AKG P8ES
A moving-iron cartridge from a microphone company, with a knife-edge pivot and a spec sheet that read like a dare.
Overview
AKG built its reputation in Vienna on microphones, but phono cartridges were never a side hustle. The P8ES sat at the top of a five-model range that also included the P8E, P7E, P6E, and the spherical-stylus P6R. The engineering underneath was unusual. The cartridges all used AKG's variable-reluctance principle with a patented transversal suspension. The stylus cantilever is centered symmetrically in a small hole in a very thin, gold-plated metal plate. That plate is joined to the gold-plated soft-iron armature by a rubber element vulcanized to both metal parts. This makes a knife-edge bearing of remarkably small size, and AKG claimed the pivot suppressed torsional and axial movement so no spurious signals were generated. The design is fully symmetrical, so the same mechanical conditions exist for transverse excitation in every direction. The large permanent magnet with high flux density in the air gap sits outside the moving stylus assembly, which keeps the effective mass of the tip down - 0.42 mg, according to the manufacturer's literature.
The numbers on the P8ES are the kind that sent dealers to the demo room. Frequency response is quoted as 10 Hz to 28,000 Hz, measured using a B&K QR-2010, and output voltage at 5 cm/sec is 3.75 mV. Tracking force runs 0.75 to 1.25 grams with an optimum of 1.0 gram. Compliance is 35 x 10⁻⁶ cm/dyne, a high-compliance design aimed at low-mass arms. Channel separation is 35 dB at 1 kHz and 25 dB at 10 kHz, channel balance is within 2 dB, and frequency IM distortion at -6 dB is 0.5 per cent or less. Impedance is 860 ohms and 280 mH, with an optimum load of 47,000 ohms and 470 pF. The body weighs 5.86 grams. The stylus is an elliptical 0.2 x 0.7 mil, and the replacement assembly is the X8S, also elliptical. Price at introduction was $135.00.
Audio (December 1978, p.90) ran the P8ES through its full equipment-profile regimen, and the results were strong. The magazine's testers reported that the cartridge had no difficulty playing all the tracking-ability bands on the Micro-Acoustics TT-2002 test record, and that its transient ability was excellent — the computer-generated high, low, and high/low mixed frequencies presented no problem. It performed superbly on all bands of the Shure Audio Obstacle Course Era III (TTR-110). The one caveat came with the newer Shure Era IV (TTR-115) record, where the P8ES did not quite pass level 5 — +12 dB above reference — of the flute and flute-bell test. As the review itself conceded, that is one of the most severe high-frequency trackability tests to be found, and very few cartridges track beyond level 4. In the same profile, Audio (December 1978, p.92) noted that the P8ES "does not have to take second place to any other cartridge known to us" on transient and tracking ability.
Audio (December 1978, p.92) reported being surprised by the transparency of the sound, attributing it to the low IM distortion, and praised the sonic clarity and bass response. The 2 dB peak at 10 kHz was measured but not audible as a high-frequency effect during listening. The P8ES did not appear to introduce a sound of its own or coloration, and it played difficult high-velocity records, including many direct-to-disc pressings, without adding anything to the music. The reviewers singled out the singing voice as an area where the cartridge was especially superb, with a clarity and naturalness seldom found. Their conclusion: the P8ES ranks among the top cartridges, with very few others its equal.
The period review flagged one practical quirk. The shape of the cartridge bottom is such that it must sit absolutely parallel to the record to avoid rubbing the surface, particularly on warped records. The supplied wedge is intended for mounting in a record-changer arm, but Audio (December 1978, p.92) found it may have to be used in a single-play tonearm too if the arm cannot be adjusted enough to keep the cartridge bottom off the record. That is a mounting consideration, not a fault, but a P8ES set up carelessly will drag. The cartridge shipped in a plastic cube with the necessary hardware in the bottom, including a screwdriver in the review sample, plus an individual response curve for that specific cartridge and mounting directions.
AKG's own advertising billed the range with the line "Sooner or later one of the remarkable AKG TS Phonocartridges will end your search for the pick-up system that most perfectly re-creates the sound your recordings were originally made from". The copy ran in Audio (October 1978, p.107) and in the buyer's guides of the period. That is salesmanship, not a verdict. The independent verdict came from the equipment profile, and it was more specific. A high-compliance, low-tracking-force design like this one wants a low-mass arm, and the fact that Thorens engineered around it is a useful data point for anyone assembling a period-correct front end.
The 35 dB channel separation at 1 kHz and the 0.5 per cent IM distortion figure are the numbers behind the transparency the reviewers heard. The 10 Hz to 28 kHz response and the 3.75 mV output go with a standard 47k/470pF phono input. Setup is not forgiving, because the parallel-to-record requirement is real. It is also not a high-output design to slap on any arm, given the 35 x 10⁻⁶ cm/dyne compliance and the 0.75-gram minimum tracking force. Replacement styli are the X8S, and given the age of these cartridges, the stylus needs checking before the first play.
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