MartinLogan Montis loudspeaker Page 2
The review samples of the Montis arrived while I was still working on my review of the PrimaLuna ProLogue Premium integrated amplifier, and though at $2299 the Premium is not an amp that most people would think of using to drive a $10,000 pair of speakers, I just had to hear how the combination would work.
Answer: surprisingly well, particularly when the ProLogue Premium had KT88 rather than EL34 output tubes installed, and I used its 8 ohm speaker terminals. The sound was well balanced from top to bottom, with just a bit of tube warmth. Some of the other amps I later tried with the Montises produced a more detailed and transparent sound, and the more powerful ones could certainly play louder without strainbut I could listen quite happily to the Premium-Montis combo without feeling deprived.
The other tube amp I had on hand was the Audiopax Model 88 Mk.II. The Audiopax driving the Avantgarde Uno speakers is a "magical" combination: detailed and transparent to the source while minimizing the "electronic" artifacts of the reproduction process. The Audiopax-Montis marriage was not a happy one. Although the Model 88 Mk.II's rated output is 30Wpcnot that much less than the ProLogue Premium's 40Wpcthe Audiopax was dynamically on the subdued side even at moderate levels, and the sweetness and liquidity that had been so appealing with the Avantgardes now came across as too soft and lacking definition.
Next up was the Simaudio Moon Evolution W-7, a 150Wpc solid-state amp. The sound of the Montis driven by the Moon W-7 was vastly different from its sound with the PrimaLuna or the Audiopax. It now had dynamics in spades, evident as an ability to play much louder without strain, as well as more clearly present the ebb and flow of music at moderate levels. Bass was more extended and better controlled; the double-bass passages in Sylvia McNair's Sure Thing: The Jerome Kern Songbook (CD, Philips 442 129-2) were more distinct. But as good as the Moon-Montis pairing sounded, and with nothing specific that I could criticize, I kept wondering what the speakers would sound like with a really topnotch tube amp more powerful than either the PrimaLuna or the Audiopax.
Enter the 50th Anniversary Limited Edition of the McIntosh MC275, aka the MC275LE. This is the latest version of a tubed model that was first produced in 1961, earlier versions of which have been reviewed in Stereophile by Sam Tellig (November 1993, Vol.16 No.11, July 2004, Vol.27 No.7) and Fred Kaplan (October 2010, Vol.33 No 10). The MC275LE is rated at 75Wpc, but reviews of earlier versions have indicated that this rating is very conservative; the amp is easily capable of putting out 90W or more before clipping. I'll discuss the MC275LE's sound in detail in my review (forthcoming); for now, I'll say that the Montis sounded best when driven by the MC275LE, the sound having all the dynamic power of the Moon Evolution W-7, combined with that harmonic "rightness" of tube amps that even the best solid-state amplifiers have difficulty achieving. The bass was very nearly as tight and extended as with the Simaudio, and better than with the other tube amps. (Interestingly, although the Montis has its own bass amplifier, the bass sounded different with each of these three amps.)
I had a hard time deciding whether I preferred the McIntosh's 8 or 4 ohm speaker terminals, a comparison complicated by the fact that the 8 ohm level was higher, which had to be compensated for by reducing the preamp level control. Finally I decided in favor of the 8 ohm terminals, which sounded more dynamic. I discussed the choice of output terminals with MartinLogan's Peter Soderberg, who has set up ML speakers in a variety of systems using tube amplifiers; he told me that, among those systems' owners, the preference was almost evenly split between the 4 and 8 ohm terminals, the latter being preferred a bit more often. In other words: Use whichever sounds better to you.
The most impressive characteristic of the MartinLogan Montis was its relative freedom from "speaker sound." A loudspeaker is a mechanical/electrical device whose every component part has the potential to superimpose on the signal resonances of its own, thus providing listeners with cues that they're listening to a speaker, not a musical instrument or a human voice. In a speaker with dynamic drive-units, you have the components of all the drivers (voice-coil, pole-piece, dustcap, spider, diaphragm, surround, frame, etc.), each adding its own resonances to the signal. Then, almost invariably, the drivers are placed in a box, which adds its resonances. The designer can attempt to control these cabinet resonances by using low-resonance materials and damping the enclosure's interior, but it's a bit of a losing battle, and the result is often little more than the substitution of one set of resonances for another. Even the very best such speakers at times give audible indications that the sound is coming from a box.
The Montis did not. The electrostatic tweeter/midrange drive-unitwhich, of course, has no box that can resonateprovided a transparent window on the sound, and whatever resonances were generated by the woofer enclosure were so well managed that I was never aware of them. And while I wouldn't go so far as to say that the electrostatic transducer had no sound of its own, the drum resonances of its stretched diaphragm were evidently distributed very effectively by the ClearSpar spacers, and were low enough in level that I was only occasionally aware of them.
As the late J. Gordon Holt pointed out many years ago, the most critical part of the audioband is the midrange. This is where the fundamentals of the human voice and most instruments lie; as long as a speaker reproduces the midrange accurately, our ears are relatively forgiving of faults at the frequency extremes. Midrange accuracy has long been recognized as a particular strength of electrostatics, and so it was with the Montis. Voices had a very natural quality; it was easy for me to imagine that Liz Callaway was in my listening room, pouring her heart out as she sang "Make Someone Happy," from her Passage of Time (CD, PS Classics PS-984). Nor did the Montis shortchange male voices. My usual test tracks featuring Pavarotti, Sinatra, and Terfel were reproduced in a way that captured the unique quality of each voice, with no undue emphasis or weakness of chest resonances. The resolution of recorded detail was in the top class, without sounding etched or clinical.
I've always been attracted by the notion of a single-driver, crossoverless speaker; unfortunately, speakers of this sort have their own set of problems, which may include weaknesses in the treble and the bass. Most speaker designers have decided that the compromises involved in single-driver speakers are too great, and that a carefully managed crossover can yield better results. In the case of the Montis, the crossover frequency is nominally 340Hz, which means that reproduction from the lower midrange to the treble is handled by a single driver: a good thing, in that it provides coherence in this important part of the audioband. However, it also means that the crossover is smack in the middle of the range of the human voice, and a host of instruments such as the cello. In my opinion, the greatest challengeand a singular achievement of the Montisis how this crossover is handled. Listening to Vincent Bélanger's cello (which I have not only heard live but, after a fashion, played myself) on his album Là (CD, Fidelio Musique FACD032), I tried to identify points where the Montis's reproduction of the instrument's sound shifted from the electrostatic driver to the woofer, but had a hard time doing sothe transition seemed virtually seamless.