Optimize Performance with Every Tape
Experienced recordists know that no two tapes are precisely identical. Even tapes from the same manufacturer carrying the same designation differ from batch to batch and change from year to year. Tapes from different manufacturers vary more widely. If you want the best performance from every tape, the Nakamichi CR4 Discrete Head Cassette Deck is for you. Test signals and accurate perfect Dolby tracking and smooth response. The procedure is quick, simple and notably more accurate than less sophisticated tape-matching systems.
CR4 Calibration
"Calibration" involves recording and playing two test tones: a low-frequency tone which is used to adjust the gain of the recording amplifier to compensate for differences in tape sensitivity and ensure proper Dolby tracking and a high-frequency tone used to adjust bias and produce flat response. Almost invariably a "3-head" design is used so that recording and playback can be carried on simultaneously.
Conventional calibration systems have several problems. Most 3-head decks use a sandwich record/play head. Record and play sections use separate cores but they are in the same housing. There's no room between them for adequate shielding and flux leaks from the record gap into the play gap. This produces incorrect playback levels and erroneous calibration. Next, with a "sandwich" head, there's no way to align the gaps after construction. Azimuth misalignment causes a loss in high frequency response; "correcting" it by reducing bias results in increased distortion, more dropouts and reduced dynamic range. To minimize misalignment error, most decks set bias with an 8 or 10 kHz tone. This reduces the calibration error but produces unpredictable response at higher frequencies. To save maney, most systems record the tones on one track and use the result to calibrate both. Under these conditions, left-and right-channel response can be quite different.
Thanks to Nakamichi "Discrete-Head technology", the CR4 canbe calibrated accurately. Record and play heads are physically as well as electrically independent and are individually shielded to prevent leakage. Physical independence permits magnetic alignment of each head for perfect azimuth and allows use of a high bias calibration tone (15 kHz). On quality tapes such as Nakamichi ZX, SX or EXII, response is flat to 21 kHz. Furthermore, in the CR4, the tones are recorded on both tracks and the average of the outputs is used to set bias thus ensuring similar response on the left and right channels.
Calibrating the CR4 is quick and simple. Just press the Calibration button and adjust the Bias and Level controls for zero readings on the left and right indicators. When you relese the button, the tape rewinds automatically.
Direct-Drive Transport
The CR4 uses one of the finest transorts available today, the Nakamichi Microprocessor-Controlled Asymmertical Dual-Capstan Direct-Drive Silent Mechanism. Its two capstans differ in diameter and rotation rate to prevent resonance and the takeup capstan is directly driven by an FG-servo motor to eliminate wow. Tape tension is controlled so perfectly that no pressure pad is needed to mainatin tape-to-head contact. A unique "lifter" disengages the pad to reduce scrape flutter and modulataion noise and thereby result in recordings of exceptional clarity.
The transport is operated by a microprocessor-supervised motor-driven cam. Cam operation is more gentle and precise than solenoid operation and it is completely free of vibration which contributes to sound clarity. The microprocessor permits remote control (via the optional RM5 Remote Control Unit or the System Remote jack on the CA-7 Control Amplifier), automatically takes up slack tape when a cassette is loaded and supervises every change in operation so you can change modes in complete safety.
Superior Design and Construction
Many reasons for the CR4's exceptional performance are found under its heavy-gauge cover. Inside is a copper-plated chassis for beter shielding, oxygen-free-copper PC boards, OFC head windings, even an OFC line cord. You'll find a quadruple-shielded transformer to prevent humm and Nakamichi's Multi-Regulated Power Supply to eliminate interstage coulping and noise. You'll find the finest components including new Dolby circuits for better performance and gold-plated input, output and headphone jacks for more reliable operation
Specifications
Track Configuration: 4-tracks, 2-channel stereo
Heads: 1 x Erase head; 1 x Record head; 1 x Playback head
Motors:
Transport: FG servo, brushless, slotless, coreless D.D motor (capstan drive) x 1; DC motor (reel drive) x 1
Mechanism : DC motor (cam operation) x 1
Tape Speed: 1-7/8 ips (4,8 cm/sec) ±0,5%
Wow and Flutter: less than ±0,048% WTD (Peak); 0,027% WTD (RMS)
Frequency Response: 20 Hz - 21,000 Hz ±3 dB (-20 dB recording level, ZX, SX, EXII tape)
Signal-to-Noise Ratio:
Dolby C NR : better than 72 dB
Dolby B NR : better than 66 dB
Total Harmonic Distortion : Less than 0,8% (ZX tape); less than 1,0% (SX, EXII tape)
Erasure: better than 60 dB (100 Hz, =10 dB)
Separation: better than 37 dB (1 kHz, 0 dB)
Crosstalk: better than 60 dB (1 kHz, 0 dB)
Bias Frequency: 105 kHz
Input: 50 mV/30 k Ω
Output
Line : 0,5V/2,2 k Ω
Headphone : 5 mW, into 8 Ω
Fast Wind Time (C-60 cassette): approx. 80 sec
Power Requirements: 120, 220, 240 or 110/127/220/240 V AC 50/60 Hz
Power Consumption: 38 W max
Dimensions (W x H x D): 430 x 100 x 265 mm (16-15/16" x 3-15/16" x 10-7/16")
Weight: 5,9 kg (13 lbs)
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