NAD Masters Series M50 Digital Music Player & M52 Digital Music Vault Measurements

Sidebar 3: Measurements

As the NAD M50 has only digital outputs, the most important thing to measure is the quality of those outputs. Using my top-of-the-line Audio Precision SYS2722 system (see the January 2008 "As We See It" and, I connected the M50's AES/EBU output, which I'd used for all of my listening, to one of its AES/EBU inputs using a 45' length of Apogee 110 ohm balanced cable.

The SYS2722's input impedance was set to 110 ohms; the NAD's AES/EBU output impedance was close to this at 125 ohms. Playing 24-bit files, all 24 bits were active in the M50's digital output. With 44.1kHz data, the actual rate of the data was superbly close, at 44,099Hz; even with 176.4kHz data, the actual rate was within 3Hz of the nominal sample rate. It is no mystery, therefore, why the Auralic Vega's fussy Exact receiver setting had no problems locking to the M50. For context, the Lynx AES16e card fitted to my listening-room PC—a Shuttle running Windows 7—had a sample rate of 44,106Hz from its AES/EBU output; my MacBook Pro's optical output offered 44,101Hz; and the coaxial S/PDIF output of the Arcam rBlink Bluetooth DAC I reviewed in March had a sample rate of exactly 44,100.0Hz!

With WAV files representing 16- and 24-bit versions of the Miller-Dunn J-Test signal—the worst case for an AES/EBU connection—the measured jitter level (with a 50Hz–100kHz bandwidth) varied between 394.3 and 443.6 picoseconds, which is only a little higher than the Audio Precision's sensitivity limit. This figure remained unchanged whether I played a WAV file or the same data from a CD or via Ethernet. Confirming this low level of interface jitter, the eye pattern of the received datastream (fig.1) was impressively open, with no blurring at the beginning and end of the unit interval. Again for context, the Lynx PC card's AES/EBU output offered 542.2ps of jitter and the rBlink 395.4ps, but the laptop's optical output was a high 1.38 nanoseconds (1380ps).—John Atkinson


Fig.1 NAD M50, eye pattern of AES/EBU data output carrying 16-bit J-Test signal (±2V vertical scale, 175ns horizontal scale).

NAD Electronics International
633 Granite Court
Pickering, Ontario L1W 3K1
(905) 831-6555

Kal Rubinson's picture

With regard to the value of the M52 compared to a NAS, I recently configured two 5-bay NAS-RAID boxes with three 4TB drives each and that nets me, in each box, about 7TB of redundant storage with room to expand to 12TB. The cost for each was about $1100 and setup was trivial. However, I can understand that some might find the prospect of such setup intimidating.

You mention the idea of the M50 recognizing and playing DSD via the HDMI, that would seem to be just a firmware modification since, in this case, the M50 would not be decoding or processing anything, just transmitting the file content. If so, nothing should stand in the way of a similar firmware modification also accommodating multichannel files (FLAC, DSD, etc.) from the same port. That would make the M50 an ideal manager for my networked system.

(This is an attempt to recall the details of a lost post.)

JRT's picture

Another alternative would be to install a VortexBox ISO on a PC. Since the ISO is a free download, that can be a very cheap solution if you have an older PC that has been replaced with a newer upgrade. VortexBox can be used for digital audio extraction (ripping), will automatically transcode to FLAC or other formats, download cover art, ID3-tag the files, and will serve those files to your networked media players, Mac OS-X system, Windows system, etc. Buy a couple of new large capacity USB HDDs, and use one to store the files, the use the other as a backup copy, and even out the mechanical wear by swapping them when new files are added.

Similarly, someone could buy themself a nice new laptop and install JRiver Media Center software on the older one (or maybe use your SqueezeBox Touch). Connect that to an Oppo BDP-105/105D universal optical disc player which includes facility for use as an external DAC, and has enjoyed very favorable reviews by Dr. Rubinson. A firmware upgrade allows a SqueezeBox touch to connect to an external DAC such as the aforementioned OPPO deck using asynchronous USB, else use S/PDIF. Or simply use a nice inexpensive asynchronous USB DAC like an Audioquest Dragonfly in the laptop.

Spend some of the money saved on music data files (regardless the recording medium), and/or better loudspeakers, and/or some excellent headphones, all of which would do more to improve playback as compared to spending a lot more money on a propietary player/server combo that may not be nearly as well supported in a few years when out of warranty and no longer current models.

If JRiver goes obsolete, it can be replaced with another inexpensive software package. VortexBox is based on a Linux distribution, under continuous improvement, and not likely to become obsolete in the near future, and regardless that the data files could be copied to another server. When the hardware eventually fails, it too can be simply replaced.

Kal Rubinson's picture

Since you mention the Oppo 105, that alone will do all the functions albeit with a clumsy interface (even with the iPad app) compared to the NAD, jRiver and, even, the SBT. However, it sees the music files on my network and is happy with all formats including DSD and multichannel. Too bad about the interface as that is what makes it uncompetitive.

wozwoz's picture

So this is a physical disc player designed for hi-res, and yet it doesn't play SACDs? Is that right? Makes no sense at all. Why would anyone buy a physical player today that doesn't also handle SACD?

John Atkinson's picture
wozwoz wrote:
So this is a physical disc player designed for hi-res, and yet it doesn't play SACDs? Is that right?

Yes, that's correct.

wozwoz wrote:
Makes no sense at all. Why would anyone buy a physical player today that doesn't also handle SACD?

I suspect that it is because a) as I understand it there is now just one source for transport mechanisms that can play SACDs and manufacturers are not comfortable without multiple suppliers for essential parts; b) the market for SACDs is now small and not growing; and c) NAD feels file playback will become predominant.

John Atkinson
Editor, Stereophile

wozwoz's picture

Doesn't really make sense -

FIRST: even cheapie Universal players for the living room can play SACDs (and DVDs and Blu-ray and CD). So, designing a supposedly hi-res player that cannot play the dominant hi-res format seems like a peculiar business decision at best, and a simple blunder at worst.

SECOND: I do agree that the market for hi-res is tiny, but I would not agree that it is not growing. At least SACDs actually sell, and the demand for them shows no sign of abating ... Indeed, there are almost 10,000 titles out now, which is more than any other hi-res format (physical or downloads) and they keep on coming. The demand is certainly there - just check out the prices people pay on Amazon and ebay (in the hundreds of dollars) for discs that have sold out.

THIRD: many new SACD players (like those from Marantz and Luxman) not only play your CDs and SACDs, but also serve as an external DAC for hi-res playback from your computer if you want to play download files. Which is exactly the point: the NAD player is missing out on what the competition is offering.

seanh1978's picture

Does anyone know why this was discontinued ?

Based purely on sonics which is the better player M50 or Marantz ?

Bruce D. Goose's picture

It is a little unusual for the m-52 to have been discontinued given that the m-50 it was designed to work with is still available, and NAD's marketing literature promotes them as an ideal combination (and they are!). I own both units and here's my opinion:

Hard drive-based dedicated audio music servers have an Achilles heel: the hard drive! Notice how many of the newer ones no longer include any hard drive? Add it yourself via usb, but the manufacturer is then no longer responsible for warranty service. Hard drives are inherently unreliable over a typical two or three year warranty period, which is common for a hi-end piece.

Some anecdotal evidence: every one of the four (!) harman-kardon dmc-1000 music servers that i have owned has had a bad hard drive, though only one of the four was brand new. The NAD m-52 i bought was also bad out-of-the-box, but it will be repaired under warranty. I should say this was a demonstrator and NAD has been helpful, but i suspect that unacceptable warranty repair rates may be the real reason for the lack of more integrated hard drive systems, and why for NAD the m-52 is gone but the m-50 remains.

BTW, sound of the m-50+m-52 is clearly superior to the sound from usb sticks. Too bad nad never makes this clear,as they might have had more takers for the m-50, which is often positively discussed in a usb-stick context.