Conrad-Johnson MF-200 power amplifier

Cycles can be seen in the fortunes of companies. Likewise cycles can be seen in the performance of companies' products. A particular range will appear to have got it just right, whatever "it" is. The designer may have hit a winning streak and thus steal a lead over the competition. C-J set a new state-of-the-art preamp standard in the late '80s with their Premier Seven, and some of that expertise and experience are beginning to pay off in the shape of new high-performance preamplifiers at realistic prices. Moreover, the pressure was on to develop better power amplifiers to match. Two important products have emerged from all this in C-J's moderately priced FET range, namely the PF-1 preamplifier and the matching MF-200 power amp. By audiophile standards, these are moderately priced at $1295 and $1995, respectively.

What do you get for your money? Well, the MF-200 is quite substantial at a solid, continuous 200Wpc, both channels driven, with sufficient current reserves to drive a wide range of loudspeaker loadings. The power amplifier is a large item, weighing almost 60 lbs. Fitted with rack handles, the panel is finished in matching satin gold alloy, neatly lettered and fitted with one control: on/off. Again, the rear panel sports a captive mains lead; inputs are gold-plated phono, the outputs heavy-duty, gold-plated 5-way binding posts. Finned heatsinks are conveniently located at the back of the unit. It does not run too hot in normal use.

Technology
The MF-200 is a low-feedback design intended to capture some of the character of tube technology. The MF-200's input is straightforward, comprising a differential J-FET pair buffered by an emitter follower. A voltage amplifier with current-source load leads to a complementary MOSFET driver. Three pairs of high-current MOSFETs make up the output stage. All sections prior to the final output are fed from regulated DC so that pure clipping is defined by the driver and not by the output. Faster recovery should result. Though the MF-200 is a feedback design, it is stated to use "uncommonly low feedback." Generously sized electrolytic reservoir capacitors are present in the shared power supply, while the critical large-value feedback decoupling component is a film type. No "electronic" protection is present; the unit relies on the natural robustness of the output devices, and on 5A voltage rail fuses.

Sound
In the context of raw power delivery, I found the MF-200 to be load-tolerant, handling the range of test speakers well. Neither the Quad ESL-63 nor the Apogee Duetta Signature caused it any bother (as the lab results will later confirm). It is a genuinely powerful amplifier, as big as anyone is ever likely to require.

First impressions were of an amplifier sounding less "solid-state" than expected. Certain aspects caught the ear; for example, the natural texture and tonality of the broad midrange, such that one could use the term "creamy." Sounds in this fundamental range—human voice, cello, etc.—were well-balanced and believable. This region was backed by a powerful bass, with close to perfect damping which proved capable of a fine level of slam and yet was sufficiently agile to show a good sense of rhythm and timing. Here the MF-200 also reached significantly above its price class.

At cruising levels, the MF-200 possessed a good upper range; it mildly sharpened orchestral string tone and suffered from a shade of thinness through the treble register. Treble sounds were low in grain or other distortion effects, while vocal sibilance was quite natural; the high-frequency range conveyed a good measure of life, air, and sparkle. Some of the competition sounded deadened and closed-in by comparison.

Stereo focus and stage width were up to the expected standard, though some image narrowing was noted toward the back of the stage illusion. While generally revealing of musical detail, there was also a window of extra transparency in the midrange which could often give an insight into the more subtle spatial properties of top-class program.

The preceding paragraphs apply to moderate domestic sound levels with medium-sensitivity speakers. When the MF-200 was driven into the upper "loud" part of its working range—where average power exceeds 1 or 2W and the peaks are 10–20dB louder (20–200W and close to clipping)—it revealed a less favorable nature. The amplifier changed gear, as if readying itself for a long climb, and sounded coarser as well as harder, with increased glare and a significant drop in clarity.

Conclusions
In this condition the performance fell back to the merely "normal" for its price group. This aspect presented a difficult prospect for the reviewer—how to judge a product with this kind of two-level performance? For this, you'll have to wait for (or turn to) the conclusion.

The conclusions are complex, dictated by the unusual nature of these two products. The designer's goal of natural, musical dynamics has necessitated a level of individuality and distinction which makes these products less universal and easy to use than much of the competition.

One leading question concerns the MF-200's compatibility with the PF-1, since they are intended to partner one another. The answer is yes, they do match in character, style, and price, and are eminently recommendable as a combination, but please note the following caveat for the power amplifier. I advise an audition; you should take the opportunity to exercise the MF-200 over a wide range of levels to satisfy yourself as to its overall capability. Despite this cautionary note, I still find that I can recommend the MF-200, not the least for its well-above-average sense of pace, life, and dynamics. In absolute power terms, it is also good value at a generous 200Wpc for $1995.

COMPANY INFO
Conrad-Johnson Design
12733 Merrilee Drive
Fairfax, VA 22031
(703) 698-8581
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