DACs

Naim Audio DAC

ARTICLE INDEX

Introduction

A Naim DAC. Oh, how long we have waited. Naim Audio is hi-fi company with its own ideas. For years they held steadfastly to their claim that the only by keeping the spinning CD in the same box as the DAC could jitter be controlled and high fidelity playback be produced. While other hifi companies made similar claims most would relent at least occasionally and offer up a DAC or two. Listening to these DACs seemed to bare out the original premise, standalone players were better. While I'm still suspicious of the original motives for all these companies, we have finally arrived in the age of DACs. It's the IPod and music servers which have precipitated the reign of DACs, jitter or no, the market has spoken.

Specifications

  • Design: PCM Digital-to-Analog Converter (DAC)
  • Sampling Rates: Up to 24 Bit, 192 kHz
  • MFR: 20 Hz - 20 kHz, + 0.1 dB, - 0.5 dB
  • Inputs: 4 Coaxial Digital, 4 Toslink Optical Digital, 2 USB
  • Outputs: DIN or RCA Phono
  • Maximum Output Voltage: 2.2 VRMS
  • THD+N: <0.002%
  • Sample rate: USB: 32 kHz to 768 kHz, 32 Bit S/PDIF: 32 kHz to 192 kHz, 32 Bit Apple Portable: 48 kHz Max
  • Dimensions: 2.75" H x 17" W x 11.9" D
  • Weight: 12.4 Pounds
  • Finish: Black Anodized
  • Price: $3,500 USA (Optional XPS2 $5,000)
  • Naim

Design

The Naim DAC accommodates the IPod through its USB inputs, one on the front and one on the rear panel. The maximum sample rate supported by Apple is 48 kHz so who cares really? Ok, almost all-ya'all care. I don't have an IPod or an Iphone but I-sure I-will be I-assimilated someday. When connected to other sources the USB inputs will support up to a screaming 768 kHz. A plan for the future since there is no known source for that data rate today. Only an IPod or USB Memory stick can be used on these USB inputs though. The USB connectors in the DAC prevent use of a cable to connect directly to a PC (or Mac). This is to prevent the hifi system from being contaminated by an ugly PC (or Mac!) ground plane. The other inputs are of the S/PDIF variety. Four inputs are provided, any one of which has an optical (Toslink) option, two have an RCA connection, the other two are fitted with a BNC connector. Outputs are the usual Naim DIN connector or RCA. Even the presence of these RCA connections is a leap for Naim which has long defended its proprietary DIN solution. A small switch on the back of the unit ensures that only one of the output modes is active.

Internally the jitter problem is solved in a unique way. The typical solution is to simply buffer the data. That is, capture it in a small memory with the clock derived from the S/PDIF stream and clock it out with a local master clock from a trusted, steady source. This type of solution has been around a while and it does indeed 'eliminate' jitter problems in the traditional sense. Jitter in digital playback has its worst effects when the unsteady S/PDIF derived clock is used for the actual D to A conversion. In that scenario the math that makes the conversion work is thrown out the window because it presumes a steady, perfect clock. Data buffering solutions use a local clock, not the derived clock for the D/A conversion. Jitter on the local clock might still be an issue because no clock can be perfect but it's no longer the S/PDIF interface that is causing the problem. It might cause other problems if it is so bad as to actually induce errors in the latching of the data into the local buffer. Or, if connected electrically, the noise from the ground plane of the digital source will become noise in the DAC. Naim has a variation on the buffer-the-data solution, Naim so distrusts the derived clock they opted to create a range of 10 local clocks to capture the incoming stream. The amount of data in the local buffer is used to make a call on whether the incoming stream should be clocked at a faster or slower rate.

In addition there is the usual oversampling (16x) but no up sampling. There is an otherwise excellent white paper by Naim on the design of this DAC that gives the usual explanation of oversampling (create extra samples with the value of 0) while completely failing to explain adequately how this could be better than creating samples with some sort of interpolation and making no mention of up sampling (which I can only guess is the process of creating extra samples with some sort of smart interpolation). The whitepaper goes on to describe the filters, discrete analog stages, vibration isolation and separation of power supplies. Mostly I will just summarize here and say that the paper reveals that Naim has considerable technical expertise as well as long experience in digital playback. The highlights to me are the DAC chips themselves (which are Burr-Brown 1704K as in almost all of the Naim CD players including the ultra-expensive CD 555) and power supply isolation and regulation. The 1704K DACs are ancient by digital IC standards, the problem with these chips was not in their sound but in their expense as their manufacture requires a 'trim' step as the resistors used in the actual D to A conversion require laser trimming to get precise values. Returning to the issue of power, when using the DAC standalone three power supplies are utilized, the whitepaper tells us: "The transformer has three isolated windings, feeding three sets of rectifiers and reservoir capacitors: one for the DSP, one for the clock circuits and the last for the DAC chips, I2V converters and analogue filters." Adding an external power supply such as an XPS that I already happen to own adds considerable expense as well as a bigger transformer and additional isolation as the master clocks now have a dedicated supply as does the analogue output stage. The DAC chips themselves remain connected to the DAC's own power supply. Naim also employs multiple voltage regulators throughout the design with the sensible goal of reducing noise on the power supply down to the realm of the (theoretical) noise in the music signal itself.


Setup

For CD playback I drove the Naim DAC from both my old Marantz CD63 and my new Emotiva ERC-1, first connected by an RCA cable that Naim supplied and later by optical. Using the Emotiva with an Ixos Ixotica DX1 was the clear winner. As I wrote in my review of the Neko D100 DAC it's a little disturbing that clear differences can be heard in optical connections. No co-mingling of ground planes is possible, jitter is eliminated by the DAC, what we are left with is hard errors in the digital transmission. If this is indeed the case they could easily be revealed with the proper equipment (which is admittedly not readily available).

I tried both the RCA and DIN outputs of the DAC. For the RCA connections I used some old Audioquest Sidewinder (I think) cables and the DIN to RCA conversion cable from Analysis Plus. For the DAC I used the power cord supplied by Naim, my XPS uses a power cord from bestdealcables.com as do the rest of the components in my system. These cables are a bargain in my mind and are perpetually on sale it seems. I use them to connect my Simaudio amplification chain (P5.3 preamp, W6 monoblocks) as well as the Naim gear to a Furman IT-Reference 20i power conditioner. When connecting to a PC was required I employed the Trends Audio UD10.1 to convert from USB to S/PDIF as the USB inputs on the Naim do not support direct connection to a computer. The manual talks mostly about connecting them to a USB Memory stick.


In Use

How did it sound then? Naim has a house sound which is analog-like, warm, not etched or grainy, especially as you move up their food chain or add external power supplies. The DAC fits this bill though it is a little more on the neutral side compared to the Naim CD players I've heard (I've heard most of them). The neutral sound of the DAC serves to create some additional separation between instruments (always my favorite) while leaving behind some of the usual warmth. The difference could also be described as more 'technical' sounding, 'precise' is probably the best term. 'Exciting' is another word that comes to mind, i.e., not 'relaxed'.

Playing the CD version of the recording I recently made of the vinyl version of Joanna Newsom's Have One On Me was eminently satisfying. While comparing it to the actual vinyl showed that the recording and CD encoding process did indeed leave some good stuff on the table the Naim DAC made it sound so good that repeated listens were required. Not long into the opening track, "Easy" a rhythm section kicks in to what had been a quiet voice and piano affair. With the Naim it had the proper bomb-like effect in my living room, never failing to make me sit up, take notice and say to myself, "damn that's good". Most importantly, at this dynamic juncture in the music, the separation and power of each of the instruments was preserved.

Adding the XPS made it all more-so. Bass was deepened for sure, making the overall top to bottom balance more proper in my system. Piano starts to get quite real sounding with the extended harmonics and attack on the notes there to draw you in, more details were apparent from each of the instruments. Naturally I did the rest of my listening with the XPS in the circuit. I should note that my XPS is not an XPS2 which is what is available now. The difference is unclear at this point, especially since my XPS was refurbished during the recent Naim Audio Recap tour.

Of course the main reason a DAC makes sense for a vinyl nut like me is the possibility of playing high resolution files. As I noted in my recent review of the Neko D100, with properly recorded high res files, the differences between DACs seems to matter less. Playing back the Joanna Newsom and Cat Power recordings I had made at 88/16 (don't ask) and 88/24 respectively, the sound came very close to the sound of the original vinyl, especially at 24 bit. I used these recordings to check the difference between the DIN and RCA outputs from the DAC. The DIN was the clear winner with fuller bass and a deeper background. Sibilants were also somehow masked by the RCA connections. Of course the actual cables used might matter as much or more than the connector, your mileage may vary.

Making a vinyl recording is a pain in the butt however and if I have the vinyl right there I'm likely to just listen to that. So, even for me most DAC use is still for CD playback. Store bought CD's were well treated by the Naim. It was no miracle worker however, older CD's recorded in the digital stone age (late 80's early 90's) were revealed for the hack recordings that they are. I've heard CD players and DACs do a worse job with these but also some that have done better. Pick just about any Cocteau Twins CD for instance, I'd rather play it back with the Neko or something with some tubes in it to smooth out the digititus. The Naim did a good job of transforming the digititus into the actual musical sounds which opened up the sound overall compared to other DACs and so should only be considered an improvement but the remainder then is the recording itself which we knew was not-so-good. A well recorded and produced CD however is in good hands with the Naim DAC. A favorite of mine for hifi demonstration is Songs from the Cold Seas by the late Hector Zazou. This CD never fails to excite and through the Naim it was beyond that. 'Wow' was my comment at the time.

After much pleasant time with the DAC I revived my vintage CDS2 by unplugging the XPS from the DAC and re-attached it to the standalone CD player. Experience has taught me that the CDS2 likes to be really warm, warmer than I can get it by simply playing CD's even. It sounds way better on hot days. Such days are still a rarity here in Portland so this comparison is not all it could be. I did let it warm up by playing a CD for an hour before listening. Playing disc 1 of my recording of Have One On Me the background was a little blacker than with the DAC as I recalled but overall the sound was thinner than the DAC/XPS combo. Piano was not nearly as textured or realistic. Notes of all kinds seem to not extend as long. Switching quickly back to the DAC sans XPS with the same disc I found the DAC more listenable, piano was restored somewhat and all the instruments were held separate to a greater degree.

Overall I felt compelled to keep listening which was not the case with the CDS2. Playing a commercially produced CD such as Bjork's Voltaic in the CDS2, the overall presentation made a little more sense. No doubt the player was designed by listening to commercial CD's. Something about the slightly more technical sound of this CD was softened by the CDS2 making the overall experience musical and enjoyable. Putting that same CD into the Emotiva to drive the Naim DAC however revealed more timbral detail in each of the instruments, along with a background of equal depth. Clearly better. Adding the XPS back to the DAC revealed hidden details, 'The Hunter' is the second track on Voltaic, with the XPS I heard keyboard accents and string parts in the background which were certainly there without the XPS and on the CDS2 but they were lost somewhere in the background. With the XPS and DAC together each of the instruments, including the background instruments were easily available and clearly presented. A flourish of drum and cymbal sounds at the end of the track was especially well served, the DAC/XPS was able to offer this up with rhythm and timing reminiscent of a live performance. Similarly, putting my Joanna Newsom recording back on, the XPS helped the DAC bring out those violins in the back ground on 'Easy' and the piano was really starting to get fleshed out.

Extra Notes

My experience comparing the CDS2 with the DAC was another lesson in the importance of break-in. I had of course done the same comparison when the DAC first arrived and at that time the sound of my CDS2 was richer than the DAC, with a blacker background from which the instruments seemed to leap, sometimes with too much enthusiasm it seemed. After a time the DAC was the clear winner for me, even without the help of the XPS. For all audio comparisons you might make while shopping, and for the best listening experience at home, make sure the components are both warmed up and broken in.


Conclusions

The CDS2 that I own has long since been replaced by the CDS3 in the Naim lineup so it would have been much more satisfying for all if I had a CDS3 for comparison but the reason I never pursued an upgrade is because the world is going to DACs, and most of my money goes into analog, call me old fashioned. At this point the money goes mostly to software (those 12" black discs) as I am completely satisfied with my vinyl playback rig (not that I don't mess around with it anyway). But I have noticed CD playback making a steady march back into my listening time with each of the new solutions I've reviewed recently (Emotiva, Neko, Naim). Real strides are being made in both recording and playback and of course there are high res files available here and there. With the Naim DAC I made the largest digital stride of all. As long as the recordings were good there seemed to be no end to how long I could enjoy listening with this DAC. To my ears the DAC moves slightly away from the Naim house sound (warm) but in doing so manages to reach into the recordings to a greater degree and pull out the satisfying texture of each instrument or voice.

Naim gear remains on the pricey side of hifi, for what this DAC delivers though I do not think the price is out of line. Once you start on the upgrade path however, with extra power supplies, you will pay a premium. But the upgrade path is fun and could be more cost effective than simply replacing a CD player or DAC completely. I've noticed that Naim has a thriving message board on their web site, something I haven't seen for any other hifi manufacturer. Naim is doing something right and I hear it in this DAC.