Theory and Practice

Last month, we looked at the differences between serial and parallel processing and applications for each. We examined the idea that, generally, serial processing is applied in situations where you want 100 percent of a signal to be processed, while parallel processing is applied in situations where you want to add an effect into the mix along with the original signal. We also examined why we typically use serial processing for dynamic effects but use parallel processing for time-based effects such as reverb and delay. Now let's take a closer look at compression in particular, and twist some of the rules.

One of the less-clear concepts in audio is that of serial versus parallel processing. As is the case with series and parallel electrical circuits, serial processing provides a single path for an audio signal on its way to the mix bus, while parallel processing allows multiple paths through which an audio signal may reach the mix bus. Each approach has its strengths and weaknesses, and knowing when to apply either of the two (or in some cases, both) facilitates better control over your mix.

The Digitally Steerable Array ("DSA") is a type of loudspeaker that is in its relative infancy compared with other sound reinforcement technology. This unique audio animal is primarily intended for small-to-medium size commercial and house-of-worship applications where priorities include intelligibility, controlled dispersion and aesthetics. DSAs present an external appearance much like traditional column-type loudspeakers, but there is way more going on internally than meets the eye. Let's take a look at the concepts behind the DSA and the technology that makes it possible.

One of the few things in audio that remains constant in spite of technological change is the concept of gain structure. Gain structure refers to the manner in which signal levels are set in (and between) various components of any audio system. Poor gain structure can cause noise of the hissing type (as opposed to hum or buzzes), distortion, lack of headroom and grossly mismatched meter readings between different devices. You might also find that your PA system does not play as loud as it should. Let's examine this in detail.

Last month, we covered the different causes of speaker malfunction. If a system is not protected properly, it can lead to a lot of money spent on speaker repair bills that could have been easily spent on other things, such as a good system limiter. But even with the best system limiter in the world, if the system is not set up properly the consequences can be just as bad as without one.

It's interesting how, just when you think you have it all figured out, something breaks and it winds up being something that you've never seen before. Just like the saying goes, "you learn something new every day." I remember when I started in this business, when something like a speaker would blow up, the reasoning would be "because it was driven too hard."

This month, we are going to switch gears from compressors and head into the world of wireless. Next month, we'll return with the second part of the column on compressors that ran last month (FOH, Sept. 2010, page 38).

How many times have you been sitting behind the front of house console and had someone ask you, "Do you know what all of those knobs do?" If the answer is "No" when you are talking about compressors, then you can get yourself into trouble.