Audio Research SP9 preamplifier Blind Listening 11/87

Postscript: Blind Listening (from November 1987, Vol.10 No.8):

JGH having written the review and JA having prepared it for typesetting, the two then set off for England to visit London's Heathrow Penta hi-fi show, organized by Hi-Fi News & Record Review magazine (full report next month). In the meantime, however, as is Stereophile's practice, a copy of the edited review was sent to the manufacturer so that they could submit a comment to appear in the same issue of the magazine. As you can see from Terry Dorn's letter on p.184, Audio Research was both a little hurt and puzzled by the negative tone of the review, and when JGH and JA arrived in London, word of this reaction had already reached the UK audiophile community ahead of them.

Despite discussions at the show with reviewers Ken Kessler and Martin Colloms, who had praised the SP9 in the October 1987 issue of HFN/RR, and with Ricardo Franassovici (RF), the UK Audio Research distributor and a keen-eared audiophile, we continued to feel that our sample had not achieved the level of performance to be expected from a product bearing the Audio Research name. A working hypothesis was put forward that our review sample had not been up to specification; this was scotched, however, when we learned that Audio Research had checked it out and found it to measure and sound as specified. "OK," said RF, "I'll set up a listening comparison between the SP9 and SP11 here in one of my suites at the show so that you can demonstrate to us what you feel to be the SP9's sonic shortcomings."

Accordingly, a group of bleary-eyed people—LA, JA, and JGH had partied a bit the night before—gathered in RF's suite at the cruelly early hour of 9am on the final day of the show. A system had been set up which, it was felt, would reveal the differences. A Goldmund Mimesis 3 amplifier fed a pair of Magnepan's new MG2.5 loudspeakers; signal source was a Kinergetics KCD-30 CD player; and the line stage of either preamplifier could be connected to the power amplifier via Randall Research interconnects with levels matched to within 0.1dB (this done by using the 400Hz test tone on the HFN/RR test CD and a handheld Fluke multimeter). Initially, it had been intended to use a Counterpoint SA-11 line preamplifier to buffer the preamps from the power amplifier and provide an immediate switched A/B comparison, but this was felt to obscure the differences. Accordingly, the more clumsy method of physically plugging and unplugging the preamplifier cables each time was adopted.

Initially, the listening was quite informal: JGH, JA, and LA would request operator Paul Crook to play a track either through the SP11 or SP9, and would then comment on the resultant sound. After 30 minutes or so of comparisons, the Stereophile team felt that the audible differences between the two preamps were pretty much as expected from their Santa Fe listening, though JGH commented that the drop in quality from '11 to '9 was not as great in the high frequencies as he had anticipated. A healthy argument ensued, along the lines of, "Well, of course the '9 doesn't sound as good as the '11 but it represents a good taste of true high-end sound at the price," though no agreement was reached as to whether this was true or not.

"Well, if you cannot be convinced," said RF, "how about taking part in a blind listening test?" LA laughed, finding it amusing that whenever a difference of opinion over subjective quality cannot be resolved, it is always the manufacturer or distributor, who wouldn't dream of assessing products in this way for his own purposes, who suddenly develops faith in the infallibility of blind testing. JGH and JA, however, felt that while the circumstances were hardly ideal—unfamiliar components, unfamiliar room acoustics, and the stress of having the person organizing the test, who had a vested interest in a null result being produced, present in the room—it would only be fair to Audio Research to put their strongly negative feelings to the test. After all, to judge from the comments in JGH's review, the performance shortfall of the SP9 was hardly subtle.

Accordingly, a piece of music was chosen—a passage from the Dutoit Decca/London Berlioz Symphonie Fantastique, if memory serves correctly—and was played four times, the order of preamps being chosen by Paul Crook and, naturally, not known to the listeners. The results were as follows:

Table: Blind Test Results

Order JGH JA
SP9 SP11 SP11
SP11 SP9 SP9
SP11 SP9 SP11
SP9 SP11 SP9

It can be seen that JGH scored 0/4, and JA 2/4, the latter the result that would be obtained by chance alone. It would seem that Stereophile cannot support its opinions under blind conditions and that Audio Research's faith in their product is vindicated.

Wait a minute, however. Consider JGH's scoring: 0% identification is as statistically significant as 100%; both are extremely unlikely to happen by chance. Examined on a more rigorous basis, JGH's results indicate that he did hear a difference between the two preamplifiers, as he correctly identified every time there was a change; under the blind listening conditions, however, his value judgments were turned upside-down, with the SP11 being identified as the '9 and vice versa, something that is not unusual in blind tests. JGH stated at the time of the test that he was getting mixed cues from the two preamps: the thinness in the '9's bass compared with the '11 in his own room and system had metamorphosed in the unfamiliar listening test conditions into a more natural balance for the '9 and an excessive and somewhat "drummy" bass from the '11.

What conclusions can be drawn from this blind test? Does it support or refute the findings of JGH's formal review?

Certainly, it is incontrovertible that a difference was heard, but whether it was one of character, as RF strongly felt, or of quality, as JA and JGH felt, is not proved either way. In fact, proving anything at all from blind testing is extremely hard—which is why Stereophile does not test equipment in this manner. Again, with respect to the SP9's sound, or lack of it, we urge you to audition it for yourself.—John Atkinson & J. Gordon Holt