Rogue Audio 66LSR preamplifier
The design/production team at Rogue Audio, veterans all of Lucent/Bell Labs, have been designing and marketing high-end gear in the Delaware Water Gap region of Pennsylvania since 1994. The 66LSR (for Line Stage Remote) preamplifier is a paradigm of the company's intent to produce a line of high-resolution, high-value vacuum-tube products. The class-A, single-ended-triode 66LSR is simple and elegant in appearance, with a machined aluminum faceplate, a heavy-duty milled aluminum remote volume control, and an external power supply. By employing design variations derived from the technology found in their full-featured flagship preamp, the Model 99, and by carefully parceling out features so as to maximize value, Rogue is able to deliver a quiet, smooth-sounding, eminently musical preamplifier for $1295.
When ordering the 66, the customer can choose between configurations that offer either a vacuum-tube phono section or a remote control. "I explored the possibility of fitting the remote-control circuitry into the same box as the phono preamp, but we'd have to compromise performance or charge more money," explains company honcho and chief designer Mark O'Brien. "Whereas the Model 99 is a substantially larger unit, there were a lot of people who wanted a remote and a lot who wanted phono, and I guess the people who wanted phono didn't care about getting up to adjust things. We wanted to keep the price as affordable as possible, because to include both it would start approaching the price of the more sophisticated, full-featured Model 99, which is $1100 more. So it didn't make sense."
On the front panel of the phono-staged 66LSR is a Record button that activates a series of relays that disconnect the tape deck from the signal loop when the deck is not in use, a feature not included in the line-stage/remote version I evaluated. The more I thought about it, the more dollars and sense this made. How many people do much taping these days? Not many, which is why the second of the 66LSR's two pairs of outputs (labeled Amp and Out 2) is internally switchable between an active mode (for driving a second amp or subwoofer) or a passive mode (for controlling an external processor or acting as a tape output).
"We'd rather offer top-of-the-line audio components than load up on features that people don't want or need," O'Brien explains. "We design our stuff to work well with other gear, so we have a nice low output impedance. The transformers and some of the rectification are housed in a separate box, but some things—like the regulation—you want as close to the audio circuit as you can get it, so that very little can get picked up between the regulator and the actual audio circuit...
"And we employ Mu-followers in all of our preamps, which allows us to achieve a beautiful bandwidth; using one half of the triode as a current-controlling device allows it to operate in a very linear portion of its range, with very low distortion. We also use voltage regulation on each of the individual heater filaments in the 12AU7 tubes, which allows you to reject AC in the heater filaments. We noticed several dB of noise reduction when you run it regulated. And while the 66LSR has a circuit board in it, most of that is dedicated to the power supply and ground. The majority of the audio circuit is actually point-to-point underneath the circuit board."
In the final stages of my listening evaluations for the Vandersteen 2Ce Signature loudspeaker, I happily used the Rogue 66LSR with a Mesa Baron power amplifier, this fitted with 5881 output tubes and generally run in 2/3-pentode mode for that extra power, dynamic range, and pentode bite. It was an exceptionally pleasing combo, the Rogue proving a very obliging sonic mate with the Baron's highish input impedance.
With a basic set of Synergistic Research Designer's Reference2 power cords, Designer's Reference and Resolution Reference Mk.II interconnects (equipped with Active Shielding, a truly marvelous aural enhancement about which I'll report in the near future), and two pairs (for biwiring) of JPS Labs Superconductor Single speaker cables, I was able to flesh out the midrange of the Vandies and tighten up the presence region and top end in a manner I found detailed, involving, and eminently musical.