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View Full Version : Sonos marketing? What does this mean?



Nikhil
2009-12-26, 23:21
From this article:

http://www.courant.com/business/custom/consumer/hc-kevin-hunt-sonos-column-1227-2009,0,602447.column


"We never bring it into the analog domain like Squeezebox and Bose," Kallai says, "which move sound from digital to analog to digital to analog. That creates a lot of artifacts."

andynormancx
2009-12-27, 03:06
I'm not sure exactly what they mean, but you probably want the previous paragraph as well for context:

"Sonos' software designers preserved the digital signal through every step, from the computer to the S5's processors to the digital amplifiers to the speakers, where it is for the first and only time converted to an analog signal detectable by the human ear."

jo-wie
2009-12-27, 03:24
I guess he's pointing to the Boom DSP -> DAC -> Class-D Amplifier signal path.

Aslak3
2009-12-27, 04:39
I'm not sure exactly what they mean, but you probably want the previous paragraph as well for context:

"Sonos' software designers preserved the digital signal through every step, from the computer to the S5's processors to the digital amplifiers to the speakers, where it is for the first and only time converted to an analog signal detectable by the human ear."

I'd love to know what a "digital amplifier" is, though. Sounds like a non-sequitur.

Lawrence

andynormancx
2009-12-27, 15:48
I'd love to know what a "digital amplifier" is, though. Sounds like a non-sequitur.


D Class amps are often referred to as digital amps, because of the way they control the volume by switching the output of a transistor on and off.

http://en.wikipedia.org/wiki/Class_D_Amplifier

I guess maybe Sonos are switching their D Class amps directly from the digital signal. It is clear what benefit that would provide, though I can't claim to understand DAC/D-Class amps etc in any great detail.

peterw
2009-12-27, 16:09
I'm not sure exactly what they mean, but you probably want the previous paragraph as well for context:

"Sonos' software designers preserved the digital signal through every step, from the computer to the S5's processors to the digital amplifiers to the speakers, where it is for the first and only time converted to an analog signal detectable by the human ear."

They're sending digital signals from the amplifiers to the speakers???

m1abrams
2009-12-27, 16:57
They're sending digital signals from the amplifiers to the speakers???

I bet that sounds wonderful :)

Seriously WTF does that mean? Speakers do NOT like a digital signal.

pippin
2009-12-27, 17:08
Each speaker has it's own DAC and amp? Have seen this being done in some automotive prototypes 10 years ago, maybe it's economically feasible now?

pfarrell
2009-12-27, 17:10
m1abrams wrote:
> Seriously WTF does that mean? Speakers do NOT like a digital signal.

There are exceptions to prove the rule. I know Meridian has sold
speakers that accept a digital feed, they have a DAC, and amp, in the
speaker housing. They were very expensive.

But for 99% of all speakers, @m1abrams is right, they expect and require
analog signals.

--
Pat Farrell
http://www.pfarrell.com/

m1abrams
2009-12-27, 17:28
m1abrams wrote:
> Seriously WTF does that mean? Speakers do NOT like a digital signal.

There are exceptions to prove the rule. I know Meridian has sold
speakers that accept a digital feed, they have a DAC, and amp, in the
speaker housing. They were very expensive.

But for 99% of all speakers, @m1abrams is right, they expect and require
analog signals.

--
Pat Farrell
http://www.pfarrell.com/

Even the Meridian speakers are what I would refer to as powered speakers that have a builtin DAC. I would not call them digital speakers that is just wrong. The speaker driver REQUIRES an analog signal, it may have a DAC/AMP bolted right to it but the speaker is still analog and SONOS statement is borderline false advertising.

usch
2009-12-27, 17:42
They're sending digital signals from the amplifiers to the speakers???
Basically that's how it works, yes. The amplifier outputs an oversampled, pulse width modulated, digital signal, which is then fed directly to the speakers through a low pass filter that eliminates the clock frequency. It's the same principle that is also used in switching power supplies, except that a power supply is designed to deliver a constant voltage, while a D-amp is designed to deliver audio signals.

The advantages are that such an amplifier has a very high power efficiency factor, and that you don't have a traditional DAC that might theoretically cause nonlinearities. The disadvantages are that you need an extremely stable power source because every hum, ripple, noise, or voltage drop is immediately superimposed on the output signal, and that a switching amplifier creates HF noise similar to a switching power supply.

dsdreamer
2009-12-27, 21:00
Basically that's how it works, yes. The amplifier outputs an oversampled, pulse width modulated, digital signal, which is then fed directly to the speakers through a low pass filter that eliminates the clock frequency. It's the same principle that is also used in switching power supplies, except that a power supply is designed to deliver a constant voltage, while a D-amp is designed to deliver audio signals.

The advantages are that such an amplifier has a very high power efficiency factor, and that you don't have a traditional DAC that might theoretically cause nonlinearities. The disadvantages are that you need an extremely stable power source because every hum, ripple, noise, or voltage drop is immediately superimposed on the output signal, and that a switching amplifier creates HF noise similar to a switching power supply.

I've no idea if Sonos uses them, but as an example of the kind of signal path that could be "all digital" consider the following:

http://www.icepower.bang-olufsen.com/en/solutions/mobile/mobilesound3/

(The above is underpowered, for the Sonos application but the concept still stands.)

seanadams
2009-12-27, 23:02
I believe SB Radio is "direct to class D". It's a nice way to do it but there are so many other considerations when you're making an all-in-one with speakers that it would be silly to rule out design choices on those grounds as a principle. For Boom we considered it but there was a particular DSP which was perfectly suited and had built-in DACs, so that was the right way to go. Maybe Caleb will come along and give us the full scoop.

usch
2009-12-28, 06:47
I guess maybe Sonos are switching their D Class amps directly from the digital signal.

You can do that, but at the expense of giving up the inverse feedback loop that is normally part of an amplifier to compensate varying load, component drift, and supply voltage issues, because you obviously cannot feed the analog output back into the digital input.

Without the feedback, however, you have to do some forward compensation in the DSP stage, which means you need to know the speaker characteristics in advance. I don't know the current Sonos product line, but as far as I can see, such a design is only feasible for units with built-in speakers.

pippin
2009-12-28, 07:09
Without the feedback, however, you have to do some forward compensation in the DSP stage, which means you need to know the speaker characteristics in advance. I don't know the current Sonos product line, but as far as I can see, such a design is only feasible for units with built-in speakers.

This is about the S5 which does have built-in speakers.

wavfan
2009-12-28, 14:05
Well, I still have Casette Tapes for my Casette Deck that had "For digital use" across the wrapping. At the time, well-estimated manufacturers that wanted to assure the "average consumer" that also CD-source material could be recorded... Likewise, "digital speakers" and "digital amplifiers" has been advertized, long before the ICE technology was remotely developed. It all boils down to marketing.

It seems a way to persue, however, in view of low power consumption and a better control of the digital signal. Credit to Sonos for also looking at the end result: The sound. I know that also Logitech use this approach - it will be necessary until we have developed digital human eardrums.... :)

My own little "wishlist" is :
External HDD -> Squeeezebox Touch -> AVI ADM9.1 speakers(w. sub).
This will handle up to 24/192 input, and will play the pantyhoses down many a combination. For years to come. At 6-7 times the cost of a Boom or an S5, though...

Cheers, Jan

huytere
2010-01-13, 21:11
If I am using the SPDIF on the SB Receiver is it pure Digital? or does it do D/A conversions internally?

Just curious, I doubt anybody could hear any difference either way.

DaveWr
2010-01-14, 00:51
Yes it is ( Sony Philips Digital Interconnect Format ). And yes it does, but nothing to do with the SPDIF, separate bit of the box. SPDIF is digital all the way back to your stored music files.

Dave

andynormancx
2010-01-14, 03:10
:( looks like the Sonos marketing was even more successful than they could have hoped for.