Teac Z-6000 Cassette Deck Review

Built like the proverbial battleship, with a die-cast frame suggestive of a top open-reel recorder, the Teac Z-6000 cassette deck offers the serious cassette recordist nearly every performance feature imaginable, including Dolby-B, Dolby-C, and dbx noise reduction, together with a basic operational simplicity that bespeaks as high a level of human engineering as of electronic engineering. The Z-6000 has three separate heads (sendust for recording, ferrite for playback), permitting instantaneous checking of recording quality. The dual-capstan transport uses a direct-drive d.c. servomotor for the leading capstan; the trailing capstan is belt-coupled. Separate direct-drive d.c. motors turn the take-up and supply-hub spindles, and a fourth d.c. motor operates the head assembly and pressure rollers, eliminating the jarring “clack” that is so often characteristic of solenoid-operated cassette decks.

The transport-mode buttons, including both record-mute and pause, all have bright LED indicators and are very well designed for light, positive operation. Cassettes are inserted, tape openings downward, into the usual slides on the back of the highly damped cassette-well door, which is easily removed for routine head cleaning and demagnetization. The well itself is illuminated, and the clear door provides full visibility of the cassette inside. A pitch control with a very wide range ( + 13.6 to —11 per cent in our measurements) is pushbutton-selectable.

At first glance the Z-6000’s array of twenty-four pushbuttons to the left of the cassette well appears formidible indeed, but a sensible arrangement makes their functions easy to learn. In the top row are buttons for various memory operations (rewind to stop, to play, or to repeat a chosen section); a COMPUTOMATIC PROGRAM SEARCH (CPS), which allows skipping forward or back by up to nineteen selections (the number chosen is displayed on a digital readout) by automatically detecting 4-second blank spaces between them; and an intro check, which plays about ten seconds of a selection and then, unless the play button is pressed, skips to the next selection and repeats the process. The buttons in the second row set the digital tape counter, which conveniently reads elapsed time in minutes and seconds (even in the fast-wind modes) for C-46, C-46L (large hub, a format used in Japan), C-60, or C-90 cassettes.

The third row of pushbuttons selects among various different monitoring functions. Source allows monitoring of either the line or microphone input levels. Cal and tape both allow monitoring of the tape output level, but with the cal button pressed the meters show the output levels before they are affected by the deck’s output-level controls; with the tape button pressed they show the levels as affected by the controls. The sync button sets the meters to monitor the program source before recording starts and to switch automatically to monitoring the tape playback while recording is in progress.

The fourth row of buttons allows the user to choose no noise reduction, Dolby-B, Dolby-C, or dbx; indicator lights on the display panel show which system is in use. The fifth row is marked input. Buttons allow selection of either line or microphone inputs or decoded playback of a dbx-encoded disc. Another button in this row inserts an FM-multiplex filter to prevent the Dolby noise-reduction circuits from mistracking if the tuner or receiver connected to the deck inadequately suppresses the subcarrier for stereo FM broadcasts. Pushbuttons in the bottom row are used to activate an external timer in recording or play modes.

The Z-6000 uses two thirty-segment peak-reading level indicators, which are accurately calibrated from —40 to +10 dB. The use of 1-dB increments from —10 to + 10 dB permits much more certainty about the actual signal level than more limited displays do. The highest peaks remain lit for about two seconds so that they will not be inadvertently missed. No specific marking for Dolby level is provided, but we found that the calibrated 0-dB level corresponded to the 250-nanoweber/meter reference level mandated by the forthcoming standards from the IEC (International Electrotechnical Commission) and the EIA/IHF (Electronic Industries Association/Institute of High Fidelity).

Appropriate recording bias and equalization as well as playback equalization for ferric, Cr02-type, and metal-particle tapes are automatically set using the detector cutouts on the rear of the cassette. While most users will be perfectly satisfied with the reference factory settings for these tape types, Teac has also provided an unusually flexible optimization system for those who wish to eliminate even the brand-to-brand (or batch-to-batch) variations within each tape type. Three built-in tone generators (300 Hz, 6,150 Hz, and 14 kHz) permit separate left- and right-channel adjustments for tape sensitivity, bias, and recording equalization using the deck's level display and a small screwdriver (supplied). The procedure takes only a few moments, at the end of which pressing the test tone off button automatically rewinds the tape to where the process started. Although a number of decks provide similar optimization systems for sensitivity and bias, the Z-6000 is one of the very few that permits separate adjustment of recording equalization. (Our only criticism of the system is that for some reason the normal outputs from the deck are muted during the adjustment procedure, making it next to impossible to connect an external meter.)

Separate left and right slider controls and a smooth master slider determine the recording level and balance, and there are separate output controls for the main and headphone outputs. The front panel also contains jacks for headphones, microphones, and a (supplied) remote-control unit with a 15-foot cable. The main input and output jacks are on the rear panel. The Z-6000 measures 17 inches wide, 17 inches deep, and 6-1/4 inches high, and it weighs slightly more than 36 pounds. Price: $1,400.

Laboratory Measurements

Our sample of the Teac Z-6000 was factory adjusted (in its reference position) for TDK AD (ferric), TDK SA (CrO2-equivalent), and TDK MA (metal), and we used these cassettes for our graphs and measurements. By using the optimizing procedure, however, we obtained almost indistinguishable results with premium cassettes from Maxell, Sony, and Fuji as well.

Playback response was measured using the BASF IEC standard calibrated alignment tapes, which now appear to be accepted in both Japan and the West. The slightly rising response below 100 Hz shown in the graph is the inevitable consequence of playing a full-track test tape with quarter-track stereo heads and represents a phenomenon called “fringing” that does not accurately indicate the bass response. Above 12.5 kHz there was a gradual rolloff in treble response to —3.5 dB (CrO2) and —4.5 dB (ferric) at the 18-kHz limit of the test tapes. This seems to represent nothing more than a very slight error in the deck's azimuth alignment.

Because the Z-6000 uses a higher “0-dB” reference level (the 250-nanoweber/meter IEC standard) than the still-prevalent 200-nWb/m Dolby level, the graph shows the high-frequency rolloff's for the 0-dB record-playback responses beginning at slightly lower frequencies than on some of the other top-quality decks we have measured in the past. This is definitely not a limitation of the Z-6000. The amount of treble energy that can be stored on a cassette is limited by the tape formulation, and the higher the recording level the lower the frequency at which tape saturation (and the consequent treble rolloff) occurs. If the higher IEC level prevails as a 0-dB reference point, the only necessary change in audiophile recording practice is to use a little more caution in letting level indicators go into the red.

The effect of the higher 0-dB level shows up on our overall — 20-dB frequency-response curves as well. Here the response was a really excellent +2.5, —0.5 dB all the way out to 20 kHz with the metal tape, but it began to drop very slightly ( —2 dB at 19 kHz) with the ferric and chrome-equivalent tapes. Lowering the nominal —20-dB recording level by just a couple of decibels would make the graphs look better, though the difference is certainly not audible.

Using a 315-Hz test tone, third-harmonic distortion at the 250-nWb/m 0-dB reference level measured 1.6 per cent for TDK AD (ferric) and MA (metal), 0.9 per cent for TDK SA (Cr02-equivalent). To reach 3 per cent third-harmonic distortion required an output level of +1.9, +3.5, and + 2.6 dB, respectively, for the same tapes. Referred to the 3 per cent distortion level, the unweighted signal-to-noise ratio (S/N), with no noise reduction, measured 54.7, 56.7, and 54.2 dB for the three tapes. Using Dolby-B noise reduction and CCIR/ARM weighting increased the figures to 65, 66.8, and 65.8 dB, and with Dolby-C and IEC A-weighting S/N’s of 68.4, 71.2, and 71.5 dB were realized.

The dbx noise-reduction system gave even more impressive S/N results. Because dbx is a 2:1 compressor-expander, a signal that reaches 0 dB on the level indicator is actually recorded at a considerably lower level, resulting in less distortion. The nominal third-harmonic distortion of TDK AD at a nominal 0-dB record level was only 0.44 per cent, with SA and MA cassettes measuring only 0.35 and 0.42 per cent. To reach 3 per cent distortion required driving the meters off the scale to +11.2, +15, and + 13.1 dB! Unweighted S/N’s with dbx were 80.6 dB (AD), 86.8 dB (SA), and 85.3 dB (MA), and with A-weighting they measured 85.4, 91.6, and 90 dB, which approaches the range of digital recording.

The Z-6000’s excellent transport design is shown by its measured wow-and-flutter of 0.022 per cent (wrms) and 0.034 per cent (DIN peak-weighted), using our Teac MTT 111 test tape. Dolby tracking error at — 20- and — 30-dB levels was within ± 1 dB with Dolby-B and ±2 dB with Dolby-C. A line-input signal of 87 millivolts (0.087 volt) was required to produce a 0-dB record indication, which corresponded to an output of 0.38 volt. Microphone input sensitivity was 0.37 mV, and microphone overload was reached at a 40-mV level—typical figures for high-quality decks today. With the pitch control turned off, the Z-6000 ran a negligible 0.2 per cent fast. Fast-forward and rewind times for' a C-90 cassette measured 113 and 108 seconds; a C-60 took 76 and 74 seconds, respectively, which is somewhat faster than average.

Comment

It is clear from our measurements that the Teac Z-6000 can faithfully record and play back any program source— including dbx-encoded discs and Compact Discs—that an audiophile is likely to present it with. As long as we kept the record level from going into the red, there was no diminution of treble response, and we failed to detect any misbehavior (“breathing”) by the dbx noise-reduction system. Dolby-B does not sufficiently eliminate hiss for the most critical applications. Dolby-C is essentially perfect in this respect, but on the Z-6000 we appreciated the dbx system even more. On prerecorded Dolby-B-encoded tapes we did detect a very mild dulling of treble sheen in comparison with our reference deck, but a very slight turn of the treble control was sufficient to restore it.

Perhaps as important, the Z-6000’s solid construction gives promise of a long useful life, and the deck is extremely easy to operate. The separate left and right record-balance controls and the playback controls were a little awkward to use, though the master record control was sensuously smooth. The light bulbs in the cassette well generate some heat, and cassettes that have just been played come out of the well slightly warm to the touch, but this is certainly not likely to cause any difficulty. The motor system is exceptionally quiet, even in fast-winding modes, and the panel layout is elegant not only in style but in feel. In sum, the Teac Z-6000 is one of the very finest cassette decks it has been our pleasure to test, and we can recommend it to the serious audiophile without reservation.

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