March 1999 Lamm Industries ML2 Mono Amplifiers by Marc Mickelson

Music on an exalted scale; beauty, grace and surprising power for a single-ended design.

Those of us who write reviews that appear on the Internet can easily judge the collective anticipation a new product brings by the amount of e-mail we receive when word gets out that a review is in the works. In the case of the Lamm ML2 amplifiers, we let the cat out of the bag on our Coming Soon list last November, right before the amps arrived. Although I haven’t been exactly inundated with e-mail, I have gotten a few messages each month asking when the review would appear -- not bad considering that the ML2s cost almost $30,000 per pair. Much of this e-mail has come from Lamm owners who admire Vladimir Shushurin's work and want to know if their speakers will work with the single-ended ML2s. Others have wanted to find out if something they've heard about the amps is true or how much of the sound they've heard at shows was attributable to the ML2s.

For the most part, I've refrained from answering any questions about the ML2s because I was working on the review, but the time of reckoning has come. So to answer a few of the more burning questions: The Lamm ML2s are single-ended amps that can drive a larger variety of speakers than other SET designs, and they are the finest amplifiers that Lamm has produced (yes, I’ve heard them all). However, on a more personal note, the ML2s are the most magnificent audio electronics that I've used, and they very well may be the most complete-sounding amplifiers you can buy.

For more answers, read on.

Black boxes

The ML2s are styled very much like the Lamm ML1 push-pull triode monoblocks that I reviewed last year for SoundStage! In fact, the only real cosmetic differences are the absence of the oval meters and switches of the ML1s and the tubes that each amp uses. The two models have the same dimensions, 20 3/8"L x 16"W x 8 1/4H, and weigh roughly the same, a hefty 70 pounds each. They both come packed in foam-lined wooden crates that protect them very well and add 30 pounds to their shipping weight. The UPS man who delivered the ML2s to me was happy to get rid of them in my garage, no carrying up the steps -- for him at least!

The ML2s use the same output tubes as the ML1s, the rugged 6C33C, which Lamm estimates will last 10,000 hours of normal use. But while the push-pull ML1s use these tubes to deliver 80 watts, the single-ended ML2s offer only 18. In addition to the 6C33Cs, the ML2s also use a single 12AX7, 5651, 6AK5 and 6N6P. Lamm warns that there are no equivalents for the 6N6P and that ML2 owners can only acquire replacements from Lamm. However, Vladimir Shushurin told me that he has a large stock of the tubes, which should provide 10 years of use anyway. Setting the plate voltage and idle current of the output tubes requires a volt/ohm meter, but it is very easy to do via probe contacts on the top of the amplifiers. On the back of the amps are sets of binding post for 4-, 8- and 16-ohm output, the on/off switch, and an IEC power-cord connector. As with the ML1s, the RCA and XLR inputs are near the front, so allot an extra half-meter of interconnect to reach them. Relays kick in when the amps are switched on, protecting your speakers from any annoying thumps and the unlikely failure of the tubes during the warm-up sequence. The ML2s are large, but they fit very well on a pair of Bright Star Big Rock 1 bases; to allow for proper ventilation underneath, you should not place them directly on a carpeted floor. Overall, the Spartan ML2s are attractive with their bevy of tubes up top, and the pair of amps operated flawlessly during the review period. One 6C33C tube had problems -- I couldn’t properly set its idle current -- and Lamm promptly replaced it. Even with this bad tube, the amp still worked properly.

The ML2 won an Innovations award at the CES in January, the third such honor Vladimir Shushurin has received. Two of the amp’s more attention-grabbing technical features are the custom-designed output transformer and high-current regulated power supply. These, Lamm claims, allow the ML2s to drive most real-world speakers and reproduce the full range of audio frequencies. Like all Lamm electronics, the ML2s are a finished design. Shushurin admits that he doesn’t know how to make the ML2s -- or any of his products -- any better, and this is good news for potential buyers who hate to be on the upgrade merry-go-round.

Lamm’s statement-product statement

Lamm considers the ML2 amplifier to be a significant new product -- for a couple of reasons. First, the ML2 is a further embodiment of Vladimir Shushurin’s design principles and thus closer to being his "ideal" amplifier. As you may recall from our previously published informational sneak peek on Lamm and its products, Shushurin has developed a mathematical model of the human "hearing mechanism" that he uses in the design of audio equipment. Furthermore, he has identified "levels" of equipment that correlate to this model. These levels correspond to certain design principles and, indirectly, the overall character of the sound produced. For Shushurin, the king of the topologies is single-ended, which the ML2 employs. In terms of Lamm’s current designs, the ML2 sits at the top of the heap, and Shushurin admits that at its price, nothing more can be done.

The second reason the ML2s are important is that through them Lamm believes it is able to illustrate more clearly a tenet at the heart of its design philosophy, that there is a direct correlation between how a product measures and how it sounds. As you may know, Shushurin is unique in the field of audio design in that he does not include listening as part of his design process. Furthermore, he argues that the field of audio reviewing unnecessarily lacks objective criteria by which the sound of a component can be discerned without performing listening tests. To some of us who do believe in listening, this may sound like sacrilege, but Lamm maintains that this is completely real and explainable.

A new idea creates new terminology, and so Lamm has introduced the notion of "absolute linearity of a system" (ALS), which, they say, is a function of a certain number of measurable variables. A discussion of all variables that make up the ALS would, according to Lamm, take up a great amount of space, but for the purposes of merely clarifying the concept of ALS, explaining three of the variables will suffice. They are: THD (total harmonic distortion) vs. frequency at various power levels, THD vs. power taken at three different frequencies (20Hz, 1kHz, 20kHz), and harmonic distortion residue at various frequencies within the audio frequency range and at various power levels. This last variable is vitally important because it guards against any "tricks," as Shushurin calls them, in the design of an amplifier.

In terms of the ALS, ideal amplifiers will exhibit uniformity in their measurements, which would relate to the following characteristics in the three variables under discussion: THD vs. frequency at various power levels would be essentially a series of straight horizontal lines at each power level; THD vs. power would show a gradual but unvarying rise in THD as power increases for each of the three frequencies; and harmonic residue would resemble a perfect sine wave, the peaks and valleys rising and falling in equal amounts. Again, uniformity is what the ideal would show, and you can see this in the accompanying figures better than I can explain it.

[see "ideal" figures]

According to Lamm, as the characteristics of an amplifier get closer to these, the "ideal" is closer to being attained, which in terms of reproduced music means achieving the highest of principles: complete extension of the sound at both extremes, and 100% accurate re-creation of the original spectral balance and harmonic structure of the recorded material -- lofty objectives for sure.

To corroborate its contention about the ML2, that it is close to the ideal, Lamm commissioned independent measurements of the amps from Bascom King of BHK Laboratory ( bhk@rain.org ), who also supplies such technical content to Audio magazine. Among the many measurements that King made are, of course, those for THD vs. frequency, THD vs. power and harmonic distortion residue.

[see graphs of actual measurements]

As you can see, the graphs of the ML2’s actual measurements are similar to those of the "ideal" amplifier. But does the fact that they are not identical prove how close the ML2s are to being ideal or how far they are away from it? Shushurin admits that the ideal is only theoretical, that such an amp cannot be built because real-world limitations -- the transformers, tubes and so on -- prevent it. However, the single-ended design topology, which inhabits Shushurin’s highest level of design and most closely relates to his model of human hearing, will, when properly implemented, also produce an amplifier that is closer by nature to the ideal, and the ALS, than push-pull and other topologies.

Are there then amps that employ other design criteria that can be ideal? Shushurin admits that it is possible to break his rules and create an amp that will to a certain degree measure like the ML2, but he also says that such an amp would only be an imposter because it doesn’t adhere fully to the complete theory -- the model for human hearing and ALS -- and thus would not sound the same as a "properly" designed amp. In fact, Shushurin maintains that if designers would try to implement his principles fully, they would discover that there are only a limited number of design topologies that will work, and the resulting products would be very expensive. This, he reasons, is why Lamm products are not for the faint-of-pocketbook: The principles behind them make them expensive to produce.

Shushurin’s theories as I have presented them here are incomplete. He maintains that a full discussion would not only be very lengthy but also divulge proprietary information. Also, and perhaps of greater importance, I am not a design engineer, so conveying this part of the ML2 story is rather like writing a term paper for a course I never took. Nonetheless, as the independent measurements show, the ML2s do seem to adhere to their designer’s principles -- the graphs are similar to those of Lamm’s ideal amp -- and so I should expect to hear in the ML2s some specific sonic characteristics that are also recognizable in other Lamm designs.

Review system

I used the ML2s with my usual set of review components -- Lamm L1 line-stage preamp, Timbre TT-1 DAC, Wadia 20 transport, ProAc Response Four speakers -- and with a number of alternates, including the Blue Circle BC3000 linestage, Mark Levinson No.39 CD player, and Shun Mook Bella Voce Reference speakers. For comparison and context, I had a set of Lamm ML1 monoblocks on hand as well as the Audio Aero Capitole stereo amplifier, whose sound I admired at the CES in January. Interconnects and speaker cables were from JPS Labs and Audio Magic, and I used a combination of JPS Labs, Audio Magic and API power cords. At one point or another, every piece of equipment rested on Bright Star Big Rock bases; the amps, however, rested perpetually on a pair of Big Rock 1s, which supported them well.

The music they make

Single-ended amps have a reputation -- part good and part bad. On the one hand they generally impart a sophisticated sense of resolution that other designs just can’t muster. They almost backlight images, making them appear in higher relief and a more lifelike manner. They also impart a sense of grace and beauty through the midrange that’s especially seductive and the reason that many audiophiles buy SET designs. On the minus side, they are generally very low in power, requiring high-efficiency speakers, and they aren’t known for offering the greatest extension at the frequency extremes, especially the bass. For the most part, SET designs involve tradeoffs that some listeners are willing to live with and others are not.

The ML2s, however, do not make apologies in any way. Although they deliver a mere 18 watts, they drove my ProAc Response Fours, rated at 89dB/W/m, to loud levels -- 93dB+ peaks -- without clipping. In fact, during the entire review period, I couldn't get the ML2s to clip, although, to be fair, I didn’t intentionally try to trip them up -- my ears gave out before they did. The Shun Mook Bella Voce Reference speakers don’t play quite as loudly as the ProAcs with the same amount of power, but even they worked well with the ML2s. According to Lamm, however, speakers like the Wilson X-1 Grand SLAMM and JMlab Grand Utopia and Utopia are probably the best to use with the ML2s because of these speakers' high sensitivity and truly full-range sound.

Of course, being able to drive speakers is no great accomplishment for an amplifier, and in all other ways the Lamm ML2s absolutely shine. Bass, for starters, is unbelievable for a tube design, not to mention a single-ended amplifier. It’s deep, powerful and never overbearing; in many ways, it’s more satisfying than the bass of most solid-state designs that I’ve heard, more integrated into the entire spectrum of the sound, not the main attraction. On "Boomtown" from Greg Brown’s wonderful The Poet Game [Red House RHR CD 68], the bass has ideal balance -- speed, impact, weight, and overwhelming naturalness. It’s just there, seemingly not as the product of a complicated and expensive audio system, but rather as an element of the recorded music. I love "Boomtown" for its insight into the sort of status-driven gentrification of places like Santa Fe and Sedona -- and its beat. The ML2s certainly enhance the latter. The ML2s can also dig deep when the music asks for it. Listen to Suzanne Vega’s Nine Objects of Desire [A&M 31454 0583 2] or your favorite bass recording and you won’t feel cheated. What you will discern is how the bass seems to fit in with the rest of the music, and how you can’t believe that a single-ended design that puts out a mere 18 watts can do this.

The bass of the ML2s is not slow or undefined, just like the rest of the sound the amps produce. These are fast and resolving amps, but in keeping with the Lamm house sound, not etched, grainy or exaggerated. Those who remember my review of the Lamm ML1s may recall that I said those amps "track the signal like radar." The ML2s are slightly better in this regard and resolve better too. I’ve been listening habitually to some infectious Texas swing from Dave Biller and Jeremy Wakefield (The Hot Guitars of Biller and Wakefield [HighTone HMG 3006]). The clarity and quickness of the steel guitar and Fender Telecaster in the right and left channels respectively are very engrossing and enhance immediacy. The music is joyous -- I can’t get the chorus to "Steel Crazy" out of my head -- and I know the Lamm ML2s are doing the driving here, so I can just sit back and enjoy myself.

There are other amps that sound fast and detailed, but these characteristics almost always come at a high price: treble exaggeration and a lack of natural shading. You can ameliorate these with your choice of speakers, source components and even cables, but the intrinsic sound is still there. The ML2s don’t play this game; they just amplify the signal in a way that is consonant with the music, period. They don’t romanticize though; a recording like the Bottle Rockets’ raucous 24 Hours a Day [Atlantic 83015-2] still sounds overly bright and aggressive where it always does. The naturally portrayed speed and detail are very easy to detect when you hear the ML2s, but to appreciate these qualities fully you have to put aside the ways in which you previously defined them. The best way I can describe the sensation of hearing the ML2s is that their sound reminds me of a jet doing a ground-level flyby -- it’s coming, it’s coming, it’s HERE, and there it goes. All of this seemingly takes place too fast to process any of the constituent parts, but the whole experience is very discernible -- you get to see a moving plane up close. And so it is with the sheer enjoyment that the Lamm ML2s engender. Analysis and hard perception seem all the more trivial because the music is right there.

Lest you begin to think otherwise, all of the SET characteristics that coax people into buying such designs are intact too. The midrange is palpable and textured, filled with subtle tonal shadings and nuance. It's as though you can examine it at any volume and still easily discern what you’re hearing. In fact, there’s a directness to the sound that makes listening at lower levels just as satisfying as at higher ones. Voice is exceptionally well reproduced through the ML2s -- no amp does it better in my opinion. On the heels of my review of Tom Russell’s The Man From God Knows Where [HighTone HCD8099], I pulled out Iris DeMent’s first collection, Infamous Angel [Warner Bros. 9 45238-2]. Her voice is ideal for the emotionally mature yet earthy brand of country music she writes and plays, and the ML2s are the amps for her music. On the bittersweet "Our Town," DeMent’s voice trails off at the end of verses in the most natural way I’ve heard -- no undue emphasis that shows up in other negative ways, no muting that blunts those last few microseconds of music. I pulled out vocal after vocal to play with the ML2s, and each showed the amps to embody the very best things about the SET movement, but with no nasties. I know -- it seems too good to be true. But it is.

Breaking the sound down to its various constituent parts conveys only part of the ML2s’ glory. Put on one of the recordings you simply love and you’ll know how these amps bring it even closer to you. For me, Television [Capitol D100197] is that kind of recording, its mixture of eerie guitar interplay showing an improvisational flair but always at the aid of the songs’ forward momentum. Tom Verlaine is one of the best guitarists that no one knows, and his cryptic lyrics on Television are as fascinating as his playing. I’ve mentioned this recording so many times that some of you will think I own stock, but it’s the one recording I pull out when I want to retreat into some engaging music. With the ML2s in use, this disc, with its floating guitars and wonderful sense of space, is satisfying at any listening level, even loud, but playing it low draws me into it all the more as I hang intently on Verlaine’s words, trying to decipher them but instead making a mental collage in the process -- the lyrics allow this. It’s rather like meditation and reminds me afterward why I listen to music, and why nothing else has the same effect for me.

Family resemblance

The natural question is how the ML2s stack up against their push-pull brethren, the ML1s. To make this short and sweet, the two models sound very much alike, but the ML2s are better in every way except for the ability to play loudly, in which case the 80 watts of the ML1s win. And in theory, Lamm would agree with this. Shushurin’s design principles mean that each is the best amp with its topology, but the single-ended topology is better by nature. However, the ML1s are no slouches -- as I say in my original review of them, they "are a no-compromise package." The ML2s just have deeper, better-defined bass; treble that’s clearer but just as natural; and a magic in the midrange that does voices supremely right. I’d quote a few recordings here, but you’d read the same things about them over and over again.

A better question is whether the ML2s represent improvement over the ML1s that’s commensurate with the difference in price, and the call is much closer here. I can say that with my speakers, if I could buy either, I would own the ML2s for everything that they do. However, if I’m looking at amps half the ML2s’ price but I can just stretch for the $20k ML1s, I would buy them and be very happy. Likewise, if my speakers are below, say, 88db/W/m efficient or I have a very large room or I like to play music at levels approaching the real thing, then the ML1s are also the proper choice. But if you can live a little larger in price and performance and a little smaller in volume…well, you get the idea.

Is it all over?

If I had to describe the sound of the Lamm ML2s with one word, it would be the one that's scattered about this review: natural. Of course, this isn’t the top-of-the-marquee term that will catch the eyes of audiophiles, but it is the best one I can think of to convey the sensation of listening to these amps. They do it all, but they are never showy. You want bass and treble extension, a gorgeous midrange, that certain magic that only great tube amps offer? The ML2s give it to you. But more important than all of these is the way the individual attributes integrate into an amplifier that serves the music better than any amp I’ve heard. Other amps are good at divulging the second, third and fourth things about recordings and their reproduction, but the Lamm ML2s nail the first thing every time -- they are for making music. And all of these things together indicate (to me at least) that there must be something to Vladimir Shushurin’s design theories. The ML2s seem to measure just as they sound: full range and with an abundance of important harmonic detail.

However, the tremendously high price of the Lamm ML2s means that they are not perfect. How does one justify the cost of audio electronics like these? I could give you an inventory of parts and the amount of time that went into producing the amps, but these would still sound hollow in comparison to what $30,000 will buy in the non-audio world, and I can’t say that this would be the wrong way to see the issue. However, perhaps it’s more productive to look at it this way: You’re paying for Vladimir Shushurin’s consummate design expertise, and Lamm is the only place you’re going to get this. I can fashion clever analogies about artists whose work is of great value, but in such cases the artwork is an end itself -- a painting, sculpture or symphony. In contrast, the ML2s, indeed all of Shushurin’s designs, are only means to a greater end -- accurate musical reproduction -- but what an end it is. The ML2s make the medium even less a part of the message, which is only good for the music we love.

The most valuable bit of advice I can give people lucky enough to be shopping for amplifiers in the $30k price range is to seek out and hear the Lamm ML2s with their speakers. The ML2s are very expensive, and man are they worth it.

...Marc Mickelson
marc@soundstage.com

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