Altering the Texture of Musical Instruments

Operating Manual - DPX-100 Graphic Equalizer - Compressor/Limiter

e.Attack time to 5mS.

f.Release time to 1 Sec.

g.Limit switch IN

2.Using a 1/3 octave (31 band) or parametric equalizer, set the EQ controls to a flat setting, and if the equalizer has an overall volume control, boost it by 10 to 15 dB.

3.Open up several microphone input channels to a normal operating level, with typical EQ settings, and turn the console master fader up to a louder than normal setting. At this point, the system should be well into feed- back, but the room volume will be constant due to the action of the limiter. You can listen to the feedback at any level you like by simply varying the limiter output level 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, band- width, and boost/cut controls of your parametric equal- izer. (Note: a graphic equalizer can also be used, although with less accuracy.) After eliminating the problem fre- quency, try to further define it by sharpening up the band- width, reattacking the frequency control, and making the cut shallower, if possible.

5.As soon as the first feedback frequency has been removed, the compressor/limiter will automatically bring up system gain until another feedback point is in- duced. Repeat the equalization procedure until it becomes impossible to distinguish individual, predominant feed- back frequencies.

6.Write down EQ marks for safekeeping if nec- essary, and return all mixer, EQ master gain, and com- pressor/limiter gain controls to normal operational settings.

Altering the Texture of Musical Instruments

It would be impossible to mention here all the ways that compression is used to create new sounds with familiar instruments. Some typical uses are:

1.Creating a “fatter” kick drum or snare sound.

2.“Thickening” acoustic guitars.

3.Adding punch and sustain to electric bass or guitar.

In general, use a gentle compression ratio, say 4:1, with a 10 mS attack time, 0.1 Sec. release time, and a low enough threshold to cause 6 to 10dB of Gain Re- duction. Try using this effect to help bring out a lead

vocal or instrumental solo in a cluttered mix. The com- pressor is also a great corrective tool when working with singers whose own dynamic control is less than perfect. A little compression helps to keep their quieter lines from becoming buried in the mix. Experimentation is highly recommended.

Voice-Over Compression (“Ducking”)

The compressor/limiter can be used to automati- cally reduce music to a background level when an an- nouncer is speaking. In this scheme, only the music signal is actually gain-reduced by the limiter. However, the de- tector is connected to respond to an announcer’s voice instead of the music’s peaks. Voice-Over compression assumes you are already using some sort of mixer to com- bine the music and mic signals. Use the direct out (send) of the mic channel to feed the detector input on the CLX unit. Note: Be sure to use a mono plug for the CLX detector input. Then use the Threshold and Ratio con- trols to determine when and by how much the announcer’s voice affects the music level.

De-Essing

A special type of saturation problem often en- countered 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, un- desirable sound. With analog recording to magnetic tape, high frequencies tend to saturate the tape sooner, and com- bined with the internal high frequency boost (record pre- emphasis) on standard tape decks, the need to control sibilants becomes apparent.

The solution is frequency-dependent limiting, which is easily accomplished with the DPX-100. By in- serting an equalizer into the Detector Patch point and boosting the equalizer at high frequencies in the 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 fre- quencies.

Realize that this technique is very different from simple equalization. Equalizing a sibilant vocal by cut- ting 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 in- stant of the sibilant. At that moment, the Ashly limiter will reduce overall gain. Frequency response is unaf- fected, and the sibilant is controlled.