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John
November 2011. I was blowing dry the ink on my coverage of the Network Bridge (and MKI PerfectWave DAC) for 6Moons when PS Audio’s CEO Paul McGowan began trickling out details of a forthcoming update to the DAC. Formally launched in January 2012, the MKII didn’t necessitate buying a brand new unit. Points for that, Paul.
Initially US$799 (for early adopters) and now US$999 (AU$1149), the upgrade kit is installed by the end user – check out the instructional YouTube video here. No need to visit a PS Audio dealer. More points, Paul.
All new-production PerfectWave DAC units (US$3999/AU$4199) are made to MKII specifications and are externally indistinguishable from the MKI. The MKII upgrade centres around a completely redesigned digital input board, firmware update (more on which in Part 2), slightly amended remote control and a Critical Link fuse.
This new digital input board is where all the new juicy stuff sits.
Paul McGowan’s Digital Lens technology was hitherto only available to users who’d appointed PS Audio’s Network Bridge as their media streamer or PerfectWave Transport as silver disc spinner. The Digital Lens buffers the incoming data stream and re-clocks it before sending it forward to the DAC. It does this whilst maintaining the native sample rate. In other words, this is not sample rate conversion in disguise. In spending three or four months with the original PerfectWave DAC, I found the Network Bridge reproduced music with greater ease and suppleness than the corresponding S/PDIF or USB inputs.
Although his timing might border on the convenient from a marketing perspective, McGowan has since expressed his dislike for sample rate convertors. He likens the SRC sound to that of a prostitute: good-looking and enticing but far from pure or natural. An SRC wears too much make-up and hairspray.
In his February 28th blog post McGowan took it a stage further by referring to the use the use of sample rate convertors as a “conspiracy” of which PS Audio were as guilty as the next guy. “…most SRC circuits (including our own) manage to make everything fed into them worse sounding”, he wrote.
Where’s the beef? A sample rate convertor (SRC) is a tried and trusted method of jitter-busting. Many manufacturers include one in their own product for this very reason. For example, by converting (up-sampling) a 44.1KHz sample-rate source file to , say, a 96KHz sample-rate, the data is re-clocked, additional data points are interpolated and layer of jitter is soothed away prior to the data stream making its onward journey to the analogue conversion stage. Theoretically, the only jitter that then makes its way to the DAC chip is that caused by timing errors in the SRC’s clock.
You could bypass the SRC in the original PerfectWave DAC by selecting “Native” on the front panel. However, that left the sound open to the detritus of jitter found in the upstream transport: CD spinner, streaming device or computer. I guess this is why the Network Bridge sounded superior. Moreover, I discerned little difference between Audiophilleo-fuelled S/PDIF and a direct USB connection to a MacMini with a Wireworld cable. Relative to the sub-$2K DACs with which I spend most of my time, the MKI appeared less prone – but probably not entirely immune – to jittery sources.
The question remained: what if you could feed the PerfectWave a vanishingly low-jitter data stream without the need for the Network Bridge or PerfectWave Transport?
With the introduction of the second iteration of the PerfectWave DAC, digital lens buffered-clocking is available on all inputs. Data entering the PWD via the Network Bridge now gets lens-d twice! To his surprise, McGowan reckons it sounds better still. (Does that imply that the first Lens treatment is less than perfect?).
Due to space limitations on the touch screen the Digital Lens has been rebranded as NativeX. Send it Redbook-ripped FLACs and you can rotate through all up-sampled rates (SRC), Native (44.1KHz) and NativeX (44.1KHz, but given the asynchronous Digital Lens treatment). These options hold fast for ALL sample rates and can be selected via the touch screen or the remote control.
Having spent nearly nine months now with this new version I can confirm the expected: that NativeX consistently sounds superior to Native or SRC-processed data. Music reproduction is nudged closer toward sharp focus and sounds altogether more alive. Being able to better discern player locations across the soundstage from left to right and front to back makes music more believable – less of an auditory illusion. The elastic and pliable qualities of the Network Bridge sound have made it across to S/PDIF and USB inputs throughly intact.
Sing it back. With the MKI back in my possession for direct comparison, the MKII offers richer tonal colour and digs deeper for inner detail. This means MKII owners will likely hear more sonic decay and recording space ambience – the space between the music – than those with the MKI. As with any upgrade, how you view these improvements will largely depend on your tendency to see the glass as half full or half empty. Let me be clear: the first version of the PerfectWave remains a seriously impressive unit.
But wait! There’s more to this auditory up-click than just the Digital Lens. Power supply quality on the digital board has been improved and a move made from digital to analogue switch gates; the same switches that are used in analogue volume controls.
Peter Foster from PS Audio’s Australian distributor explains:
“One of the more remarkable results of PS Audio’s digital audio research programme is the use of analogue gates in a digital signal path. This is some of the magic of the new MKII PerfectWave DAC.”
“Digital gates switch on and off based on the input state. The ‘problem’ with digital gates, at least for high-end digital audio, is that they are driven into saturation in the ‘on’ state. This means that the junction is saturated with excess electrons. When you try to turn the gate to the ‘off’ state you must first sweep out all of the excess electrons before the gate can start to switch off. This may seem inconsequential with digital signals, but if you are transferring a clock signal with digital gates, the uncertainty how long it takes to sweep the excess electrons out of the saturated gate introduces clock jitter.”
“So why is an analogue gate any better? An analog gate works very differently. The output of an analogue gate simply tracks the input voltage rather than ‘switching’ to the other state when the input voltage reaches a certain threshold level as with the digital gate. It can therefore respond instantaneously to a state change because the junction is never saturated with excess electrons.”
“Even if you had a perfect, noise-free clock source, jitter would be introduced as it passes through a series of digital gates. Surely this miniscule amount of jitter is irrelevant you might say. Surely it has no effect on the music? Well, this is the really astonishing thing. If you use analogue gates in the digital path, removing the last little bit of jitter in the system caused by saturation effects, the music comes alive.”
Another draw card of (both versions of) the PerfectWave is the 32-bit volume control. It steps down like this:
- steps 100 – 40 are 0.5dB each ( 0dB to -30dB attenuation)
- steps 39 – 10 are 1.0dB each ( -31dB to -60dB attenuation)
- steps 9 – 0 are 2.0dB each ( -62dB to -80dB attenuation)
You might no longer need your pre-amp. Some users might find feeding their power-amplifier direct from source sounds too lean and clean. Or just too loud. The Audion EL34 Sterling sports an analogue volume pot that allows you to dial in various combinations of DAC and power amp. Purists might wince but pegging the Audion at around two-thirds of its maximum kept my PWDs above 50 on the PS Audio’s volume bar, thus ensuring no bit-stripping on Redbook content. However, the majority of my listening took place with integrated amplifiers (Sansui AU-719, Trafomatic Premise, NAD 3020, Red Wine Audio Signature 15) with which the PerfectWave volume was maxed out.
The addition of balance adjustment to the remote control will be useful to some (but not me).
The Wolfson WM8742 chip that lies at the heart of the decoding process is the same silicon found in the Rega DAC. Like volume attenuation and input selection, the WM874’s in-built digital filters can be accessed from both the front panel and the remote control. The differences between each filter are excruciatingly subtle. When it came to poorer recordings I played favourite with Filter 2 (Minimum phase ‘soft knee filter’) – it sandblasted the edges off the more aggressive transients of poorer/thinner recordings. If you’ve a fair number of 80s CD rips, this is the filter with which to start. Indecisive types should go with ‘auto filter’. Here the DAC auto-detects the incoming sample rate and engages the filter that PS Audio believes is optimal.
Changing up filters did more for my listening experience than phase switching.
The USB input is built around the freshly ubiquitous XMOS chipset. It’s asynchronous and can man-handle up to 24/192 (limited to 24/96 on the MKI). I tried to cleave SQ daylight between the USB and S/PDIF inputs with a KingRex UD384 convertor and couldn’t. Ditto M2Tech Hiface Two. Well, almost; my results were insufficiently definitive to be reported here.
This introduces a paradox for the consumer: why spend big on a best-in-class USB-S/PDIF convertor when you could put that money toward a DAC that’s better at hosing jitter? With NativeX at your fingertips, the PWD MKII proves it is one such beast. At around US$2k (depending on mods), Empirical Audio’s Off-Ramp USB convertor is consistently reported to be superior to the Audiophilleo and JKSPDIF. Would feeding the PS Audio DAC from such a low jitter source sound superior to a Native-X’d high-jitter source? (That’s a question that can only be answered as and when I get my hands on an Off-Ramp).
When operating at the uppermost percentiles of what’s possible from any given DAC, it’s easy to end up chasing your own tail. And that’s pointless, frustrating and futile. Moreover, so absolutely enjoyable is the PerfectWave DAC MKII that not caring about those final few tweaks – digital cables, USB cables and digital attenuators – is just that bit easier. When I listen to music through the PWD MKII, I forget about trying to make it sound better.
In Part 2: Further listening experiences, firmware updates and the PS Audio community.
Associated Equipment
- Logitech Squeezebox Touch + Hiface Two
- KingRex UD384 + UPower
- MacMini + JKSPDIF MK3
- Red Wine Audio Signature 15
- Audio EL34 Sterling
- Trafomatic Premise
- Sansui AU-417
- Sansui AU-517
- Sansui AU-719
- NAD 3020
- Magnepan MMG
- WLM La Scala
- WLM Gran Viola
- Usher S-520
- ProAc Tablette Reference 8
- Zu Omen bookshelves
Audition Music
- Frazier Chorus – Ray (1991)
- Built To Spill – Carry The Zero (1999)
- David Byrne – Rei Momo (1989)
- Elvis Costello’s – Spike (1989)
- Catchers – Mute (1993)
- Elvis Costello – My Aim Is True (1977)
- Radiohead – TKOL Remixed (2011)
- Julian Cope – Peggy Suicide (1991)
- Cocteau Twins – Heaven Or Las Vegas (1990)
- Thin White Rope – The Ruby Sea (1991)
- Talk Talk – The Colour Of Spring (1989)
- Prefab Sprout – Steve McQueen (1985)
- The Cure – Kiss Me, Kiss Me, Kiss Me (1987)
- Pink Floyd – Animals (2011 Remaster)
Further Information
