UpTone Audio USB Regen Manufacturers' Comment

Manufacturers' Comment, UpTone Audio USB Regen

Editor: While we wish to thank Michael Lavorgna, Kalman Rubinson, and John Atkinson for their terrific team coverage of our USB Regen, I would be remiss not to take this opportunity to express our tremendous gratitude to the audiophiles and music lovers around the world who have made the Regen a runaway success—well beyond what we had initially imagined—in just a few short months.

As I pen this reply in late August, over 2000 units have been sold since its launch in May-and with zero advertising! That's crazy, especially for a small firm such as mine, but it is a testament to the power of word-of-keyboard, as continuous and near-unanimous reports are shared by Regen users around the world, hearing results with DACs, computers, and streamers, from modest to mega.

The Regen circuit was designed by my close friend John Swenson. He is a truly brilliant engineer whose day job is designing the power-distribution networks deep inside large custom computer chips (the sort of devices that run high-speed network data centers), so his knowledge and understanding of the root causes and physical factors at play in digital interfaces are formidable. While his audio design talents are broad and considerable—several other groundbreaking products are in the works—we chose to tackle the shortcomings of the ubiquitous USB interface first. When Michael Lavorgna reviewed our USB Regen for Stereophile's sister website AudioStream.com, he was gracious in publishing our concise "white paper," wherein John explains the challenges inherent in USB input circuitry and how the Regen addresses them. We encourage those interested to click here to learn more about this topic.

With regard to John Atkinson's valiant attempts to measure differences at his DAC's analog outputs with the Regen in and out of the chain, allow me to paraphrase a recent post of John Swenson's from the ComputerAudiophile.com forum, where the two of us hang out:

"Measuring the signal integrity of the USB signal is something fairly easy to do with a 3–4GHz scope and an eye-pattern test. Jitter measurements are a lot harder[;] at the exceedingly low level we are looking at[,] it takes some rather expensive test equipment. Unfortunately[,] where a lot of the final jitter happens is inside the DAC chip[,] and that is essentially impossible to measure.

"None of the standard audio tests have been able to find any difference in the analog audio output. Part of the problem here is that in order to make any sense, the analog-to-digital converter used in the test equipment must have lower jitter than the jitter you are trying to measure the effects of. People doing these measurements are using ADCs that have known jitter levels significantly greater than what the best DACs have. This makes these tests pretty useless for measuring the supposed effects caused by changes in jitter.

"The theory I am going on for these effects is that the operation of the USB receiver is generating noise in the DAC's power and ground system, and this should be measurable. I'm putting together a test setup to better measure this. Yet that is still an intermediate effect[;] I don't know how to test the analog out well enough to actually measure the analog changes. I think I would have to build the world's best ADC in order to do so. Don't hold your breath on that.

"Improvements at this level do not cause changes to gross frequency response or distortion, yet they do make things sound 'more real.' The problem is that nobody knows what the actual changes are that cause people to perceive the sound as being more real. If we did[,] it would be a lot easier to set up tests to look for it. And on top of that, because it is so intertwined with the aural perception system, it is probably different for different people."

So perhaps by the time this appears we will have published eye-pattern measurements to at least demonstrate the Regen's positive effect on USB signal integrity. But beyond that, everyone will just have to continue judging the merits with their own sensitive instruments—their ears. Of course, that's what ultimately counts for musical enjoyment.

Again, thank you for the lovely review, and remember: The best DAC you have never heard may be your own. It's great to Regenerate!—Alex Crespi, UpTone Audio

UpTone Audio LLC
Mariposa, CA 95338
(209) 966-4377

Venere 2's picture

This is not a criticism, but it would have been informative to include a manufacturer's comment. Maybe the manufacturer of the Regen can offer an explanation, as to how the device can improve the sound, but that these improvements/differences could not be shown in the measurements that were conducted.

I have no trouble believing that this device can improve the sound without the changes being measurable; but an explication as to why would be interesting.

John Atkinson's picture
Venere 2 wrote:
This is not a criticism, but it would have been informative to include a manufacturer's comment.

I have added the Manufacturer's Comment to this reprint.

On the question posed by another reader why a DAC would need to use the 5V USB supply, many designs power the USB receiver chip from the USB bus, to try to minimize contamination of the processor's power supply for the D/A and analog circuitry with RF noise.

John Atkinson
Editor, Stereophile

UpTone Audio's picture

I have no trouble believing that this device can improve the sound without the changes being measurable; but an explication as to why would be interesting.

Thank you for your interest in learning more. At the beginning of his original review on AudioStream, Michael Lavorgna was kind enough to include our entire condensed "white paper" discussing some of the specific technical limitations of USB audio interfaces and how the REGEN addresses them.
You can find that at this link: http://www.audiostream.com/content/uptone-audio-usb-regen

Alex Crespi

music or sound's picture

I guess these devices are becoming quite popular and new ones are announced like iFi purifier2. From the reviews it is not quite clear whether there is a sonic benefit from USB outputs of only computers or also of USB streamers like Aurender (the former is designed for any use and the later is supposed to be audio specific).
Or is the culprit the USB input receiver design of the DAC. So do different DACs (which use different input receivers) have similar benefits of these devices?
Most DACs (except some portable ones) are not powered by USB so why is 5V necessary (except maybe for initial hand shake).

Kal Rubinson's picture

You raise good points. I used the Regen with what I had but, absent engineering specs from Regen and from the USB devices to which one might connect it, one cannot generalize.

You ask who is the culprit here? I don't know but most finger-pointers suggest, as you do, that it is the influence on the DACs rather than out-of-spec USB sources.

As for the 5V, that is necessary to wake-up self-powered DACs.

mrvco's picture

It is hard for me to make the "bits are bits" argument when it comes to USB since it was developed as a general purpose interface that also carries power and has seen significant improvements since its inception twenty plus years ago, so it is not surprising that there would be further room for incremental, application-specific improvements. That being said, there seems to be far more bang-for-the-buck associated with the various regen products than the much maligned and far more expensive high-end USB cables.

Venere 2's picture

Thanks to you both, John and Alex for posting the manufacturer's comment and white paper. Very interesting and informative!

robpriore's picture

I spent a lot of time wrestling with dirty USB power and I concluded the only thing to do is cut it out entirely. It's not reasonable to think that the noise pollution can be cleaned up by adding additional circuitry between the computer and DAC. Those circuits generate noise.

There are other options out there. I suggest folks go on to Google and search for "Dirty USB Power" and you'll find other solutions, better tailored to this problem than adding more circuits to the very important link between computer and DAC.