Aavik’s Design Philosophy
At Newport, as well as in subsequent conversations, Børresen told me more about his thinking behind the design of the Aavik U-300. He was not aiming for an entry- or mid-level integrated amplifier. Instead, he wanted to embrace the benefits offered by a single box, and design an all-in-one unit that would compete favorably with the best equipment in the world. As noted, he decided early on that the only way to provide major power for virtually any loudspeaker, in a relatively small enclosure, was through Class D circuitry. Even though the circuit might have a negative connotation to some audiophiles, he was convinced that he could do better and that the proof was in the listening.
Børresen also extolled the inherent virtues of an integrated amplifier/DAC/phonostage: Very short connections and no interconnects required! And he was not necessarily looking at this as a cost saving, which it undeniably is. Instead, his point was that with proper circuit design and layout in a single box, there was great potential for the resulting sound to be faster and more unfettered than if the signal were traveling through yards and yards of interconnect between components. Again, he did not say that separates could not sound fast, and he was not putting down any particular design. He simply remarked that, with a well-engineered integrated, there was potential for faster, more open sound.
The designer gave me a breakdown of the philosophy and circuit implementation for each of the main sections of the U-300. The U-300 phono section is based on a discrete, floating, balanced, ultra-low-noise, bipolar input circuit. He said he did this to maintain the inherent floating, balanced signal of a moving-coil cartridge. Paralleling several transistor pairs has resulted in a dead-quiet phonostage. At 62dB, the U-300 phono section has ample gain for any of the better moving coils. Børresen believes that designing a phono section to accommodate a wide range of cartridge outputs is detrimental to absolute performance. Accordingly, he designed this section to accommodate mc’s from the lowest output to approximately 1.5mV. This narrower focus allowed him to avoid the JFETs used in most competing designs. Moreover, the use of six, individual, low-noise power supplies for the phonostage, together with a 4-layer PC board with shortest possible traces, has allowed Aavik to obtain an extremely high 94dB signal-to-noise ratio. Cartridge loading is adjustable from 50 ohms to 5k ohms.
The U-300 24bit/192kHz DAC section is also designed in-house and offers five digital inputs: two TosLink, one USB, and two SPDIF. The DAC’s circuits are fitted with ultra-low-jitter onboard clocks to minimize timing errors in digital-to-analog conversion. Børresen indicated that when designing the DAC, he had to decide if it should handle both PCM and DSD. In his view, multi-format architecture, at least at this time, does not offer the ultimate performance of a single-format DAC; thus, he settled on a PCM-type DAC, a decision that he said made it easier to deal with all bit depths and sample-rates in an optimum manner.
For the amplifier section, Michael stated that Class D was the obvious choice as no other technology offers comparable performance in regard to power, size, and the need for cooling. He acknowledges the inherent issues with Class D designs and does not assert that Class D is superior to Class AB or Class A amplifiers. But he does believe that great progress is being made in Class D technology and has devoted a lot of time and energy to building the best Class D amplifier he can at this time. Someday, he speculates, Class D may become the best performer of them all.
The rear panel of the U-300 is reasonably accommodating. Aside from the five separate digital inputs, it has a dedicated RCA input for the phonostage and three other line-level, single-ended inputs. A really useful feature is that the gain of each input may be separately adjusted in three steps: 3, 6, and 12dB. This makes it much easier to match volume levels from different sources. The loudspeaker binding posts are easy to use and will accommodate bare wire, spades, or banana plugs.
Is anything missing? At first I thought it would be helpful to have at least one balanced input, to accommodate owners who already own a balanced cable they prefer. But as I used the Aavik, I came to realize the absence of an XLR in was not really a hardship. Connections from a turntable are always going to be single-ended. With its choice of five digital inputs, only a digital connection is required between a transport and the Aavik DAC. Of course, if one also wants to use additional line-level sources, such as a tuner or a different DAC, single-ended cables would be required.
Some users might also want a volume-controlled line-out, but Børresen explains that is not really the purpose of the U-300. It was designed to literally encompass all front-end and amplification needs, rendering line-out superfluous for most users. If the intended system is fairly complex and includes subwoofers, for example, he correctly points out that many high-quality subs allow connection at speaker level for most coherent performance.
The Aavik remote is clever and worth a few words. A small piece of brushed aluminum with three controls, it was designed by Apple! In fact it’s the same remote Apple uses for many of its products. In the Aavik application it controls volume, allows selection of source, and enables muting.
So the U-300 was conceived to be competitive with the best high-end separates and is gorgeous to behold. It sounded wonderful on two different sets of Raidho speakers at two different shows. But only a trial period at home would let me know if Børresen was right about whether I had no need to be concerned that this small box could get the best from Maggie 20.7s.