User manual PHASE LINEAR AUTOCORRELATOR

[. . . ] Connect tape output on your receiver (preamp) to the input on the 1000 and connect the 1000's outputs to your receiver's (preamp) tape input jacks. The tape monitor on your receiver or preamp should be in the monitor position. Refer to the Operating Instructions for correct operation and adjustment of the Correlator and Peak Unlimiter circuits. AUXILIARY EQUIPMENT Outboard units such as Dolby or DBX may be used with your 1000 but the 1000 must be placed "after" the units in the signal path and "before" any equalizer in signal path, or as shown. Any source played through the 1000 will be processed. It is not necessary, therefore, to process a signal prior to recording since it will be processed on playback. [. . . ] The Dolby system is a noise preventing system designed to prevent additional noise from adding to the signal during tape recording. The Dolby system is a two pass or closed system which cannot remove noise once it has contaminated the signal, but prevents it from increasing during the tape recording process Both systems provide approximately 10dB of signal to noise improvement. It is possible to obtain a full 20dB increase in signal to noise by operating the Dolby system in tandem with the AUTOCORRELATOR. A tape recording that has been "Dolbyized" during recording may be "de-Dolbyized" by a Dolby decoder, then processed through the 1000. An interesting psychological phenomenon occurs when high frequency hiss is removed from the program source. It often seems that the absence of hiss is accompanied by a loss of high frequency program material, when in fact, no loss has occurred. At first, with certain kinds of music, the psychological suggestion that high frequency material has been removed along with the hiss is very difficult to overcome. With other kinds of music, it is very obvious that only hiss has been removed. However, after a brief exposure to noise-tree music, this psychological phenomenon seems to vanish as one becomes accustomed to a noise free background. Once acclimated to a noise free background, it becomes rather unbearable to listen to hisscontaminated music. Historically, it took several years before Ray Dolby was able to convince the world his system was able to reduce noise without affecting the high frequencies. This situation was caused by the aforementioned psychological effects. PEAK UNLIMITER/DOWNWARD EXPANDER Actual operation of the Peak Unlimiter circuit is relatively simple. Initially, set threshold control to the full counterclockwise position with the circuit engaged and source turned on. Gradually rotate the threshold control knob clockwise until the peak indicator lamp flashes on the peaks of the program material. No setting is necessary for the downward expand circuit since it is automatic CHARACTERISTICS OF THE EXPAND CIRCUIT The threshold adjustments will vary with the type of program material being played due to the different degrees of compression and gain riding used at the studio. You will find that the threshold setting for phono is different from either FM or tape sources. Generally the more compression used in recording and broadcasting, the more difficult it will be to make the indicator lamp flash on the peaks. It will want to conti nuously stay either on or off, which is not an optimum setting. This is because there are few if any peaks to expand due to excessive compression. MAINTENANCE & SERVICING CLEANING To keep your 1000 clean and looking like new, occasionally clean the front panel with a soft paper towel and full strength ammonia This will remove dulling films which have a tendency to build up on the brushed finish. REPAIR FACILITIES Only qualified technicians should be allowed to repair your Phase L near 1000. [. . . ] It must be appreciated that in the music output of phono disc or tape, the noise (hiss or uncorreIated sound) is always present "outside" the gates, and is always ready to "rush in" along with the music when a gate is opened. By automatic adjustment of the various threshold levels at which the bandpass gates are opened, the incoming signal passed through the gates is almost always of such amplitude, frequency, and correlation that the wellknown "masking" phenomenon occurs, and the noise is subjectively "covered. " SPECIFICATIONS TOTAL DISTORTION: Less than . 250%. PEAK UNLIMITER: (Nominal peak unlimit rate attack threshold, front panel variable) . 5 dB/micro second for +6 dB peak unlimit operation. NOMINAL AMPLITUDE ATTACK THRESHOLD: 2 volts peak at input to peak unlimiter. [. . . ]