Pro-Ject Pre Box S2 Digital: MQA HW decoding at reasonable cost

[Miska]

S2D doesn't have isolation for the USB, so one needs to be a bit careful what is driving it. It is also very high resolution, so one can also hear things more in detail.

 

[Jud]

As I understand it, though not isolated, it won't draw power from the USB-B port if the separate USB-C port has a power supply attached.  Of course that's two connections where attention should be patient quality.   

[Miska]

12 minutes ago, Jud said:

As I understand it, though not isolated, it won't draw power from the USB-B port if the separate USB-C port has a power supply attached.  Of course that's two connections where attention should be patient quality.   

 

It is not about power, but you still have ground and common-mode signal between data lines and the ground.

 

There's no USB-C anywhere in mine? Just normal USB2 micro-B for power.

 

Also note that grounds of the two are connected.

 

[asdf1000]

1 hour ago, Miska said:

Also note that grounds of the two are connected.

 

For critical listening, I just power S2 DAC and UpBoard Gateway with a single 5Vdc USB powerbank.

 

Even though sharing same powerbank for 2 inputs of S2 DAC means sharing some noise, the mains ground loop (and mains RF) is killed.

 

[Jud]

3 hours ago, Miska said:

 

It is not about power, but you still have ground and common-mode signal between data lines and the ground.

 

There's no USB-C anywhere in mine? Just normal USB2 micro-B for power.

 

Also note that grounds of the two are connected.

 

 

Yes, sorry, micro-B. I run power from an LPS-1 and the USB cable from an ISO Regen in line after the microRendu.

[left channel]

This month's Sterophile includes a follow-up review of the S2D by Herb Reichert, who focused on listening. Last month it earned a recommendation based on measurements, but this pass was all about the ears. In the end he found it "simply a good DAC at its price-point". I've written something like that several times here. And I agree with him that the sound, though generally neutral, can also be described as more driving and "masculine", while "missing a radiant, sensuous, feminine side".

[jamesg11]

So ... what dac(s), heading up the steps of the $ cost  ladder, would next cover both gender sounds ...?

[left channel]

1 hour ago, jamesg11 said:

So ... what dac(s), heading up the steps of the $ cost  ladder, would next cover both gender sounds ...?

 

🙂 The only DAC he compares it to is the Mytek Brooklyn.

[Ralf11]

listen to the RME

 

[matthias]

On 4/13/2019 at 1:54 AM, Em2016 said:

For critical listening, I just power S2 DAC and UpBoard Gateway with a single 5Vdc USB powerbank.

 

Looking for a similar solution.......

Do you have a recommendation for a powerbank?

Thanks

 

Matt

[asdf1000]

56 minutes ago, matthias said:

 

Looking for a similar solution.......

Do you have a recommendation for a powerbank?

Thanks

 

Matt

 

I use this Mophie:

 

http://www.mophie.com/shop/universal-batteries/powerstation-XXL

 

[Jud]

I personally am very happy with the Pro-Ject. It may actually work better with the software DSD modulator I'm using than my previous DAC. Not feeling the lack of any gender-linked characteristics in my music.  

 

Edit: If the reviewer was listening with the Pro-Ject's internal upsampling, rather than software upsampling to DSD512 as I'm using, then it's possible we could have different experiences with this DAC.

[Jud]

2 hours ago, matthias said:

 

Looking for a similar solution.......

Do you have a recommendation for a powerbank?

Thanks

 

Matt

 

1 hour ago, Em2016 said:

 

I use this Mophie:

 

http://www.mophie.com/shop/universal-batteries/powerstation-XXL

 

 

Please note that a "battery" supply will have its own SMPS and/or one or more regulators between the battery and whatever you're running, so you are not actually powering direct from a battery.  Unless you know what regulators are in a particular battery supply, assume they are not the expensive top of the line lowest noise components.  (Why would they be when the primary intended use is powering a smartphone?)

 

The advantage of course is that the battery isn't connected to the same power as the rest of the system.  But you can get essentially the same advantage from the $17 UpTone SMPS, which is wired to shunt noise to ground.  I have 3 in my system.

[matthias]

13 minutes ago, Jud said:

 But you can get essentially the same advantage from the $17 UpTone SMPS, which is wired to shunt noise to ground.  I have 3 in my system.

 

Thanks Jud,

but afaik the Uptone has an output of 7,5V. I need slightly more than 5V output.

 

Matt

[left channel]

3 hours ago, matthias said:

 

Looking for a similar solution.......

Do you have a recommendation for a powerbank?

Thanks

 

Matt

 

Pro-Ject offers battery and linear PSUs designed to match the S2 line: https://www.project-audio.com/en/category/hifi-electronics/s2-line/power-s2-line/

[matthias]

4 minutes ago, left channel said:

 

Pro-Ject offers battery and linear PSUs designed to match the S2 line: https://www.project-audio.com/en/category/hifi-electronics/s2-line/power-s2-line/

 

I have seen it, but 2600mAh is very low for the asked price.

 

Matt

[bluesman]

2 hours ago, Jud said:

 Not feeling the lack of any gender-linked characteristics in my music.  

 

I think I read somewhere that we’re all equal now. Has audio been exempted?

[Miska]

5 hours ago, matthias said:

I have seen it, but 2600mAh is very low for the asked price.

 

Batteries are not automatically better because they end up having switching regulator between the battery and DC output. And that's pretty much like having SMPS...

 

[matthias]

35 minutes ago, Miska said:

Batteries are not automatically better because they end up having switching regulator between the battery and DC output. And that's pretty much like having SMPS...

 

Do you know 5V powerbanks with non-switching or without regulators between battery and DC output?

Thanks

 

Matt

[Miska]

17 minutes ago, matthias said:

Do you know 5V powerbanks with non-switching or without regulators between battery and DC output?

 

Such will be hard to find. It needs to have a device that takes in something natural to Li-Ion battery instead of something like 5V.

 

Cell voltage of a Li-ion battery is around 3.6 - 3.8V so you get that or some multiple of that. Overall, you need a device that can take a flexible input voltage instead of some constant voltage. Maybe S2D actually can, but it is just not what USB specs say which is 5V...

 

If you want to run "USB powered" device both within the specs and non-switching, you need traditional LPSU instead of a battery. OTOH, running S2D from a switching PSU is not a problem - mine performs just fine with the stock SMPS wall-wart.

 

 

P.S. You can design a battery PSU with for example 2x 3.6V output and use linear LDO regulator to produce 5V output, but that will increase battery drain. Certainly doable though, but just not something you will easily find because it increases battery drain. Pro-Ject is just totally silent about what goes on in "Accu Box S2 USB", it would take someone to open one up for inspection to figure out.

 

[Ralf11]

if the 5V device can handle 6V fine, then lead-acid...

 

or... find a table of native voltages for different electro-chemistries and go from there

[asdf1000]

5 hours ago, Miska said:

 

Batteries are not automatically better because they end up having switching regulator between the battery and DC output. And that's pretty much like having SMPS...

 

 

But much better than SMPS (or linear PSU) as they are 100% de-coupled from mains power issues (ground / leakage current loops and associated mains RF).

 

This can sometimes (depending on system) be much bigger issue than voltage regulation (which gets sorted inside the DAC eventually).

 

I know SMPS issues don't show on S2D measurements shown so far, but the sound seems smoother running on USB powerbank than SMPS to my ears... Re-connecting SMPS makes things sound a little brighter (again, subjectively).

 

I've found this with many 5Vdc powered DACs, not just S2D.

 

Even Chord Qutest - Rob Watts like powerbanks for the same reasons:

 

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/page-65#post-14097431

 

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/page-11#post-13970690

 

Ideally yes, ultra low noise linear regulated battery power would be best but you may already get some immediate benefit by de-coupling from AC power, even with USB powerbank...

[Jud]

12 hours ago, matthias said:

 

Thanks Jud,

but afaik the Uptone has an output of 7,5V. I need slightly more than 5V output.

 

Matt

 

Do you have a Rendu or one of the Regens? They will convert the voltage for you. So will an LPS-1, though that is not an inexpensive power supply compared to some non-ultracap LPSs, for example.

[Jud]

10 hours ago, bluesman said:

 

I think I read somewhere that we’re all equal now. Has audio been exempted?

 

There was a rather florid magazine review related some posts back ascribing the Pro-Ject a masculine sonic character.  🙂

[matthias]

3 hours ago, Em2016 said:

 

But much better than SMPS (or linear PSU) as they are 100% de-coupled from mains power issues (ground / leakage current loops and associated mains RF).

 

This can sometimes (depending on system) be much bigger issue than voltage regulation (which gets sorted inside the DAC eventually).

 

I know SMPS issues don't show on S2D measurements shown so far, but the sound seems smoother running on USB powerbank than SMPS to my ears... Re-connecting SMPS makes things sound a little brighter (again, subjectively).

 

I've found this with many 5Vdc powered DACs, not just S2D.

 

Even Chord Qutest - Rob Watts like powerbanks for the same reasons:

 

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/page-65#post-14097431

 

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/page-11#post-13970690

 

Ideally yes, ultra low noise linear regulated battery power would be best but you may already get some immediate benefit by de-coupling from AC power, even with USB powerbank...

 

There is a very interesting thread about battery power supplies on diyaudio though quite long:

 

https://www.diyaudio.com/forums/power-supplies/327105-develop-ultra-capacitor-power-supply-lifepo4-battery-power-supply.html

 

Matt