Rogue Audio Eighty-Eight Magnum Stereo Power Amplifier 
Home Theater Power Amplifiers Stereo Amplifiers
Written by Brian Kahn   
Tuesday, 01 October 2002

Rogue Audio is a fairly new company in the world of high-end tube audio gear. Formed in 1994 by Mark O’Brien, who remains involved with the company as its president and head designer, Rogue Audio strives to provide reasonably priced, high-quality tube gear. A review of the Rogue Audio components reveals that the company spends its time and resources on items that will improve sound quality and not on gingerbread that is unlikely to be used often by audio enthusiasts.

The Rogue Audio Eighty-Eight Magnum power amplifier is a good example of Rogue Audio’s efforts to provide high-quality sound, without frills, at a very fair price. The Eighty-Eight Magnum amplifier retails for $1,995, only $400 more than the non-Magnum version. The Rogue products can all be purchased in their regular versions, or for a small increase in price, the Magnum version with upgraded parts reminiscent of a "The Parts Connection" upgrade kit. Rogue Audio states that the Magnum line accounts for the majority of their sales.

It is easy to see why the Magnum line is becoming popular, following Rogue’s philosophy of a lot of bang for the buck. The Magnum series upgrades include upgraded power supply components, capacitors, resistors, binding posts, tube sockets, tubes and wiring. No flashy upgrades, no fancy options that only a few will use, just solid engineering where it counts. While I have not had the opportunity to listen to the non-Magnum version of the Eighty-Eight, reviewing the upgraded parts list alone indicates that it is probably a wise investment.

The Eighty-Eight came well-packed, bolted to a wooden base and the large driver tubes boxed separately to keep everything safe. After I removed the Eighty-Eight from the box, I was able to see the silver faceplate was made of heavy machined aluminum, with a large black circle in the middle. The circle is slightly set back, with a brushed silver power button in the center, a blue power light just above it. This design won’t grab your eye the way the new Krell or the Conrad Johnson 17LS preamplifier will, but it will definitely score much higher on the aesthetic charts than the typical black box audio component. Once I removed the amplifier from the wooden base, I was surprised that the chassis was a bit flexible with the cover removed. The amplifier was stiff enough with the cover attached and I would caution against moving the unit with the cover detached to avoid damaging the chassis with excessive flex.

The cover is made of heavy black steel and is well-perforated to allow fan-assisted tube cooling. I was a bit wary of noise when I saw the fan, but later found it to be very quiet and non-intrusive during listening. The back panel features high-quality binding posts and single-ended inputs, as well as a detachable power cord. There are no provisions for bi-wiring or balanced inputs. The lack of balanced inputs was a conscious choice by Rogue Audio, as the addition of balanced inputs would have added at least two hundred dollars to the price without any sonic benefits. This is in line with the Rogue Audio philosophy of delivering maximum value for money.

The circuit topology of the Eighty-Eight utilizes 12AX7 paraphase input tubes feeding two 12AU7s per channel. The 12AU7 mu-follower drivers feature low distortion and desirable impedance characteristics to drive the two Russian-made Electro Harmonics 6550 output tubes. The Eighty-Eight can be run in Ultralinear mode for 60 watts per channel, or triode for 35 watts per channel. There are user-selectable four and eight ohm output taps. Both the tap selection and the selection between ultralinear and triode modes require removing the cover. These selections can be made with simple re-configurations within a minute or two of removing the cover. There are no other internal adjustments to be made, as the circuit uses a cathode biasing design, eliminating the need for bias adjustments.

The Setup
I set the Eighty-Eight Magnum power amplifier up in my reference two-channel system. I placed the amplifier down on an amplifier stand, providing a solid surface and plenty of working room. It is important to select a location that provides plenty of ventilation, as the unit uses a fan to keep the tubes from overheating. I removed the top easily enough with a Phillips screwdriver and went to work on the tubes. The only tubes needing installation are the four large output tubes, which were easily installed in a couple of minutes.

The other internal settings, discussed above, are the selectable impedance taps, which permit choice between triode and ultralinear modes. The amplifier ships in the ultralinear mode. To switch modes, the user simply sets four switches to the desired mode. Selecting between the four and eight ohm taps is slightly more complicated, but still easily done in a few minutes. The amplifier comes with the eight ohm wires connected to the inside of the speaker binding post. The four ohm wires are covered with plastic sleeves. To switch between four and eight ohms, simply disconnect one set and connect the other.

The Music
I listened to the Eighty-Eight with both my Martin Logan Ascents and B&W CM4s, using the latter for the majority of the work. The Ascents were only used for a short time, enough to satisfy my curiosity. I wanted to see if a tube amplifier could drive the hard to drive electrostatics, they could. I ran the Ascents with the Eighty-Eight in Ultralinear mode and had no problems at moderate listening levels.

After letting the amplifiers break in for a few days, I placed Sheryl Crow’s new album “C’mon, C’mon” (A&M Records) in my system. Crow’s voice was full of life, with a presence and warmth that I had not heard without a tube in the signal path. While listening to the well known “Soak Up The Sun” track, I was surprised to find the Eighty-Eight delivered deep and weighty bass, as this is generally an area of weakness in a tube amplifier. No, the Eighty-Eight didn’t have the tight bass control of a good solid state amplifier, but it did provide more weight and extension than I anticipated. I found the Rogue to exhibit the typical tube qualities of being a bit softer in the bass, slower on the attack than high-end solid state amplifiers. This didn’t detract from enjoying bass guitar and drums on most kinds of music but was noticeably thick and distracting on some miscellaneous dance albums I had lying around that have lots of deep synthesized bass lines. The vocals were definitely the Eighty-Eight’s strongest point and this makes sense, given that tubes generally roll off earlier in the high end than their solid state counterparts do and they lack the low-end dynamics of solid state. However, tube components can do things with vocals and midrange that few if any solid state amplifiers can. The Eighty-Eight takes advantage of its tubed circuitry and is capable of rendering a midrange full of body and ambience, sweet and smooth without a hint of grain.

As I continued to listen to the album, I enjoyed the large soundstage, which extended back quite far, beyond my front wall. I could sense a lot of ambience in the soundstage, although the exact positioning of the instruments was hard to pinpoint at times. After listening to the Crow album, I was curious to hear how the Eighty-Eighty would perform with male vocals. I listened to Marc Cohn’s eponymously-titled album. (Atlantic Records) While I was duly impressed with the musicality of the piano on the “Walking In Memphis” track, I felt that Cohn’s voice had a bit less body than I had anticipated. I listened to more tracks, including “29 Ways,” which starts off with the drums deep in the soundstage. I found the instruments sounded great, lots of weight, musical, detailed in all but the lowest octaves, etc. I was curious about the thinness I heard in Cohn’s voice. I changed the operation of the amplifier from Ultralinear to triode, and listened some more. I immediately noticed that there seemed to be more ambience and the midrange became even smoother and sweeter. Cohn’s voice was noticeably more vivid, with an added sense of weight. The added ambience and texture came with more softness than experienced in the Ultralinear mode. This additional softness will easily negate the digital harshness found on some recordings, but does come at the cost of some detail. Listening in the triode mode was very musical and easy on the ears. I doubt that one could get fatigued even after many hours.

Still curious about the thinness in Cohn’s vocals, I decided to try some other male vocals. First, I switched the amplifier back to Ultralinear mode, as that is how I had done most of my listening. I searched for a recording I knew to be good and ended up using Toy Matinee’s eponymously-titled DVD-Audio disc (DTS/Unitone Records). Kevin Gilbert’s vocals did not disappoint, leading me to believe that it was the recording and not the amplifier that was the primary contributor to the thinness in Cohn’s voice. The first track “Last Plane Out” grabbed my attention with the guitar and bass work even before the vocals began. The guitar and, seconds later, the bass came alive, each with its own sense of space and well balanced with each other. I think that the extra resolution provided in the DVD-Audio format was well utilized. I found that the midrange on the DVD-Audio disc was even better than that of the CDs. The additional resolution provided added dimensionality, which was easily heard while listening through the Rogue amplifier. The highs even seemed to benefit, as the cymbals in the opening of “The Ballad of Jenny Ledge” were crisp and three-dimensional without being harsh.

Before switching back to triode mode, I grabbed a little bit of rock 'n' roll. I inserted Van Halen’s self-titled album (Warner), skipped to the “Eruption” track and cranked it up. I found that the Eighty-Eight was able to drive my B&Ws to some pretty loud volumes with ease, never sounding harsh. Eddie’s guitar solo sounded great and I found myself turning it way up, much higher than normal. At extreme volumes, the amplifier began to run out of steam, the soundstage began to shrink and the dynamics withered. When I reduced the volume to sane levels, the soundstage and dynamics returned. The next track, “Ain’t Talking ‘Bout Love,” played at moderately high levels confirmed that the Rogue could not transcend one of the limitations of tube-based amplifiers. The Rogue could not provide the in-your-face dynamics that prove to be so elusive for tube amplifiers. On the other hand, this goes hand in hand with the characteristics of tubes that so many love.

I then changed the amplifier back to triode mode, to get even more of the tube characteristics I just mentioned, namely the warm midrange. I liked the amplifier's ability to change between Ultralinear and triode modes, allowing the user to tailor the sound to individual tastes. I preferred the triode mode for most listening, especially more intimate recordings. I listened to all sorts of recordings with the Eighty-Eight for hours on end in the triode mode without any sense of aural fatigue. I only felt the need for Ultralinear mode when I wanted to crank it up, and even then, the triode mode usually worked fine.

With the amplifier in triode mode, I went to some more mellow music. I listened to Pink Floyd’s Dark Side of the Moon (Capitol Records/ Mobile Fidelity), wondering how a triode tube amplifier would work with some rock 'n' roll that was of a more subtle variety, and immediately noted that the low beats in the opening of “Breathe” were reproduced with a good sense of weight and solidity, even though there was a slight loss of detail. On the track “Money,” the guitars retained their edge and had ambience and weight not often found in solid state systems. The amplifier had plenty of power to drive the system to moderate indoor levels without any hint of strain. The limitations imposed by the tubes did not compromise the listening experience and trading the last bit of frequency extension for the incredible midrange proved to be a good bargain. Indeed, this is the trade that one makes with tubes -- if one is willing to give up a bit of dynamic range and frequency extension, there is much to be had in the midrange.

Finally, I listened to Tchaikovsky’s 1812 Overture (Telarc). Yes the infamous cannons weren’t as crisp as I have heard them before, but the wind and string sections were phenomenal. The strings and horns were smooth and sweet. I felt like they were right before me, and their sense of body made it seem that I could almost reach out to them.

The Downside
Tubes, unlike solid state, can be finicky and will, at some point, need maintenance and/or replacement. Rogue Audio states that the tubes should last two to three years when listened to for 40 hours a week, as the amplifier is designed to run cool, extending tube life. We were unable to confirm this and it quite honestly sounds a bit too good to be true, even with the measures taken to extend tube life. Normally, output tubes last around 2000 hours, meaning that at 40 hours a week, you will be replacing tubes on an annual basis at $150 a set. That’s nothing compared to tube sets for more expensive amps, which can cost as much as an entire Rogue amp.

Tubes put out a considerable amount of heat. It is imperative that the amplifier is given plenty of ventilation room and little children and pets are kept at a distance. Tubed components are also more sensitive to vibration and need to be placed accordingly for them to perform at their best. Most solid state amps can just sit there and rock without much hassle.

Sonically, the Rogue Eighty-Eight’s main downside, one shared with many tube amplifiers, is lack of extreme detail, especially at either end of the frequency range. Listeners craving detailed high end, or those who study the bass line on Holly Cole’s “Train Song” every time they audition a new component, are not likely to be pleased with a tube amplifier.

To tube or not to tube? That is the question -- are you willing to give up some dynamic range and frequency extension for a warm, liquid midrange? The choice is up to you, but if you opt for tubes, the Rogue Eighty-Eight Magnum Amplifier is a true bargain in the world of high-end tube amplifiers. Those who enjoy tubes and do not need to have the prestige of a more established brand would do well to check out the Rogue. The amplifier exhibited a level of liquidity and ambience that one would be hard-pressed to find in a comparable priced solid state unit. The Eighty-Eight lacks some of the detail that you would expect to find in a similarly-priced solid state unit, but it also has none of the transistor glare and grain that often comes along with solid state, which is again part of the trade-off. For those who are willing to "go tube" and are seeking an amplifier in the $2,000 range, the Eighty-Eight Magnum delivers the warmth and ambience that make tubes desirable with very little sacrifice elsewhere.
Manufacturer Rogue Audio
Model Eighty-Eight Magnum Stereo Power Amplifier
Reviewer Brian Kahn

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