A Matter of Measurements

Beginning with this issue, Stereophile readers will notice that more of the subjective equipment reviews are augmented with technical reports describing certain aspects of the component's measured performance. Although test data have lately been increasingly included in reviews, Stereophile has recently made a major commitment to providing readers with relevant measurements of products under review. We have just finished building an audio test laboratory featuring the Audio Precision System One, a sophisticated, computer-based audio test measurement system.

"Measurements?", I can hear readers saying. "Didn't Stereophile create the field of subjective audio reviewing?"

Yes, we did. And we have no intention of departing from the path forged nearly 30 years ago by J. Gordon Holt. The decision to measure some performance criteria in no way changes our basic philosophy: the way to musical truth is through the ears, not the oscilloscope.

So why measure?

Including a product's measured performance in a subjective review improves the service we provide our readers, and increases the fairness to manufacturers who make the products. Following are some of the benefits of measuring:

1) There may be an unusual design quirk in a component (revealed by measurement) that makes it unsuitable for use with other equipment. For example, a recent measurement of a power amplifier's high output impedance indicated that its sound would be very dependent on the load it was driving. The amplifier would be a "chameleon," having a different sound with every new pair of speakers. If the reviewer happened to audition the amplifier with several pairs of speakers the amplifier meshed with, a buying recommendation might have been given without warning the potential purchaser of the risk inherent in the product. Recommending a component that does not merit a recommendation is the worst disservice Stereophile can do its readers.

2) Measuring protects manufacturers from an undeservedly bad review. A review sample may be defective and not representative of the product. For example, a review of a CD player contained criticisms that the player was harsh and bright on some discs. Subsequent measurements revealed a de-emphasis error that caused a 1.4dB boost above 10kHz. The de-emphasis error was a defect in the review sample, and did not properly reflect the product. Although problems with initial review samples will continue to be reported to Stereophile readers, the manufacturer will have a chance to replace the unit with a second sample and receive a review that more accurately describes the sound of the product.

3) Reviewers (and manufacturers) will be spared the agony of opening a review sample, only to find it defective. These defective units will be disqualified early in the review process and not sent to reviewers for evaluation. Consequently, delays in reporting on important new products will be avoided.

4) Most important, however, is the opportunity to correlate subjective impressions of a component with measurable phenomena. This will be a significant endeavour, and, when the process produces results, well worth the time and energy spent.

It can be argued that "objective" measurements are, in reality, subjective. One must make a subjective decision as to which "objective" measurements are important. For example, the decision to measure and include in every review an amplifier's THD specification implies that the reviewer thinks THD is an important performance criterion. This belief is certainly subjective.

The bottom line here is that these measurements will not detract from the high-quality subjective reporting Stereophile readers have come to expect. There will certainly be no "laundry list" of meaningless measurements cluttering every review. Rather, the additional technical information will be included only if it has relevance to readers' purchasing decisions, explains a sonic phenomenon discovered by the reviewer, or is interesting in its own right. Such an approach can only enhance the review and, in the process, help fulfill our most important goal: providing readers with the information needed before spending those important audio dollars.—Robert Harley