PrimaLuna DiaLogue Premium Preamp and HP Stereo/Mono Amplifiers

Tube Audio Made Simple

Equipment report
Tubed power amplifiers,
Tubed preamplifiers
PrimaLuna DiaLogue Premium,
PrimaLuna DiaLogue Premium HP
PrimaLuna DiaLogue Premium Preamp and HP Stereo/Mono Amplifiers

When Kevin Deal, of Upscale Audio in California, and Herman van den Dungen, of Durob Audio in the Netherlands, both audio importers and distributors, started collaborating in the late 1990s, they found that they shared a common concern. They both felt the existing tube component market was plagued by too many examples of high-priced, poorly built entrants of questionable reliability, and that when presented with such uninspired choices, more and more music lovers would forgo the joys of listening to and owning tube gear.

With classic designs like the Marantz 8B or Dynaco ST-70 in mind, they felt that music lovers should have better access to gear that drove tubes with reduced distortions and extended tube life and reliability. Ideally, these designs would use point-to-point wiring, and offer strategic features (such as PrimaLuna’s AC Offset Killer and Adaptive AutoBias) to further extend the lifespan and performance of the tubes in the system. The biggest gains would be dependability, ease of use, and the enhanced sonic properties such a design would afford. Overall, they wanted to create tube products that offered an enhanced user experience. So over the course of about three years, starting in 2000, they joined forces to start PrimaLuna, with these goals in mind.

You may read more about their efforts in Jim Hannon’s engaging and entertaining section of The Absolute Sound’s Illustrated History of High-End Audio, Volume 2: Electronics. The short version is that after some three years of preparation, planning, and development, in 2003 PrimaLuna became a reality with the introduction of the ProLogue series of components to the European market. Its initial success led to wider distribution, and to the creation of the DiaLogue series of components in 2006. It is the current flagship products in that DiaLogue line that are the subject of this review.

One of the many methods brought to bear to realize the PrimaLuna vision included manufacture in China. While others have tried this with limited success, PrimaLuna has effectively leveraged the reduced costs of overseas production by paying fanatical attention to quality control, with constant parts-sourcing monitoring and rigorous adherence to the manufacturing rules Kevin and Herman put in place and stringently enforce. This excessive oversight, continuously and methodically applied, seems to have had its desired effects.

Next, rather than hire a full-time design team, they decided it would be much more cost-effective to contract designers from other successful houses. As such, their designs are primarily the work of Marcel Croese, who was Chief Engineer at Goldmund in Switzerland.  However, Herman also has added two more engineers to the design team.  

Both the Premium preamp ($3199) and HP amplifiers ($3899 stereo, $3899/each monoblocks) share an identical dark metallic grey chassis, 15" wide, by 8.3" tall, by 14.2" deep. Using the same-sized chassis is a smart production move, reducing waste and duplicated efforts. The HP amps weigh in at just over 66 pounds each, while the Premium preamp tips the scales at a substantial 53 pounds. The results are particularly sturdy components, surprisingly more massive than you would expect at a mere glance.

The lower 3½" of each chassis is allotted to the circuitry, with a 3/8"-thick front panel (available in silver or black) accommodating controls. There is a rocker power switch on the front of the left side panel; all the jacks and the AC connection are on the rear. The upper rear section, roughly 4¾" tall, 5½" deep, and the full 15" wide, houses the transformers under a slot-vented enclosure. Finally, the upper front section is open, housing the respective tube complement, protected by a unique black curved guard employing two arched rectangular pillars that flow from the front top of the transformer housing to the top of the front of the chassis just behind the faceplate, with round cross bars running left to right between them, and glass end covers. The whole look is more than just vaguely reminiscent of a “roll-top” desk.

The DiaLogue Premium preamplifier is a dual-mono, tube-rectified linestage, using a pair of 5AR4 rectifiers, and three 12AU7s per channel (one driver, two inputs in a conspicuous attempt at lowering distortion and increasing dynamic range and bandwidth), all arranged in a slight arc under the tube guard. Finally, in a row immediately behind the 12AU7 array are the two rectification 5AR4s flanked by a set of Nichicon 330 microFarad capacitors. Very attractive, functional, and easy to access.

The choice of the 12AU7 seemed obvious, with more in current production today than virtually any other tube made, as well as significant stockpiles of vintage NOS varieties. The owner’s manual touts that you may substitute ECC82s, ECC802Ss, E82CCs, 5814s, 6189s, or even CV4003s.

The volume control is a Japanese-built, high-quality, Alps Blue Velvet potentiometer, with input selection accomplished using premium sealed Fujitsu relays, rear-mounted and very proximate to the input jacks. When an input is selected, only that particular relay closes. As all the other relays are left open, this quite effectively isolates noise and signals from other sources. An additional benefit of this choice is drastically shorter signal paths, further minimizing pick up of radiated or generated noise.

The preamp’s front panel offers the volume control to the far left side, a centered status indicator LED (red for standby, green for ready) with a mute indicator just above it, and a rotary source selector switch to the right. The back houses, from left to right, a set of tape (monitor) outputs, five sets of inputs (CD, Tuner, Aux1, Aux2, and Aux3), and two sets of amplifier outputs, all single-ended. There are no provisions for XLR connections. To the right side is a grounding post and the EIC AC socket.

The remote is a 19-button, 7⅞" long, 2⅜" wide, 13/16" high black rectangle, with rounded sides. Besides volume control, mute, and direct input selection, it includes function control for the PrimaLuna CD player, and a button for on-the-fly switching of the amplifiers between ultralinear and triode modes. Unique in my experience, two black rubber O-rings circle the remote, one each near the very top and bottom, seated into channels recessed into the chassis itself, assuring that the remote will not be scratched by, nor easily slide off, any surface that it is placed upon. Nice touch.