ADC TRX-3 Phono cartridge Review

Like previous ADC cartridges, ADC’s TRX “Zero Resonance” phono cartridges, of which the TRX-3 is the top model, all employ the induced-magnet principle of operation. While usually classified as moving-magnet designs, induced-magnet cartridges do not have moving magnets. Instead, a magnetically permeable armature is attached to the stylus cantilever and located close to a fixed magnet. This arrangement induces magnetic flux into the armature and effectively turns it into a moving magnet. The armature’s magnetic field moves in response to the stylus motion and in turn induces signal voltages in the cartridge’s fixed coils.

In the TRX-3 a high-energy samarium-cobalt magnet energizes a three-pole mu-metal armature, which is located near the pivot point of the tapered tubular beryllium cantilever. The cantilever pivot point is accurately maintained by a fine tension wire. To reduce the mass of the moving system, the stylus is fashioned on a rectangular shank, which has less residual mass after the stylus has been cut than the usual square shank. In the interests of high positioning accuracy, low mass, and ruggedness, the stylus is nude-mounted perpendicular to the cantilever. The stylus itself is a line-contact configuration with contact radii of 0.06 and 0.12 mils.

The “Zero Resonance” in the cartridge’s name refers to the reduction of undesirable resonances by such techniques as the use of a rigid one-piece die-cast aluminum-alloy body and by the anchoring of the replaceable stylus assembly by means of a screw. The lowered mass of the stylus/cantilever assembly also helps reduce the effects of high-frequency resonances. Price: $300.

Lab Tests

We installed the ADC TRX-3 in the moderately high-mass tone arm of a typical high-quality turntable. Initial tracking tests with high-velocity test records showed that the cartridge tracked well at its nominal 1.2-gram vertical force rating, but an increase to the maximum rating of 1.4 grams made a substantial improvement in its tracking ability. We used 1.4 grams for the balance of our tests.

Similarly, frequency-response measurements using several values of load capacitance confirmed that the recommended load of around 275 picofarads (pF) gave the flattest overall response, although the audible differences between the extremes of 170 and 400 pF were not significant (about 2 dB maximum output change in the 10,000-Hz range and virtually none at 15,000 Hz). We used a 300-pF termination for our testing of the cartridge.

The ADC TRX-3 impressed us by the unusual symmetry of its measured performance. Although some cartridges have well-matched output levels at 1,000 Hz, it is most unusual that both the frequency-response curves and the crosstalk curves for left and right channels are essentially alike over the full audio frequency range. In this respect the TRX-3 was clearly the most outstanding cartridge we have tested so far.

The intermodulation distortion of the TRX-3 was fairly low, and there was no evidence of severe mistracking at the 27-cm/s maximum recorded level on the Shure TTR-102 test record. High-frequency tone-burst distortion, from the Shure TTR-103 test record, was low and varied little over the 15- to 30-cm/s range of the record. Other high-level tests, including the German HiFi:2, were tracked easily.

The ADC TRX-3 has a very high stylus compliance, rated at 40 microcentimeters/dyne, and therefore it should deliver its best performance when installed in a relatively low-mass arm. The effective mass of our arm and headshell (not including the 6.5 grams of the cartridge) was about 24 grams. The whole assembly resonated with the stylus compliance at 6 Hz. Although this is well below the optimum range of 8 to 12 Hz, we had no difficulty in playing any reasonably flat record with this tone-arm/cartridge combination (even if it were installed in a very low-mass tone arm we would not expect the TRX-3 cartridge to resonate above a frequency of 8 or 9 Hz).

In spite of our reservations concerning the “Zero-Resonance” nomenclature of the cartridge (resonances can be reduced to insignificant amounts, but they usually cannot be entirely eliminated), it does indeed have very well-suppressed resonance properties. In particular, the square-wave response to the CBS STR 112 test record was about as good as we have ever seen. The top and bottom of the 1,000-Hz square wave were flat and free from identifiable ringing, and there was only a single cycle of fairly low-level ringing at each of the transitions of the square wave. The unavoidable high-frequency stylus resonance appeared to be at least 30,000 Hz, if not higher, in frequency.

Comments

Given the excellent specifications and measured performance of the ADC TRX-3, one would not expect to find anything wrong with its sound. In this respect, our listening tests produced no surprises.

When discussing a cartridge of this quality, however, it is rather difficult to make meaningful distinctions between its sound and that of other fine cartridges. This is closely analogous to the situation existing with amplifiers, and for the same reason. Once the quality of performance of a system component has reached a sufficiently high level, any clearly audible differences are likely to be the result of a flaw rather than an improvement in its performance.

After that lengthy aside, I can simply say with some assurance that the TRX-3 is about as smooth-sounding and free of coloration as any cartridge I can think of. Certainly its frequency-response and crosstalk characteristics are superb, and its trackability and low distortion easily meet our own standards for a true top-quality cartridge. The TRX-3 is a worthy flagship for the ADC cartridge line.

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