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

[asdf1000]

2 hours ago, left channel said:

Thanks @Nihilnisibene. If the response tells you to contact them through the website, note that your messages will go to a local dealer unless you select as your location a country that has no dealers. Like Bermuda.

 

Very true. Although I like the Facebook channel. Perhaps applies a little more pressure with more eyes watching, in the case of bug fixes etc.

[left channel]

24 minutes ago, Em2016 said:

 

Very true. Although I like the Facebook channel. Perhaps applies a little more pressure with more eyes watching, in the case of bug fixes etc.

 

Yes, especially since their "tech support" is the same PR/marketing staff in charge of the Facebook page. Maybe even the same one guy.

[asdf1000]

8 minutes ago, left channel said:

 

Yes, especially since their "tech support" is the same PR/marketing staff in charge of the Facebook page. Maybe even the same one guy.

 

LOL. With 'more eyes watching' I meant more public (current and/or potential customers) eyes watching.

 

Agreed though, it's probably a one man band at the Pro-Ject end.

[left channel]

:-) I know what you meant. It's frustrating though: they want their dealers to support this product, as with previous products. But neither the dealers nor anyone we can contact at Pro-Ject HQ seem ready to do that.

[57gold]

If one plans to attach to PC with USB, can one use a LPS with this unit?  Or must it be powered by the PC?  Manual seems to indicate this.

 

Thanks.

[left channel]

42 minutes ago, 57gold said:

If one plans to attach to PC with USB, can one use a LPS with this unit?  Or must it be powered by the PC?  Manual seems to indicate this.

 

Thanks.

 

The manual doesn't tell the whole story. When you plug in an external PSU, the power input automatically switches away from USB. Most of us have found this improves USB performance. As the manual says the designer of this DAC, John Westlake, doesn't recommend using the supplied PSU or any switching PSU when you're on USB input, but he does recommend using an external linear or battery PSU in that mode, and he designed in support for doing so.

 

Apparently the manual writer didn't get the memo so that feature is not documented, but there you have it direct from the man who designed it. Some of us have perceived good results with the stock wall-wart or other switching PSUs anyway (like the iFi iPower), but in the end most of us have moved on to linear supplies ranging from simple wall-warts to the UpTone UltraCap and beyond. A purpose-built battery PSU would be good too.

 

Pro-Ject recently announced one of each for the fall: the PowerBox S2 (linear PSU) and the AccuBox S2 USB (battery PSU).

[57gold]

Thanks, makes sense to be able to use USB and an upgraded LPS.  Wonder if a USB without power would function and possibly reduce noise?

 

See that there are a number of China made LPS with 5V 2A for reasonable $s that look well made.  Use a Keces LPS with my Brooklyn+. 

 

My son digs the B+ but is kind of a frugal guy...so the S2 plus an $80 LPS would be in his comfort zone.

[left channel]

 

16 minutes ago, 57gold said:

Wonder if a USB without power would function and possibly reduce noise?

 

In measurements and subjective listening it's generally been found that using an external PSU gives the largest improvement, while improving the USB power and/or signal offers a much smaller benefit. 

 

At least one user tried making a USB cable that removes USB power entirely, and as I recall that caused problems. I believe the device still needs to sense at least some power there to know a USB signal is coming in.

 

16 minutes ago, 57gold said:

My son digs the B+ but is kind of a frugal guy...so the S2 plus an $80 LPS would be in his comfort zone.

 

If this S2 is in your son's comfort zone but he likes the B+, you folks may also want to take a look at the recently-announced Mytek Liberty.

[GromitInWA]

I use my S2 with a Raspberry Pi. Right now, it just uses USB power from the RasPi that uses its standard SMPS. If I go with a separate LPS, presumably I would connect it to the S2 rather than to the RasPi?

[left channel]

4 minutes ago, GromitInWA said:

I use my S2 with a Raspberry Pi. Right now, it just uses USB power from the RasPi that uses its standard SMPS. If I go with a separate LPS, presumably I would connect it to the S2 rather than to the RasPi?

 

Yes, and I'm sure the RasPi's power supply could be improved too. Some LPS models will power both, though I would keep them separate. There are plenty of cheap 2.1mm-to-microUSB adapters out there so you have many choices for the S2.

[57gold]

S2 has more technology than the Liberty...and my son has grown up with devices (mandatory laptop in 5th grade), studied advanced math at U and writes code for commodity trading as part of job.  

 

So, the S2 with fancy chips, MQA, accepts high sample rates...a techie barrel of monkeys for not a lot of $s.

[left channel]

3 hours ago, 57gold said:

S2 has more technology than the Liberty...and my son has grown up with devices (mandatory laptop in 5th grade), studied advanced math at U and writes code for commodity trading as part of job.  

 

So, the S2 with fancy chips, MQA, accepts high sample rates...a techie barrel of monkeys for not a lot of $s.

 

They both do MQA, but yes, the Liberty lacks a full information display, goes a notch lower on DSD and USB PCM, and uses one ESS9018K2M chip instead of dual ESS9038Q2M chips. Having said that, I am looking forward to hearing how their sound compares, along with comparison of build/parts/firmware quality and overall support. I am not planning to be the guinea pig this time though. ;-)

[asdf1000]

3 hours ago, 57gold said:

S2 has more technology than the Liberty...and my son has grown up with devices (mandatory laptop in 5th grade), studied advanced math at U and writes code for commodity trading as part of job.  

 

So, the S2 with fancy chips, MQA, accepts high sample rates...a techie barrel of monkeys for not a lot of $s.

 

Let's not forget the late Charles Hansen's (Ayre) post on what he considers the most important features of a DAC's design.

 

Fancy chips are down the list. Having said that, Myek make really great stuff and this S2 DAC is no slouch.

 

 

[fgribas]

On 2/18/2018 at 8:09 PM, Miska said:

 

I don't use "Best" or "Test" mode. I have "Audio Quality" = "User"... Distortion Compensation = Enabled, Filter = Sharp Rolloff

 

The THD levels visible in his plots look like the ones with distortion compensation disabled.

 

But this plot looks looks somewhat like expected:

 

"Best" has the distortion compensation disabled, and "Test" has it enabled.

 

 

I've been reading all Amir's thread on his forum and now I'm quite confused. 

 

@Miska the image you pasted has the following text:

 

We see that "best" sharply raises the noise floor by some 25 dB! In doing so the noise now masks all of those distortion products. Seeing how there is some 32 dB of gain in the above measurements, the "best" mode likely has less signal to noise ratio than needed for 16 bit audio. When I have time I will do some listening and see if there is an audible difference. For now, I would probably use the DAC in "Test" mode. 

 

What I understand by that is Distortion Compensate Enabled suppresses harmonic distortions by raising the noise floor. Kind of a trade-off. Am I right?

 

After that post, Amir said:

 

I need to do more testing but in preliminary measurements, Enabling distortion compensation seems to raise distortion, not lower it! Since this is backward I like to perform more tests and only post them when I am sure.

 

So he ran more tests. Measuring a 1kHz residual noise and distortion, it seems that Distortion Compensate Enabled raises 2nd harmonics distortion, but lowers 3rd harmonic distortion.

 

 

What we see here is that when we turn off Distortion compensation, we actually get a reduction in distortion in 2nd harmonic. There is a trade off elsewhere though with third harmonic actually increasing. We also see some small spikes with compensation enabled that are not there when we turn it off. So the overall picture is a mix. 

 

 

And then a new THD+N test that really confuses me, showing that "when we sum the total distortions+noise, distortion compensation is doing the opposite of what its name indicates."

 

 

 

Here is the specific post:  https://audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-pro-ject-pre-box-s2-digital.2370/page-4#post-66480 

 

After that, other users asked him to run the tests with different filters (Fast roll off is one of them), but always getting the same conclusion: Distortion Compensate Enabled actually raises the noise floor.

 

 

 

After scratching my head a little, I tried to listen the differences. I always used Distortion Compensate Enabled, but I made some A/B enabling and disabling it. I don't have measurement equipment, that's only my listening impressions. And the impression is that disabling Distortion Compensate actually gives me a darker background (lower noise floor), specially playing only vocals with no other instruments.

 

Still scratching my head...

[Miska]

26 minutes ago, fgribas said:

 

@Miska the image you pasted has the following text:

 

We see that "best" sharply raises the noise floor by some 25 dB! In doing so the noise now masks all of those distortion products. Seeing how there is some 32 dB of gain in the above measurements, the "best" mode likely has less signal to noise ratio than needed for 16 bit audio. When I have time I will do some listening and see if there is an audible difference. For now, I would probably use the DAC in "Test" mode. 

 

What I understand by that is Distortion Compensate Enabled suppresses harmonic distortions by raising the noise floor. Kind of a trade-off. Am I right?

 

What is confusing? "Best" has distortion compensation disabled?

 

So read it like "Best" = "Crappiest", "Test" = "OK'ish".

 

Do not use it in either mode, but instead in "User" mode. But if you certainly want to stick to either of two presets, use the "Test" one which probably has distortion compensation enabled.

 

But those measurements you refer to are self-contradictory.

 

In my measurements I don't remember seeing changes in noise levels with distrotion compensation enabled/disabled. But level of distortion changes.

 

With distortion compensation enabled, and filter set to sharp rolloff, measured SNR is 120 dB.

 

 

[fgribas]

7 hours ago, Miska said:

But those measurements you refer to are self-contradictory.

 

That's exactly what's confusing. On his first measurement, THD+N was better with Distortion Compensation Enabled. On the following tests,  THD+N was better with Distortion Compensation Disabled.

 

I don't use Test or Best, as I don't like their filters. I'm using Hybrid Filter, but that doesn't matter cause I'm upsampling everything to DSD256 and DSD512. Used to have Distortion Compensation Enabled, but now I'm using it disabled. 

[mfsoa]

FYI I ordered a unit from my dealer (my brother) in the US (NJ) and was told it won't be available until late May.  I told him to get a bunch...

 

-Mike

[exdmd]

Torq over at SBAF is doing a full review of the Pro-Ject Pre Box S2 and found with firmware 2.12 there are a few bugs:

 

Quote

• Some people find their settings aren’t saved if they power the unit off. I have not seen this myself, but it wouldn’t surprise me.

• The “Distortion Compensation” option works backwards currently. Turning it “On” in the menu increases distortion. Turning it “Off” reduces this. It is known to be a simple flag-inversion and will no doubt be fixed in the next update.

• V2.12 was supposed to fix an “MQA dropout” issue. It has improved it, but not eliminated it. What happens is that you’ll be playing an MQA file and all of a sudden the MQA indicator will go out, the volume will drop significantly, and then after a few moments the MQA indicator will come back on and everything will return to normal. You can go hours without it happening, and then have it happen three times in as many tracks.

 

[asdf1000]

28 minutes ago, mfsoa said:

FYI I ordered a unit from my dealer (my brother) in the US (NJ) and was told it won't be available until late May.  I told him to get a bunch...

 

-Mike

 

Audio Advisor in the US say they expect stock in both silver and black, in April.

 

[asdf1000]

3 hours ago, exdmd said:

• The “Distortion Compensation” option works backwards currently. Turning it “On” in the menu increases distortion. Turning it “Off” reduces this. It is known to be a simple flag-inversion and will no doubt be fixed in the next update.

 

 

Hmm more different observations about distortion compensation.

[Miska]

10 hours ago, fgribas said:

 

That's exactly what's confusing. On his first measurement, THD+N was better with Distortion Compensation Enabled. On the following tests,  THD+N was better with Distortion Compensation Disabled.

 

I don't use Test or Best, as I don't like their filters. I'm using Hybrid Filter, but that doesn't matter cause I'm upsampling everything to DSD256 and DSD512. Used to have Distortion Compensation Enabled, but now I'm using it disabled. 

 

I think the confusion is because setting either "Best" or "Test" overrides any other settings. And when you for example change the distortion compensation setting it goes into "User". So if he has touched the settings in wrong order they are not what he was expecting.

 

Note that distortion compensation also applies to DSD and I'd recommend to keep it enabled.

[left channel]

16 hours ago, exdmd said:

Torq over at SBAF is doing a full review of the Pro-Ject Pre Box S2 and found with firmware 2.12 there are a few bugs:

 

 

 

Thanks, I enjoyed that, especially his expert use of a capacitive caliper. :-) But in his last post about the firmware, he's actually missing the post-MQA filter bug that caused Pro-Ject to mistakenly withdraw 2.12 for a few weeks. I've messaged him about that, and also offered some clarification on the issues he listed.

 

The problem with settings not being saved turned out to be, for all or most users, not pressing in the volume knob to confirm their selection. This is not documented in the user manual. The Pro-Ject support manager has acknowledged this and apologized. Only one user who posted about settings being saved has not replied since to confirm that was the only problem; he may have returned his unit.

 

I also commented on his other two points. I'll watch for his response and let you know.

[exdmd]

How can a company roll out a product with poor inaccurate documentation and firmware flaws? Does not exactly inspire buyer confidence and gives the impression they do not have their shit together. Looking forward to Torq's comments on SQ.

[fgribas]

 

16 hours ago, exdmd said:

The “Distortion Compensation” option works backwards currently. Turning it “On” in the menu increases distortion. Turning it “Off” reduces this. It is known to be a simple flag-inversion and will no doubt be fixed in the next update.

 

@Miska apart from the confusion regarding user settings, could this be the reason for what I'm talking about? It seems that on firmware 2.12 the flag inverted, and using Disabled apparently turns on this ESS chip feature. Someone mentioned it on Amir's forum also.

 

What FW version you had when you measured Dist. Compensation On/Off ?

[left channel]

 

27 minutes ago, exdmd said:

How can a company roll out a product with poor inaccurate documentation and firmware flaws? Does not exactly inspire buyer confidence and gives the impression they do not have their shit together. Looking forward to Torq's comments on SQ.

 

Yes I've become quite frustrated over this. The documentation was written by their Czech manufacturing partner before the product was even finished. That was also where the product should have been thoroughly tested, but they clearly do not have experience doing this type of QC. Pro-Ject management seem to think the very small contract development team would deliver it 100% without bugs, but that is simply not how these projects work and they were not at all prepared for ongoing firmware support. They also seem to think one PR manager and their dealer network can support this product, which is simply naive. As I've mentioned, Pro-Ject is a turntable company and they are learning how to do this as they go.

 

That's just firmware. Don't get me started on their parts sourcing.