- Written by Rick Schmidt
- Published on 07 November 2011
Introduction to the CEntrance DACMini
CEntrance is a Chicago based company with engineering in the US and Moscow, Russia, design in Holland, and manufacturing facilities in Asia but final assembly in the US . Let's just say 'multi-national'. They got their start in pro audio making microphone/guitar pre-amps with analog to digital converters, the MicPort Pro and AxePort Pro in amazingly small packages. Designed to plug inline on the microphone or guitar cord with a USB output (the units are powered by the USB connection) they provide the smallest possible recording studio, enabling musicians to plug a microphone or guitar 'directly' into a computer as if they were plugging into tape deck. Here, we review the CEntrance DACMini.
The natural extension was to go the other way with a USB powered DAC in the same small package, the DACPort. 24/96 DACs available in line level or headphone models. This product was well reviewed throughout the audiophile press. I first heard it at RMAF in 2008. The experience was disconcerting, how could this little thing, powered with that 5V, computer power supply afterthought on the USB interface sound so good? I was impressed but I'd been listening to different systems all day, maybe I was deluded, audio fatigued.
The DACMini is the latest product from CEntrance, using the same DAC technology as the DACPort but in a larger, rather beautiful package, with both headphone and line level (RCA) outputs. Inputs are via USB or S/PDIF. Analog inputs (RCA) are also provided. That latter input might make one think that the DACMini functions like a preamp but it only provides input switching, the volume knob is for the headphone output, the RCA outs are fixed at line level. The line-outs are automatically disabled when headphones are plugged in – preventing embarrassing unintended loudspeaker accompaniment for your late night listening.
CEntrance DACMini SPECIFICATIONS
- Design: USB DAC
- Digital Resolution: 24-bit (Also Supports 16-bit)
- Sample Rate: USB: Up to 96kHz, S/PDIF: Up to 192 kHz
- Interface: USB1.1 or 2.0, Driverless Local Clock: 10 ppm Precision, Immeasurable Jitter
- Compatibility: PC, Mac, Linux
- Nominal Output level: +6.0 dBV (RCA Analog Outputs)
- MFR: 20 Hz - 40 kHz +0.0 dB / -0.1dB (Line or Digital Inputs)
- S/N Ratio: (A-Weighted): 144 dB (Line Inputs); 113 dB (Digital Inputs)
- THD+N: 0.00022% (Line Inputs); 0.001% (Digital Inputs)
- Crosstalk: -128 dB (Line Inputs); 118 dB (Digital Inputs)
- Output Impedance: 25 Ohms (Line Output); 10 Ohms (Headphone Output)
- Maximum Output Power: 1.5W; +13.5 dBV (32 Ohms Load) +18.6 dBV (300 Ohms Load) +19.0 dBV (600 Ohms Load)
- MSRP: $795 USD
- SECRETS Tags: DAC, USB DAC
Design of the CEntrance DACMini
The headphone amp is a class-A amplifier design. The unit I reviewed was the standard model with 10 Ohms of output impedance. A modified version is available that lowers the headphone out impedance to 1 Ohm. CEntrance offers this mod to enable the flattest possible frequency response and for best coupling with low impedance headphones. Also available is a modification to provide more gain at the headphone output, for better driving of high impedance headphones (such as electro-static models).
Additional modifications are available - a black anodized case and Variable Output to convert the DACMini into a preamp.
There is no power supply upgrade which is what I first went looking for when I realized the supplied supply was a switching model. My power supply prejudice prompted me to push back on CEntrance about this.. why no PS upgrade mod?? I got this reply from Michael Goodman CEO and chief designer: "The external power supply that ships with DACMini is a specially designed, ultra-quiet, high-stability power supply. It is optimized for best performance in audio products. Inside DACMini, there is a number of additional power supplies with galvanic ally isolated grounds -- they totally decouple the internal circuitry from the external power supply."
Yeah, yeah, but have you tried a linear PS?
"We've had a number of outside parties attempt to improve the audio quality by using an external linear power supply. Nobody reported hearing any audible difference. Technology has moved on from the time when switching power supplies were a total taboo in audio."
And there is this from the design blog for the DACMini (http://www.centrance.com/products/dacmini/blog/)
"DACMini is so insensitive to external power because its internal power station utilizes a high-frequency transformer-isolated circuit to re-generate all the needed voltages, maintaining cleanliness and stability of audio power independently of brownouts and spikes on the line."
And this.." A cheaper USB DAC does not need an isolated power supply, because its own self-noise will mask any noise related to ground differences. On most USB DACs, when you turn the volume control fully "on", you will hear a loud hiss, which covers up the computer switching noise. However, with DACport and DACMini, we are employing breakthrough headphone amp technology, which ensures no noticeable noise floor in the headphones. It's actually "pitch black" in the headphones when you crank the volume knob all the way up. Now, at this level of low-noise performance nothing masks the computer grunge anymore, so additional isolation is needed to fully get rid of the ground-coupled signal impurities. This is why for DACMini we designed a transformer- and opto-coupled power supply that fully disconnects the analog ground from the digital ground. Galvanic isolation ensures that you are hearing the actual music and not the artifacts of computer chips clicking "on" an "off" on the motherboard."
Ok, ok, I give, we'll see when I listen. I had to ask though.. Opto-coupled power supply? This means that the digital signals are sent optically at key junctions, like at the input and output of the DAC, so that the power supplies for the different parts of the circuit are isolated. Simple and utterly effective, so much so that it's hard to believe that no one has done this before. Of course, cost might be a factor. The DACMini is pioneering a price point that gives me a bit of hope for the future of hifi – charge a little bit more for a high end product, in the consumer realm, and maybe some people who didn't know what was possible will give it a try. It's hard to know though what people will spend, to me the $795 price tag for the DACMini seems quite reasonable but I'm into this stuff. The ace in the hole for the DACMini is its design. It's the perfect mate for a MACmini. The two stacked together would look pretty cool.
Getting back to the power supply though – just for one second – bare with me - one of the satisfying aspects of traditional, heavy iron power supplies is heft. When one is paying big (or even small) dollars for an electronics product it's much easier to justify if the thing has some mass to it. Well the DACMini has heft. As I said the case is strikingly beautiful with a sparkly glow, but it is also substantial. By my crude estimations the DACMini weighs 2.5-3 lbs and feels and looks like it was made to last. A paper available on the CEntrance web site goes into detail about the internal design of the case. At what must be considerable expense, the inside is compartmentalized for the different functions. The compartments are separated with tongue and groove construction to provide thorough RF isolation. This is not just a pretty box.
That isolation is all the more necessary because there is not just a DAC in there, there is a processor as well. Gathering the data from the USB input, volume control, switching inputs and the on/off switch are all handled by the processor, not by mechanical switching which is firmware upgradable. The volume control, while handled by the processor is done in the analog realm which is what you want, digital volume control means throwing bits away.
But what about the DAC in there? Which one is it? Wolfson? Cirrus? I had all but given up on finding out. CEntrance doesn't divulge this info even though it is the custom to do so. Well your intrepid reporter poked and prodded to get the story behind the DAC. The DAC chip in the DACMini is the AK4396 from the Japanese company AKM. Michael Goodman explained that this DAC chip is special in that even though it is a delta-sigma design it is a new variety with far less noise. Delta-sigma D/A conversion requires a high clock rate, many multiples of the sampling rate, which brings its own set of noise issues. I'm not sure what exactly but the AK4396 does something radically different (or so it is claimed) in delta-sigma conversion that greatly reduces (ala 60db) the noise issues from this high frequency circuitry. It is a different sort of sound as compared to other DACs I had heard. Liquid and very listen-able (i.e., not fatiguing). The Transporter from Slimdevices/Logitech also employs an AK4396.
Setup of the CEntrance DACMini
Setup is about as simple as can be for an audio product. I first tried the DACmini using a wired (not optical) S/PDIF connection from my ancient Marantz CD63, plugged in my Grado SR325i cans and I was ready to go. When I later tried out the line level inputs I used my Audioquest Sidewinder RCA interconnects. A sizable chunk of time was spent using the DACMini as a DAC, driving my main stereo system which consists of SimAudio gear and Daedalus speakers. For a brief bit I tried my AKG 401 phones which proved inferior to the Grados.
CEntrance DACMini In Use
The first CD I tried with the DACMini was Lida Husik's Faith In Space, a lovely bit of textured electronic from the 1990's that loved the DACmini (or vice versa). The interesting thing with electronic music is that a high fidelity playback system will make it exponentially better than mass market equipment would because a good hifi will reveal hidden textures to the synth sounds. With the DACMini those textures were rich. The highs had terrific detail, Lida Husik's voice was sweet as it should be and the bass was chunky which is how I expect this recording to sound.
I tried a crude jitter test by first feeding the DACMini from my vintage Marantz CD-63 and then from the new Emotiva ERC-2. I had its predecessor the ERC-1 in my system for a few months and so ended up using it with a variety of DACs, I discovered that it was a superior digital transport compared to the Marantz. I now have the ERC-2 in for review so after a time using the Marantz as a transport I switched the optical toslink (the highly recommended Ixos Xotica) over to the Emotiva. Going back to Lida Husik's Faith in Space, with the DACmini's line-outs connected my Simaudio system driving my Daedalus speakers, the electronic instruments emerged from a blacker background with more detail when I used the ERC-2. Similar with Lucinda Williams Car Wheels on a Gravel Road, her voice was sweeter and I heard more of it – more breathiness, more accents, more twang when she twanged. Also when using the Emotiva to drive the DACMini, I was reluctant to remove a disk to switch to another, I just kept listening. Note that this test presumes that the ancient Marantz doesn't commit some even more base sins than merely jitter. It's possible that it has outright errors in its output bit stream. Wouldn't be surprising at all.
Comparing the Emotiva as a CD player (i.e., using the DAC inside the ERC-2) the sound was a bit warmer than the DACMini but the background not as black. I need some more time with the ERC-2 but as I listen now I have a slight preference for the DACmini. The DACmini costs about 2x what the Emotiva does so there is some order in the audiophile universe. Both of these products are swinging way above their weight class however.
The chassis of the DACMini never seemed to vary much from room temperature even with extended listening but I wonder if the class-A amplifier inside liked to be warmed up because I kept finding that the sound was better the longer I listened. The sound was impressive enough at the start of whatever CD I put in first but by the end I would inevitably be enrapt. With Hector Zazou's Songs from the Cold Seas this was exactly my experience as I was unable to stop listening all the way through the record, even as I was thinking – man I should go back to the beginning and see if it sounds even better than when I first put it in because it's really rockin' now. But I couldn't stop listening to the track I was on. When I did finally get to the end I restarted the disc and I do think that the backgrounds were slightly blacker but that's not the kind of difference I can clearly recall after 60 minutes of listening. I recommend an extended listening session with the DACMini if you're trying it out.
I quoted from the extensive DACMini design blog above: ". It's actually "pitch black" in the headphones when you crank the volume knob all the way up". I can verify that this is true, and impressive. The 'black background' that us crazy audiophile reviewers are always going on about though is a combination of this quiet noise floor and dynamics (micro and macro). That is, how well do the instruments emerge from the background and distinguish themselves? The most challenging reproductive challenge I know of in this regard is the piano. All the various sounds that a piano makes – the hammers hitting the strings, the strings themselves, the sounding board – not to mention the variable decay controlled by the player via the foot petals – add up to several closely related 'instruments' for an audio system to sort out. I've heard a couple of (crazy expensive) systems reproducing jazz or rock music well enough that it seemed like if I could be fooled into thinking the band was there in the room. Not so with piano though. I've never thought 'jeez it sounds like there's a piano over there'. An aside – one trick that helps with this is to have speakers with a large sidewall that is not well damped, even if it is MDF, it seems to mimic the sounding board of pianos. Still, it gets you closer but not all the way there.
So, for eight hundred bucks plus headphones, can the DACMini do what even the most high end systems can't do? Well no. On track two of Songs from the Cold Seas, a track sought after by Bjork fans, she sings a haunting traditional Icelandic song, 'Visur Vatnsenda-Rosu' accompanied by piano amongst other things. At various time some piano is added to an already long list of instruments. On the highest-end systems of the audiophile world this piano kicks in with impressive force and the overtones and harmonics of this complex instrument are preserved, to some degree anyway. The DACMini did an impressive job with the overtone bit, but the initial slam seemed contained within the space allotted. That's an important thing to note – in the space allotted – the overall sound of the DACmini always sounded right, whatever music I was listening to, the sound was right. This means not only reproducing the highs and lows but also the dynamics. Large scale dynamics is when the volume on a recording jumps, perhaps because a new instrument is introduced. With this recording, I got more if it when I switched the toslink back to my Naim DAC. A DAC which costs four times as much not counting the outboard power supply and with that power supply ends up occupying about 20x as much shelf space. At one fourth the cost, and with a headphone amp built in, the DACmini came ridiculously close to the Naim in overall musical satisfaction and non-fatiguing enjoyment.
But the DACMini was born to be paired with a computer, specifically a MACmini. I don't have a MACmini but I do have a Dell laptop (running Windows7) and another desktop system running XP. There was a driver issue with the Dell that seemed to lock the DACMini onto the USB connection (did I say it's not a MAC?). I put the blame squarely on the Dell laptop which has some sort of a home theater package that seems to prevent all kinds of things from working. With my home-built XP system there was no such hiccup. In both cases though the sound through the USB connection was lovely. I sometimes thought maybe the sound was a little smoother, more liquid, through USB than S/PDIF but it wasn't enough to make me try to do extensive A/B comparisons.
While using the USB connection I was able to listen to some 88.2kHz recordings I had made from the vinyl version of Joanna Newsom's Have One On Me. With this high res recording there was not much to complain about and a lot to enjoy. I could still hear a slight loss in micro dynamics (and not in macro) as compared to my Naim but the differences just became less and less important. I've had similar results with high res recordings from other DACs which shows us once again that the unfortunate constraints of the CD standard have really cost us all.
I did have one other nit during my otherwise completely enjoyable time with the DACMini – the USB and power connectors both don't seem to insert all the way to the chassis, leaving about an eighth of an inch of the outer conductor exposed. I pushed as hard as I dared, it wasn't that they weren't in enough, it just seemed like they weren't in 'all the way'. A small thing soon forgotten once you've set the unit down and started listening.
Conclusions About the CEntrance DACMini
The DACMini from CEntrance is a great audio value in a gorgeous package. A lot of engineering expertise went into the design and it shows… sounds? You know what I mean. I'm a big fan of leveraging pro-audio for home systems and it seems like CEntrance is on the case. The design blog for this product has a lot more detail than I quoted above and if you read it you'll see the passion that was applied to the DACMini development. My listening told me that passion was well placed, enabling the musical enjoyment that is the reason we're all into this stuff.