplifier.

Sonos built its own custom discreet output stage because there was no off-the-shelf part that could balance efficiency and heat management inside the Amp’s tightly-packed chassis.

Similarly, it uses a custom power supply designed to fit into the form factor and to provide clean audio output. The Amp’s signal to noise ratio is 116dB with under 0.1 percent total harmonic distortion.

Rappoport said Sonos engineers and designers “combined the functionality of the heat sink and the chassis, and we ended up mounting all of the electronics onto a single heat sink. The digital electronics, the analog electronics, even the antennas are mounted to the perimeter of that heat sink, and then the enclosure comes down around it.”

The speaker connectors are custom, removable thumb screw-style banana plugs that can be swapped out if you prefer standard banana plugs. They accept 10-18AWG speaker wire.

Rather than force people into using its own Sub speaker, Sonos retained the sub output on the Amp for flexibility. “We don’t make an in-ceiling sub. We don’t make an in-wall sub,” Rappoport acknowledged. “If we want to give choice to deliver architectural sound experiences, we knew that we had to provide that provision.” An advantage over the Connect:Amp is that users can adjust crossover on the new Amp between 50 and 110Hz (in 10Hz increments).

There are two ethernet jacks; the second can be used if you want to hard wire another Sonos device. The Amp also includes 802.11 b/g/n (but not ac) Wi-Fi if you prefer that over ethernet.

That plastic horizontal strip at the bottom is an IR sensor. Because everything needs an IR sensor.
^^^
Wow, I can’t believe a professional review used “discreet” where “discrete” was called for, but I guess copy editors are just “too expensive” these days. Sigh.
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I assume the Sonos Amp is using the newly designed chip mentioned in this press release from October 2017.

https://www.qualcomm.com/news/onq/2017/10/04/premium-audio-quality-class-d-amplifier-more-about-qualcomm-ddfa

I wonder if this same chip processes the line input?

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