Astatic MF 200 Phono cartridge Review

Although the Astatic Corporation has II been manufacturing phono cartridges for at least fifty years, its name may be unfamiliar to many audiophiles. Until recently the company has been known principally as a manufacturer of low-cost piezoelectric (crystal and ceramic) cartridges for mass-market record players sold under many brand names.

Astatic has now entered the component hi-fi area with a line of four magnetic cartridges manufactured in Japan to their specifications and bearing prices ranging from $80 to $267.50. They all use the same basic construction and operating principle, which Astatic calls “Moving Flux” (MF). The pivoted end of the stylus cantilever carries a small square magnet that is placed very close to the shaped cores of the coil assemblies. The magnet is moved by the stylus as it follows the groove modulations, and a varying amount of flux is thus passed through the coil cores.

The cartridge specifications suggest that the MF design is more efficient than that of most moving-iron or moving-magnet cartridges. Although the coil inductance is only 90 millihenries (compared to many hundreds of millihenries for most magnetic cartridges), implying a relatively small number of turns of wire in the windings, the rated output is about 3.5 to 4 millivolts. The MF cartridge, even though it uses smaller coils, can generate an output-signal voltage equal to that of a conventional moving-magnet cartridge, indicating a highly efficient magnetic system. The low inductance also means that the cartridge's frequency response should be relatively independent of external load capacitance.

The two lowest-price models of the Astatic MF series have spherical and elliptical styli, while the two higher-price units have Shibata-type parabolic styli. We tested the next-to-the-top model, the MF 200. Its Shibata stylus is rated to track at 1.75 grams ±0.25 gram, and it has a rated frequency response of 10 to 20,000 FIz ±2.2 dB (and up to 40,000 Hz with no tolerance specified). The user-replaceable stylus assembly includes a hinged guard. Like all the Astatic MF cartridges, the MF 200 is available factory-installed in a four-pin universal low-mass headshell (as the MF 200H) for an additional $22.50. The price of the Astatic MF 200 is $160.

Laboratory Measurements

The Astatic MF 200 was installed in a typical tone arm and was operated at its rated tracking force of 1.75 grams. Preliminary response measurements with various values of load capacitance showed no significant change over a range of 160 to 400 picofarads, so we used 160 pF in parallel with a 47,000-ohm load as the cartridge termination.

The output voltage from the 3.54-cm/sec standard level bands of the CBS STR 100 test record was 3.4 millivolts, with a channel unbalance of 0.7 dB (well within the 1.5-dB specification). In the test arm, the mass of which was not especially low, the highly compliant MF 200 resonated at 9 Hz with an amplitude of 7 to 8 dB. The vertical stylus angle was 22 degrees.

The frequency response was measured with several types of test records, including the CBS STR 100, B&K 2009, and JVC 1005. The results were consistent with all these records. The frequency response of the cartridge was almost perfectly flat up to 10,000 Hz and rose some 5 or 6 dB between that frequency and 20,000 Hz. This suggests that the stylus resonance is above the audio range and relatively undamped. With the JVC 1005 record (which sweeps to 50.000 Hz) we measured a sharp resonant peak of 10 dB amplitude at 30,000 Hz. The output at the record’s upper limit was down only 10 dB from the midrange level, and at 40.000 Hz it was down only slightly from the reference midrange output level. The response to the 1,000-Hz square wave of the CBS STR 112 record showed about three cycles of damped ringing (initially at a rather high level) at the 30,000-Hz stylus-resonance frequency, followed by ringing at about 40,000 Hz (which we know to be in the record). The midrange channel separation was about 20 dB, and the separation was a fairly uniform 10 dB from 20,000 to 50.000 Hz.

The tracking distortion of the MF 200 was measured with the Shure TTR-102 and TTR-103 test records. The intermodulation distortion with the TTR-102 was under 2 per cent up to about 11 cm/sec velocity, rising slowly to 4.5 per cent at the record’s maximum level of 27 cm/sec. The high-frequency tone-burst distortion with the TTR-103 increased slowly over the 15- to 30-cm/ sec range of the record. In neither case was there any evidence of significant mistracking, and the measured distortion levels were typical of other good cartridges we have tested.

Subjective tracking tests were even more impressive. At 1.75 grams, the MF 200 had no difficulty with the high-level tones on any of our test records, including the 100-micrometer level of the German Hi Fi Institute record. Fewer than a handful of cartridges we have tested have been able to play that level without serious mistracking. In view of these test results, it was no surprise to find that the MF 200 was able to track the highest levels of every band on both Shure “Audio Obstacle Course” records (ERA III and ERA IV). There was a trace of hardness on the bell section (level 5) of the ERA IV disc, but not enough to constitute mistracking in our judgment.

Comment

Astatic, in a brochure on the MF cartridges, likens their sound to that of a good moving-coil (MC) cartridge. The comparison is apt, since the two have much in common despite their different modes of transduction. The low-inductance windings of the MF cartridge make it almost as independent of external loading as any MC cartridge, and its output is higher than any of them, including that of so-called “high-output” types. Most MC cartridges have a rather high-amplitude, undamped stylus resonance somewhat above the audible range. In most cases, this results in a rising response between 10,000 and 20,000 Hz. That is exactly what we found in the MF 200, and for the same reasons. The Shibata stylus gives the MF 200 outstanding high-frequency tracking ability. Its high compliance is higher than that of any MC cartridge we can think of, and it is responsible for the excellent low- and middle-frequency tracking ability of this cartridge.

All in all, the MF 200 is an uncommonly fine phono cartridge. A few years ago, it could have been touted as ideal for playing CD-4 quadraphonic records, for its maximum response at 30,000 Hz would have assured solid recovery of the recorded pilot carrier. With stereo records, if you like the “airiness” or definition that results from a rising high-end response, you will surely like the sound of the MF 200. It seems likely that this phenomenon explains much, if not most, of the popularity of moving-coil cartridges, despite their recognized tracking limitations and high cost.

The Astatic MF 200 seems to combine the best of both worlds—the low impedance and excellent high-frequency response of an MC cartridge with the higher output and superior low- and middle-frequency tracking ability of the finest moving-magnet cartridges. It is an auspicious entry into the component hi-fi market for one of the oldest names in audio.

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