Project Stream Box S2 Ultra

(Magnus) #21

Ok, I don’t understand that. What I am saying is that electronic noise is coming from many sources, including for example a Raspberry PI. The noise then traverse the DAC and affect the analog section of the DAC which in turn affects the sound after being amplified (muffles the sound, hides details and so on).

A good example is to connect a DAC directly to a regular computer. The DAC will still receive the bits, but it will also receive a lot of electronic noise from the computer, which affects the sound a great deal. By using a streamer, ethernet cables (and their opto-coupling) will remove most electronic noise. Using a pair of media converters and fiber will further remove noise (in fact, it will remove all noise up to the fiber, but the last fiber converter will produce its own noise).


If the sound of your DAC is affected by noise over a digital connection, you should demand your money back and buy a DAC from a honest manufactorer.

(Martin Webster) #23

If you have well-engineered components this is simply not an issue. The noise simply cannot be heard at these levels.

Since you can hear something (that you shouldn’t) I’d be looking for another more likely source for the audible noise.

More likely, you are introducing noise, and messing with the signal by adding devices that are unnecessary. Evidence shows that “noisy” computers and streamers do not impact the noise floor as much as you suggest.

(Rune) #24

Yes and they use the same software as well (Volumio). The Stack Audio chassis looks nice.

(OuYang, Ming-Kang) #25

Why is pro-ject stream box ultra s2 so expensive (700euro for an R-PI)?

John Westlake explains additional works on this streamer in above link, FYI.

(Rudi) #26

I fully agree with @Martin_Webster
Noise that you can easily hear is likely to be caused by a faulty component or by a severe component mismatch.
In order to qualify as well designed, gear will have to adhere to established engineering principles (output impedance / input impedance matching etc.) and if it does, it should not produce any audible noise. If this were not the case, recording studios would not be able to reliably produce high quality recordings.
This is not to say, that there are no audible differences between gear. But they are unlikely to be easily audible. They are likely to require a high resolution system, suitable music material and a high degree of attention by the listener to be audible in a well done blind test.

(Magnus) #27

In digital audio, there are 2 issues that can affect the sound quality, electronic noise and jitter. With asynchronous USB, jitter is (almost) solved, but noise is the bane of digital audio.

All DACs are affected by electronic noise coming over the digital input. Every single one, from DragonFly to Lampizator. Typically you can’t hear the noise, but it affects the sound quality. Even DAC with internal galvanic isolated USB have this problem.

Let me take an example: about 40 seconds into the excellent Joan of Arc by Jennifer Warnes, there are some background sounds (from guitars I think). When I added fiber (and got rid of some electronic noise) I could hear this better with new details. In other words, I could not hear the electronic noise, but I could hear the difference when it was lessened.

(Rudi) #28

I would have two questions about this:

  • By how much was the electronic noise reduced before and after? How did you measure - at the DAC’s digital input or at the DAC output?
  • I assume you used a blind test to establish the differences in the background guitar sound? What was the methodology used?

I am not trying to be difficult, but our brain does trick us when we listen for differences and expectation bias is not eliminated. Been victim to this many times myself.

(Magnus) #29

No methodology or measurements, I just could hear new details. I could also hear a an added clarity. Btw, using fibers to reduce electronic noise is not something new, check this for example:

The new Sonore product called opticalRendu, and new streamer from Lumin, X1, also use fiber for this reason.

(Magnus) #30

But lets not steal this thread with endless discussions about electronic noise over digital cables. Its been done lots already. My point is that the main reason a product like Stream Box S2 improves the sound is because it reduces electronic noise coming into the DAC. And from what I have read about the Stream Box S2, its an excellent product both in sound quality and in functionality.

(Martin Webster) #31

Hook, line, and sinker.

(Magnus) #32

A silly comment, especially since you are 100% wrong. But don’t take my word for it, this has been a known problem for a long time, and DAC designers and gurus has talked a lot about this. For example, there is a youtube video by Gordon Rankin about these issue (he was the first one to implement asynchronous USB).

Or Rob Watts at Chord Electronics, whos opinion is that noise over USB is such a big problem that toslink is preferred, despite the inherent jitter and bandwidth problems with toslink. I seem to recall that the lead designer at PSAudio thinks something similar.




What is next? That it is not audible, but affects the brain in a way …
So cheap

(Magnus) #34

The self-noise from my speakers is audible from 5 cm, but not when playing music and especially not from my listening position. Hardly anything strange with that. The effect on the sound caused by electronic noise is audible though.

But lets see, on one side we have @AE67 and @Martin_Webster who claims electronic noise over USB does not affect sound, on the other side we have Gordon Rankin, Rob Watts, John Westlake, John Swenson, the guys at Sotm and many many more (including me).

I am not going to bother posting anything more about this, for some reason this feels like a debate with people from Flat-Earth Society :slight_smile: And besides, this thread is about Stream Box S2 Ultra.


@Martin_Webster, @Magnus -
Against my better judgement about jumping into the fray, I offer that differences in speaker sensitivity might be the cause of your divergent viewpoints.

(Rune) #36

Because it is not a RPI!

It is only the CM3 module that is an RPI

The rest is a custom design. So it would be more appropriate to compare it to other branded streamers.

From a software point of view the CM3 is a big advantage.

All even super expensive streamers use off the shelf SOC’s

(Martin Webster) #37

Possibly. :slight_smile: Under normal ambient conditions you shouldn’t hear noise with well engineered, well matched components. But, I agree, that with very high sensitivity speakers you are more likely hear noise from the listening position. I can’t hear noise from my speakers, which have a reasonably high sensitivity of 90dB. Also, noticing noise only when playing nothing is hardly a good measure of performance.

But the question is whether this is intrinsic noise or noise interference caused by a poorly configured system. If noise is masking subtle guitar in a recording then something is seriously amiss; noise should not intrude on the listening experience to this extent.

Noise from an RPi-based streamer or PC does not affect the noise floor significantly* when amplified by the gain of an amplifier. Moreover, those engineers mentioned in @Magnus’ last reply are clearly cognisant of the potential issues of noise at the input and have designed DACs/ streamers/ RPi hats to minimise these effects. We should not need to add superfluous components to address noise if designers’ have already done their job correctly.

Of some interest, my Raspberry Pi/ Allo DigiOne combo when connected to my amplifier’s linear power supply auxiliary output and an ultra-low noise LDO is far noisier than using a stock switching power supply! A tweak turned bad? That said, this is still inaudible under normal conditions.

*see Archimago’s Musings on RPi noise and jitter.

(Tim Chapman) #38

Wow - all this from my innocent comment on a product I own, understand and happily use!
I did not want to start a troll fest.
The level of ignorance is baffling.

(Tim Chapman) #39

Thanks Magnus!

At any rate, people seem to be confusing aural noise with data flow disturbance. The issue is about supplying a dac with an ‘ordered’ data stream. All dacs have to error correct. Pops, clicks, jitter and time smearing are the result of disorrderly data streams. This is the noise - not an aural noise from electronic ‘hums’. People seem to be confusing the two.

Hey ho - back to talking about the product please?

(Marc Verschaeren) #40

I tested that same unit as well and found a big improvement. The Stream Box ensures proper delivery of the digital data stream to the DAC, which then allows it to perform better.