Objective proof the UpTone Regen ISO can improve a DAC's output(*)

[plissken]

As some may or may not be aware Amir at AudioScienceReview.com has been benching DACs for some Jitter/Distortion base lining.

 

The worst measuring DAC he has is a Schitt Modi 2 that he applied the Regen ISO against (other DAC's remained unaffected).

 

[plissken]

10 minutes ago, pkane2001 said:

 

Looks like it cleans up the dirty 5v supply pretty well.

 

Sure does.... The galvonic isolation on or off didn't seem to make a difference.

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9 minutes ago, wgscott said:

 

So they can sell you this:  http://www.schiit.com/products/wyrd

 

If the wryd solves the issues seen then shame on Schitt for not implementing it in DAC.

[plissken]

39 minutes ago, internethandle said:

 

That seems like an odd conclusion given that 

 

a) Schiit obviously would not agree their product measures poorly (or have an explanation for why it measures poorly with Amir's equipment), and so it follows they then would be unlikely to offer a product to fix a problem they don't believe or want people to believe exists.

 

b) Schiit claims nothing about actual improvements to sound via the Wyrd, or at least objectively believe it shouldn't be possible. It says so right on the product page. They do advertise that objectively it measures less noisily than a motherboard USB port. 

 

c) They don't give a schitt to optimize the USB buss on their DAC's and therefore don't believe what Amir shows with their products and absent other products really matters.

[plissken]

27 minutes ago, Speed Racer said:

 

I am pretty sure my sentence is clear. 

 

I think it would be in UpTones interest to hire a 3rd party firm with an AP or other like analyzer and send a Modi 2 and ISO Regen and if the results are reproduced post them on their website. 

 

Not sure if it's cool to call out other manufacturers in this industry.

[plissken]

7 hours ago, Superdad said:

 

Except when he demonstrates that he is when it comes to measuring devices with power supplies.  He just posted a big "Whoa, stop the presses" report claiming the ISO REGEN adds 60Hz harmonics to its output:

http://audiosciencereview.com/forum/index.php?threads/uptone-iso-regen-review-and-measurements.1829/page-6#post-46377

 

But it is completely obvious that what he is measuring are the byproducts of the leakage current loop being formed by the interaction of leakage currents between the supplied Mean Well SMPS and the SMPS of his Audio Precision analyzer!

 

Yes, we all know that SMPS have higher leakage currents due to the required 'Y' caps on their outputs.  But it takes two supplies to form an AC leakage loop, and if both supplies are SMPS then the results will be as seen.  Of course the preamps that most people will run their DACs into don't have an SMPS.  Since his AP test gear does it is obvious that his set up is the cause.

For proof, look no further than his own graph showing that with his linear bench supply the leakage spurie are decreased.  

Yet Amir erroneously concludes that the ISO REGEN is polluting the 5VBUS line!

 

This is not even the first time Amir has made this error.  He did so with the microRendu powered by the iFi iPower.

 

There are a few simple tests he could do to more clearly show this, but given his "credentials"--and the tremendous nastiness coming at us from his forum--I have zero desire to guide him.

 

Then how do you explain that the computer with a SMPS driving the Behringer cleanly?

My take away from what you are saying is a get a 5 volt 1 amp linear supply. 

[plissken]

6 hours ago, internethandle said:

Objectivists I've run into tend to claim that hearing computer activity through a DAC is impossible,

 

I've yet to see subjectivists say that. Years ago I took a balanced cable and floated the ground at the output and when SE into an amp. You could hear everything going on inside the computer. Mouse, heavy CPU events, HD access (paging operations, file load etc). 

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6 hours ago, internethandle said:

 

How much of what Amir is measuring, in other words, should (objectively!) be audible? I'm asking these things mostly out of ignorance and/or genuine curiosity, so please don't take me for necessarily poking holes for the sake of doing so. 

 

If you read his write ups, which I don't believe you have in full based on the above post, you would see that Amir does say that some of this has no audible consequence. 

[plissken]

5 hours ago, tmtomh said:

 

So @skew, you're a new member and had a grand total of 2 posts here, and you thought it would be cute or in some way relevant to quote plissken's comment, amending it to say "Amir my love"? Are you an infant? What are you, 9 years old? Totally bush league. Wouldn't mind if Chris booted you from the forums.

 

I reported the post. Would help if others did also. 

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5 hours ago, Superdad said:

At the airport so I'll skip quoting.  But I just thought I would reiterate that typically the device (DAC, DDC) that the ISO REGEN is feeding does not have an SMPS, so while a leakage loop will still form (more likely just be added to as loops between the DAC and preamp supplies already exist), it won't produce nearly the harmonics that would be seen between two SMPS--as in Amir's test set up with AP analyzer's SMPS.

 

To quickly address plissken's Q:  I recall that Amir uses a laptop, and while I don't know if he runs it on battery, one can still see spikes from direct computer to DAC connection.  

 

And I believe that Amir did point out that he is very zoomed in and that what your PS is doing, while not optimal is simply inconsequential to SQ. It doesn't technically improve things with the Behringer so the advice is the $$ needn't be spent. 

[plissken]

48 minutes ago, pkane2001 said:

 Also, the AC leakage currents don't seem to be a problem for a few of the other DACs that he had on the bench, so there may not be a need in LPS-1 for these?

 

 

Correct barring any instrumented results posted to the contrary. Power supplies always feed back into the common house wiring. 

 

It's the power supplies job to deal with this however. 

 

Given that you can get a 15,000 mha USB battery pack for $20 on Amazon I don't see a reason that you couldn't run a lot of DAC's out there on this for a very long time if you are paranoid about the SQ and AC leakage currents.

 

Nothing I've seen or heard so far would convince me it's a problem for most DAC's. The power supply in my Emotiva DC-1 is pretty robust and most likely takes care of the issue. 

[plissken]

11 hours ago, Superdad said:

which he completely misinterpreted as being the ISO REGEN putting mains noise on the 5VBUS line into the DAC.

 

Maybe it isn't but it's not there with his lab supply. His lab supply does take care of a 180Hz bump that was their with USB bus power.

 

Three different ways of powering the ISO Regen and one of them makes the 60Hz noise the worst and the knock on harmonics. 

[plissken]

9 minutes ago, Superdad said:

That is an assumption on his part based on his simplistic tests. He focuses strictly on residual noise.

 

He rejects the premise that improved USB signal integrity and impedance match have an impact on DAC function.

 

I think Amir needs to broaden his thinking and methods. 

 

He's focusing on the claims made on your own site. He's done two measurements: Jitter and 60 Hz Mains suppression.

 

When do you think you are going to have some detailed measurements of a DAC's output that isn't what Amir measured with the Schiit Modi 2? 

 

As long as an inspec USB cable (90ohms?) is used there shouldn't be any impedance mismatch. John Swenson has even said a compliant cable at 3 feet or less is going to give you the best S.I. 

 

I don't think it's on Amir to proof your own product however. 

 

Is there anything hes measured so far that you could, in a material manner, disprove?

[plissken]

1 minute ago, Superdad said:

 

No need. Amir's own graph and set up makes the error plain as I originally explained. Two SMPS. Big leakage loop spurie. 

 

No, the only leakage loop spurie is with YOUR SMPS. The USB bus power and his lab power supply don't exhibit this.

 

Is this one of those hidden camera shows?

[plissken]

15 minutes ago, scan80269 said:

Sorry for the long post here, but there are many factors at play that I'd like to comment on.

 

A USB bus powered DAC has an advantage over a self-powered (by DC or AC) DAC in that the former can help eliminate at least one potential AC leakage loop from the system

 

Agreed and in the past I've recommended Intel Atom and Z8*** based systems that could be either driven with a battery or with a linear regulated supply. I also have recommended CMNR supplies. 

 

15 minutes ago, scan80269 said:

ISO Regen by its design offers USB signal regeneration as well as USB bus power regeneration.  Whether these features are beneficial to a particular DAC will heavily depend on how susceptible the DAC design is to upstream USB crap.  Not all DACs in the market today are equally immune to dirty USB from upstream such as from a notebook.

 

Whom besides Amir has given us a glimpse into how DAC's behave on a Laptop? If we want to call that 6 DAC's now that he's measured using the J-Dunn test (John Atkinson uses this test heavily) while not a trend does show a strong indicator that many DAC's deal just fine with the condition of the SI of the USB out on his Laptop. 

15 minutes ago, scan80269 said:

 Within my limited collection of DACs with USB interfaces I have examples of one DAC benefiting tremendously SQ wise with ISO REGEN + LPS-1 while another DAC yields no perceptible SQ improvement given the same treatment.

 

What DAC would that be the shows the improved SQ? It's one of the things that I have asked for multitudinous times of Alex and never received an answer until Amir did the benching he did. 

15 minutes ago, scan80269 said:

 

There are way too many fallacies on both proponents and opponents of USB decrapifiers.  I will list just a few that came into my mind today:

 

Over-generalizations / Over-simplifications:

* Heard no improvement with device added to my DAC ==> device must be worthless
* Heard big improvement with device added to my DAC ==> device must be universally beneficial with any DAC
* A measurement shows no improvement with device added to my DAC ==> device must be worthless
* A measurement shows visible improvement with device added to my DAC ==> device must be universally beneficial with any DAC

 

I know MANSR, BE17, ELSDUDE, myself haven't personally went with those generalizations. It's been understood that there may be some DAC's so poorly implemented as to benefit. It's not cut and dry. 

 

15 minutes ago, scan80269 said:

Fallacies:
* No difference observed in a measurement ==> cannot sound different
* Difference observed in a measurement ==> must sound different
There are plenty of real-world counterexamples to either of these
* Relying solely on measurements to judge the sonic merit of a product
* Relying solely on listening to judge the technical merit of a product
* Underestimating the complexity of a modern digital audio system and the ways SQ can be impacted

 

Here's another: *It can't make a device sound worse. 

 

15 minutes ago, scan80269 said:

Other thoughts:

* Single instrument measurement (with a single graph as output) is far from being an all-encompassing representation of DAC output

* USB de-crapifiers are NOT a panacea

* Sonic benefits of USB de-crapifiers can vary by both DAC and USB source used in the system, with results ranging from big to none

* USB DAC/DDCs are not all equally good at immunizing themselves from upstream USB crap

* Design know-how on effective immunization is relatively recent and not yet widespread (though should become more so with time)

* More USB DACs existing today show vulnerability to upstream USB crap than those that don't (to different extents)

* Galvanic isolation (or lack thereof) is not the only factor impacting SQ of a USB DAC

* Implementation of galvanic isolation can represent a tradeoff, for example jitter aggravation, especially if not carefully designed

* Designing the ability to block AC leakage loops into any device is NOT trivial

 

 

My concerns with Amir's measurements are not so much that they are invalid or improperly done, but rather in how he interprets the measurements and reaches over-generalized conclusions with them.

 

 

 

Amir seems to be open to feedback. 

[plissken]

4 minutes ago, scan80269 said:

Regarding jitter, Amir (and/or his followers) have adopted an assumption regarding the total correlation between incoming USB signal jitter and DAC analog output jitter.  Has it occurred to you that some DACs may be capable of complete de-correlation between the two two jitters, i.e. high incoming USB jitter doesn't necessarily translate to high analog output jitter?  Better DAC designs should be able to take a boat load of bad incoming USB jitter and signal integrity (waveform, etc.) and still output excellent analog with no hints of the USB crap coming through.

 

 

It has occurred to be because Benchmark Audio connected a 100' cable with very high BER and their DAC was entirely stable and they did this years ago. 

 

My suggestion: Get an Ethernet based DAC with an ungodly amount of RAM for buffering. 

[plissken]

Just now, kumakuma said:

 

Sal, welcome back from the ASR ghost town! Out of curiosity I checked that place out and it looks like there's about ten active users and  about one new post every two hours in the forums. I don't think Alex needs to worry much about anything Amir posts. No one's reading it.  

 

They're reading it here....

[plissken]

4 minutes ago, scan80269 said:

In that specific case with Benchmark Audio, do you know if the digital audio data were transmitted over Ethernet using TCP or UDP protocol?  Just curious.

 

 

Benchmark doesn't have any Ethernet enabled DAC's. 

[plissken]

Just now, Superdad said:

 

Do I really need to explain this again?  His Audio Precision analyzer uses an SMPS.  So the leakage of it and that of our supplied Mean Well SMPS interact to produce the extra 10-20dB of harmonics (still very low down at -120 -- -130dB)

 

And AC spurie are still seen with his "lab" supply--because it too has a little leakage and interacts with the PS of his AP.

 

It's not lost on me that the AP has a SMPS. What's lost on you is that your SMPS made things the worse out three options: Your SMPS, his lab supply, or vanilla USB bus power. 

 

My money is still on someone falling flat on their face with DAC that keeps it's shit together on USB bus power when tested for it blind.

 

You want to do this at RMAF in October? 

[plissken]

11 minutes ago, scan80269 said:

It's the latter.  USB DACs all have to re-clock the incoming data from USB clock domain to digital audio domain (based on 44.1KHz or 48KHz multiples depending on sampling rate carried by the digital stream).  There's a FIFO implementation in some form in every USB DAC.  A well designed reclocking circuit in a DAC can prevent the USB side jitter from contributing to the jitter on the digital audio clock side.

 

This is another area where Ethernet based DAC's are going to win out. The non-realtime, high bandwidth, low latency, deep cache and much better implemented clock domain boundaries. 

 

Just give me an appliance with  an 1/8th, 1/4th, or 1/2 GB of buffer and kiss the rest goodbye. 

 

I like my DC-1 but my next DAC won't have a USB port on it. 

[plissken]

On 8/6/2017 at 9:28 AM, Superdad said:

 

Because it is not a ground loop he is forming (though if he puts the ISO REGEN switch in the defeat position, his setup--using single-end connection to the AP and having the same computer connected to both the DAC and the analyzer--would surely form one of those too!).  No, he is forming an AC leakage current loop.

 

 

Amir just responded very well to what I and other were pointing out. No matter the straw man you want to parade about, the ISO regen with power supply made things worse. End of story. 

 

Quoted in full:

 

OK, back from the trip and had a bit of time to answer this. I am going to provide two answers. One high level that is easy to understand and should completely do away with this argument. The second answer, will be a deep dive into power supplies, emissions control, safety, etc. that explains why the problem is created with ISO regen and not otherwise.

First, here is the argument from the first link above:


In a nutshell, he is saying that because ISO regen uses a switchmode power supply and so does the Audio Precision (how he knows the latter is beyond me seeing how he doesn't have one), and that switchmode power supplies have a "required Y capacitor" that what I am observing with respect to increased mains frequency and harmonics in the output of the DAC as measured by my Audio Precision Analyzer, is unavoidable. He is also pointing to an iFi post which was measurements of their power supply (and not the DAC) as proof point of this.

Here is the diagram for how I measured the Behringer UMC204HD as is:



Right away we see the flaw with the statement Alex is making. There are plenty of switchmode power supplies in my playback and measurement chain. The Behringer was powered by the USB power of my desktop workstation. This is a custom PC I built with a switchmode power supply. I don't pretend to know what power supply configuration is used in the Audio Precision Analyzer. I do have a laptop connected to it that controls the analyzer over another USB bus and the laptop was connected through yet another switchmode power supply to mains.

So if switchmode power supplies have "required Y capacitors" and anything upstream of the analyzer would create mains harmonic noise, it should have been there all along. But it was not at nearly a significant level until I changed to this configuration:



In this configuration, yet another power supply made by a half-decent Chinese/Taiwanese company called Meanwell is added in the middle of the chain. This is powering the ISO Regen which in turn generates a new USB bus power. In this configuration we managed to increase the mains related harmonics as I showed before:



By now it should be obvious that the mere fact there are switchmode power supplies upstream of the DAC/USB bus does not at all say that the measurement scheme is faulty. The only change here was insertion of the ISO regen and it created the heightened noise products in the output of the DAC. Clearly what Alex is saying regarding design and operation of switchmode power supplies is incorrect (I will dig into this in the later detailed post).

But let's say for the moment that he is right. Nothing about that means that we can't measure the output of the system with the Audio Precision Analyzer. The AP acts just like any other audio device. It has an analog pre-amp, power supply for the same, and other bits to capture that stream. There is no law against such an audio having a switchmode power supply. Class-d amps for example mostly have switchmode supply. Is Alex saying that in such configuration ISO Regen does screw up the fidelity of the system? If so, why is that not indicated in the specification for the device?

Last but not least, I suspect the last thing anyone would think of when reading about a device that says it provides isolation, that it actually creates current leakage of its own!

Summary
There is nothing wrong with the testing as performed. Had UpTone bothered to measure the performance of their system with DACs, they would have likely found this issue and hopefully would have re-looked at their system architecture and chose a different design. AC mains current leakage, ground loops, etc. are part and parcel of unbalanced, RCA connections. Fact that adding yet another power supply to what is already a complex configuration causes more mains related distortions should not be surprising. Simplicity sometimes is our friend and ISO regen moves away from that.

 

Amir
Founder, Audio Science Review
Founder, Madrona Digital
Contributing Editor, Widescreen Review Magazine

 

 

[plissken]

56 minutes ago, lmitche said:

Yes, I read Amir's response before making my post above that contains a recommendation that will likely fix Amir's testbed.

 

But there's nothing wrong with his test bed. Swap out the AP for a USB controlled pre-amp. It's a perfectly legit setup that is in many homes. 

[plissken]

54 minutes ago, scan80269 said:

And I suggested yesterday that Amir replace the Mean Well SMPS with a battery to power the ISO REGEN and re-measure.  A purely scientific control experiment with only one component changed.

 

UpTone's LPS-1 power supply should also do the trick, but given Amir's obvious anti-UpTone stance, I thought a battery would at least be "neutral territory".  

 

 

But the ISO Regen is supposed to be an isolating device. You are now advocating ANOTHER isolation device to help with an isolation device. 

 

So lets say that Amir puts a battery on the ISO Regen and the 60Hz AC mains leakage current goes away. You are simply saddled with a parts heavy configuration that gets you back to running the Behringer 204HD straight cabled from from the computer. 

[plissken]

54 minutes ago, lmitche said:

When we had this same conversation about the Amber Regen I was told that no one has an isolation transformer in their audio systems. My response was that no one has an AP in their audio systems. Clearly care must be taken to ensure that the testbed doesn't impact the results especially when those results are posted in a public forum.

 

The 60 Hz mains AC leakage noise isn't there with the AP in the loop though. Again, Amir and BE17 pointed this out: The AP for all intents and purposes is just another piece of audio gear.  It is what it is and no matter the amount of swinging away you want to do is going to change that fact. 

[plissken]

43 minutes ago, scan80269 said:

So are 60Hz & harmonics at -110dbFS or lower amplitudes supposed to be audible at the DAC output or not?

 

 

Nope. But it's measurably making things worse and it's antithetical to the sales pitch given about the device.