A/B CD

According to the Oct. issue’s Annual Equipment Directory, there are now some 50 + consumer models of CD players on the market, with prices ranging from $399 to $1.600. Most people considering the purchase of a CD player usually audition a number of units, listening to them under extremely variable conditions of room acoustics and associated play back equipment. Many people also seek guidance by reading magazine reviews, and most are aware of price differentials between CD players due to the inclusion of "bells and whistles--features and conveniences in various models. The more knowledgeable also know that CD players employ either the 16-bit/44.1-kHz sampling rate system espoused by Sony or the 176.4-kHz oversampling and noise-shaping sys tem favored by Philips.

The burning questions from potential CD buyers are, "Do some CD players sound better than others?" or "Do higher priced CD players sound better?" or "Which CD player sounds best?'' Much confusion attends these questions, because while some golden-eared audiophiles state that sonic differences between CD players are easily perceived, there are writers and reviewers who contend that most CD players sound alike. They state that if any audible differences between players exist, they are so slight as to be inconsequential. Although this is certainly not a very satisfactory answer, there is a germ of truth in such allegations. In a casual listening test of the kind usually performed in a typical sound room of an audio dealer. CD players do tend to sound alike.

It occurred to me that a more satisfactory resolution to an appreciation of the sonic differences between players could be realized through the inherent characteristics of the CD medium it self. Consider that a CD is an absolutely uniform, invariable and infinitely repeatable sound source that will never wear out! One does not have to elaborate on the multiple variables involved in the playback of a vinyl record-but to make the point, these are the matters of pressing flaws, surface noises, and improper arm and cartridge geometry resulting in poor groove/stylus interface and resonance problems.

Then there are rumble overlays, incremental wear that ultimately destroys high frequencies and increases distortion. One could go on and on, and when considering all these things, the fact that we can get good sound (for a while) from vinyl records seems well nigh miraculous.

Because a CD has the qualities I have just enumerated, it is, in fact, the best sound source for A/B testing, an invaluable tool for the evaluation of preamplifiers, amplifiers, loudspeakers-and, of course, Compact Disc players. The ability to quickly and accurately repeat a desired passage of music for the testing of a particular component parameter is the exclusive province of the CD player. The time saving is tremendous and, of course, there are no concerns about vinyl groove fatigue and wear.

Evaluating CD players for sonic differences is simplicity itself. Required are two identical CDs (the choice of music is a matter of taste. but as a general rule. classical music affords greater dynamic range and a more useful instrumental complement) and a preamplifier with at least two high-level inputs. CD player X is fed into one input. CD player Y into another. It is necessary to have both CD units begin playing the first selection on the disc.

Because different players have different start-up times after their play but tons are pushed, a stopwatch is essential. If the start time on unit X is 5 S and 7 S on unit Y, Y will then have to be started 2 S earlier. Synchronizing two players is usually easy to achieve by using the fast forward or reverse controls. Once in step, it is easy to simply switch between the inputs on the pre amplifier for A/B comparisons; this should not be too much of a hassle for a good audio dealer. If the customer can't hear any differences between players, the purchasing decision can devolve into a matter of bells and whistles and/or styling or price.

You may recall that in the September issue. I reported on the new Meridian CD player. The Meridian people in England made an OEM deal with Philips for their pioneering CD-100 player and then specially modified this unit, at tempting to achieve higher performance. It had been postulated by a number of engineers that, quite apart from the problems inherent in digital anti-aliasing filters, almost any CD player could be improved with upgraded analog circuitry. Bob Stuart of Meridian holds similar views, plus a few other ideas about how to improve CD playback. More credit to him for taking the plunge and actually producing such a player.

I recently conducted A/B tests of the Meridian MCD and Philips CD-100 players and also performed very comprehensive, straightforward listening tests using a broad spectrum of music.

I can state right now that the initial impressions I had of the Meridian CD player at the Summer Consumer Electronics Show have now been completely confirmed. In fact, its performance parameters are beyond my expectations. As you read my comments, keep in mind that while the Meridian CD player was most extensively modified, it was being compared to the Philips player which has, at least, the same basic characteristics.

I fed the Meridian CD player into the auxiliary input, and the Philips player into the tape input, of the excellent Spectral DMC-10 Gamma preamplifier.

Synchronization of the two units was easy, since their access time was the same: Simply pressing the play but tons simultaneously locked the two players into perfect sync.

By circumstance, I happened to have four CD recordings in duplicate. I first loaded the players with a Telarc disc (CD-80080). This is a collection of such pieces as the Pachelbel "Kanon." Vaughan Williams's "Greensleeves" and Tchaikovsky's "Serenade for Strings"--all beautifully recorded and performed by Leonard Slatkin and the Saint Louis Symphony Orchestra.

The single most significant difference between these CD players is the markedly superior retrieval and presentation of ambience with the Meridian MCD. There is a spacious, open nature to the sound, with more air around the instruments. The Meridian has a cleaner, more well-defined sound, and instruments are more articulate. The music on the Telarc CD was scored for strings, and the sound of the violas and cellos in the upper bass/ lower midrange region was more delineated and had better projection on the Meridian unit. This player also afforded a smoother sound to the higher strings. The differences I perceived between these two units were clearly audible: it was not necessary to strain my ears.

As a change of pace, I loaded both players with the very fine. new Sheffield CD of Dave Grusin's Discovered Again (CD-5). Switching between the Philips and the Meridian once again verified the superior playback of the Meridian unit. The pop music in this highly detailed recording (typical of Sheffield) was reproduced with stunning clarity. Transients on the piano and percussion were utterly clean.

I went back to classical music, using Mahler's Symphony No. 1 (CBS MK 37273) with Zubin Mehta conducting the New York Philharmonic. The repetitive nature of the scoring in the first movement made comparison infinitely easier The differences between the players were striking, there being much more ambience presented by the Meridian. Here again, there was more air around instruments, particularly the woodwinds, and brass sounds were cleaner. Alas, the strident high strings that plague so many CDs, including this Mahler recording, were only marginally smoother and less edgy. I'm afraid the excesses of close up multi-miking, with microphones that have a tizzy top end, are beyond sonic redemption--even with a superior CD player like the Meridian. Having said this, it must be noted that, nonetheless, the increased ambience and spatial presentation make the music more listenable on the MCD.

For my last comparison I used Telarc's blockbuster Star Tracks recording (CD-80094). This combines some opening and closing special sound effects with passages from the Star Wars trilogy, Close Encounters of the Third Kind, and E. T. This CD offers a glorious feast of brass fanfares, soaring strings, and percussion of awesome impact. Intelligent miking, using three spaced Schoeps omni mikes, brings a recording of outstanding quality good by all standards with the Philips player, but absolutely stunning with the Meridian. All that I had come to expect from the MCD-the more realistic presentation of ambience, more air, better definition, and cleaner sound--was very apparent.

The Meridian MCD has the attractive styling of the original Philips CD-100 but is finished in a soft, nappy charcoal gray. All control lettering has been enlarged. As in Levinson equipment and some other components, the circuitry is designed to be constantly energized from the a.c. line, and fluorescent track indicators glow dimly as a reminder of this. When the power button of the Meridian player is pushed, it turns on the motor, which is verified by the track indicators becoming brighter.

The emphasis in the Meridian CD player is on quality, not frills. Best of all, because of the strength of the U.S. dollar in England, the selling price may decrease from its $850 list price.

To return to the original question:

Yes, Virginia, there are sonic differences between CD players, and the duplicate CD. A/B testing technique can help in hearing these qualities. To be sure, some of the differences will be quite subtle, and you may have to fight the ambient noise of the sound room. But it certainly beats choosing a CD player just for its looks!

(adapted from Audio magazine, Bert Whyte)

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