Product: Tentlabs b-DAC
Manufacturer: Tentlabs - The Netherlands
Cost: 980 € (YMMV)
Reviewer: Maarten van Casteren - TNT UK
Reviewed: December, 2011

The name Tentlabs will not ring a bell for most of you. It's a small company, located in the Netherlands and founded by Guido Tent. Tentlabs are mostly known for DIY upgrade products, like high quality clocks and voltage regulators to upgrade your CD player or DAC. They even organise courses where you can learn the noble art of audio modification on your own equipment. In recent years Tentlabs have also started to make kits and complete products, and these have created quite a stir in the Netherlands. One of the first ones was a top loading CD player, which got absolutely raving reviews from the few reviewers lucky enough to get their hands on one. They then introduced an amplifier, which was also very well received, and now there's the b-DAC. Guido is also known as the digital guru of the Netherlands and has a reputation for being able to create digital sources that sound very musical and relaxed. His other area of expertise is valve amplification, which should give you an indication of the sort of sound Guido is aiming for.

I actually have used one of Tentlabs products before. It was a clock module, for which I build my own power supply following the design on the Tentlabs website. I installed it in the CD player I was using at the time, a Micromega Stage 3, and it actually transformed the sound. I was really surprised how much difference it made. The player was quite harsh before and sweetness itself after the modification. I do have to add that Micromegas normally are not harsh at all, but this one had its power supply and output stage upgraded, which made it a lot brighter, but also brought out this jitter problem. It just shows that, yes, modifications can really work and, no, it doesn't always work out the way you intended. But in this case the result was excellent in the end, thanks to the Tentlabs clock.

The b-DAC is the latest product of Tentlabs, and extremely interesting for three reasons. Firstly, it utilises some of the same technology used in the famous Tentlabs CD player, secondly it is much more affordable, compared to that same CD player at least, and thirdly it is extremely versatile. In short, it promises high-end sound for a mid-budget price, and throws in excellent flexibility for good measure. There are plans to also add a matching transport, by the way, creating a complete, two-box CD player, and even a matching amplifier, the b-AMP. I used the b-DAC with the coaxial digital output of my own Astin Trew CD player which turned out to work very well indeed.

The b-DAC is a very pretty little number, that's for sure. It's compact and well proportioned and the anodised aluminium front is solid and rounded off in a nice and chunky way. The Tentlabs logo is cut out in the thick metal, adding a distinctive touch of class. The rest of the case is wrapped in matt stainless steel, with no screws or other things showing to spoil the looks. Very stylish indeed, at least to my eyes. The front only features a single control that can be rotated to set the volume and pushed to select several other functions. The only other thing on the front is a blue display, which is dimmable and very clear.

In spite of its minimal, functional looks, the b-DAC actually is an extremely versatile little machine. It not only contains a DAC, but also a full volume control, so it can be plugged straight into a power amp. It features both single ended as well as balanced outputs and accepts optical and coaxial digital signals, and even sports a USB input for use with a computer. The latest models will also accept EAS signals and spdif via BNC, according to the Tentlabs website. In addition, it even features a digital output, which provides a low jitter digital signal.

And jitter is the name of the game here. Guido has built himself quite a reputation for high quality clocks and other jitter reduction methods. Obviously, all incoming data will be reclocked and the clock used in the b-DAC is of extremely high quality. Power supply is taken very seriously too, as Tentlabs also sell fancy voltage regulators, with no less than 12 regulators used in this DAC. The DAC chip used is a PMC1792, and the maximum resolution is 24 bit at 192 kHz. All signals are upsampled, to either 48, 64, 96 or 192 kHz. In addition, there are two filter settings: steep and more gentle. All these options can be set using the single control and the display.

To sum up, there's very little this DAC cannot do. It will take any possible input, including USB, in any available format and output it to a preamp or directly into a power amp, in single ended or balanced mode. The only thing I can think of that's missing, beside the ability to make you a cup of tea, is DLNA network streaming, which seems to be getting more and more popular lately, and perhaps a headphone socket. In an ideal world it might even have analogue inputs and replace my preamp completely. But even without these, this is a Swiss army knife of a DAC that's extremely easy to use, compact and good looking.

When I took a look inside I was a little surprised. The PCB is quite small and there's actually not that much in there, but it certainly looks very neat and tidy and it does feel very well put together. Elegant and confidence inspiring, I would say. Build quality overall is outstanding, certainly for the price, and the whole package feels like a premium product.

In use this DAC is very flexible. For example, you can program it to accept command from a remote control. Sadly, it doesn't accept all remote control codes, and I couldn't find one that would work with it. Perhaps it would be better to just supply a cheap one with it, and keep the learning functionality just in case someone would like to use it with another remote. It was a bit disappointing, though, as my CD player, for example, also has volume control buttons for use with the Astin Trew amplifiers. It would have been great to be able to use these for the DAC, basically allowing control of the whole system with a single remote.

The sound

Guido does make quite strong claims about the technical capabilities of this DAC. According to Tentlabs this is one of the best measuring DACs on the market, with distortion at less than -120 dB, extremely low jitter and near perfect rejection of mains frequency and noise. It has been designed and carefully voiced to be as neutral and clean as possible. The aim here was technical perfection and the complete elimination of any digital artefact.

The b-DAC certainly makes a good first impression. The sound is detailed, tight, precise and clean, but also smooth, open and spatial. My own digital reference is the Astin Trew AT3500 plus, and I still haven't found a player for less than £2000 that can beat it. The b-DAC is only half the price of the Astin Trew, and basically matches it for sound quality. When plugged straight into my Usher power amp it actually betters the CD player, in spite of the fact that I use the excellent Django preamp. This just shows that even extremely good preamps cannot compete with a direct connection, and makes the b-DAC a very good choice for a fully digital system, in my opinion.

What impresses most is the complete absence of digital signature, whatever input used. The days that any affordable digital source sounded edgy are gone, of course, but even for modern standards the b-DAC is impressively clean and relaxed. There's a real sense of atmosphere on good recordings, and the music never gets that slight touch of artifice that is still common with many CD players or DACs in this price range. In a direct comparison with my Astin Trew the only difference is a slight touch of warmth in the sound of the CD player combined with a marginally more silky top end, which is welcome and consistent with the use of a valve output stage in the Astin Trew but perhaps not completely neutral. The b-DAC in turn is one of the best behaved digital sources I've yet encountered, basically just letting the signal through, almost as if it doesn't touch it at all. The fact that it has to convert a stream of numbers to music doesn't seem to bother it at all and what comes out feels as neutral and natural as it gets. But, for me at least, the Astin Trew still won the day, by a whisker, with its slightly richer tonality.

When I played around with the upsample frequencies and filter setting I didn't hear enormous differences, I have to admit. Perhaps the lower sampling frequencies sounded a bit more grounded and physical to me, with the higher rates perhaps a bit smoother. This is the same for the Astin Trew CD player, so possibly a trend in general. The differences with the b-DAC were smaller than with the Astin Trew, but the CD player actually allows you to completely switch off upsampling, while the b-DAC still upsamples from 44.1 to 48 kHz in the lowest setting. The b-DAC can also be supplied with a lower frequency clock, by the way, in which case the sample frequencies are 44.1, 58.8, 88.2 and 176.4.

I did take the b-DAC to a friend of mine who has a Naim CD5 with flatcap power supply, and is also using a Benchmark DAC with his SqueezeBox. I know from earlier comparisons that both these sources are excellent and a very good match for the Astin Trew CD player. We swapped the Benchmark for the b-DAC and again noticed that the Tentlabs DAC sounds a bit cooler than the Benchmark. In comparison, both the Naim CD player as well as the BenchMark DAC sound fuller, with a little bit more punch and weight in the bass. The b-DAC has excellent focus and precision, but both other digital sources presented a soundstage that had slightly more depth and layering to it. The b-DAC also sounded a bit 'shorter', with marginally less sustain, but at the same time seemed to have a 'blacker' background. In the end, my friend and I did prefer both the Naim CD player and the Benchmark to the b-DAC, although it also has to be said that the differences weren't gigantic. Sadly, we weren't able to plug the b-DAC straight into his power amp, as Naim use DIN connectors for that, and we didn't have the correct adaptor. I suspect strongly that the outcome would have been different had we had that option.

When I discussed these findings with Guido he wasn't surprised. He knows the Benchmark DAC and the Astin Trew player, and is convinced that the added warmth is a result of harmonic distortion. It is a well known fact that adding harmonic components will lead to a stronger perception of the fundamental frequency they are derived from. It is even possible to suggest a fundamental tone by only providing the harmonics, while completely removing the tone itself. This means that adding harmonic distortion to a signal will make it sound warmer to the ear. This is one of the reasons valve amps can sound warmer and richer. In addition, the presence of noise can have the effect of smoothing the sound a little bit and making the upper frequencies sound a bit softer. According to Guido, this explains why the b-DAC sounds slightly dryer and more precise, as its distortion and noise are virtually zero. Guido also admits that adding some harmonic distortion can indeed make a system sound more pleasant, but the aim with the b-DAC was to design and built a DAC that was as pure and clean as possible, without taking away or adding anything to the recording.

I also have to add that this seeming lack of warmth bothered me much less when I was just listening to the b-DAC in isolation instead of comparing it to other digital sources. The ear adapts to the slightly cooler tonal balance easily enough, and once that has happened you are left with a very rewarding sound that will never irritate or disappoint. It also, obviously, depends enormously on the rest of your system how welcome or necessary some added warmth really is.

This leaves me with a consistent impression of the b-DAC. Even though it is very clean, transparent and free of any digital artefacts, it also failed to beat the three other sources I compared it to in terms of perceived sound quality. The Astin Trew and Naim CD players as well as the Benchmark DAC all sounded warmer and more musical than the b-DAC, which was ever so slightly clinical and dry in comparison. This changes for the better when you plug it straight into a power amp. It now still sounds a bit dry and analytic but resolution, dynamics and focus are so much improved that the overall sound becomes very impressive. It somehow manages to be very engaging and detailed, but still relaxed and unhurried at the same time. So, the direct connection really plays to the strengths of this little DAC, even if it cannot completely resolve the relative shortcomings.

I fully believe Guido's claim that the apparent lack of warmth of the b-DAC is caused by the other sources adding small amounts of harmonic distortion. In one way I am somewhat concerned by that, as I don't really want any component in my system that distorts the signal in any way, but at the same time I do have to admit that, in my system, I preferred the warmer sound that this seems to result in.

Conclusion

The bottom line with this little machine is that it is a very good DAC for the money, with a clean and focussed sound. If that was all, then I would be more than happy to give it my recommendation, with the provision that it does almost seem to be too honest for its own sake and many other DACs and CD players provide a slightly richer sound.
As it happens, this little box also contains a volume control and the b-DAC really comes into its own when plugged straight into a power amp. If all your sources are digital then this is one of the best solutions available for the money. It is neutral to the point where it could be perceived as slightly dry and analytical, but if you can live with that then this is an excellent choice and I can only give it my highest recommendation.