Test CDs!
Stereophile Test CDs 1 Through 4
Reference Recordings For Subjective
And Analytical Comparisons
Part One Of A Series

Review By A. Colin Flood
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  It is easy to spot a tweaking audiophile. When they are not sifting the pages online at Enjoy the Music.com™, they are often swapping out pieces of equipment and measuring things with hand-held meters.

The hand-held meters are analog or digital sound pressure level (SPL) meters available at Radio Shack for $40 or $50. Used with a CD of test tones and sounds, either meter shows the general SPL between components in the movie and music reproduction system. It provides objective measurements for analytical comparisons. Using a special microphone, the meters read up to deafening 126dB SPL, with slow or fast responses, on an A or C weighted scale. They are not 100 percent accurate. Their readings have to be taken with pinch of pepper, but at least you get the flavor of the system. You can't be a tweaking audiophile if you don't have a SPL meter.

» The good thing about the Rat Shack SPL analog meter is it within 2dB, and lets you scope out the frequency response of your room, loudspeakers and amplifiers. It lets you see where the bugs are hidden. Finding the problems will present solutions to improve your system.

» The bad thing about the SPL meter is that it is not accurate. Take what it says as gossip, not gospel. It will show you the general curve for a piece of equipment, not the absolute truth. Measuring several different pieces in the same room allows you to generalize as to their sonic characteristics. If everything dips down at 50Hz, for example, you can assume that room reflections have something to do with it.

» The other problem with the ubiquitous RS meter is that once you have tweaked your own movie and music reproduction system, unless you keep making changes ad infinitum, you will rarely need the meter or the Test disc again. Instead, intrepid retailers and local audio clubs should loan out this useful tool.

The thing you need with your newfound toy is a Test CD, and there are over a dozen from which to choose. Some are new - some are old. Some discs have great test tones, specialized signals and reference sounds. Some are simply incredibly well recorded music samplers, with notable qualities useful for tweaking audiophiles. A few Test CDs have musical solos; great for isolating the particular tonal qualities of a system.

The Series

This intermittent series briefly runs down a dozen of these useful discs. In the series:

» Four Stereophile magazine discs

» Three Reference Recordings

» Three DMP classics

» Telarc foot stomper and tapper

» Chesky jazz

There are two basic kinds of Test CDs and this series covers them both. The first kind reviewed here is dryly clinical. The objective test tone and measurement CD for analytical comparisons. These usually include some form of music and/or sound tracks, i.e. instrument solos or barnyard noises. The sound tracks allow for subjective comparisons with the real world.

The second kind of Test CD is just as useful, but in a far more emotionally involving fashion. This is the reference quality music CD. Without any objective measurements, this is a recording devoted to squeezing the very last drop of realism, accuracy and musicality out of the performance, venue, equipment and engineers. DMP and Chesky stand out in this round-up for their attempts to give superior audiophile quality recordings to modern jazz music. One disc in particular, includes tracks which tweaking audiophiles have to hear when critically auditioning equipment.

In this regard, all of the discs give examples of ultimate recordings: "state of the art" for is available at the time; technology marches relentlessly onward. The first creaking disc is covered with the dust of a decade.

Test CD

The oldest, and only marginally useful, selection in this discography is the original Stereophile Test CD (1990, $8.95). Stereophile is one of the oldest and still remaining hard-copy magazines devoted to movie and music reproduction systems. It is renown not only for it's A, B, C, recommended categories for equipment, but also for its "price is no limit," sky high equipment selections.

Stereophile magazine makes dozens of CDs now, four of which are designed for tuning and appreciating your home movie and music reproduction system.

Their first test disc is a set of 14 mostly classical recordings made by Stereophile's contributors with the best recording processes available at the time. There are comparisons of a dozen professional, but old, microphones and converters. It also provides the raw feel of a live high school marching band. The CD has acoustic guitar, flute and piano recordings, plus the now famous "Lesley Test" ("Summertime," sung by the wife of Enjoy the Music.com's own editor, Dick Olsher, with Stereophile at the time).

From the work of Fletcher and Munson at Bell Labs in the 1930s, we know that the human ear at normal 70dB conversation levels hears only 400Hz to 6kHz. Not a very wide range compared to the "20Hz to 20kHz" that is always referenced. Yet, we hear with extra special sensitivity between 1 and 6 kilohertz at all levels! Therefore, the accuracy and dynamics of a movie and music reproduction system in the 1kHz to 6kHz range is hyper-crucial.

As a large harp, laid on its side, fitted with a black-lacquered case and hit with soft hammers, the grand piano plays from a rumbling 25Hz up to the critical 4,600Hz. Most acoustic instruments have much less range, between only 80Hz and 1260Hz. Only a few wind instruments, and the violin, reach above the grand piano's upper range: the clarinet, flute, oboe and piccolo.

This means we are particularly sensitive to those instruments. Movie and music reproduction systems have to work especially hard to make these instruments sound accurate. Therefore, Test CDs with solos or duets of these instruments are particularly useful. Indeed, many of the Test CDs have flute solos or duets for just this purpose.

The four very nice flute pieces on the first Test CD let you hear, if not measure, the quality of the mid-range. The solos reveal midrange tone and resonant problems in loudspeakers. The piano shows the width, flatness and dynamics of the loudspeakers. An organ piece shows the size of the concert hall as well as the depth of the bass extension.

Test tones help the tweaking audiophile identify the frequency response of their systems. This disc though, is limited in the test tones it provides. It covers only the bass region, from 200Hz to 20Hz.

The disc includes: 1kHz sinewave tones, proper channel identification (with a dog), channel phasing and pink noise. The 1kHz tone is used to get an idea of how your loudspeaker sensitivity in your room compares to its rated sensitivity. The phasing is particularly useful for locking down the central image and creating a soundstage where the instruments have separation. Stereophile made a mistake on the test tones in the first CD, which they cleaned up in the second.

This aging disc is less expensive than other brand-name test discs and is a good example of what you once got with Test CDs. Too bad it is limited to the bass decade for test tones. Except for the nice recordings, skip it, move on.

Test CD 2

Two years later ('92, $9.95), the magazine came out with an updated Test disc. It includes 11 music tracks, including drum and guitar solos, plus 20 tracks for testing loudspeakers and rooms, distortion & jitter demonstration tracks, CD player & tape recorder test tracks and high level test tracks.

Every reference recording should have plenty of solos. They reveal the tone and dynamic range of the mid-range, without the interference of other instruments. Solo instruments playing a single note at a time would be even better.

This second Stereophile test disc has excellently recorded violin and organ, flute and piano duets, with drum, electric and acoustic guitar solos. The drum track, the booklet, says should be played LOUD. A drum track is "a good test of a system's dynamic range, LF extension, image specificity, and ability to differentiate pitch." This disc adds a soundstage map, so you can hear the location of recorded clapping within a church.

The second test disc from Stereophile is well worth the extra buck. It extends the range of frequency response test tones. It adds the 1/3-octave warble tones for the midrange, from 250Hz to 2kHz; and the treble range, from 2.5kHz to 20kHz. The tones are accessible by index. There is also something called a "Music Articulation Test Tone" to allow "you to get a handle on your loudspeaker positioning and your listening-room acoustics." The tones consists of rapid bursts starting at 28Hz, rises in pitch to a peak at 780Hz, then descending back down.

Three tracks compare different levels of second, third, and seventh harmonic distortion levels with a pure tone. Two tracks compare "a pure tone with distortion signatures typical of a classic tube amplifier near its clipping point, an inexpensive Class-B solid-state amplifier and a panel speaker near its overload point." Following tracks compare the audio affects of CD jitter. See if you can hear the differences.

From there, the disc gets more sophisticated. There are spot frequency tones, to assess the frequency response and crosstalk. There are de-emphasis test tones, which if your CD is operating correctly, should all measure identical in level. A "Noise Modulation Test" attempts to predict the audible performance of a player's D/A conversion by measuring its noise modulation. Two ultra-high test tones (at 19kHz and 20kHz) are inaudible, but included for test purposes.

Overall, a very useful, low cost Test CD.

Test CD 3

The 1995 Test CD 3 (1990, $11.95) overlaps the previous two discs, but moves towards HT systems. If recording techniques are improving as technology advances, then age is important in selecting a test CD. Only four other discs in this series are newer than this one. Test disc three is two bucks more than the second and well worth the premium. You can order all three Stereophile Test CDs and save on each individual cost, but there is nothing essential about the previous two.

The third Test disc has both five channel and stereo phase ID, microphone techniques, data compression, chromatic scale, burn-in noise, demagnetizing tone, along with a unique noise track. The track is a binaural recording of the Montréal Formula One Grand Prix and puts the headphone listener in the grandstand. The better your movie and music reproduction systems is, the more important these esoteric sound demonstrations become.

The music tracks on the first two Test CDs are almost exclusively classical. For Test CD 3, Stereophile features a variety of excellent tracks from audiophile record labels. These include Telarc classical, Reference Recording jazz, the wonderful vocals of Sara K. from Chesky, Muddy Waters style blues, Herbie Hancock and Stanley Clarke, a classical guitar technique striking electric bass strings, English choir, and a Chopin piano piece. No subtle flute or dynamic drum solos however.

As befitting a venerable magazine, the booklet accompanying the Stereophile discs are the best! They explain the tests and recording techniques. They tell you how they did the test, what you should do and what you should hear. Very educational.

Overall, the most useful, relatively low cost Test CD.

With both 15 useful, objective tests and 10 wonderful audiophile-quality music selections, so far, this is the disc to beat. Stereophile offers a package deal for the first three, but except for the recordings and their explanations, I don't know why you would need the others. It will be interesting to see how discs from the other firms stack up against this one.

Test CD Four

Finally, Stereophile wised up to its ageing Test CD franchise and last year brought forth a new progeny ($9.97). The latest disc is a compilation of the more useful previous tests, therefore I did not buy this CD.

This disc is limited in tests. It includes Channel Identification and Channel Phasing, which is useful any time you swap front-end equipment. Yet, the Maxell CD Lens Cleaner disc (CD-345) will give you channel, sound and polarity tests, plus it cleans your CD player.

The few CD Four tests include: Reference Tone, Dual-Mono Pink Noise, Chromatic Scale, 1kHz 1/3-octave warble tone, Bass Decade 10-second 1/3-octave warble tones, Midrange Decade and Treble Decade.

This disc quickly moves to 13 fairly recent classical music recordings The 1996 flute recording tells you the SPL. Clarinet, piano, "notoriously difficult" horns and violins compromise this mainly classical Test CD.

I like Test CD Four for its newer recordings, but its useful objective tests are limited.

So far, Enjoy the Music.com™'s review of Test CDs includes Stereophile magazine's four low-cost, but quite useful offerings. Coming up next in this series:

» Reference Recordings' competitive swing and classical discs - one with a useful clap track

» DMP's multi-channel SACD

» Telarc's 5Hz dinosaur footsteps

» Chesky's musical offerings

The series also includes the one disc any tweaking audiophile has to play for critical listening. Enjoy the testing... and the music.