BOULDER 812
Preamplifiers
The Boulder 812 is a modern front-end that puts a preamplifier, a DAC, and a headphone amplifier under one hood. Although the brand is synonymous with boulder-like behemoths, the 812 is surprisingly smal. It has a square footprint of 300mm and was developed to complement the same sized 961 stereo power amplifier. This way one can have two boulders in the house without needing a crane to move them.
Function and form
The rather compact size owes to switching power supplies that are used to power digital and analogue sections of the device, as well as all the circuits being placed on PCBs. The 812 accepts digital data through four USB sockets, Ethernet, two optical inputs, and a coaxial SPDIF input, as well as it can read data from a USB-B drive and accept the network signal wirelessly via AirPlay or Bluetooth. The digital inputs are upsampled to 24bit/192kHz before the data are sent to Analog Devices D/A chips. Streaming capabilities include UPnP and Roon. The analogue signal is accepted by two pairs of XLR (no RCA inputs) and is maintained as analogue (no digital conversion) from input to output.The analogue section is based on FET devices and provides maximum gain of 19.4dB. Interestingly, while the analogue-based optical volume control works with 1.0dB increments, the user can set independently each input’s sensitivity (including the digital ones) with 0.5dB accuracy. There is also one XLR preamp output which bypasses the variable volume of DAC. Everything is handled by Boulder Controller App. If need be, you can purchase a standard remote controller at an extra.
Preamplifier/Headphone Exchange button on the fascia switches between these two modes. On the front of the 812, under a rectangular cover, there are 4 headphone outputs: an XLR, Sony’s Pentaconn output, and two jacks (1/8” and 1/4"). The 812 allows for using all the 4 headphone outputs simultaneously. As there is a Raspberry computer at the heart of the 812, the user ca also program (via app) the Boulder to have both headphone and preamplifier outputs on, or program any of the 812’s input for use in home theaters with master volume level controlled by a surround sound processor.
Bass management
The way the Boulder 812 looks will polarize opinions. No doubt that Colorado-based manufacturer succeeded in using organic shapes, here represented by interestingly arranged cooling fins. It is a design feature, rather than a practical one – the 812 does not get particularly hot in operation. Every time I looked at the preamp, it reminded me of a wrung towel, though. On the other hand, I liked the compact dimensions of the preamp. Its mate, the Boulder 961 power amplifier, can only deliver 50 watts per channel into 8 ohms, and that justifies the size. I listened to the 812 in two audio set-ups: In my resident system where the 812 was paired with Constellation Audio Taurus and it was not a good match, and in the system of the owner where the 812 was paired with Bryston 14B3 Dual Mono Amplifier (a beast that delivers 2x 600W into 8 ohms and up to 2x 900W into 4 ohms) and the results were (almost) spectacular. I have to yet audition some of the top of the range Boulder models. The 812 was a great performer, although not completely flawless by my standards.
Clarity & delicacy
There is an undeniable trend to ‘humanize’ digital technologies. Since their dawn, the switching amplifiers used to have the reputation of good bass performance, great dynamics, yet somewhat granular top end paired with overall sterility. But wait – the Class D have made important advancements and today’s amplifiers have successfully addressed early imperfections. There is still some way to go, but I dare say that some switching amps are better that similarly priced Class A and AB amplifiers. However, there is also the other polarity of this humanization. In the quest of making the digital technology analog-like sounding, the job is sometimes a bit overdone. Aavik I-280, that we reviewed, is such an example. Too much smooth, too much warm, too much dense. Aavik is able to compensate this by the adjacent electronics, cabling, and speakers from within Audio Group Denmark stable. The Boulder 812 preamp covers a similar territory – it tries to sound like wires, tubes, and solder, with PCBs, FETs, and switching tech.
Tonal accuracy
I would summarize the 812’s sound by two words: clean comfort. This preamp gives an impression of grip on sound, from bottom to top, which helps keep things organized. The instruments and voices are locked firmly within the soundstage, and although the 812 projects the soundfield a bit more upfront that I am used to, the projected space still has impressive width and depth. The bass of the Boulder 812 has wonderful control; the smear is reduced, so it may seem that there is less bass weight, but it is not true – it is because the bass is very well controlled in time domain, with no hanging or ringing. At the same time, the subjectively less pronounced bottom end, combined with subjectively slightly rolled off top end that effectively fights nasties like sibilants and edginess, let the rich tapestry of the 812’s midrange stand out. This provides the aforementioned listening comfort, as the preamp is easy on ears. Yet everything is presented one or two degrees warmer from what I would call a neutral temperature. Like the Aavik, the Boulder also slightly suppresses the ambience of recordings in favour of the colourful palpable radiance, as if the sound was slightly obscured in a velvety haze that made it softer for ears and lusher and more romantic, an exact opposite what one would expect from a switching amplifier.
Spatial resolution
It is also interesting – although with not very surprising results – to compare the Boulder 812 with Bryston BP-19 (half the price of the 812) and D'Agostino Progression (double the price of the 812) preamplifiers. In its overall presentation, the 812 does not split the difference between the other two, rather it wanders towards the D’Agostino sound, which makes the 812 a really good deal.
The Progression sounds even fuller and richer than the 812 and at the same time it is airier and more open sounding, although one may argue that the 812 has better grip on details. Although it may seem contradictory, the best summary of it is that the Progression is more organic-sounding, more relaxed, wholesome and mature. The BP-19 is not a competitor to the 812 and the Boulder crushes it.
To me, the 812 was built for those who want to have the Boulder flavour without robbing a bank. I think it would be worth revisiting this preamplifier as a combo with the Boulder 916 stereo power amplifier – these two have been conceived to match and I would certainly expect good synergy there.
Manufacturer's website: http://www.boulderamp.com
Associated components
- Sources: Aurender N10, Roon Nucleus, Linn Unidisk 1.1
- Amplifiers: D’Agostino Progression preamplifier, Bryston BP-19 preamplifier, Bryston 14B 3 Dual-Mono power amplifier, Constellation Audio Pictor preamplifier, Constellation Audio Taurus power amplifier
- Loudspeakers: Wilson Audio Alexia 2, Magico M3
- Interconnects and speaker cables: Kubala-Sosna Emotion, Siltech Explorer, Nordost Valhalla V2, Nordost Odin, MIT MA, MIT MA-X XLR, MIT V2.1 Oracle, Audioquest Diamond Ethernet
- Power conditioning: Nordost QRT, Nordost Valhalla V2, Shunyata Research Triton v2/Typhon, Shunyata Research Python Zi-Tron
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