“Don’t I know you? Haven’t we met somewhere before?” My very thoughts when I first laid eyes on the Rogue Audio RP-7 preamplifier. Then I remembered: It was the Rogue Audio RP-5 that I reviewed back in Issue 260. In all fairness to my powers of observation, the new RP-7 is nearly the spitting image of the RP-5. Externally, it’s the same handsome, full-featured linestage tube preamplifier. Dressed in an immaculate brushed silver aluminum enclosure and accented by round balance and volume knobs and an oval display, there’s a hint of retro-style informing its looks—appropriate considering the quartet of tubes glowing discretely within. So then, given the obvious similarities to the RP-5, what exactly is an RP-7?
The RP-7 is basically everything you may have wanted in the RP-5 and much more. And for some, actually a little less. A quick stroll around to the back panel clarifies this. Arrayed neatly across the expanse of real estate is one of the most comprehensive input layouts I’ve seen in a long time. No longer limited to unbalanced RCA inputs and outputs like the RP-5, the RP-7 goes all-in by offering dual pairs of balanced XLR inputs and outputs. They are MOSFET-buffered to provide a low output impedance for driving long cables or difficult amps. And these are in addition to the trio of RCA line-level inputs and the pair of RCA outputs. You can never have enough outputs, and these (unbalanced or balanced) are especially handy should you get the hankering to add a subwoofer or second amplifier. Adding a finishing touch are the fixed output and processor loop (it will bypass the active circuitry) and unity-gain inputs.
With only minor changes, the front panel retains the commonsense layout of the RP-5. Arrayed along the lower portion of the panel are microprocessor-controlled input buttons that include a selector for mono playback. The display has been upgraded to OLED (custom-designed for Rogue) from the fluorescent unit of the RP-5. Large, readable characters provide volume, balance, and source info. The balance indicator button has been replaced by a display-defeat button, indicative of the more serious sonic intent of the RP-7. Another key change is the excellent stepped-attenuator volume control providing 192 steps and 0.5dB increments—a clear advancement over the RP-5’s 60 steps at 1dB per increment. There are no op-amps in its signal path. Carried over from the RP-5 is a “slow-start” on/off sequence with automatic muting when powering up or down. A ¼” headphone output provides the finishing touch to the RP-7’s comprehensive package.
How did Rogue find the interior real estate for balanced operation? Here’s where the “little less” aspect comes in—the RP-5’s phonostage took the hit. This is due to the fact that the RP-7 is based around an entirely different circuit than that of the RP-5, one that’s more complex and space intensive. Permit me, but I think it was a justifiable sacrifice. At this price level, vinyl enthusiasts become real sticklers for their LP playback rigs. They require a wider range of settings, and easier access to those settings as well. Additionally, of all the analog components that benefit most from an “outboard” chassis and the isolation it offers, the phonostage is top of the list. Noise and resonances are much harder to control when a phonostage and its delicate low-level signals reside within the preamp. And as it happens Rogue Audio makes some fine outboard phonostages in its Triton, Ares, and Ares Magnum designs.
Internally, the tube complement comprises four 12AU7/ECC82’s. Rogue employs a mu-follower—a high-gain, low-output-impedance inverting stage known for good power-supply rejection ratio, low noise, and low levels of non-linear distortion. Like the RP-5, the RP-7 incorporates Rogue’s RP-X hardware/software platform, developed in-house in order to bring more functionality to Rogue’s designs. The tube circuitry is computer optimized for accuracy, ultra-quiet operation, and reliability. The headphone amplifier is a tube/solid-state hybrid that’s fed from the outputs of the tube stage. It’s been designed to offer sufficient power to drive higher-impedance headphones.
The ten-button remote control, the same as the RP-5’s, allows you to access volume, balance, source, mute, mono, and on/off functions from your listening position. In my opinion a more upscale version in a brushed silver housing would better complement the RP-7, rather than the econo-black plastic unit that is supplied. One operational nitpick: The mute feature is not accessible from the front panel; you can only mute via the remote control. So keep that RC handy!
In an email conversation I asked Rogue Audio’s founder Mark O’Brien about the primary aim in designing the RP-7. He replied that “the overarching sonic goals were high levels of transparency and dynamics along with a super-low noise floor. If the circuit layout is executed properly you will also get a great soundstage. I tend to design our flagship models based on what I want in my own system at home, so besides great sound I also wanted a full-featured preamplifier. I appreciate the flexibility of having lots of inputs, a processor loop, and the ability to seamlessly integrate the preamp into a home-theater system.” He went on to add that “you are ultimately listening to the power supply so I focus a great deal of attention and design budget in this area. In the case of the RP-7 there are 17 different power supplies, almost all of which are fully regulated. The high voltage tube supplies are probably much larger than they need to be, but the end result is a very low noise floor and great dynamics. Each of the tube filaments is also individually regulated for low noise. The RP-7 design is far too complex to be implemented with point-to-point wiring so we use very high quality, military-spec circuitboards with heavy copper. Exotic parts include oil-filled Mundorf coupling capacitors, Vishay resistors, and Vishay HEXFRED diodes, among others.”
Sonically the RP-7 advances upon the musicality of the RP-5. Like a family member that attended finishing school Rogue has taken the musical voice of the RP-5 and further burnished its performance in areas that were already very, very good. What remains is the “rose-blush complexion” that warms the mids—the harmonic cushion and velvety textures are all present and accounted for. In fairness, the RP-5 didn’t strike me as possessing an old-world, tubey signature, but it nevertheless conveyed vestiges of that classic warmth and romance—some modest colorizing that I regard as hugely musical. The RP-7 steers a little further away from that inviting glow, but achieves a purity factor in its tonal presentation that is more discernably neutral, with greater dynamic clout, a sweeter top end, a weightier tonal spine, and increased fluidity and polish. Its dynamic envelope was simply wider across the micro and macro expanses, its transients quicker off the mark.
Perhaps most importantly, there is also a newfound solidity and control in the bass and lower midrange that more securely anchors the music—from a rock band to an orchestra. This was a trait I immediately clocked when I cued up the hit “Just What I Needed” from the Nautilus pressing of The Cars’ eponymous debut LP [Elektra]. The track had the tight, crisp drum and electric bass groove that Top 10 pop records are built on. In comparison, the RP-5 had a more relaxed attack. The RP-7 removed a little bit of that softness, giving the music a stiffer sounding board for transients to ricochet off. I could hear the improved immediacy every time I could discern the location of a tambourine or mandolin, an acoustic guitar or a snare rattle or rim shot within the soundstage. Importantly, the bloom factor remains strong when it came to bass violin, timpani, and cello. Vocalists, such as a cappella songstress Laurel Masse from the album Feather & Bone [Premonition], were better focused and more stably imaged, which added to a stronger three-dimensional presentation while also reproducing acoustic venues with greater depth.
The RP-7 zeros in on tonal clarity and color saturation with the best of them in this bracket. Not only did the Rogue better reproduce music’s micro-dynamic gradations, but it also achieved a more finely tuned sense of texture. As I listened to Beethoven’s Ninth with Solti conducting the Chicago Symphony [Decca] the personalities of each orchestral section—woodwinds to brass to strings—were depicted with a wider range of expressiveness and contrast. The RP-7 was so respectful of the tonal and timbral qualities that make up each of these groups it was as if the preamp had undergone advanced sensitivity training.
Much more than merely a “signature” edition, the Rogue Audio RP-7 represents a significant upgrade over the excellent RP-5, ascending to an entirely different class. In virtually every observable parameter it surpasses its lower-priced sibling, while aggressively holding the line against the worthy competition it will encounter in a more demanding and expensive market segment. Surpassing expectations? Just another day in the life of a Rogue.
Specs & Pricing
Type: Vacuum tube preamp
Tubes: Four 12AU7/ECC82
Inputs: Three RCA, two XLR, unity gain, processor loop
Outputs: Two RCA, two XLR, one fixed
Dimensions: 18.5″ x 4.5″ x 17″
Weight: 30 lbs.
Price: $4995
ROGUE AUDIO, INC.
P.O. Box 1076
Brodheadsville, PA 18322
(570) 992-9901
rogueaudio.com
By Neil Gader
My love of music largely predates my enthusiasm for audio. I grew up Los Angeles in a house where music was constantly playing on the stereo (Altecs, if you’re interested). It ranged from my mom listening to hit Broadway musicals to my sister’s early Bob Dylan, Joan Baez, Beatles, and Stones LPs, and dad’s constant companions, Frank Sinatra and Tony Bennett. With the British Invasion, I immediately picked up a guitar and took piano lessons and have been playing ever since. Following graduation from UCLA I became a writing member of the Lehman Engel’s BMI Musical Theater Workshops in New York–working in advertising to pay the bills. I’ve co-written bunches of songs, some published, some recorded. In 1995 I co-produced an award-winning short fiction movie that did well on the international film-festival circuit. I was introduced to Harry Pearson in the early 70s by a mutual friend. At that time Harry was still working full-time for Long Island’s Newsday even as he was writing Issue 1 of TAS during his off hours. We struck up a decades-long friendship that ultimately turned into a writing gig that has proved both stimulating and rewarding. In terms of music reproduction, I find myself listening more than ever for the “little” things. Low-level resolving power, dynamic gradients, shadings, timbral color and contrasts. Listening to a lot of vocals and solo piano has always helped me recalibrate and nail down what I’m hearing. Tonal neutrality and presence are important to me but small deviations are not disqualifying. But I am quite sensitive to treble over-reach, and find dry, hyper-detailed systems intriguing but inauthentic compared with the concert-going experience. For me, true musicality conveys the cozy warmth of a room with a fireplace not the icy cold of an igloo. Currently I split my time between Santa Fe, New Mexico and Studio City, California with my wife Judi Dickerson, an acting, voice, and dialect coach, along with border collies Ivy and Alfie.
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