THE RIGHT OF ASSEMBLY

above: An ML-7A preamp being tested in the Levinson facilities.

Over the years, certain products have earned a reputation as the very best that money can buy, and their names have become synonymous with high quality. One of the most obvious and best known of these products is the legendary Rolls Royce motorcar; others in this exalted category are such sybaritic essentials as Purdy shotguns and Patek Philippe watches. People buy these ultra-expensive products because they are precision-made from the very finest materials, with much hand-crafted construction and immaculate finish.

Another allure of these products is their long-term reliability and performance, their sheer elegance, prestige and pride of ownership, and, admittedly, even snob appeal.

In the relatively short history of high fidelity sound, no audio component has attained the lofty stature of a Rolls Royce. However, since the emergence of high-end electronics, there have been a number of expensive, well-designed audio components whose makers have aspired to a very high level of quality. I think it is safe to say that Mark Levinson is among those companies which have assiduously pursued the goal of making audio components with uncompromising standards of high quality. Having used a number of Levin son units for some years, I have always been interested in their technical aspects and how they were made. Recently I was invited to visit the new Mark Levinson plant in Middletown, Connecticut, and herewith are some of my impressions and experiences.

The Mark Levinson plant occupies 30,000 square feet of space in several modern buildings situated on 12 acres of park-like land. The buildings contain the administrative offices, laboratories, and production facilities for all Levinson products. The complex is also the head quarters for Madrigal Ltd., the distributing company for Mark Levinson products as well as importer of audio components from Meridian, Accuphase, Jadis, Cabasse, Lurne, and Carnegie. The buildings were formerly owned by a French oil-exploration company, and one of them has concrete walls and a concrete floor several feet thick! This is now undergoing renovation as the new Levinson sound room. Obviously, this kind of structure will avoid all diaphragmatic flexure! Chairman of the board Sanford Berlin and president Mark Glazier guided me through all the Levinson facilities while explaining their philosophy. They are committed to the manufacture of musically accurate preamps and power amplifiers, not to units which sound good because of some "pleasant" coloration. This philosophy was further ex pounded on in discussions I had with chief engineer Kevin Burke. He admitted that it was a decided advantage, in developing new designs and circuit topology, to be relatively free of cost constraints. With costs subsidiary to results, a more open-minded, aggressive, and exploratory attitude towards innovative ideas and topologies is possible, always with the goal of optimum performance.

The first stage of manufacturing for all Levinson products is a check of incoming parts. Many high-quality parts are used, and a number of them are purpose-built for Levinson. These include special high-precision potentiometers and toroidal transformers.

High quality notwithstanding, all parts are checked for dimensional accuracy, electrical performance, and adherence to specifications. Tolerances for resistors and capacitors are checked and matched where desired.

Levinson makes all of their own high-precision p.c. boards. These are assembled from the inspected parts, then individually or wave soldered, and then inspected with high-power three dimensional microscopes for shorts or other flaws. The p.c. board work is as good as or better than Mil-spec, and in fact the plant can qualify for military defense production. All Levinson products are hand-crafted, with teams as signed to make p.c. boards and other subassemblies for a specific product.

All subassemblies are electrically and mechanically checked from approved engineering blueprints and samples.

Thoroughness extends to documenting the assembly history of each p.c. board lot. All metalwork-including chassis, faceplates, heat-sinks, etc. is checked for dimensionality to ensure accurate assembly, and particular attention is given to Levinson's special anodizing treatment and engraving.

Faceplates are rejected if even the tiniest flaw is detected.

A team assembles a particular preamp or power amplifier, and then elaborate testing to specifications begins. After a burn-in period, thermal and electrical cycling of the unit is per formed. A final check of specifications and inspection of metalwork is done, and the unit undergoes listening tests at operating temperature.

As you might expect, laboratory re search into all aspects of audio is virtually the lifeblood of a company like Levinson. Levinson is enjoying great success with its new flagship amplifier, the pure Class-A Model 20, a direct development of this time-consuming research. Even at $9,600 per mono block pair, Levinson is selling all the Model 20 amplifiers they can make, both in this country and abroad. The Model 20 embodies much innovative circuitry, including high-current, low impedance driver stages; a precision thermal-tracking bias circuit; a heavily biased, low-impedance output stage, and a highly refined soft-clip circuit.

Further technological advances include a high-current-capacity unregulated power supply, with separate components for positive and negative lines ("rails"); fully electronically regulated, independently tracking power supply rails for all stages, including the output; extensive bypass capacitor techniques; the elimination of impedance-smoothing output Zoebel net works to maintain a high damping factor over a wide bandwidth, and full protection and dissipation circuitry which does not interfere with sonic performance. The Model 20 has a rated output of 100 watts into 8 ohms and 200 watts into 4 ohms, and will deliver 400 watts into 2 ohms with a THD of less than 0.4%.

Levinson's newest amplifier is the Model 23. A dual-monaural design on a single chassis, it incorporates many of the refinements that resulted from research on the Model 20. The Model 23 is a Class-AB amplifier with a rated output of 200 watts into 8 ohms and 400 watts into 4 ohms. It has a current output of about 50 amperes. Part of this is due, no doubt, to the hefty 1,250-VA toroidal transformer. The Model 23 employs a modest amount of negative feedback and can safely operate into load impedances as low as 1 ohm. Its price is $4,400, and it will be available as you read this.

I listened to the Model 23 and found it an exceptional performer, with tight, deep bass, a good sound stage, and a lovely, smooth top end. However, good as it is, it simply isn't in the ultra-performance league of the Model 20. I had the Model 20 at home, teamed with the great ML-6B preamp, and I drove Dun tech Sovereign loudspeakers with it, using MIT double "shotgun" speaker cable. This combination produced a truly extraordinary sound, with extremely clean bass reaching down to subterranean levels, a very broad sound stage, depth that clearly delineated the layers of the orchestra, and the most refined, sweetest, smoothest, and most harmonically correct top-end I have heard from any amplifier. On the evidence of the Model 20's sound, one has to conclude that the extensive re search devoted to this truly musical amplifier, and the expensive, painstaking, hand-crated construction that went into it, have paid off handsomely.

Now if we could all just find a way to win the lottery . . .

(adapted from Audio magazine, Mar. 1987; Bert Whyte)

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