An Audio Obstacle Course: The Shure Trackability Test Record
Shure Bros. TTR-101.
Shure’s new “Supertrack” V-15 Type II pickup was designed as an answer to all those high-powered discs whose excessive modulations make them shatter all over the place on lesser pickups, But just in case anyone didn’t happen to own any of these difficult discs, Shure decided to issue one of these, too. The result is a collection of some of the meanest modulations ever gathered together in one place.
Each “test” is a series of four short musical excerpts, recorded at progressively higher levels but otherwise identical. Among the nastier items(from a pickup’s viewpoint) are orchestral bells, piano, accordion, and harpsichord, but everything on here is likely to give every pickup something to struggle with.
Also included are some silent grooves to evaluate hum, rumble, and surface noise, and an area of blank, ungrooved surface for checking bias compensation. The latter is the only thing we are really dubious about, because it doesn’t work the way it should.
Shure advises us to adjust the bias compensation until the stylus stays where it’s placed on the blank area, skidding neither toward nor away from the center spindle. The resulting bias adjustment, however, yields what appears to be over-correction, for the pickup then breaks up on left-channel modulations before the recorded level is high enough to cause right-channel distortion. We still prefer to use this left–right comparison method for checking bias compensation, and the left–right bands on Shure’s disc are an ideal way of doing this. With bias properly set (and assuming both channels of the system to be matched in volume and in component lineup), both channels will be equally clean, or equally distorted, on both the right- and left-channel tests.
How effective are the other tests? We found them to be at least as valid for comparison purposes as our own stock of horribles—the pile of discs we’ve accumulated for checking tracking ability. We found one section—the loudest accordian passage—to be a bit too much even for the Type II V-15. But we also found that our previously determined ranking for the relative trackability of the pickups we’ve tested was verified right down the line when using the TTR-101. And although you may be shocked by what you find when you try it on your own system, remember that there are pickups that can track it almost perfectly cleanly. (Incidentally, loudspeaker peaks and very small amounts of amplifier distortion can exaggerate tracking distortion out of all proportion to its actual severity, so don’t be in too much of a hurry to blame your pickup if it makes a very poor showing.)
This is one of the few listening-type (as opposed to metered) test records we’ve found that really does what it’s intended to do. And what more could we ask? Shure’s TTR-101 costs $3.95 and is well worth it. But it may persuade you to buy a new pickup.—J. Gordon Holt
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