Magnavox CDB-650 CD-player Review

The Magnavox CDB-650 compact disc player is manufactured by Philips, co-developer of the compact disc system. It uses a combination of advanced integrated circuits and an ultracompact laser assembly to provide exceptional performance together with some unusual operating features.

The low inertia of the CDB-650’s laser scanning assembly provides rapid slewing response—average track-access time is no more than 1 second—and accurate control combined with excellent shock resistance. The fully integrated electronic section of the player includes an exclusive Philips single-chip decoder and error-correction system and an improved quadruple-oversampling digital filter (operating at 176.4 kHz), which, in addition to a stopband attenuation of 60 dB, reduces passband ripple to a negligible 0.02 dB. A single digital-to-analog (d/a) converter chip contains two 16-bit D/A converters, one for each channel, which eliminates the need for multiplexing and the resulting interchannel time delay.

The Magnavox CDB-650 is a front-loading machine with a conventional front panel. Large pushbuttons control the disc drawer and the play, stop, pause, and fast-search functions. The forward and reverse search controls have three operating speeds. The music remains audible at the two slower speeds but is inaudible at the fastest speed. There are also the usual buttons (here labeled next and previous) to move the pickup in single-track increments. Unlike most CD players, the CDB-650 requires a second touch on the play/replay button to return to the start of the current track.

When a disc is first loaded, the display shows its total number of tracks and total playing time. During play it normally shows the current track number (and index number if the CD has indexed sections) and elapsed playing time in that track. One of six small program buttons between the main controls and the display window switches the time display to show the remaining time on the disc. Other buttons engage the scan and repeat functions (the scan function plays the first 10 seconds of each track on the disc before proceeding to the next one) and set the start and finish points for repeating any desired portion of a track.

The remaining button, marked FTS, is associated with the most novel feature of the Magnavox CDB-650. The letters stand for Favorite Track Selection, which allows specific portions of a number of discs to be programmed into a nonvolatile memory for playback whenever any of the memorized discs is loaded. The selected program segments can be whole tracks, indexed portions of tracks, or even nonindexed segments identified by start and stop times. Up to 785 selections can be memorized from a maximum of 226 different discs (the memorized information includes the disc identification code as well as the program selections). Once memorized, the information is available at any time, even if the player has been turned off or disconnected from a power source in the meantime. A memorized program segment can be removed, if desired, by storing another selection in the same location.

The front panel of the Magnavox CDB-650 also contains a four-position slide switch that selects normal play, single-track play, a COPY PAUSE mode, in which the player inserts 4 seconds of silence between tracks (useful for making cassette dubs for playback on machines that access selections by searching for silent intervals), and an AUTO pause mode, in which the player automatically pauses at the end of each track until play is manually restarted. The front-panel stereo headphone jack has its own volume control.

A small section of the front panel, above the headphone jack and volume control, hinges down to reveal the program keypad. The keys, numbered from 0 to 9, are used to program the machine for playback of up to twenty tracks in any order. They can also be used for direct access to any single track. The hidden control panel also contains a clear key to cancel any selected operating modes or programming, such as when the wrong button has been pressed. These keys are also used with the FTS button for programming the player’s memory system. The CDB-650 is supplied with a hand-held infrared remote control that duplicates all of its front-panel functions except power on/off and disc-drawer open/close.

On the rear apron, in addition to the regular audio output jacks, there is a second pair of jacks carrying signals that have been modified by precision analog filters to add a touch of “warmth” to digital recordings if these are deemed to be on the “cool” side. All of the signal output jacks are gold-plated. A digital-subcode output jack is provided for use with future accessories such as digital sound processors or CD-ROM systems, and a REC(ord) SYNC jack supplies a synchronizing signal to compatible cassette recorders for automatic tape dubbing from CD’s. A remote connector can be used with an optional accessory sensor to allow the use of the player’s infrared remote-control unit when the CDB-650 is enclosed or located out of direct range. The CDB-650 also has external heat-sink fins on its rear apron, unusual for a CD player.

The Magnavox CDB-650 measures 16-1/2 inches wide, 11-7/8 inches deep, and 3-3/8 inches high, and it weighs just under 9 pounds. It is available finished in black or silver. Price: $410.

Lab Tests

Although many of the specifications of the Magnavox CDB-650 are much tighter than those of other CD players we have seen, it easily surpassed all of them (within the accuracy limits of our measurements). Rarely have we seen the performance of any consumer product specified so completely and with such conservatism.

The most striking characteristic of the CDB-650 was the flatness of its frequency response. We are accustomed to measuring a virtually flat response from any CD player, but the approximately ±0.05-dB variation from 20 to 20,000 Hz that we measured from the CDB-650 was not only half its published rating, but quite possibly the flattest response we have ever measured. Even the high-frequency “ripples” in the response curve (which accounted for virtually all the variation we measured) were nearly undetectable.

Since no specific figures were supplied on the “warming” filter used for the player’s secondary output, we were curious to see what the resulting response might be. The differences from the untreated main output turned out to be extremely subtle. The response began to slope gradually downward above 4,000 Hz, reaching — 0.5 dB at 10,000 Hz, — 1 dB at 15,000 Hz, and — 2 dB at 20.000 Hz.

The main-channel outputs, measured with a 0-dB, 1,000-Hz test signal, were 2.1 volts, with an imbalance of only 0.04 dB. The shape of a square-wave test signal was typical of the response of a digital filter, though with somewhat less prominent ripple than most. Even at 20.000 Hz, there was virtually no interchannel phase shift between the main output channels. The same could be said for the secondary output channels, modified by additional analog filters. Only at 10.000 and 20,000 Hz could we detect a trace of phase shift (less than 1 degree). Although the audible significance of phase shift at these frequencies has not been demonstrated, these measurements represent an impressive achievement that has not even been approached by any other CD player we have tested.

The CDB-650’s noise level was barely detectable on our Sennheiser noise meter—its A-weighted reading was —125 dB relative to a 0-dB output signal. Channel separation was between 102 and 108 dB over the range of 1,000 to 20,000 Hz. The total harmonic distortion was 0.0018 percent at 0 dB, 0.008 percent at — 10 dB, and 0.006 percent at -20 dB.

The player had no difficulty tracking the calibrated defects on the Philips TS5A test disc. The slew time from Track 1 to Track 15 of the Philips TS4 disc was 3 seconds, roughly similar to that of most recent CD players. We confirmed the manufacturer’s claim that the CDB-650 can access most tracks on a disc in well under 1 second. And the instantaneous transition from Track 17 to Track 18 of the TS4 disc was handled flawlessly.

The headphone output was 12 milliwatts into 8 ohms, 58 milliwatts into 200 ohms, and 38 milliwatts into 600 ohms. The player’s ability to deliver its maximum output into headphones of medium impedance is a plus, since these are the headphones most commonly used. We found the headphone volume to be good. The impact resistance of the CDB-650 was excellent, rating an A on the top and right side, a B + on the left side near the transport mechanism. It had no problems with fairly vigorous finger tapping but could be made to skip when struck hard with the knuckles anywhere on the case.

Comments

Given the strong performance similarity of most CD players (a logical result of the CD format’s strictly defined recording and playback parameters), it is usually difficult to establish any objective order of preference among them. As a rule, features, price, and perhaps the effectiveness of a machine’s error-correction system are the prime factors influencing the consumer’s perception of relative quality. There is also, of course, the matter of the subtle (and sometimes not-so-subtle) audible quality differences that are claimed by some to exist, but these so far seem to defy objective analysis.

If CD players can be said to be equal in most respects, it is nonetheless true that some are “more equal than others.” In our judgment, the Magnavox CDB-650 is possibly the “most equal” of them all. We have tested some forty-seven CD players over the past several years. Although a couple of others have matched or even slightly surpassed the Magnavox CDB-650 in a few of their measured characteristics, none has come even close to equaling its overall performance.

It is unlikely that any practical or audible benefit results from a noise level of — 125 dB rather than one of — 95 dB, or a 20,000-Hz phase shift of zero degrees instead of 90 degrees, or a channel separation greater than 100 dB at 20,000 Hz instead of only 85 dB, and so on. Nevertheless, these and all the other outstanding measurable properties of this machine convey a clear impression of excellence that cannot be disregarded. We also checked the player’s various operating modes, including the unique FTS. system, and found that all worked as claimed. This level of performance would be understandable in a premium-priced machine—indeed, it should be expected, and it would be a major reason for the selection of such a product over others. To find it in a player priced just above the least expensive models is nothing less than remarkable.

In the midst of so many superlative qualities, it came almost as a relief to find that the CDB-650 was not quite perfect! Our first surprise came when we were listening to it and a cordless telephone a few feet away from the player rang. The CDB-650 immediately shut down, returning to its start-up condition. This behavior could be a handy added feature if the player went into the pause mode, but it was unintentional and became annoying after a while. Apparently something in the player’s control or tracking circuits was sensitive to the radio frequencies used in the phone system, and the CDB-650’s molded-plastic chassis provided insufficient isolation from them.

The second problem appeared when a couple of our CD’s would not load up and run (the display read error). One disc worked correctly after it was removed and replaced in the disc drawer, but the other would not play until we put a second disc on top of it. We suspect that this was a problem with the laser focusing of our test sample (serial number 1) and doubt that it is typical of the product design. Both discs have played properly on every other player with which we have used them.

Finally, curious about the efficacy of the “warming” filter used for the secondary output, we connected the two outputs of the player to two high-level inputs on our preamplifier and did some A/B listening tests. With musical material, we could detect no difference between the two outputs. When we played a pink-noise test signal, however, a slight response loss above 10,000 Hz was clearly audible in the secondary output signal. We can merely repeat the manufacturer’s suggestion that you use this feature if you like its effect and ignore it if you don’t.

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