Pioneer PD-M6 CD Changer Review

Most of the Compact Disc players we have tested have been very much alike in their electrical performance—and so far beyond most analog record players or cassette tape decks that comparisons are difficult to make. For the most part, the real differences between CD players are in their operating features, including their programming facilities, remote-control capability, physical size, and specialized applications such as use in a car or as a battery-run portable.

The Pioneer PD-M6 is certainly unique in terms of operating features, since it is the first “CD changer” designed for home use. It can be loaded with as many as six CD’s, which can be played in any order— and individual tracks on them can also be played in any order. The PD-M6 even has a random-play feature that will automatically select a random program from the six discs.

The PD-M6 comes with a six-disc magazine, as well as a single-disc tray, that fits into a 1 x 5-inch loading slot on the front panel, rather as a video cassette fits into a VCR (the slot is covered by a hinged door when no magazine is inside). The six-disc magazine contains six disc trays, which swing out one at a time for disc insertion. Since the disc magazine loads at the bottom of the player, the laser system is above it, so that discs must be inserted with their labels facing down (opposite to the usual orientation).

Most of the front-panel controls (light-pressure pushbuttons) have conventional functions, including fast manual search with the program audible, track skipping in both directions, and the usual play, pause, stop, and eject.

The programming system of the PD-M6 is highly versatile, although it lacks the index and phrase programming capability of some other players. A row of buttons numbered 1 through 6 selects the disc to be played or entered into memory for programmed play. If no disc is selected, the six discs are played in numerical sequence starting with the first. After the disc number has been entered, the track number (from 1 to 99) is selected using a row of ten buttons numbered 0 through 9 below the disc buttons. If no track is selected, the disc is played from its beginning.

The two-step operation—disc selection, then track selection—can be used for direct access to any part of any disc. The machine can also be programmed to play up to thirty-two selections in any order by using the PGM MEMORY button. Pressing the repeat button causes the entire programmed sequence to be repeated indefinitely.

If the random play button is pressed, the PD-M6 automatically enters a random playback sequence, selecting the discs in a random order and playing a randomly chosen track from a disc before proceeding to another disc and track, and so on. The repeat function also operates in the random-play mode. By loading the magazine with the appropriate discs, it is possible to assemble over six hours of music that will play in a different order each time it is repeated.

The display panel of the Pioneer PD-M6 is unusual because of the different types of information it presents. The numerical readout normally shows the current track number and its elapsed time in minutes and seconds. The display can be changed to show the total disc playing time and number of tracks or the current disc and track number. The numerical disc-number readout is somewhat redundant, however, since the lower portion of the display contains six disc symbols that resemble Pac-man figures. A red bar appears in the “mouth” of the currently playing disc. The display can also be used to check the programmed sequence of discs and tracks by successive operations of the program check button.

The Pioneer PD-M6 comes with a wireless remote-control unit that duplicates all its programming and control functions except power and eject. The player has a front-panel headphone jack with its own volume control (the line outputs are at a fixed level). The single-disc tray permits the machine to be used exactly like conventional CD players. Of course, the six-disc magazine can also be used with a single disc if desired. Additional magazines can be purchased, enabling a user to prepare a variety of multidisc programs.

The PD-M6 measures about 16-1/2 inches wide, 12-1/4a inches deep, and 3-3/4 inches high, and it weighs about 14 pounds. It is finished in black with gold markings. Price: $499.95.

Lab Test

The six-disc magazine simplified our testing of the PD-M6, since we could load all of our customary test discs into it and access any track as required. The output voltage was 2.07 volts from a 0-dB recorded tone, or 1.85 volts with the standard El A load of 10,000 ohms in parallel with 1,000 picofarads of capacitance. The two channels’ output levels were nearly identical. The frequency response was +0.1, —0.2 dB from 20 to 15,500 Hz and down 0.5 to 0.9 dB at 20,000 Hz (there was a slight difference between the left- and right-channel output at the lowest and highest frequencies). The square-wave response of the PD-M6 indicated that it uses analog low-pass filtering in its outputs. The interchannel phase shift ranged from 5 degrees at low and middle frequencies to 77 degrees at 20,000 Hz, suggesting that it uses a single digital-to-analog converter multiplexed between the channels.

Other aspects of the player’s performance were much like those of most CD players we have tested. The noise level, distortion, and crosstalk were all very low (at 100 Hz the crosstalk was too low to measure, better than 110 dB below the 0-dB output level). The PD-M6 operated perfectly in its various programmable modes as well as when playing single discs in normal sequence. The servo action of the laser optical system was slightly faster than in many other players, taking 3.5 seconds to slew from Track 1 to Track 15 of the Philips TS4 disc (4 to 5 seconds is typical). The transition between Tracks 17 and 18 of that disc, which have no silent interval between them, was flawless. As often happens with recent CD players, the maximum defect levels of the Philips TS4A test disc were tracked (and corrected for by the player’s circuits) without any audible difficulty. When we drove 200-ohm phones from the PD-M6, the available volume was more than ample.

The final, and often the most difficult, test we apply to a CD player is to estimate its resistance to physical shocks in the form of slaps by the open hand on its external surfaces. The Pioneer PD-M6 proved to be exceptionally resistant to this sort of treatment, earning a solid A grade. It definitely does not have to be treated gently to avoid loss of tracking.

Comments

Although we used the six-disc magazine for most of our tests of the PD-M6, we also played a number of discs one at a time with the single-disc tray. Operationally, there were no detectable differences between them. Incidentally, there was some audible mechanical noise whenever a disc tray was pulled out of the magazine by the mechanism in the player and again as it was returned to it. We weren’t disturbed by this noise, which is to be expected, and during actual playback the player was totally silent.

We have been impressed by Pioneer’s unconventional and innovative approaches to digital-disc technology, first with the unique CLD-900 CD/LaserDisc player and now with the PD-M6. CD players may sound pretty much alike, but imaginative products such as these underscore the fact that there are some real differences among them.

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