The entire digital circuitry is housed in a module that can be removed by loosening screws on the bottom of the chassis and sliding the module out the rear panel. The module includes the digital inputs, PLL, digital filters, Ethernet streaming circuits, and DACs. Consequently, it is possible for Brinkmann to upgrade the digital section as technology changes while keeping the core performance platform of the power supply and analog output stage.
All of this cutting-edge digital technology feeds a vacuum-tube output stage. Each channel is built around a matched pair of NOS (new old stock) Telefunken PCF803 tubes. This unusual tube, developed in the 1960s for color television, contains one pentode and one triode in the same envelope. The PCF803 was designed to provide at least ten years of service, but the tube is operated more gently in the Nyquist than it would have been in a television. Brinkmann has secured a supply of the tube for replacement in the future. The only analog filtering after the DAC is a pair of Lundahl transformers, which must have a very gentle roll-off with a very high cut-off frequency compared with the typical analog filter found in other DACs.
Finally, the balanced headphone jack is driven by the tube output stage rather than by an IC amplifier outside the main signal path. Headphone listening thus benefits from the dual PCD/DSD signal paths as well as the tube output stage. The headphone output is activated, and the main output is muted, by pressing the “Headphone” button above the headphone jack.
It’s readily apparent that a lot of thought and effort went into creating the Nyquist. This is clearly a statement-level product. Helmut Brinkmann is known for his obsessive listening evaluations to every component in the product, including those that are apparently insignificant. Through this listening he’s discovered many sonically beneficial techniques, particularly in vibration isolation. The Nyquist is also beautifully executed, and it doesn’t hurt that Helmut Brinkmann personally inspects every product before it leaves the factory.
I heard a demonstration of a pre-production Nyquist at last year’s Munich at the front end of Vandersteen Model 7 Mk.II speakers. That room was, by general consensus, one of the best (if not the best) at Munich last year—which, given the level of gear on display throughout the show, is saying a lot. That demo, plus the Nyquist’s inclusion of MQA decoding, the tube output stage, and Brinkmann’s reputation all suggested that a full evaluation was in order.
Brinkmann calls the Nyquist an “analog digital-to-analog converter.” That may sound like an oxymoron, but it reflects Brinkmann’s design approach and intent. As it happens, that moniker also perfectly describes the Nyquist’s sound. In fact, “analog” is perhaps the best single word to illustrate the Nyquist. This is a DAC that, even with standard-resolution files, sounds very “un-digital.” All the qualities that analog is famous for—dimensionality, treble smoothness, bloom, timbral purity—were readily apparent, but coupled with digital’s strengths of image solidity, pitch stability, and bass impact. The Nyquist had a natural, almost relaxed, quality that I found deeply engaging. I would sit down with a notepad for a critical listening session to categorize the Nyquist’s strengths and shortcomings and find myself hours later without a single note—but feeling musically fulfilled.
A large part of why the Nyquist sounds so analog-like is in its reproduction of bloom, dimensionality, and what Jonathan Valin calls “action”—the elusive characteristic of air expanding and contracting around an instrumental image in response to that instrument’s dynamic changes. The Nyquist was the antithesis of flat, dry, sterile, and lacking in air. Instead, the soundstage was gloriously infused with a tangible space between instruments, with a puff of air around them. Digital has the tendency to starkly render images, with precise specificity and sharp outlines, but somehow fails to capture the ethereal component of three-dimensionality of both the soundstage and the images within it. Images lack body and roundness, sounding flat and dry. The whole thing has a “freeze-dried” character.