Model: Modulus 3A Category: Preamplifier (Tube) Suggested Retail Price: $2,295.00 Description: Line and Phono Stages, External Power Supply, Stepped Attenuators. Add $575.00 for Optional Moving Coil Phono Board. Manufacturer URL: Audible Illusions Manufacturer URL: Audible Illusions
Review by Auditious1 (A) on September 29, 2002 at 14:54:01
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for the Modulus 3AI go back almost 20 years with Audible Illusions products, starting with an original Modulus preamp. Now, I suppose, it would be called a Model 1. It assumed duty in my system, sometimes as a dedicated phono preamp, and sometimes as the system's main preamp. Although I was aware of the outstanding performance of the various iterations of the Model 3, at the time I simply couldn't afford one. It turned out that it was a good thing that I had to wait.
Now the latest Audible Illusions M3a has become the heart of my system. The advance that the M3a has brought toward the realistic reproduction of music in my listening room could not have been more dramatic. The M3a is built, seemingly, to NASA standards. It is as quiet as death. It reveals the power, the inner detail, and the genuine warmth of the music as has no other component that I have ever had in my systemâ€"and I have had quite a few state-of-the-art devices here, either as guest performers or as permanent residents. It is also quite powerful in its rendering of the full dynamic range and top-to-bottom frequency content of real music.
My initial impetus for writing about the Modulus was my desire to respond to some of the critical remarks that I read in Audio Asylum regarding the use of NOS tubes in the Modulus. The contributors of those comments were using tubes in the M3a that the manufacturer recommended against using. When those tubes failed early, they placed the blame on the preamp! They complained that the Modulus was a â€śtube eater.â€ť Of course, the accusation is unfair because it is untrue. Iâ€™ll have more to say about that later. Once I started thinking about the tube complement in the M3a, my thoughts naturally turned to considering just what it is about this relatively affordable product that makes it a true constituent of the high-end field regardless of its price. So this writing has grown to be a full review of the Modulus.
The Modulus is a purist product and it has purist parts and features. It has dual volume controls that enable the listener to adjust the channel balance with precision. And those volume controls are custom-built, stepped attenuatorsâ€"the kind of volume controls that highly sophisticated home builders have for years been painstakingly constructing by hand for their serious-minded, no-compromise projects. The Modulus power supply is placed outside of the main chassis at the end of a five-foot umbilicus. This feature completely eliminates the possibility of introducing transformer hum or field inductance from the power supply to the preamp's sensitive audio circuitry. This, again, is a purist design strategy. It is usually found only in preamps that cost far more than the Modulus. A look under the "hood" of the Modulus reveals more purist design and implementation measures. The kind of parts employed exclusively in the construction of the Modulus are ordinarily found only in either extremely expensive preamps or in home upgrade projects of very serious DIY builders and circuit hotrodders who will do anything practicalâ€"and practically anythingâ€"to get the last nth of resolution and accuracy out of their home-brewed projects.
But the Modulus offers some desirable qualities that even the best home builders seldom get right: it is quiet, it is impervious to outside noise, and it is relatively dope proof. For a tubed component, that is saying a lot, because, even with its purist features and fanatical construction standards, the M3a is readily approachable by a fairly wide range of audio hobbyists. You don't have to have solder on your sofa in order to enjoy a no-compromise tube component if it's the M3a, because it is one of the most well behaved, non-fussy pieces of tube gear on the planet. Just set it up according to the simple, clear instructions in the manual or on AI's voluminous website, give it some nice new tubes every year or two, and laissez les bons temps rouler.
The M3a offers performance that other manufacturers of tube gear almost never get right. The most remarkable of these performance advantages is the Modulusâ€™ ability to reproduce accurately the full frequency spectrum of music, including the lowest bass signals available on todayâ€™s playback media. On my system, the low-frequency output is fed via a custom Nelson-Reed crossover to a modified B&K ST202 amp, and then to a pair of very large, Rohrer Acoustic, dual-isobaric, cylindrical subwoofers that are capable of shaking my entire listening room with very powerful, very low bass. Those subwoofers are flat to 25 cycles, and they still have meaningful output below that. That is the kind of bass that you feel, and not just hear. It comes right up through the floor beneath you on material with loud, very low bass content, such as the soundtrack album from American Beauty. (I am referring to the real soundtrack music by Thomas Newman, Dreamworks 0044-50233-2, not the anthology of pop songs quoted in the film's soundtrack. That appears on a different album.) With the M3a, the low-frequency content of the music rumbles upward from the Stygian Depths of Hell and shakes the couch that I ride ecstatically in my listening room. I have had to go around the listening room locking down or removing objects that shake and bounce sympathetically with the powerful low-bass output that I get from the Modulus on this CD source, among many others.
No other preamp, tubed or solid-state, that I have auditioned on my system has ever come close to that kind of bass response. And it's not just copious, blunt-force bass either. It is bass response that is very definite as to pitch, and it is tonally quite accurate, even at the very bottom of the frequency range. When the Modulus plays the pedal-tone lower register of a large cathedral organ, for example, it has the correct timbral character of a real pipe organ. In contrast, most components that are capable of reproducing low bass response yield impressive bulk down there, but do not have the damping and control to yield clean pitch definition and timbral accuracy. I am an experienced musician, and I am quite familiar with the tonal character of acoustic instruments. To my knowledge, no other preamp comes anywhere near to the tonal accuracy and control of very low bass that is one of the hallmarks of the M3a.
The same control that the M3a imposes upon its low-frequency output is imposed throughout its rather broad frequency range. From the satisfying snap of plucked acoustic bass, to the lush, tonally rich and sweet vocal range, to the thrilling, airy twinkle of little bells and cymbals, the Modulus keeps music's tonal content and timbral implications right in the groove with its tight control of musical information.
Time and again, with my musician's knowledge of the sound of real instruments, the output of the Modulus makes me say, "Yes, that's it; thatâ€™s right." To my knowledge, only the CAT preamp comes close to the ability of the Modulus to create a sense of the airy quality of real high-frequency extension. (I am speaking of first-hand knowledge here. I have not heard the highly regarded but expensive Hovlandâ€"yet.) Many audiophiles misunderstand the nature of high-frequency playback. It is not so much evident in the sound and sparkle of tiny percussion instruments like, for example, triangles and small bells, although, to be sure, that is part of the experience. Rather, it is apparent in the sense of air and space that a playback system portrays around the instruments. This air serves to delineate the spatial relationships of instruments and voices within the three-dimensional sound space, and, at the same time, it defines that very space. The M3a delivers true high-frequency competence (on a playback chain that is otherwise capable of high-frequency response), but always with a sense of ease and relaxation to the music.
The better the input source that I give the Modulus to play, the better it sounds. I have recently had the pleasure of upsampling some of my favorite audiophile CDs using the amazing Integra 8.2. Upsampling works rather well. Every CD in the collection sounds substantially better when upsampled. In brief, the perceived effect is that, among other benefits, upsampling clears the noise from the sound stageâ€"noise that one didn't formerly realize was there. When upsampling clears away the fog of digital noise, there remains a deep intertransient silence that permits stereo images to stand out dramatically from the aural background. And that kind of profound quiet throws a strong spotlight on the stability and solidity of three-dimensional stereophonic images and their domination of their positions within the aural space. The soundstage expands to the rear of the speakers and forward to the listening position and beyond. In addition, tonal colors are much more vivid and rich. When upsampling is used to clear away the pervasive pall of digital noise, the stereophonic images stand out dramatically in open, airy space, with all of their vivid tonal colors shining undiminished.
If one could use the analogy of cleaning the glass in order to describe greater transparency in audio playback, one could as well describe the benefit of upsampling by employing the analogy of cleaning away a whitewash that attenuates tonal colors and timbral nuances and conceals spatial information. The outcome of cleaning away the digital noise is not subtle; in fact, it's outright startling at times. Turn on the upsampling and the soundstage deepens and the images instantly migrate to new and compellingly believable positions, some forward, some to the rear. The envelope of ambient sound seems to expand right past the listener's head. Tonal colors deepen and sweeten. Such profound inter-transient silence permits music's subtle details to persuade the ear-brain that the listening experience is, above all, about musical reality.
Peter Moncrief has written extensively in International Audio Review about the deleterious effects of noise and other spurious audible artifacts of musical storage and playback systems. I endorse and enthusiastically support his point of view. Even a little noise of any kind and from any source can have a disproportionately harmful effect. Thatâ€™s because noise does not merely obscure the subtle details of musical reproduction; it does substantial harm to the portrayal of musical reality. Noise of all kindsâ€"hum, hiss, or digital artifactsâ€"will intermix and intermodulate with music, changing its inner details, distorting its meaning and diminishing the weight of aural evidence that persuades the listener that musical reality is taking place in his listening space. Upsampling does a great deal to clear the noise out of the sound field, making stereophonic images appear in bold relief against a background of sonic "black." It gets the aural garbage out of the way of music's essential subtle informationâ€"the fine detail that cajoles the ear into believing that a reasonably honest portrayal of reality is at hand.
So why am I discussing the lack of noise and the spatial, tonal, and imaging advances of digital upsampling? Because all of the implications of the discussion above point just as well to the unparalleled excellence and ultra-quiet performance of the Modulus. Because every instant of musical enchantment around my audio playhouse marches right down the middle of Modulus Street. The new advances in digital playback media yield great improvements in the realistic reproduction of music. And the Modulus just serenely passes the music right on through without diminishing or altering the fidelity of the message.
Whatever else the M3a contributes to the presentation of musical enjoyment, the M3a is quietâ€"dead quiet. Phono in to main out, with the Gold Phono Board MC stage installed, (encompassing 90 dB of gain!), and at full volume, the preamp is truly, deeply, and blissfully quiet. It's also quite impervious to the abundance of noise in the environment here (in San Francisco). We have blasting RF, we have residue of DC floating on the AC lines and we have other abundant AC spuriae that degrade the 60-cycle AC sine wave. No matter: the Modulus just rejects all of that auditory garbage in a way that no other preamp that I have ever had around here has done. That virtue alone is more beneficial and more consequential for the honest and compelling reproduction of music than I could possibly say (although I gave it a good try above).
Digital upsampling also contributes improvements to imaging specificity, depth of field, and the rendition of timbral nuances. And even better improvements are available in the marvelous new SACD format, which, again, is immensely better in all regards compared to the original 16-bit, 44.1 kHz CD standard. But here is the point of all this: Every bit of the improvement that is yielded by the new, higher density CD formats has to pass through the Modulus line stage. The vast improvement provided by the new digital formats allows the excellence of the Modulus to shine through once again. If the Modulus were not as transparent, as quiet, and as accurate as it is, the huge differences between the sound of upsampled CDs or SACDs, compared to the old CDs, would not be so apparentâ€"at least not to such a considerable degree. The gains would simply be minimized or lost. But as much as I improve the source input to the M3a, it just keeps sounding better. I wonder how good it could get; that is, how much better is the new M3a capable of being, depending on the quality of the input that I feed it? Of course, thereâ€™s no certain answer to that. But I suspect that it will be a long time before the M3a becomes the limiting factor in my system.
As I mentioned previously, not all commentators have had unqualified praise for the Modulus. It has received some criticism for being hard on tubes. Whether that's true or not depends on the type of tubes one uses. Several of the best of the truly modern tube preamps in production today employ what is known as a "ruggedized" tube. That would be a 6922/6H23EB tube, which, in the case of the Modulus, is a military-grade Russian tube. Many tube users enjoy swapping these tubes for older 6dj8 types. Some â€śtube rollersâ€ť report good resultsâ€"and good durabilityâ€"from 6dj8 tubes, and some do not. But rapid wear should not be surprising to them, since the 6dj8 tube was never designed to be used in high-performance audio circuits. It is an RF-receiving tube that was primarily designed for use in oscilloscopes and TV sets. Low microphony was not one of its design goals. The 6922 is manufactured to much hardier specifications, and the M3a is designed with the 6922â€™s operating parameters in mind. Audible Illusions' website recommends replacing them every 12 to 18 months, depending on use, of course. Tube preamp lovers may elect, however, to replace their tubes for reasons other than wear. Changing tubes can serve to fine-tune oneâ€™s system or simply to upgrade it, depending on oneâ€™s agenda. Tube rolling can be an effective and affordable way to improve oneâ€™s system, especially considering how expensive it can be to gain even small improvements by making changes elsewhere in the playback chain.
Unfortunately, many audiophiles who don't know much about the subject are averse to owning tube equipment because they dislike the fact that a component has tubes that require changing from time to time. This, they see as a liability. It's not; it's an opportunity! If you don't like the sound of your preamp, then pull its tubes and save them for another day. In their stead, pop in some exciting new tubes. Any tube preamp owner's manual will provide the instructions. And good tubes exist aplenty these days. Audible Illusions provides abundant information on its website (www.AudibleIllusions.com) about how to do it. AI even provides numerous recommendations as to exactly which tubes will work in the M3a circuit and recommends tube dealers who are well prepared for the care and feeding of tube rollers. Audio Asylum and other user-oriented websites such as Audio Review and Audiogon include audiophile forums that specialize in the subject of tube swapping.
Tubes are also employed in the M3aâ€™s phono stage, which I have not discussed so far. The Modulus is one of the few audiophile-quality preamps in current production that include a phono stage. Phono stages can be tricky circuits to design for two reasons: the high amplification of low-level signal sources is readily susceptible to the introduction of noise, and a phono stage must incorporate inverse equalization to compensate for the RIAA curve that is used in the engineering of all phono records. By any name, that's still equalization, and it's much too easy to get it wrong, as evidenced by playing almost any other phono stage available today.
The Modulus gets it right despite the complexities inherent in designing a sophisticated fixed equalization circuit such as the inverse RIAA curve. If anything, the M3a phono stage is remarkable in its tonal consistency with the M3a line stage. Short of using test gear to measure the spectral output of a component, I like to judge its tonal accuracy by playing acoustic instruments on my systemâ€"something like well-recorded grand piano. One of my favorite reference sources to use in evaluating a preampâ€™s line stage is the Rosalyn Tureck recording of the Bach Goldberg Variations on Deutsche Grammaphon (2GH2 459599). It's a little too closely miked, and Tureck's performance is rather plodding in places, but the CD captures the weight and tonal correctness of a large grand piano. This recording gives a good baseline for the speed and accuracy of the Modulus' line stage. The Modulus plays it beautifully, accurately, and powerfully, with an extra serving of goosebumps in the form of thrilling realism.
To evaluate the tonal accuracy of the Modulus' phono stage, I prefer to use a wonderful Proprius piano recording: the KĂ¤bi Laretei, Proprius LP, number 7793. Although she is perhaps not
the worldâ€™s most renowned pianist, Laretei plays Chopin, Grieg, Schumann, Debussy, and Beethoven with verve and understanding. The recording is both tonally neutral and powerful in its retrieval of the lower-register weight of the instrument. On the right playback setup, Proprius 7793 can be quite compelling its presentation of the size and power of a big concert grand piano.
The remarkable thing is that the Modulus phono stage sounds exactly like its line stage: fast, quiet, powerful, and absolutely tonally neutral. Its transient speed is apparent on the air and shimmer that it portrays in its rendition of the grand piano's upper register and its envelope of ambient sound. This is a fairly rare accomplishment for any kind of preamp, but the Modulus does it in grand style. There are not many components out there that can do what the Modulus does: it captures both the power and the delicacy of a grand piano played in a natural acoustic space.
The Modulusâ€™ standard phono stage can handle phono cartridges with outputs exceeding 1mV. Since my Audioquest AQ7000 has about half that output, it requires a step-up stage, which, in the case of the Modulus, is implemented in the form of the optional, John Curl-designed Gold Phono Board. This is a factory-installed option that is, in its performance, highly reminiscent of the famous Vendetta Research head amp, which John Curl designed and manufactured himself. Curl, who is certainly one of the world's preeminent circuit designers, must have devoted considerable effort to tailoring the Gold Phono Board to be consistent with the hallmark tonal neutrality of the Modulus. My AQ7000 cartridge is very happy running straight into the 47-kOhm load of the Curl step-up board, which has plenty of quiet gain to handle even the lowest-output moving-coil cartridges.
This is analog playback par excellence. And therein lies the central idea of the M3a: it is a purist preamp that has been designed, above all, for serious audiophiles who commit serious audiophilia, for example, playing those quaint, old-fashioned vinyl phono records. The Modulus M3a has been built from the ground up to take the fullest advantage of the best playback sources available today: upsampled CDs, SACDs, and vinyl LPs. I am inclined to agree with reviewers in print publications such as The Absolute Sound and Stereophile who believe that only a handful of preamplifiers in the world are in the same class as the M3aâ€"and those preamps cost much, much more.
Product Weakness: Solid but old-fashioned appearance Product Strengths: Quiet operation, tonal neutrality, low-bass definition, dope proof, giant killer
Associated Equipment for this Review: Amplifier: Streets 950A and Modified B&K ST202 as a woofer amp Preamplifier (or None if Integrated): Audible Illusions Modulus M3a (updated) Sources (CDP/Turntable): Maplenoll Apollo Air Bearing w/linear-tracking air-bearing arm and vacuum platter Speakers: Martin Logan CLSII electrostatics w/latest factory updates and custom Rohrer Acoustic dual-isobaric subwoofers Cables/Interconnects: Distech, Clarity Audio, Ichord, Etc. Music Used (Genre/Selections): Acoustic: classical and jazz Room Size (LxWxH): 23' x 15' x 9' Room Comments/Treatments: None. Room sounds wonderful Time Period/Length of Audition: Owner, 5 months Type of Audition/Review: Product Owner
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Topic - REVIEW: Audible Illusions Modulus 3A Preamplifier (Tube) - Auditious1 14:54:01 09/29/02 (2)
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