KEN MICALLEF KLH Model Five LOUDSPEAKER
Stereophile|October 2021
In May of 2019, I heard about a promising jazz vinyl and hi-fi estate sale happening on New York’s Upper East Side. Little did I know then what treasures the dig would yield.

Jazz Record Center’s Fred Cohen had called from the UES apartment, the former residence of late CBS Records and Sony Entertainment mastering engineer Harry N. Fein. Fred said, “The records are kind of beat, but the apartment is jammed with tape decks, turntables, cartridges, tubes, midcentury modern furniture—get up here.”

I called NYC turntable technician Mike Trei, who’s always up for a dig. Upon picking me up from my Greenwich Village pad in his pearl black 1991 Mercedes, we zoomed uptown on Park Avenue. Well past Grand Central Station, we found the address on a quiet residential block.

At the doorway to the apartment, two muscled Russians were removing a ratty red velvet couch. We squeezed past them into a tiny living room. Books were strewn everywhere. A window sucked in hot, sticky air. A Zenith Seville console stereo, a crusty BSR McDonald turntable, and a ’60s-era Ampex Model AG-350-2 1/4 tape machine stood sentry. Where were the records and other audio booty Fred spoke of?

Mike found a side door, jammed shut. We applied two-shoulder pressure and stumbled our way in. The 10' × 6' space—Fein’s secret workshop—was a time traveler’s dream of audio exotica.

SPECIFICATIONS

Description Three-way, acoustic suspension, standmount loudspeaker with three-position Mid-HF attenuation switch and included metal-frame slant-riser base. Driver complement: 1 aluminum-dome tweeter; 4 pulp-paper cone midrange driver; 10 pulp-paper cone woofer. Frequency response:

42Hz–20kHz ±3dB. Low-frequency extension: –10dB at 32Hz. In-room sensitivity: 90.5dB/2.83V/m. Free-field sensitivity: 87.5dB/2.83V/m. Power handling: 200W, 800W peak. Recommended amplification: 20–200W. In-room maximum SPL: 112.3dB. Nominal impedance: 6 ohms (3.5 ohm minimum at 140Hz). Crossover frequencies: 380Hz and 2850Hz (both 2nd-order). Inputs: gold-plated five-way binding posts.

Dimensions 13.75 (350mm) W × 26 (660mm) H × 11.5 (292mm) D. Weight: 44lb.

Finish English Walnut or West African Mahogany.

Serial numbers of units reviewed 20210200445, 20210200446. Manufactured in China.

Price $1998/pair. Approximate number of dealers: 125. Warranty: 10 years.

Manufacturer KLH Audio, 984 Logan St., Noblesville, Indiana 46060. Tel: (833) 554-8326. Web: klhaudio.com.

Dixieland, swing, comedy, and vocal albums lined an in-wall case. Fein’s CBS mastering work was represented: Grachan Moncur III & The Jazz Composer’s Orchestra’s Echoes of Prayer, The Billie Holiday Story Volume II, and Jingle Bell Jazz. A Teac SX-3300 reel-to-reel deck sat on the floor. I pulled open a drawer crammed with Fairchild 225A mono, GE VR-1000, and Shure V15 cartridges. A closet produced a Scott Stereomaster 299-f integrated amp and a slate-gray, Streamline Moderne–looking Fairchild Model 202 tonearm complete with three Fairchild mono carts in turret headshells. Wedged into the back of the closet, their chunky cabinets faded and scratched, grilles seemingly blanched yellow by the sun, was a pair of vintage KLH Model Five loudspeakers.

Produced between 1968 and 1977, the KLH Model Five—like its siblings Models Six and Seventeen—was one of the most popular American loudspeakers ever.

KLH Research and Development Corporation was founded in 1957 by Henry Kloss, Malcolm Low, and Joseph Anton Hofmann. As John Atkinson wrote in 40 years of Stereophile: The Hot 100 Products, “The late Henry Kloss had the Midas touch: whatever his fancy alighted on turned into sonic gold.”

At KLH, Kloss developed the Model Eight FM table-top radio, the Model Nine electrostatic loudspeaker, the Model Eleven record player, and the first reel-to-reel tape recorder to include Dolby noise reduction: the Model Forty. Kloss also founded Advent Corporation (1967), Kloss Video Corporation (1977), Cambridge SoundWorks (1988), and in 2000, Tivoli Audio. And three years before KLH was established, Kloss and inventor/teacher Edgar Villchur launched Acoustic Research, Inc. (“AR”), which mass-produced the country’s first sealed-box, acoustic suspension loudspeaker (the AR-1) and first suspended turntable (the AR XA), both affordably priced.

MEASUREMENTS

I used DRA Labs’ MLSSA system and a calibrated DPA 4006 microphone to measure the KLH Model Five’s frequency response in the farfield. The manual doesn’t specify a vertical listening axis, but with the loudspeaker sitting on its Slant Riser Base, it appears that the tweeter axis will be typical for a seated listener. My reference axis for the measurements was therefore in line with the tweeter. I used an Earthworks QTC-40 mike for the nearfield responses and Dayton Audio’s DATS V2 system to measure the impedance.

KLH specifies the Model Five’s free-field sensitivity as 87.5dB/2.83V/m; my estimate was 87.9dB(B)/2.83V/m, which is within the margin of experimental error. The Model Five’s impedance is specified as 6 ohms with a minimum magnitude of 3.5 ohms at 140Hz. Fig.1 was taken with the Acoustic Balance switch set to HI. The impedance magnitude lies between 4 and 8 ohms over most of the audio band, with a minimum value of 3.7 ohms at 122Hz. The electrical phase angle (dashed trace) is generally low, but the EPDR1 drops below 2 ohms between 64Hz and 93Hz with a minimum value of 1.82 ohms at 74Hz. The Model Five must be used with amplifiers that don’t have problems driving 4 ohms. Repeating the impedance measurement with the Acoustic Balance switch set to MID increased the impedance above 1kHz by 1 ohm; with it set to “LO,” the impedance rose by another ohm in the treble.

The traces in fig.1 are free from the small discontinuities that would imply that resonances of some kind are present. However, the enclosure seemed lively when I rapped its walls with my knuckles. When I investigated the cabinet’s vibrational behavior with a plastic-tape accelerometer, I found a fairly strong resonant mode at 215Hz on the sidewalls and top panel (fig.2) and others at 441Hz and 602Hz on the top and back panels. Even though it has a relatively high Q (Quality Factor), the mode at 215Hz is sufficiently low in frequency and high enough in level that it might add some lower-midrange congestion.

The peak at 42.7Hz in the impedance magnitude trace suggests that this is the tuning frequency of the woofer. As it uses a sealed enclosure, the Model Five’s low-frequency response, measured in the nearfield (fig.3, below 300Hz), rolls off with a relatively gentle 12dB/octave slope below the tuning frequency. The peak in the upper bass, which is due to the nearfield measurement technique, is a little higher in amplitude than I usually see.

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