Magnum Dynalab MD 208 receiver Larry Greenhill's Followup

Larry Greenhill's Followup from March 2001, Vol.24 No.3

"The MD 208 is as musical, sexy, and uncomplicated a performer as I've ever entertained in my listening room," raved Chip Stern in his recent review (January 2001) of Magnum Dynalab's solid-performing two-channel AM/FM receiver. Although CS discerned many subtle audio qualities in the MD 208's audio circuits, his urban location prevented him from evaluating the receiver's RF performance—he lives in the Inwood section of New York City, a thick jungle of row after row of prewar iron-structured buildings that produce horrendous amounts of multipath interference.

"So for judging such basic attributes as stereo separation and selectivity and signal/noise ratio, I must defer to suburban guru and hardcore FM aficionado Larry Greenhill, who will offer his take on the MD 208's FM package in an upcoming issue."

Nineteen miles to Chip's north, I am indeed in a very different situation. My outdoor roof antenna is higher than the nearby wooden houses, and is pointed in the direction of the broadcast towers of my favorite New York stations. Also on hand are several other FM tuners for to use for comparison, including a Day Sequerra FM Reference, and Magnum Dynalab's 206 and their outboard RF amplifier, the 205 Signal Sleuth.

Beautiful Dreamer
The MD 208 receiver is one of the larger components in the Magnum Dynalab catalog. Its rack-mount-wide front panel features an illuminated digital volume readout above a row of seven steel-gray buttons and red LED indicators: from left to right, a power idle switch, Mute and Stereo indicators, BW1 and BW2 switches (which activate a normal, wide-open bandwidth or a narrow, highly selective bandwidth), and a button that toggles the left VU meter between displaying signal strength and multipath.

The MD 208 shows the same design approach found in Magnum Dynalab's more expensive, performance-oriented FM tuners. Rather than automated tuning sweeps, non-defeatable muting, and other "conveniences," the MD 208 offers discrete FM controls. No memory presets complicate the user's enjoyment of this tuner. IF bandwidth can be selected, allowing one to tune in weaker, 5kW classical stations while tuning out the overmodulating, 50kW mega-monster grunge-rock stations splattering crunch guitar over half the FM band. Muting can be defeated.

The Signal meter, on the left, has two functions. When the button is pushed on and the LED lights, it serves as a signal-strength meter; the higher the reading, the better. When the same button is toggled off, the meter becomes a multipath detector; the lower the reading, the better, "0" being ideal.

To the right is the Center Tune meter, which Magnum Dynalab says "indicates the setting of the FM tuner's front-end. In normal situations, the FM tuner should be tuned so that the needle is in the center." When the tuner is activated, the Signal and Center Tune meters and the digital frequency display are illuminated.

As CS noted, the MD 208's chunky handheld remote exerts smooth, quiet control over the digital volume potentiometer and input selector (activating a loud clicking relay to illuminated tuning meters and digital FM frequency when switched to the FM source), but does not control any tuner functions. This is disappointing; other FM tuners reviewed in this magazine, such as the Myryad MT-100, can be tuned remotely.

Tuner Functions
Magnum Dynalab's president, Larry Zurowski, noted in his "Manufacturer's Comment" that the MD 208's tuner is an upgraded version of MD's $1500 Etude FM tuner. He claims it sounds better when bundled with the MD 208's preamp and power amp, as this minimizes the standard buffer circuitry and interconnects. Despite being encased in the same chassis as the power amplifier, the tuner section functions as well as it does because it's shielded by an aluminum plate that runs right below the tuner board. As in MD's other FM tuners, the MD 208's RF front-end uses analog circuits rather than the more common digitally synthesized tuning found in car radios.

Magnum Dynalab builds the MD 208's three-stage front-end entirely in-house, using the same type of ceramic filters found in the company's more expensive tuners. The front-end is tuned for minimum distortion, selectivity, and sensitivity at three frequencies: 92.1, 100.1 and 107.3MHz. The company's MD 102 analog FM tuner ($2500) uses a five-stage analog front-end, while the top-of-the-line MD 108 Hybrid FM tuner ($5500) employs three entirely discrete front-ends, one for each bandwidth.

Setting up the MD 208 went smoothly. Connecting to AC (with the detachable power cord) and to my antenna was easy. MD 208s shipped to North America are fitted with the AF@coaxial antenna connector.

Next, following Don Scott's recommendations (Stereophile, Vol.20 No.8, pp.21-23), I disconnected the antenna and listened to the MD 208 playing interstation static. As DS described, "It should sound full-spectrum, deep, and crisp, with a muted smoothness at the same time. No squeals or birdies (oscillations) should be heard, as this indicates distortion being generated in either the front-end or IF amplification stages, which will give a tuner a nasty, gritty quality." The MD 208 emitted roaring, full-spectrum static, although the bass component was not as strong as heard with the FM Reference.

I usually test tuners by running a closed-circuit FM broadcast (described in Vol.14 No.12), which permits the repeated playing of musical selections broadcast locally in the listening room. Unfortunately, the equipment for this test was not available. Instead, I compared the MD 208 to my analog-tuned, $5500 Day-Sequerra FM Reference tuner (Vol.21 No.1, p.189), now out of production. A Mini-Circuits ZFSC-2-1 precision signal splitter connected to my rooftop antenna splits the resulting signal to two 8' lengths of RG-59U coax attached to the antenna inputs of the two tuners being compared. The signal splitter has an insertion loss of 3dB, and the cable connectors reduce the level by an additional 2dB, for a total loss of 5dB. This results in fewer stations being received, so the actual number of stations received by any tuner cited here is a very conservative estimate. However, because each tuner receives the same attenuated signal, comparisons using the outside antenna are still meaningful.

I took care to tune both units to the same frequency; if one was left tuned to alternate frequency, it was very easy to pick up that tuner's IF oscillator when the two units were exactly 10.7MHz apart (10.7MHz is the IF frequency). The tuners' audio outputs were matched by attaching a precision stereo potentiometer between one tuner's stereo outputs and the line-level input of my Mark Levinson ML-7A preamplifier. Then it was possible to switch the ML-7's input selector between Tuner (the MD 208) and Auxiliary (the FM Reference) with no change in gain level.

Both the MD 208's and the FM Reference's rotary tuning controls provided easy and intuitive tuning. The MD 208's signal-strength and center-channel meters provided accurate tuning and more clearly detected multipath interference, and were easier to use than the FM Reference's oscilloscope display, whose 'scope trace has dimmed.

RF Performance
The MD 208 was easy to tune and pulled in a clear signal, as was revealed when I swept the FM band with it and the FM Reference. (Muting was defeated on both tuners.) The FM Reference pulled in 50 stations with the antenna left pointing southwest, toward the Empire State Building. (I didn't log in the full 200 stations Don Scott pulled in from his home in Connecticut because I did not rotate my antenna.)

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