July 2003

World Premiere!
Manley Labs Mahi Monoblock Amplifier
Review by Rick Becker
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  My first actual glimpse of the Mahis was back in March at the Montreal show. They were sitting on silent display next to the physically larger Manley Neo-Classic SE/PP 300B monoblocks, which were sitting next to some much larger monoblocks that were playing the music. "Oh, my G-d," I gulped, with a hollow, sinking feeling. The Mahis looked so small that I thought they would never work in my 6,000 cu. ft. listening room. It had been a couple of months since EveAnna Manley had promised me a review pair. Maybe I would get lucky and she would forget to send them. 

Two weeks later my mother passed away and a week after that, the Mahis arrived without warning. The boxes were small. My life was in upheaval, but I figured I should at least pop them into my rig and get them broken in. I almost did damage to them before I realized they were shipped with the tubes in their sockets, surrounded by foam. Taking one out of the box, I felt I could easily shot put it across the living room... well, maybe the short way. Setting them on 2.5-inch thick slate foundations on either side of my Plinius SA-100, they looked like little cathedrals next to an NFL indoor stadium. Twenty watts triode, 40 Watts ultra-linear was just not going to work--not without much larger transformers than what the Mahis came equipped, or so I thought.

I edged the volume up slowly, not wanting to burn out the voice coils of my speakers with too little power. At 75dB in the listening position, the music was immediately different than what the Plinius gave me, and proceeded to become more inviting over the next hour. And of course, the off-white glow of the tubes was a completely different experience than the bright blue led on the silver faceplate of the Plinius. The front faces of the Mahis were cantilevered out over the edge of the slate, and the bulb that illuminated the faceplate shone down on the front edge of the slate from the underside of the amplifier. Listening in the dark with Linda at my side, I broke into laughter. "What?" she exclaimed, not having the faintest idea why I was laughing. "Look," I pointed out. "They look like little South Sea restaurants in a diorama!" We laughed our deepest belly laughs for almost a minute. 

During the first few weeks I listened to the Mahis while eating breakfast and late in the evening after long days filled with my work and dealing with the aftermath of my mother's death. Early on, a quick comparison of triode versus ultra-linear modes had me listening exclusively in the triode mode. And after a week or so, it dawned on me how much I was enjoying the music at such a low level--a good 10dB lower than usual! I started to inch the volume up and listen more critically. As I reached my more normal listening level of 85dB to 87dB, with occasional peaks up to 90dB, it became clear that in some ways the Mahis were out-performing the Plinius. The midrange was more holographic and the music in general was more inviting. At first I thought it was just the soft clipping that everyone attributes to tube amps. Then, at some point, perhaps a month after I received the amps, I revisited the ultra-linear mode, rated at 40 watts. It sounded much better this time, but the soundstage was still more compressed from front to back than in triode. The amplifiers were finally reaching their stride after a break-in period that had yielded incrementally imperceptible improvements in daily use in the triode mode. Be forewarned not to throw the triode/ultra-linear switch while the amplifiers are fired up. It might work 99 times out of a hundred, but you won't enjoy the music if it is in the shop. To be safe, the factory recommends you flip the switch only while the amplifier is turned off.

The variable feedback switch (bottom left under "MANLEY" in photo), on the other hand, can be thrown while listening and it is very educational. Early on, it was really evident why the middle position is labeled STD (standard). In the MIN position the image was brighter, more present, but the music wandered all over the soundstage. In the MAX position the music was so repressed I don't even know why it was included. I settled in on Standard and left it there for most of the review period. 

When I revisited it at the end of the review period, I realized the variable feedback switch is like the usher at the concert hall. It seats you in different positions. Maximum feedback puts you at the back of the hall, with a very tight sound, but a very dim view of the performers surrounded by the dark walls of the theater. Standard puts you just forward of the middle of the hall, with a precise soundstage, reasonably good view of the performers, and just a little darkness at the edges of the stage, the ceiling above, and the rows of people in front of you. Minimum feedback puts you just behind the orchestra pit. There is a hint of darkness at your peripheral vision, but you are almost moving your eyes from side to side to follow the music as it move about the stage. Minimum is most like being there. Of course, most audiophiles want a combination of Standard and Minimum, but you are not going to get it from this amplifier. You have to throw the switch, sit down, and enjoy the music. 

The tonal balance of the Mahis was distinctly different from the Plinius in the early going. With the Plinius, from the upper midrange through treble, it was as though I was looking out into the universe across the radius of the Milky Way. The notes, and their harmonics, like stars, seemed to go on forever, eventually to the point of becoming milky clouds of high frequency that my ear could not resolve. With the Mahis, it was like looking out into the universe at right angle to the spiral of our galaxy. The notes, like stars, were crystal clear, but they were limited in number, and it was a lot darker between them, almost as if there were no upper harmonics. Most likely that was the result of the fine resolution of the Russian EL84 tubes, the quietness of the amplifiers, and the absence of any grain. If that description is not clear enough for you, stop your motorcycle at the side of the road on a 9,000 foot mountain pass in Wyoming, and look up. It will come to you. 

At the other end of the tonal spectrum, the Mahis seemed to go as deep as the Plinius, at least to the 28Hz functional limits of my Coincident Partial Eclipse II loudspeakers, but there was a little less tightness or control of the bass notes, and the Plinius was more effortless. Nonetheless, the bass notes with the Mahis were more three-dimensional and contributed more interest in the music. Soundstaging was also distinctly different between the two amps at this point in the reviewing process. The Mahis exhibited considerably more depth in triode mode than the Plinius, but the soundstage width was limited pretty much to the distance between the two loudspeakers. The net effect was that I felt like I was sitting farther away from the performers with the Mahis, and enjoying the music more. I easily became so engrossed in the music that not once, but twice I failed to recognize that a recording of Mahler's First was not actually stereo, but mono!

What does all that mean? Are the Mahis "dark"? Well, they certainly are dark in the sense of their black wrinkle powder coat paint jobs and subdued glow of the EL84 power tubes, but musically, "dark" is often seen as pejorative. It is time to toss out that kind of thinking. With the music coming from the Mahis I find myself emotionally responding to the fundamentals of the notes, which reside, for the most part, in the bass and midrange. Pace and rhythm come to the forefront. These amplifiers make me want to get up and dance! If you can't find the beat with the Mahis, you're probably listening to New Age music. A sampling of violin music proved that there was nothing more to be desired at the top end.

The bass response far outstrips my expectations for this amplifier, but apparently beefing up the energy storage capacity of the B+ rail from 49 Joules in the earlier 50 Watt monoblocks to almost 180 Joules in the Mahis is the reason. For comparison, a friend of mine who collects old Dynaco amplifiers tells me that they had less than 10 Joules of energy storage. What does this mean? Say you were playing a modest rock and roll tune by Melissa Etheridge, and turned the Mahis off. The music plays on and finally fades to black some ten seconds later. It also means this amplifier does serious bass for a low powered tube amp and has plenty of reserve power to handle complex music passages. Size matters here, and while you might expect that much larger transformers would be helpful, such is not the case. My friend explains that there is a delicate balance between tube size, the size of the wire in the transformers and the size of the transformer themselves. From what I heard, I would say the Mahi is pretty close to the ideal.

Stepping Back

In the milieu of the first two months of listening, in addition to the family crisis, was my personal obligation to write my review of the Montreal show. Consequently, the review of the Mahis evolved in a casual manor. There was no yellow legal pad beside me this time, just lots of listening until the next great idea popped into mind.

And the next great idea, (after the initial great idea of using the Balanced Power Technologies C-10 power cords -- see my earlier review), was to try some HAL-O tube dampers on the 6414 driver tubes and 12AT7WA input tubes (again, see my earlier review). These little HAL-Os improved the focus of the music both up front and deeper into the soundstage. The soundstage width improved to slightly outside the loudspeakers and the depth extended beyond the front wall out into the front yard another five feet or so--not bad for a $40 investment!

With this success under my belt, I thought it only fair to plug in my beloved Musical Design SP-1 preamp in place of my reference, since the Musical Design was a lot closer in price to what a potential Mahi owner might actually use. With HAL-O tube dampers on both the SP-1 and the two small tubes on each Mahi, this combination didn't give up much in overall musical delight. Focus suffered a little, as did the overall smoothness of the presentation, with the SP-1 being neither as extended in the treble, nor as tight in the bass as the CAT pre-amplifier. The soundstage seemed as brightly illuminated as before and I felt no urgent need to switch back to the CAT. In most cases I expect a typical Mahi owner would likely have a better preamp than the SP-1, or, perhaps, no preamplifier at all, running directly from a CD player with a variable output. With its low (460 mV) input sensitivity, this should work quite well. Nonetheless, the excellence of the CAT preamplifier was not wasted on the Mahis.

Up to this point, I might have summarized the Mahi as a very competent amplifier worthy of praise and recommendation, but not a breakthrough product. It was always engaging and fun to listen with them in my system; better than with my Plinius in several important areas.

It Ain't Over 'Til It's Over

A reviewer's system is often an organic, ever-evolving entity. As much as we value a constant, known system into which we can plug a new component for evaluation, in reality, reviewing opportunities sometimes come out of the blue. And I, for one, have an invisible sign on the front wall between the loudspeakers, which frequently lights up with the words "What if...?"

The "What if...?" sign came on late in the reviewing process as a result of my Montreal report. Stillpoints expressed appreciation of my high praise of his room, but lamented my lack of mention of his Stillpoints. What can I say? The eye of the hawk doesn't see every mouse in the field, and the Stillpoints were well hidden deep under every rock in his system at the show. A week later I had two sets of Stillpoints and several sheets and strips of ers magic paper in my possession. I wasted no time in putting three of these resonance control cones under each Mahi.

To make a long story short, (and save the details for an in-depth review), the Stillpoints transformed the Mahis from a very good amplifier into a world class one. The resolution became razor sharp without any harshness, not that there was any to begin with. It gave me that U R There experience. The soundstage now went three feet to the outside of each speaker, when such wide soundstaging was inherent in the CD, and another ten feet deeper into my front yard. The width of the soundstage at the rear almost matched the width at the front, rounding off slightly at the back corners. The spatial clues revealed by the enhanced micro-dynamics gave the music more presence, and the musicians were precisely and firmly positioned on the stage. Hearts of Space on NPR became Hearts of SPACE! My system was flying at an all time high.

But how can that be? How did this 20-Watt amplifier that I was afraid to crank the volume on, come to rule my audio roost? After the Stillpoints arrived, the differences between triode and ultra-linear mode diminished as the sound in both modes greatly improved. I still prefer the triode mode for most listening, but classical orchestral music seems to do better in ultra-linear. The other night I got nailed by one of those symphonies with cannon fire in the middle of it. Heavy metal, on the other hand, seemed to just cruise right through on the Mahis, probably due to the compression in the recording process, and the strength of the B+ rails. The extra watts in the ultra-linear mode also gave me the confidence to play the music a little louder. Not until I reached 100 db peaks did the clipping become really noticeable. Perhaps someone out there will do the math and tell me that, in such a large room, I must be blind to clipping. If so, then I consider myself blessed.

Normally, I am not one to listen to music at loud levels. Appropriate levels, yes; head-banging, no. A couple of articles in print journals recently addressed the benefits of listening to music at the level at which it was recorded to avoid distortion of tonal balance. If I get occasional peaks much above 95dB, or the spl meter consistently dancing much above 90dB, I am at the upper limit of my comfort zone. Remember earlier I wrote that I started out with the Mahis being totally enjoyable at 75dB at the listening chair? All this starts to point to the unsung hero of this review, the Coincident Speaker Technologies Partial Eclipse II loudspeakers. With an efficiency of 92dB, and a benign impedance load that does not dip below 8 ohms, this loudspeaker was born for tube amplifiers. Not 2A3 amplifiers, for sure, but not necessarily tube amps reminiscent of a case of Coca Cola bottles, either. It should be no surprise that EveAnna Manley and Israel Blume, (El Hombre at Coincident Speaker Technologies), presented their wares together at the last CES. 

Would the Mahis perform as well with a more typical loudspeaker? My young computer guru brought over his Paradigm Reference Studio 20 monitors with basic wood stands. These loudspeakers are rated at 8 ohms and 89dB efficiency, and are well respected at their $650 price point. The results were considerably less impressive than with the Coincident loudspeakers. And this, again, should be no surprise. Three db less efficiency in a loudspeaker requires double the power at a given listening level. The impedance curve of the Paradigms might not be as smooth as the Coincident's, and the loudspeaker stands for the Paradigms were no match for the floor standing Coincidents, which rested on Symposium Isis Platforms on top of 2.5-inch thick slate. To further prove the point, we replaced the Mahis with the Plinius amplifier and the performance of the Studio 20s improved markedly. One trial does not prove the point, but I think this example points the argument in the right direction. The Mahis need to be matched with tube-friendly loudspeakers for optimal results. A smaller room would also help a less efficient loudspeaker.

Styling

In some circles they say, "presentation is everything," but not in high-end audio. Yet styling does count in high-end audio, for much more than many people like to think. We're much more comfortable talking about sound concepts like "tube sound," "transistor sound," "horn sound," "digital sound," "analog sound" and so on, even as the audible differences in these different technologies seems to be diminishing with the introduction of new products. More so in the last decade than the present, we talked about corporate sounds, too: the Audio Research sound, the Cary sound, the conrad johnson sound and so on. Yet, the products of most successful corporations also have a corporate visual style, or "look," that influences the buying decisions of people, builds brand loyalty and fortifies their corporate identity.

Perhaps because Manley Laboratories has, like they sing in an old blues song, "one foot on the platform, one foot on the train," they have avoided being acoustically typecast. Maybe, because they make products for both the recording industry as well as the "enjoy the music" crowd, they have a more knowledgeable perspective on what goes into the microphone and what comes out of the loudspeaker. A New Age musician friend informs me that from the pro audio side of the fence, Manley is a most revered manufacturer. A quick scroll through their website seems to indicate that their pro audio products are the heavy end of their business.

Manley also has a distinctive visual corporate identity clearly influenced by pro audio gear that has evolved somewhat gracefully under the leadership of EveAnna Manley (pictured right holding a Mahi monoblock amplifier), at least on the "enjoy the music" side of recorded music. The Stingray integrated amplifier was an instant classic, perhaps revealing a more feminine touch than the subsequent Steelhead phono stage or the retro-styled Neo-Classic 250 monoblocks. The black wrinkle powder coat paint scheme harkens me back to my little boyhood when I used to stand beside my father as he worked his ham radios in the post-WW II era. Over the years, our basement filled up with cabinets and radios with various sizes and shapes of vacuum tubes inside. Is there any wonder that I can relate to these monoblocks? It is clearly an industrial styling with deep authentic roots in the recording industry, no matter how gracefully applied are the modern retro touches.

The very fact that the Mahi is a monoblock configuration is itself a styling statement--one that seems to be all the rage these days. Thirteen out of twenty non-integrated tube amplifiers in the Stereophile Recommended Components list in Class A and Class B, are monoblocks, and two others can be ordered that way. Furthermore, the $2,000 to $3,000 price range is presently a hotbed of tube amplifier activity, so somebody must be buying these things. 

While the Mahis replace a more pedestrian 50 Watt Mono model (which also used the EL84 tube), they are evolved from the Stingray integrated amplifier. EveAnna tells me the music sounds a bit better with the Mahis, which have a slightly larger B+ rail capacity, plus the benefits of separation of channels and use of shorter loudspeaker cables. This assumes, of course, a proper pre-amplifier, an extra set of good interconnects, and a pair of amplifier stands, are added with the Mahis. I have seen, but not heard the Manley Stingray, so I can not tell you whether the extra system complexity and cost justifies the improvement in sound. Most likely that decision will be made on the basis of style and the limitations of space. Certainly the Stingray is the more visually intriguing amplifier, but the Mahis are far ahead of the budget imports from the Far East, and distinctly different from the Nuovo Chinese upper end products. Construction is flawless and solid. The transformers are dead quiet. The labeling of the tubes, bias settings, switches and so on, right down to EveAnna's signature at the back of the amplifier are letter perfect. Small as they are, you will not want to hide them. 

While not an expert on tubes or tube amplifiers; this has been an adventure. Nor did I get involved with any tube rolling of other brands or new old stock, a direction that those so inclined may find delightful. EveAnna has chosen modern tubes for their reliability and repeatability in the future. In that same vein, the modifications I explored involved the addition of other readily available products, not the replacement of parts that came with the Mahis (aside from the power cord, that is). Almost as an afterthought, let me add that biasing the tubes was so easy that it should discourage no one who can hold a meter probe in one hand and twist a screwdriver with the other.

Summary

Two CDs capture the essence of the Mahis in my experience with them. The first is Jimi Hendrix' "Live at Winterland," which, in a lesser system, is a dreadful recording. With the amplifiers on Stillpoints, in triode mode with standard feedback, the Mahis cut through the noise and delivered a rock steady three-dimensional presentation of the Jimi Hendrix Experience that let me hear every note. Switching into minimum feedback mode transported me to just in front of the stage back in 1968. The other CD is the Burmester CD3 with the "Poem of Chinese Drums," where once again, 20 watts in triode mode, standard feedback, the Mahis put these drummers right in my listening room... well, just outside in the front yard if the truth be known, such was the soundstage. At reasonable listening levels in my large room, it was truth of timbre, transparency, focus, soundstaging, and most of all, the ability of the music to move me emotionally that allowed the Mahis to win me over. The build quality is excellent. The styling is retro-industrial. They almost fit into your back pockets, and they make listening incredibly fun! Granted, they are a hundred times more expensive than the Manley T-shirts, but they are affordable enough to turn wannabe's into believers that "Tubes Rule." They are "The Little Engines That Could."

The System: the boys in the band, without whose contribution, this review would not have been possible:

Linn LP-12 Valhalla turntable with Sumiko MMT arm, Audio Technica 160-ML cartridge and None Felt turntable mat, on Symposium Acoustics Svelte Shelf

Sony CDP-X77ES player as transport, Illuminati D-60 cable, Muse model two dac on Symposium Acoustics Rollerblock Jrs

Sony ST S550ES tuner with Fanfare FM-2G antenna

Convergent Audio Technology SL-1 Signature Mk III preamplifier on Symposium Acoustics Rollerblock Series 2 with TC balls, power supply on Mini-Isis Platform

Plinius SA-100 power amplifier on Symposium Acoustics Isis Platform on architectural slate

And a special round of applause for:
Coincident Speaker Technologies Partial Eclipse Mk II loudspeakers on Symposium Acoustics Isis Platforms on architectural slate

JPS Labs Power AC In-Wall cable and power outlet
Interconnects: 24 gauge Mil-Spec wire with locking RCAs
Loudspeaker Cable: Coincident Speaker Technologies CST-1

Specifications

Output Power: 40 Watts

Vacuum Tubes: four EL84 for output, one 12AT7WA for input, and one 6414 as driver 

Frequency Response: 10Hz to 90kHz (+0.5dB) 

Input Sensitivity: 460 mV nominal 

Input Impedance: 100 kohms 

Load Impedance: 5 ohms 

S/N Ratio at 50 Watts: -80dB 

Dynamic Range: 86dB 

Dimensions: 12 x 10 x 5 (WxDxH in inches) 

Shipping Weight: 17 lbs. each

Price: $2,500 per pair

Company Information

Manley Laboratories, Inc.
13880 Magnolia Ave.
Chino, CA 91710

Voice: (909) 627-4256
Fax: (909) 628-2482
E-mail: emanley@manleylabs.com
Website: www.manleylabs.com