Aavik Acoustics U-380 integrated amplifier

Finally—a way to get a handle on the sound of Aavik Acoustics electronics. I’d heard the Danish-made components many times at shows, but always in the context of Ansuz Acoustics cables and Børresen Acoustics loudspeakers. As much as the threesome was inevitable—all three companies are owned by Michael Børresen, Lars Kristensen, and a third shareholder—there was no way to determine the unique sound of each component in the mix.

Not that I hadn’t tried. Reporting from the 2019 High End show in Munich, I noted the distinguished “earth-rooted bass and midrange” produced by the combination of Aavik M-300 mono power amplifiers, Børresen 05 loudspeakers, and Ansuz cabling. “There’s a very special, aged-in-wood component to its bass sound that I find fascinating . . . combined with clear highs that, while not shy, are capable of conveying intimacy.” But that was with a pair of the Aavik M-300 class-A monoblocks (since replaced by the M-380).

The subject of this review, and my first opportunity to audition an Aavik product in a known reference system, is the very different U-380 class-D integrated amplifier ($39,000), which includes a PCM-based DAC as well as a phono stage. A second optional phono stage is available for systems with two tonearms. (When installed, it replaces one set of analog inputs.)

Readers may recognize the names Børresen and Kristensen. The men, who met while Børreson was studying engineering at Aalborg University, and Kristensen was running an audio store, founded loudspeaker company Raidho Acoustics in 2001. Børresen served as speaker designer and Kristensen handled sales; at the same time, Kristensen also conducted Nordost cable demonstrations at shows and dealerships. After the financial crisis of 2008 altered the audio landscape, Dantax became a financial partner in Raidho. In 2017, Børresen and Kristensen moved on from Raidho, and with the help of a third shareholder, who handles marketing, took ownership of Aavik electronics and Ansuz cabling from Dantax. Børresen loudspeakers hit the market at the start of 2019.

The Aavik U-380, which was introduced in fall 2019 at the Rocky Mountain Audio Fest, has the same functionality and circuitry as the model U-300 it replaced. However, every printed-circuit board (PCB) has been rerouted, some components have been updated, and lower-noise automotive transistors have been introduced to the phono stage. “We identified 10 or 15 places on every module where we could do something with a higher degree of perfection, and that’s what we did,” Børreson explained during one of many long WhatsApp chats and exchanges.

Asked about the meaning of the name Aavik, Børresen said that it means “a Bay of Eels” in old Danish: “It’s the name of the area where we have our factory. Today, its name is Aalborg, which means ‘the Castle of Eels.’ As for the ‘U’ in U-380, it signifies ‘unity of function.’ I think one of the U-380’s strong points is that it has a very good DAC and an excellent phono stage. I wanted to make something at a very high level and stuff it into one box. The Scandinavian way of thinking is for something less intrusive in the room. When I started designing the exterior, I wanted something to be simple yet a bit high-tech and three-dimensional. With only the three buttons and a large volume knob, I’ve achieved my goal of simplicity overall.”

Børreson also designed the phono stage’s analog circuitry and the DAC’s analog conversion and current-to-voltage elements. Fritz Sørensen added to the enclosure design, and Mikkel Simondsen, as the primary designer of the DAC, was responsible for the digital circuitry, control software, board layout, etc.

In describing his engineering goals, Børreson said, “When we come to hi-fi, the idea is to impose as little as absolutely possible on the sound. It’s okay for a guitar amp to have a specific tone—a Gibson has a different character than a Fender—because some musicians like it. But when we reproduce things, we should be true to what’s on the recording. We listen for scale, density, and color of tone, impact, slam, presence, and extension, [and work to] maximize dynamics rather than filtering them away. When you have a transient, how long does it remain floating in the room? How well and long can you hear the complexity of overtones to a violin? These things all relate to the extremes of resolution. You can measure distortion and other things, but they don’t matter. Every time we take away noise, even if the noise level is below the floor at which we can hear, it matters. If you lower a power supply’s noise suppression from –120dB to –130dB, it’s so low that it shouldn’t matter, but it does. As another example, you may not be able to hear above 14kHz, but if you play a sound wave at 18kHz and another at 19kHz, they modulate at 1kHz, which you can hear. Everything you design, you design from the point that enough is never enough.”

Børresen, like many high-end audio designers, holds strongly to his beliefs. “When we made the DAC section, clock precision was important. When you know what a piece of cable does to a clock’s phase shift, and how it destroys the timing, you discover that an outboard clock is not the best way of doing things. If you want a clock to resample or multiply, the clock’s output has to be at the point of the signal it’s trying to synchronize. If it’s 10cm away, you have induction in the trace, and that skews the clock and affects precision. Similarly, where you position a power supply matters. Regulation of our DAC’s 14 power supplies is located right at the legs where regulation is required.”

The U-380, which has a 6-layer PCB, employs the Pascal M-PRO2 module, which Børresen prefers because it doesn’t triangulate. “When most class-D modules modulate the signal, they use an oscillator with a triangular waveform. This is why they are noisy and in need of heavy filtering in the output. The Pascal, which uses a sinewave oscillator to modulate the density of signal, doesn’t have the noisy high-frequency component of other class-D amplifiers and needs much less harsh filtration and inductance at the output.

“Immediacy and transparency come from very low inductance. I think that’s the biggest differentiator between a class-D module and a class-A module. With class-A, the response is more immediate because you maybe only have 20% of the inductance that is needed in the output of a class-D amplifier. But I think ours is absolutely the best class-D module you can buy because of the way it does PWM.” That’s pulse width modulation, the technology underlying both DSD and class-D amplification.

The U-380’s mixed-mode DAC, which Børresen describes as “the closest thing you can get to a R2R ladder DAC,” uses a 24/192 Texas Instrument Burr-Brown 1794. “When you turn down the volume, the specifications get better and the noise doesn’t increase. This is because we increase the amplifier’s feedback ratio around the line stage, which lowers noise and distortion and heightens performance. Technically, we do this by using a low-noise precision DAC to set the resistor values in the feedback network.”

The U-380’s phono section has 62dB gain that, according to the product manual, is “suitable for most low to medium output MC cartridges.” Cartridge load impedance is adjustable in 18 steps from 50 ohm to 10k ohm. The manual includes a cartridge balance setting chart. The phono stage uses a large BISS bipolar transistor designed for automotive purposes. “The go-to solution is a JFET, but in my opinion, JFETs are not very clear and transparent, so the sound is a little muffled,” Børresen said. “Because of the transistor’s large die, it has very low noise. . . . Because the noise is so low, I can run it balanced. The advantage of using a floating balanced input is that you can servo out any bias currents. The reason you normally cannot use bipolar transistors in a phono stage without any capacitor coupling is because there’s a chance that base current would leak out, go through your cartridge, and destroy it. But here we have a balanced pair of bipolar transistors on one chip; this creates a floating balanced bipolar input with a very, very low noise floor. We have successfully made a phono stage with a –94dB noise floor. Find any phono stage out there that’s as quiet as this one. You can’t; it’s simply impossible.”

NEXT: Page 2 »

Aavik Acoustics

Rebslagervej 4, 9000

Aalborg, Denmark

+45 40 51 14 31

aavik-acoustics.com

Page 1
Page 2
Page 3
Specifications
Associated Equipment
Measurements

Click Here: kids football tracksuits