Stand Loudspeaker Reviews

What was old is new again. McIntosh Laboratories has been in business long enough that they are able to bring new design thinking, materials, and construction methods to products from their extensive back catalog. Example: McIntosh's first successful loudspeaker, the ML1. The venerable Binghamton, New York, hi-fi company recently released a redesigned "Mk II" version ($12,000/pair, stands included).

In this, McIntosh is not unique; KLH, JBL, Klipsch, and other companies have rethought and reworked vintage products for the current marketplace, employing new approaches and technologies. Think of it as remastering classic hardware.

I asked McIntosh President Charlie Randall how he thought about the process of updating and reissuing classic designs. His response: "We always pick products that have been pivotal in McIntosh's history, as well as products that are timeless in performance. Obviously, we incorporate new parts and materials to bring the products up to today's standards. There is a careful balance between protecting the past and playing in the present so as not to diminish the brand."

Then and now
Ken Kessler's handsome, thorough book on McIntosh history, McIntosh—For the Love of Music, spells out the details. McIntosh made one earlier attempt to design a speaker, the three-way F100 from 1952 (footnote 1), but it was not considered a success and was quickly discontinued. After that, the company stuck to electronics until about 1970, when Roger Russell, then McIntosh's chief acoustical engineer, designed the ML1, a sealed-box, acoustic suspension, four-way loudspeaker featuring a 12" woofer. Russell's design included companion equalizers that were intended to enhance the bass performance. Russell has described his technical work in detail in his own online history of McIntosh (footnote 2).

Many but not all of the ML1 loudspeaker's features are retained in the ML1 Mk II. Like its ancestor, the ML1 Mk II is built into a sealed-cabinet acoustic suspension enclosure. The dimensions are unchanged: 26" high, 15" wide, and 13½" deep. That's bigger than a typical bookshelf speaker but much shorter than you'd expect a floorstander to be. One of the simplest, most important improvements offered with the new model are dedicated stands, which get the speakers up off the floor and rake them back, for much better on-axis behavior in most listening setups. The stands are labeled at the bottom front with a striking, diecast-aluminum McIntosh badge. Each speaker weighs 66lb, and each stand adds 19lb. Around back are two pairs of McIntosh's excellent gold-plated speaker taps, allowing for biwiring or biamping.

The exterior surfaces of both the cabinets and stands are finished in an oiled satin veneer of American Walnut. The substantial, detachable grille plates are framed with thick slices of that same walnut—solid, not veneer—held in place by powerful neodymium magnets. The louver-blind design of the earlier grilles has been replaced with a simpler, more sonically transparent stiff-mesh grille material made from a coated, web-like fabric that's said to be tough enough to afford protection from toddlers and cats.

Sturdily ensconced on twin legs, the ML1 exhibits personality, as if it was about to start trotting around the room. Some people have described the look as retro, and it certainly has that Arts and Crafts–era vibe. If you are seeking a speaker with a hi-tech, sci-fi look, you'd best look elsewhere.

Beneath the surface
Most of the changes from the earlier ML1 are under the hood. The earlier ML1 employed four drivers; now there are five. A key element common to both is a 12" woofer in its own sealed-interior enclosure. There are two 4" lower-midrange drivers—the earlier model employed a single 8". Higher frequencies are handled by a 2" soft-dome upper midrange and a 20mm (roughly 0.8") treated-titanium dome tweeter. The earlier version's paper (for the cones) and cotton (for the surrounds) have been replaced by polypropylene and rubber. The frequency range of the new speaker is specified by McIntosh as 27Hz–45kHz.

Sealed-box acoustic suspension speakers are less common today than they used to be. I asked McIntosh (footnote 3) to contrast this approach with the vented approach more often used today. "We wanted to capture as much of the original design's intentions as possible. Acoustic suspension core-design principles lie in lowering distortion through utilizing much of the very linear air spring in the sealed enclosure to control resonance. Sealed-box designs roll off at 12dB/octave below resonance. A vented design rolls off at 24dB/octave below resonance." So while a vented (bass-reflex) speaker can go lower for a given cabinet volume, the slower rolloff of a sealed box mitigates this to an extent. "At about 70% of the vent resonance frequency, the sealed system has a greater output and with a more controlled motion. That equals lower distortion."

Particularly interesting is the evolution and function of the 12" woofer. This was a key design element then, and it is now. I've never had a hi-fi loudspeaker in my house that contained a 12" woofer. When properly constructed and powered, a 12" driver can yield a visceral "oomph" that smaller drivers have trouble matching. Back in the day, engineer Roger Russell went to great lengths, including with those outboard equalizers, to find a way to drive a loudspeaker as low as 20Hz with a flat frequency response. Today, McIntosh has achieved similar behavior using what they call their "LD/HP" (Low Distortion High Performance) Magnetic Circuit Design, which is patented. As implemented in the ML1 Mk II's new 12" woofer, LD/HP reduces second and third harmonic distortion while increasing efficiency and power handling. Other developments applied to the new woofer include a rear vent through the magnetic assembly, which improves heat dissipation, and increased space under the voice-coil and spider assembly, which helps control noise. The ceramic magnet and gap shapes are modeled for long linear excursion. The voice-coil is constructed from four layers of copper. McIntosh claims transient response that rivals woofers twice the size. (That would be a very large woofer indeed.)

The ML1 Mk II's specified maximum power handling is 600W; that's a lot of power. Plus, you can rest easy in knowing that McIntosh has included self-resetting, high-current PTC fuses in the crossover network to protect the loudspeakers from damage.

The second-order crossover networks employ materials and techniques that were not available in 1970, like inductors with low DC resistance and capacitors with low equivalent series resistance. It's a four-way design—one of the most 1970s-looking things about this speaker is the proliferation of drivers on the broad front panel—with, of course, three crossover frequencies, at 180Hz, 500Hz, and 4500Hz. This combination of crossover points avoids the range in which the fundamental frequency of most vocals occurs.

Another design element that differs from the earlier version is the positioning of the upper drivers. The four in the upper part of the cabinet are placed symmetrically, mounted together on a machined aluminum plate. McIntosh claims that this results in improved imaging; I found off-axis reproduction excellent, making this a loudspeaker of choice for listeners who want to be able to enjoy their music outside the "sweet spot." McIntosh told me that the developers of the new ML1 utilized "extensive computer modeling, included on- and off-axis prediction."

Sealed enclosures are not known for sensitivity; the sensitivity rating for the ML1 Mk II is 85dB/2.83V/m, which is average. The manual recommends a minimum of 75W for amplification; McIntosh commented, "This very much depends on the average output level one wants to achieve. In a typical listening room with moderate reverberation, one should be comfortable with 200Wpc."

The stated nominal impedance is 8 ohms, which, if corroborated, would make the speaker an easy load despite the modest sensitivity. I requested and was provided with a graph of impedance behavior. There is a single peak in the low frequencies, corresponding to the woofer's resonance in the cabinet, then a mild rise to lower- and upper-midrange crossover points. The lowest point for impedance on the graph lies around 4 ohms near 50Hz. John Atkinson's measurements will reveal more.

Ready, set, listen
I have found the quality of McIntosh's shipping containers to be excellent; the ML1 Mk II was no exception. Packed in four separate boxes and quite a bit lighter than several other loudspeakers I have auditioned recently, the speakers and stands were set up in a jiffy.

A sealed cabinet is an advantage with setup, since you don't need to worry about vents interacting with room boundaries, yet jamming speakers into corners is not a good idea unless that's the designer's intention, as it is with Audio Notes and certain Klipsches. The sturdy stands come with a choice of smooth metal casters or spikes, to work with different floor types. Once the stands are sited, the speakers are easily placed on top. Once that's done, you're ready to connect wires.

Using the small wrench provided for McIntosh's excellent speaker taps made connecting a snap. It was all in the family this time, as in my Downstairs System, I currently run the McIntosh MA252 integrated amplifier, which is capable of delivering 100W into an 8 ohm load.

I view the concept of break-in with one eyebrow arched; we are crossing the line into audio voodoo here, in my opinion. However, the one component category where the idea of break-in makes most sense is with loudspeakers: The idea that moving machined parts with tight tolerances may take some time to loosen up and get in the groove seems reasonable to me. I admire my fellow audio writers who have the willpower to let things run in for days or weeks before they pay any attention to it, but I'm too impatient usually—with something new, I want to hear results right away.

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Footnote 1: An interesting if random observation: Ford Motor Company's F100 was introduced the following year, in 1953.—Jim Austin

Footnote 2: See roger-russell.com.

Footnote 3: I actually asked specific people—not the whole company—but when answers came in by email and I asked who they should be attributed to, the answer was "McIntosh," so here you go.