Metrum Acoustics Pavane

Hardware Review

Metrum Acoustics Pavane
Monday, February 9, 2015
digital to analogue converter DAC
René van Es

Dutch DAC specialist Metrum Acoustics has always been at the forefront of digital technology, but with its latest creation it has re-written the rules of digital to analogue conversion so comprehensively that René had no choice but to buy one.

The story of Metrum Acoustics started for me in 2010 when the first NOS Mini DAC entered the market. After several versions and upgrades, the NOS Mini became the Octave and was joined by the Hex DAC some three years later. The man behind Metrum Acoustics is not the type to sit down and relax, on the contrary, Cees Ruijtenberg is a true music lover and technician who’s always looking for ways to improve his creations. It has taken him a full year to develop his latest product for the conversion battlefield: the Pavane DAC.

The Pavane is the result of fresh thinking and an awful lot of testing and listening to what is called a FPGA/DSP “forward correction module” and transient converters. What goes on inside the converter is not easy to explain, but I will give it a try. The signal coming in from the S/PDIF (RCA or XLR), optical or USB input is converted into an I2S stream. The I2S data is fed into the FPGA and split into two new formats, both I2S. These data streams are manipulated in the FPGA in such a way that when they reach the transient converter chips as two separate balanced clusters for each channel, the converters will interpret the data in such a way that they always use the highest segment of the ladder converters inside the transient modules. Put in other words, the MSB (most significant bits) and the LSB (least significant bits) are both marked as MSB and use the top 24 resistors inside the R2R converter. The analogue output parts of both streams are now at the same level, which is of course not what we want, the original LSB stream should be about -60dB in level. The final step in the process is summing the two analogue signals and restoring them to the original levels. The crossover point is not strictly defined and the splitting up of 24 bits into 2 x 12 bits is impossible to explain simply, but it might give you some idea what goes on inside the Pavane.  But why manipulate the data stream? Well, whatever R2R converter is used, problems always arise with the LSB part, because the signal is smaller and at a lower level irregularities occur, non-linearity arises and digital noise becomes part of the analogue signal. In the Pavane these nasty side effects are damped by -140 dB or more. They will never be part of the analogue music signal. Now this looks simple on paper, but it took about a year to write the algorithms for the FPGA, develop the transient R2R converters and start up production.

 

 

High class
The outside of the Pavane is also rather different to other Metrum components. It’s a full size converter with aluminium casing that can be silver or black, and covered by black glass on the top. The ingenious and luxury housing has no screws on the front, top or sides. The curved front plate holds one large push button for standby and five small ones for choosing the input. Optical, RCA, BNC, AES/EBU and USB are standard and a blue LED above each button will indicate the input in use. An orange LED lights up when there is no data at the input. A small remote control makes it possible to choose an input from the listening position. On the back are the inputs, the RCA (single ended) and XLR (balanced) outputs, next to the mains inlet and switch. If you want a headphone socket, triggers, volume control, look elsewhere, the Pavane is a high class, fully optimised digital to analogue converter and nothing else. Inside the box two boards are used for the actual conversion, each with its own mains transformer and power supply. The other boards contain the FPGA/DSP circuit, the USB module and the control parts. These circuits also have their own transformer and power supply. The XLR output is electrically separated from the RCA and both may be used at the same time. The balanced signal coming from the dual differential converter is summed in a Lundahl transformer, followed by a FET driver before it reaches the RCA connections. Utmost care was taken to make sure that the XLR and RCA outputs sound the same, nevertheless if you have the option to connect the DAC over XLR I recommend you do so.

In my system a highly praised Aqua La Scala Mk II D/A converter is in daily use, connected over AES/EBU to my NAD M50 digital music player and over XLR cables to the preamp. All I had to do is replace the Aqua with the Metrum and connect it to start listening. Having left it on for 30 hours I realised that the Pavane should never be switched off between listening sessions or put on stand-by if you want to hear it at its best. Like every DAC the unit needs temperature stabilisation and stabilised circuits for minimum jitter, 24 hours warm-up is the minimum they need. The first few hours of use after the DAC arrived at my place where impressive, but listening the next day was a revelation to say the least. A state of affairs that continued over the period it was in the system. Being used to high end DACs from Esoteric, Aqua, NAD, Metrum, Apogee and some other brands, I thought I had heard it all. They all differ from each other, have their strong points and weaknesses, you might prefer one over the other, like I preferred the Aqua over Esoteric because of its more romantic presentation. But I was in for a big surprise with the Pavane.

 

 

The first thing I do before listening proper is to determine what connection is the best in my system. The M50 has coax (RCA) and AES/EBU (XLR) digital outputs. It came as no surprise that the XLR connection sounded a little more pleasing with a fraction more detail and a slightly wider stereo image. This has been the case with every converter with an AES/EBU input, so that means the NAD works best that way. However with the Pavane the two inputs were very close, and it was the Audia preamp that made me decide to use the XLR balanced connection. The differences are small and may be due to the Pavane’s output stage, the cables or the preamp. A far bigger difference will be made by system components and room acoustics for that matter. In the end I settled for balanced in and balanced out. More important is the measured roll off at lower frequencies that the Aqua DAC shows (-2dB at 20Hz). The Pavane gives a straight line frequency response and I had to reduce bass output on the PMC fact.12 loudspeakers to compensate. Please note, a flat frequency response is preferred and the bass reduction is a room acoustics issue (greater bass extension is a good thing, Ed.).

Converting vegetarians
Finally we get to the listening. The hardest part is to put into words the overwhelming feeling of happiness that the Pavane’s presentation and naturalness brought to my system, more so than any DAC that I can remember. Except maybe for a professional Apogee Electronics PSX-100se DAC back in 2002, that was the first time that CD brought real excitement and tears to my eyes. 13 Years later I have no idea how the Apogee would hold up, but I do know that the Pavane is amazingly good and probably a lot better. It proves to my mind that oversampling, upsampling or DSD conversion are only necessary to overcome the shortcomings of lesser DAC chips. Let me start with an old favourite, the Infected Mushroom CD Converting Vegetarians and the track Avratz. It should have a very wide and deep soundstage, stomping bass that hits the stomach and numerous sound effects all over the place. The bass is as tight as could be, detailed too although it is fully electronic. I would say that the depth created is an imaginary five metres, which is exceptional for my room. Sound escaping the speakers is no surprise with PMC, but this time the loudspeakers disappear even with my eyes open. The same sort of trick comes from Trentmøller’s Filur remix on a Dali demo CD. The pumping bass resembles a proper club sound. I agree that this might not be the sort of music for most would spend almost five thousand euros on a DAC, but the music does show how exceptional the converter is. The same Dali CD contains tracks like The Gates of Istanbul from Loreena McKennitt, Breaking Silence by Janis Ian and Take Five played by the Dave Brubeck Quartet. With Loreena it is mostly the impact that counts: the weight of the bass. Yet her voice remains crystal clear. The ancient instruments played by her band members excel and sit in a totally coherent soundstage appears where each finds its own place. Moving on to Janis Ian the almost tender opening of the song contrasts with the high level of the instruments. Over and over it is the perfect soundstage that is so impressive. The old Brubeck recording with its left-middle-right mix shows exactly how stereo was done in those days. Cymbals sound old fashioned with rivets around the outside, they haven’t been made like that for years. The drum kit is tight and lifelike, the saxophone amazingly open while piano holds the rhythm. May I use the ‘A’ word, I’ll take that as a yes, it sounds very analogue. Dynamic, rich, fast and punchy.

Next on my list is Dead Can Dance. I own the vinyl version of Into The Labyrinth that was always far superior to the CD. The Pavane DAC comes close, very close in every aspect. As if I had swapped my trusty MC cartridge for another brand. I won’t sell the vinyl version, however there’s no need to play it so often. Listening to The Wind That Shakes The Barley, I almost offered Lisa Gerrard a cup of tea after the acappella song. The acoustics of the room she performs in are very clear and there’s a distinct an echo on her voice. To emphasize the bass quality of the Pavane I play Stanley Clarke’s Spanish Phases for Strings & Bass. A long, long time ago we used this track to push loudspeakers beyond their limits, well the Pavane DAC would have come in handy. Except nowadays the bass is a lot more controlled than on the vinyl version. I play it loud, louder than normal, since the Pavane seems to be devoid of distortion in any form. Next is Patricia Barber with Nardis from her CD Café Blue. I love the way piano is recorded on most of her CDs, pure and powerful, detailed and rich. This is no different with the Pavane, but the drums explode into the room, ending in tiny cymbal strikes, moving from left to right and back. The Pavane is extremely detailed but avoids getting bogged down in technical performance. Somehow the synergy between detail and musicality has reached its apex. For musicality I might call this DAC the Aqua, but the romantic sauce and second harmonic distortion that makes the Aqua so easy on the ear is no longer needed.

The thing that sprung into my mind after the Pavane had properly warmed up is that is sounds so clear of distortion. This probably has everything to do with the movement of the LSBs into MSBs and back and back again, something that’s exclusive to Metrum as far as I know. Over the test period this experience did not change. You might know the old expression ‘inky black background’, it’s the best way to describe the absence of the digital artefacts that make listening tiresome, even unnatural. When I listen to Garden Of Early Delights by Pamela Thorby and Andrew Lawrence-King, a high resolution download, I wonder if it could be bettered by another converter. I honestly do not know. I have probably reached a limit with my system in my room, but I said that before about the Aqua DAC. Please do not suddenly consider the La Scala a bad product, it is one of the best DACs around for the price, it’s just that the Pavane goes beyond that level of performance. Back to the music then. Pamela’s flute is so well recorded as is the harp that follows the music that it makes the hairs stand up on my neck.

 

 

The order
After extended listening I cannot conclude other than this converter deserves the highest praise. The way this DAC handles music is outstanding and to be honest, after only a few days of listening I ordered one from the next production run. At time of writing that means I have to wait a couple of weeks, but it will be worth it. From the moment that the Pavane arrived it was clear that it had to stay. The absence of noise, distortion, jitter, you name it, makes room for the music, whether the music be jazz, pop or classical. I have yet to find a track that does not sound outstanding, unless the recording itself lacks quality. This converter is ruthless with bad recordings, it doesn’t hide anything like more romantic sounding DACs do. But feed it with high quality stuff and you have to own one. A year ago I would not have believed this performance level is possible at this price. Metrum Acoustics is probably leaving competitors in disbelief. Me, in a few weeks I be will be one of the lucky guys who owns a Pavane.

Specifications: 

Non oversampling DAC. Forward corrected, four DACs/channel in differential mode.
Power supply: 45 VA, 3 separate transformers.
Mains voltage: 110/115V, AC 220/230V, 60/50Hz
Inputs: 1x optical Toslink, 2x coax (BNC and RCA), AES/EBU, USB  
Outputs: 2x RCA gold plated Neutrik cinch connectors. 2x XLR balanced.
Output voltage: RCA - 2 Volt RMS max. XLR – 4 Volt RMS
Frequency response: 1Hz-20 kHz -2.5dB at 44.1kHz sampling. 1Hz-65kHz -3dB at 192 and 384kHz (USB)
Distortion: 0,01% THD
S/N Ratio: -145dB at 2Volt RMS
Output impedance: RCA 100 Ohm, XLR 200 Ohm
Sample rates: Optical 44-96kHz. Coaxial , USB and AES/EBU 44.1-192 kHz. USB 44.1-384kHz
Dimensions: 440 x 320 x 100mm.
Weight: 10kg.
 

Price: 
Pavane (black or silver) £3,849/€ 4.950
Manufacturer Details: 

All Engineering
T +31 343437331
www.metrum-acoustics.nl