This raised the question, how could a $175 gizmo half the size of a deck of playing cards improve the performance of a DAC costing thousands of dollars? It piqued my interest so much that I emailed Mr. McGowan about it and, indeed, he confirmed that it notably improved the sound coming through his DACs.
I scoured the internet, reading post after post in Computer Audiophile and elsewhere. One reviewer wrote that it improved the sound of his LampizatOr Lite 7 DAC, which I happen to own.
That’s pretty amazing, I thought. At $5,300, the Lite 7 sports a large pair of DHT triode vacuum tubes in single-ended mode. Unlike some of its other siblings at LampizatOr, it uses solid state rectification, as opposed to a rectifier tube, resulting in a more neutral, less glowing signature. For the money, it’s superb. I am curious to see what effect the REGEN might have on its performance.
The general online consensus favored the REGEN, but there were others who claimed that it was just another clever marketing ploy — or “snake oil”, as some called it — designed to separate gullible audio enthusiasts from their money.
Fast forward to a month ago, when I was breaking in my review sample of the REGEN. I was considering building a replacement server for my Toshiba C-55 Satellite laptop computer, which is getting old and struggles playing converted SACD files. My computer programmer friend, Tom, came by for dinner with his custom-made computer server, claiming it would be a better fit for my system (if I liked it, he suggested that he could help build me one like it).
We were listening to Chris Young’s 256 bitrate country album, I’m Coming Over, that I downloaded for my stepdaughter’s boyfriend when Tom arrived. Getting to work after dinner, we loaded a free music playing program, the Amanero driver for my DAC and several albums onto his server and connected it to my DAC with a Straightwire USB-Link cable. A 96/24 FLAC song from Pink Floyd’s Division Bell album sounded amazing with Tom’s server, but when we played the lower res Chris Young recording, it sounded digital and edgy.
Then, I realized that the REGEN was still hanging from the USB cable attached to the inactive Toshiba laptop and not on the USB cable connecting Tom’s server to the Lite 7 (I had two identical USB cables on hand). I reinstated the REGEN into the loop and the difference was dramatic: It lost some of its sharp edge and now sounded warmer and more analog — just as it had earlier over the Toshiba.
“I can really hear the difference!” my wife exclaimed as she and the kids resumed dancing and getting their country groove on. Meanwhile, Tom (who’d never heard of the REGEN) looked dumbfounded.
Why and What Exactly is the Regen?
Signals are sent to a DAC in “packets”, according to John Swenson, a well-known engineer who engineers the circuits of Uptone’s products (owner Alex Crespi coordinates the design, operation and production aspects of the business). The data packets coming in on the USB bus are not continuous; there is significant time in-between packets. The processing of packets produces noise on the power supply and ground plane in bursts. These are referred to as packet noise. Swenson maintains that with a rate of 8 KHz, strong components of this noise appear in the audio band. Moreover, this noise can cause result in jitter in clock oscillators and produce re-clocking error.
The REGEN is an active single-port USB 2.0 hub. Swenson writes, “All hubs actually
contain two USB interfaces and a full-blown USB protocol engine. It is not just working at the analog level, it is actually receiving the data from the computer, putting it in a buffer and retransmitting (and the other way for the packets from the DAC).”
He says that it uses a USB hub chip to regenerate and re-clock data signals with lower noise and jitter, giving it better integrity and reducing the load that the DAC has to process, which results in better performance (see the appendix for more detail).
About half the size of a deck of cards, the REGEN comes in an aluminum case that’s 57mm 46 mm x 18 mm x 22 mm. The input is a USB 'B' jack, while the output is USB 'A' jack. The REGEN also features a DC jack is 5.5mm x 2.1mm. It comes with a male to male USB A/B adapter plug (which Crespi recommends and I use) to attach the REGEN to the back of your DAC and a six inch long USB A/B adapter if you don’t want to use the solid adapter. It also comes with a Switched Mode Power Supply with an 18-inch power cord and a transferable four-year warranty.
· Toshiba Satellite C655 laptop computer with JRiver Media Center, ripped CDs, FLAC and DSD files
· Straight Wire USB Link USB cable
· LampizatOr Lite 7 DAC
· Straight Wire Solo interconnects
· Schiit SYS passive preamp
· Straight Wire Solo interconnects with CAMAC connectors on one end (to connect to the Mark Levinson amp) and the other with RCA connectors to the preamp
· One pair of AudioQuest Hard Y Adapter (1 Male to 2 Female RCA splitting the SYS output to the amp and the subwoofer)
· Hsu Research ULS-15 Mk 2 subwoofer
· Mark Levinson ML-9 amplifier
· Straight Wire SoundStage SC external bi-wire cables
· Von Shweikert VR-5 HSE speakers
The Listening Room
The listening sessions take place in a room that’s 16’ x 20’ with 10’ ceilings that, interestingly enough, Straight Wire’s CEO, Steven Hill (who stops by after day two of AXPONA 2016) describes as “amazing”, noting that with a large opening to the left, reflections to that side largely disappear, while the fireplace to the right largely diffuses reflections to that side.
The Listening Session
I sit, pen and yellow legal pad in hand, in a leather slung over steel framed chair located at the point of an equilateral triangle position with the speakers, which are 8’ 9” feet apart. The results are captivating.
“All Blues” Brian Bromberg. Wood album. 44kHz.
Without REGEN (WOR): In this solo performance, Bromberg’s upright acoustic bass sounds very resonant and true to life in presenting his various slaps, plucks and overall playing of this Miles Davis classic.
With REGEN (WR): The presentation is a smidgen louder and has a greater sense of air and the environs of the recording room, with an enhanced background echo that takes a tiny bit longer to decay. It’s subtle, but a tad smoother and has a distinct more analog sound. The listening experience is more pleasurable and compelling!
“St. James Infirmary”. Louis Armstrong. Satchmo Plays King Oliver album. 44 kHz.
WOR: The tinny din of the drumstick keeping time on the ride cymbal, Louie’s trumpet are compelling and true. Armstrong’s vocals are luscious and full. The muted cornet, the clarinet and piano playing mournfully, the trombone kicking — it’s all very well presented.
WR: As good as the recording sounds earlier, the detail is now more refined. There’s more of a delay of the decaying notes coming off the ride cymbal. The background vocals are enhanced and Armstrong’s lead vocals are a touch warmer and its harmonics better revealed. A slight chuckle is more noticeable. The trumpet, clarinet, trombone and ride cymbal are more holographic.
“I Love Porgy”. Mi Nina Simone. Little Girl Blue album. DSD.
WOR: Simone’s silky, sultry vocals (which emanate from the left channel), comped by the piano and brushed drums on the right make a compelling presentation. A lovely understated piano solo, as well as Simone’s vocals are very natural sounding.
WR: Simone’s vocals are a little fuller bloomed, while the piano and brushed drums are more defined. Her vocals sound a smidgen more natural — as in vinyl played over a $30,000 turntable.
“Come Pick Me Up.” Ryan Adams. Heartbreaker album. 44 kHz.
WOR: The bluesy harmonica playing full-on is a shade sharp, as are Ryan’s vocals, which are still quite natural. Nevertheless, the mix of drums playing off the banjo’s arpeggio, the drumstick hitting the snare’s rim and the overall mix as Adams beckons his lover to “Come pick me up” is a compelling and intoxicating listen.
WR: The attack of the harmonica is a touch less hard-edged and more details emerge, like the strike of the floor tom just before he starts singing. The banjo arpeggio is a little fuller and warmer, as is the overall tone. The overall presentation is a little more focused in detail, more musical and engaging. Frankly, it’s a little more like being there in the room with the band.
“Goodbye Yellow Brick Road”. Elton John. Goodbye Yellow Brick Road album. DSD.
WOR: It is hard to believe that this was originally recorded via 16 track tape in 1973. Elton John’s piano is solid and balanced, his vocals crisp and defined. The synthesizer is very present, while the snare and bass drum have plenty of punch. Background vocals are ethereal. The guitar is full bloom, comping as he sings, “It’ll take you a couple of vodka and tonics to get you on your feet again.”
WR: The overall impact is warmer and more holographic. Details emerge, like nuances in Davey Johnstone’s electric guitar. The tone of Elton John’s piano is a little more rounded and palpable. The vocal backgrounds take on a wider soundstage. Overall, it just feels like the Regen is feeding the LampizatOr Lite 7 DAC a better, more enhanced signal!
“Bennie and the Jets.” Elton John. Goodbye Yellow Brick Road album. DSD.
WOR: It’s a gorgeous soundstage, as the clapping and cheering crowd envelops the room. Elton John’s piano lead is solid and very palpable. The crowd erupts as a his vocals intone the legendary line, “Hey, kids, shake it loose together…” It’s altogether very satisfying. Echo in the backdrop is atmospheric. You hear the acoustic guitar peek through at various stages in the left channel. The drums are crisp, the whistling clear. Elton John’s transition from falsetto to chest voice when he segues from “Oh, Bennie she’s really keen” to “She’s got electric shoes, a mohair suit…” is electrifying. The synthesizer flitting between left and right channels against the driving piano, drums, crowd, and chants of “Bennie! Bennie, Bennie and the Jetssssss…” is intoxicating.
WR: The claps at the beginning, as well as the crowd’s cheering sounds more like flesh and blood as opposed to a good recording. The timbre of the piano, as well as his vocals and transitions from head to chest voice are more natural.
“On Green Dolphin Street (Live)”. Stan Getz. Serenity album. 44 kHz.
WOR: Victor Lewis’s lilting on the riding cymbals, the voicing on Getz’s silky tenor saxophone, Kenny Baron’s comping on the piano and Rufus Reid’s vibrant upright acoustic bass ease the crowd and the listener into a luscious West Coast Jazz treat. There’s a great sense of atmosphere as the song builds in intensity. The snare, kick drum and floor toms crescendo to a flourish of clapping as Baron takes the lead. The imaging on his piano is on point, as is Reid’s follow-up bass solo is taut, with the ride cymbal and high hat comping adding to the overall effect. There’s a cough in the background. The imaging is detailed and balanced, underscoring the fact that the LampizatOr Lite 7 DAC is indeed world class.
WR: Getz’s sax is a little more defined. Detail and texture in the riding cymbal is enhanced. Kenny Baron’s piano strokes are more focused, less soft. In fact, his notes float in the air more. The sound stage appears to have expanded slightly.
Both versions are delightful, burt with the Regen, the performance is more focused and musical. The audience clapping and cheers, the ringing of the cymbals as wooden sticks strike them — it’s all enhanced and in the room.
A ‘Life Hack’ for Audio
The Random House Dictionary describes the term, life hack, as “…a tip, trick, or efficient method for doing or managing a day-to-day task or activity.”
For the audiophile, who’s constantly looking for new ways to wring out that extra bit of aural magic from his system, that term seems very fitting. With everything I throw at it, when the REGEN is in play, my system simply sounds warmer and more engaging, producing an effect similar to what I’d imagine the Lite 7 DAC might sound like if I replaced its solid state tube rectifier with a rectifier tube like it’s $10,500 brother, the LampizatOr Big 7, sports. For $175, it’s a no-brainer — the REGEN now sits proudly in my system.
Now, I just have to upgrade my music server. But, that’s another story.
What follows is a white paper that Alex Crespi sent me.
UpTone Audio — USB REGEN explanation. August 2, 2015
To explain how the UpTone Audio USB REGEN works and why it is so effective with such a wide range of USB input DACs, we first need to define some technical terms and some problems inherent in USB audio interfaces—hopefully in not-too-technical language:
PHY: PHY is an abbreviation for the electronics that interface to the physical bus. PHYs exist in most every type of data interface (Ethernet, FireWire, optical, etc.) A USB PHY serves two primary functions: to convert the analog voltages used on the Data-plus and Data-minus wires into a digital format normal logic can understand, and convert the high speed one-bit-at-a-time serial data stream into a slower parallel set of wires to be sent to the USB protocol engine (XMOS processor, FPGA with USB core, etc.). The lowly PHY chip is actually a tremendously noisy and complicated device containing several PLLs and clocking at various phases—and there is no such thing as an optimized-for-audio PHY. The PHY part of a DAC’s USB is highly susceptible to the condition of the USB signal, its "Signal Integrity" (SI).
SIGNAL INTEGRITY: A high-speed USB signal runs at 480 mega bits per second, which is fairly high. SI is comprised of the rise/fall times of the signal edges, amplitude of the signal, noise sitting on top of the signal and jitter of the edges. Variations in any or all of these can decrease the SI. The computer determines this initially, and then it can get significantly degraded by running through cables and connectors.
The decrease in SI can be so large that it becomes difficult for the PHY to determine the actual bits. Thus the PHY contains several methods used to pre-process the analog signals in order to make it easier to determine the bits. When the SI is very good, the PHY can turn off the pre-processing steps and easily determine the bits. As the SI degrades the PHY turns on different parts of the pre-processing as needed. Each of these steps takes a fair amount of power to operate, thus creating noise on the power and ground planes. The more processing the PHY needs to use to determine the bits, the more noise is generated. Thus part of the packet noise is directly related to the signal integrity of the incoming signal. The higher the SI, the lower the noise.
PACKET NOISE: In a DAC the data packets coming in on the USB bus are not continuous—there is significant time in-between each packet. Thus the processing of these packets produces noise on the power supply and ground plane that come in bursts, and we refer to this as "packet noise". Since the rate of USB packets is 8KHz there are strong components of this noise in the audio band. This noise can
cause jitter in clock oscillators, re-clocking flops, and DAC chips. It can also go directly into noise on the output of DAC chips.
Part of this noise is determined by the USB protocol engine (chip after the PHY) and is going to be constant for a particular DAC.
POWER DELIVERY NETWORK (PDN): In order for a power supply to properly respond to instantaneous load variations, it needs to have a low impedance over a very broad range of frequencies. For digital audio this is from low Hz to hundreds of Mhz range. The entire supply flow from mains AC to board layout and capacitors on the board play a role in getting this right. The process of frequency optimizing the PDN is something that is done in expensive high-speed network equipment, but is almost never done in consumer products, especially audio equipment. (And our experience with the REGEN points to this being quite important for digital audio.)
UpTone Audio — USB REGEN explanation. August 2, 2015
Okay, now that some definitions and issues have been set forth, let’s look at how the UpTone Audio USB REGEN addresses them.
To recap the issue:
The lower the signal integrity (SI), the harder the PHY has to work, which produces greater packet noise. If the SI is very good, the packet noise from the PHY is less than that from the protocol engine. As the SI degrades the packet noise from the PHY can dominate.
Again, the packet noise consists of two parts: noise from the USB protocol engine and from the USB PHY. The protocol engine noise does not depend on the input signal quality, just the data, so its impact is always going to be the same no matter what is done with the input. The PHY is the part that actually connects to the electrical signals on the bus, ITS contribution to packet noise IS dependent on the quality of the input signal.
It is very important to keep in mind that all this is what happens INSIDE the DAC by its own operation, it is NOT noise on the USB bus that is somehow getting into the DAC as is commonly thought.
At this point there aren't any DACs that have been specifically optimizing their USB inputs for SI and impedance match, it's too new as a specific concept to design to. But the best DACs do optimize this to some degree, whether by trial and listening or as a by- product of optimizing for something else.
So tell us how the darn thing works already!:
The REGEN is at its core a single-port USB 2.0 hub. All hubs actually contain two USB interfaces and a full-blown USB protocol engine. It is not just working at the analog level, it is actually receiving the data from the computer, putting it in a buffer and retransmitting (and the other way for the packets from the DAC).
It uses a selected USB hub chip to create a new USB stream to deliver a very high signal integrity to the DAC's USB PHY, thus decreasing the PHY’s contribution to packet noise. It is called “REGEN” since it completely REGENerates the data signals that cables are messing up—it’s not just a re-clocking. Because it uses clean power and a low jitter clock, the output of the hub has low noise and low jitter. To be most effective, and to maintain best signal integrity and ideal impedance matching it is best positioned right at the input to the DAC, thus its small size, low weight, and included male>male USB ‘A’>’B’ adaptor.
The result is that the PHY in the DAC doesn't have to use any of its pre-processing circuit arsenal so the packet noise is as low as it is going to get.
Does the REGEN eliminate the need for a good USB cable and other computer optimizations?:
No. The hub chip inside the REGEN has its own PHYs and protocol engine, which themselves generate packet noise on ITS power and ground planes. So the REGEN itself is also sensitive to the SI of the signal fed to it, which is why good USB cables and specialty USB host boards feeding it still make a difference—maybe just not as much.
A lot of time was spent on the design and board layout to minimize this packet noise but it is still there. The impedance of the "Power Delivery Network" (PDN) over a broad range of frequencies determines the amplitude of the packet noise produced by the hub chip. The REGEN’s frequency optimized PDN is what makes it such a good sounding source.
UpTone Audio — USB REGEN explanation. August 2, 2015
The ideal solution would be to figure out how to prevent all this noise from crossing out of the USB input system and getting into the DAC chip and clock. Unfortunately this is really tough and nobody has completely figured out yet how to do so. Thus every DAC ever built will have some level of susceptibility to external influences, some more some less.
The question everybody asks then is:
Well what about DACs that have full galvanic isolation after the USB system and re- clocking on the DAC side? Unfortunately USB input noise of all sorts still makes it through to some extent and reaches the DAC master clock. Exactly how this works is complicated, John Swenson has written in-depth about this elsewhere The upshot is that neither galvanic isolation nor re-clocking completely get rid of it. They help attenuate it some, but don't get rid of it.
The REGEN’s secondary function is to ignore the 5V USB bus power coming down the cable from the computer (or other host) and to provide—to DACs that require it—a very clean and isolated 5V supply. The REGEN has a separate ultra-low-noise regulator for this. (For DACs that don't use the 5V wire, that regulator in the REGEN is not used for anything.)
Lastly (unlike another hub-chip based device out there), the UpTone REGEN uses a 4- layer board, primarily to allow a proper impedance match. With a standard thickness 2- layer board it is impossible to attain a proper impedance match to the hub chip. The pins on the chip are small and close together, this necessitates very thin board traces. With a two layer board the distance between ground plane and these traces (this is called a differential micro-strip configuration) produce an impedance that is much greater than the spec. With a 4-layer board the ground plane can be much closer to the top layer, and that allows for appropriate impedance with the very narrow traces. The REGEN also uses surface-mount USB jacks that allow for appropriate trace width and spacing to continue the impedance matching through to the USB jacks. The result of this is that there will be very minimal reflections at the REGEN side. Even if the DAC does not have good impedance matching—which is pretty common and which WILL cause a reflection at the DAC end—it will be absorbed at the REGEN because of the proper impedance matching.