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At this point, the system should be well into feedback, but the room volume will remain constant due to the action of the limiter. You can listen to the feedback at any level you like by simply varying the CL-50E’s OUTPUT volume control, although below a certain monitoring level, the feedback will stop. 4. Try to determine the feedback frequency, and then equalize it by adjusting the center frequency, bandwidth, and boost/cut controls of your parametric equalizer. (Note: a graphic equalizer can also be used, with less accuracy.) After eliminating the problem frequency, try to further define it by sharpening up the bandwidth, reattacking the frequency control, and making the cut shallower, if possible. 5. As soon as the first feedback frequency has been removed, the Ashly CL unit will automatically bring up system gain until another feedback point is induced Repeat the equalization procedure until it becomes impossible to distinguish individual, predominant feedback frequencies. 6. Return all mixer, EQ overall gain, and compressor/limiter gain controls to normal settings. 22 ASHLY Recording The Ashly limiter can be used to prevent saturation of magnetic recording tape and to control tape hiss. In professional recording studios, the saturation level of the tape, system headroom, and the output level of the console are all known quantities, making the application of limiting and compression very easy. Ouiput MIXING CONSOLE The CL-50E used to prevent tape saturation and improve S/N ratio. ► • Input TAPE HECOHDER An example of the use of limiting to prevent tape saturation and improve signal-to-noise performance was given in the earlier discussion of the RATIO control. By shifting the input GAIN upward, further compression and improved signal-to-noise can be achieved, at the expense of dynamic range. De-Essing A special type of saturation problem often encountered in recording is the sibilant (Ssss) sound of the human voice. High-frequency, sibilant sounds can reach very high energy levels, so that a voice that is otherwise undistorted breaks up on the esses, producing a raspy, undesirable sound. With the current trend toward crisp, bright equalization of vocal tracks, the problem is magnified. Add to that the inherent tendency of magnetic tape to saturate earlier at high frequencies and the internal high-frequency boost (record pre-emphasis) of a standard tape recorder, and the need to control sibilants becomes apparent The solution is frequency-dependent limiting, which is easily accomplished with the CL-SERIES. By inserting an equalizer into the Detector Patch points and boosting the equalizer at high frequencies in the ASHLY 23 vicinity of the sibilant, the limiter’s detector circuit becomes more sensitive to this particular range of frequencies, and so will limit the bothersome sibilants more than other frequencies. Realize that this technique is very different from simple equalization. Equalizing a sibilant vocal by cutting high frequencies would result in a loss of important high frequency information at all times, whereas de-essing has no effect whatsoever on the signal except at the instant of the sibilant. At that moment, the Ashly limiter will reduce overall gain. Frequency response is unaffected, and the sibilant is controlled. "De-Essing" with the CL-50E The Compressor/Limiter As A Special Effects Device Loudness Enhancement Compression has long been used as a tool to make an audio signal appear louder. A gcx)d example is in broadcasting, where competing stations with identical transmitters and power attempt to sound louder than each other. Since they are all restricted with respect to maximum audio level (modulation), their best tactic is to squeeze the dynamic range of their programs to just a few dB. The audio output level of the station virtually never changes, and the listener perceives this continuous high-level sound as being louder than the same material in an uncompressed form. Although both compressed and uncompressed programs reach the same peak levels, the compressed signal stays near peak level more of the time, and thus 24 ABHLY appears louder. This technique makes the broadcast more intelligible over the road noise in your car, and increases the geographical area over which the broadcast is audible to the home listener. A similar, if less pronounced, effect can be used in sound reinforcement and recording applications. In general, use a gentle compression RATIO, say 4:1, with a 10ms. ATTACK time, 0.1 sec. RELEASE time, and enough GAIN to cause 6 to 10 dB of GAIN REDUCTION. Try using this effect to help bring out a lead vocal or instrumental solo in a cluttered mix. The compressor is also a great corrective tool when working with singers whose own dynamic control is less than adequate. A little compression helps to keep their quieter lines from becoming buried in the mix. Altering The Texture Of Musical Instruments It would be impossible fco mention her...

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