Theory and Practice

Last month, we discussed some of the issues that plague rooms with poor acoustics, as well as some ideas on how to deal with them. An issue closely related to room acoustics is distribution of sound, which can be hindered by room shape or interior design, even in rooms with favorable acoustics.

An ongoing struggle facing all live sound engineers is the impact of poor room acoustics on their mix. All too often, we find ourselves mixing music in spaces not intended for live music, or spaces designed for live music with minimal concern for acoustics. Sometimes we mix music in theaters that, once upon a time, were acoustically designed for unamplified music, the favorable properties of which go out the window once a PA is brought in-house.

It’s almost become a rule that you’ll find a “system EQ” patched between the main L/R outputs of a mixing console and the subsequent stage of a PA system. Even in cases where digital mixers already incorporate onboard “patchable” software EQ, many system designers provide an outboard hardware EQ to facilitate quick and easy adjustments, especially in festival situations where not all engineers may be familiar with a particular desk.

For the vast majority of engineers, lead vocal is the most important part of the mix. Unless you’re dealing with an instrumental group, ensuring that the lead vocal can heard at all times is paramount. Background vocals can be equally important, because the musical interplay between lead and background or harmony vocals often define a musical arrangement. Here are techniques you can use to keep vocals in the spotlight of your mix.

Springtime is almost here, and that means festival season is close. Mixing for tens of thousands of people can be as stressful and frustrating as it is exhilarating, given the typically tight time schedule that’s the nature of this beast. A bit of planning can take some of the sting out the process, as can the understanding that (more often than not) such shows are a compromise by nature.

One could argue that the drum kit is the most difficult instrument to capture on stage. You have multiple elements requiring attention (some of which are sonically very different from each other), the instrument has huge dynamic range, its physical size makes coverage a challenge and you have to keep the mics out of the drummer’s (and harm’s) way. The trick to getting a good drum sound is to start with a good-sounding kit and then to have the proper mic selection and placement. I’m not being a smart-ass on the first part of that statement. If the kit sounds good to start, you’re halfway there. The other half, as noted, is mic selection and placement. This time out we’ll concentrate on mic techniques applicable to rock, pop, country, rap and R&B. Down the line we’ll discuss drum miking techniques for jazz.

Since the dawn of time, engineers have struggled with the task of getting good guitar sounds on stage. One of the big issues is stage volume: the musician cranks it up to get “their sound” while the engineer and audience get blasted with ear-crushing levels from the stage. Inevitably, the PA has to be cranked up to overcome the stage volume. Let’s assume, for the moment, that the musicians you work with have their stage volume under control (whether it be via volume knob, moving cabinets off-stage, or threats of violence) so that you can actually hear the guitar through the PA and create a mix. There are some tried-and-true methods you can use to get great guitar tones.

Last month, we discussed the basics of filters and examined in detail the concept and application for high-pass filters (FRONT of HOUSE, Nov. 2011, page 41). This time we’ll check out low-pass, band-pass and band-reject (a.k.a. “notch”) filters.

Among the more useful tools in the audio toolbox are a variety of filters. Some engineers shun the use of filters in favor of EQ, which can, of course, be very powerful, but filters are your friends and can do things that EQ can't. The three most common filters used in pro audio are high-pass, low-pass and band-pass. In case you need a refresher: a high-pass filter cuts low frequencies, a low-pass filter cuts highs, and a band-pass cuts high and low frequencies simultaneously, allowing a midrange band to pass.

Several times over the past few months we've briefly mentioned the idea of modulation as an effect parameter. Now it's time to take a closer look. Modulation is often applied to delay for creating a wide variety of time-based effects, such as flange and chorus. The word "modulate" means to change, and in this case, we are referring to a change in delay time.

In last month's T&P, we examined reverb and some of the ways that you can manipulate it for maximum effect (pun intended). This month, we'll dive into the bouncing world of delays and how you can use them to enhance your mix. As we did with reverb, let's briefly revisit the parameters available in a typical delay, whether it's hardware or software.

How much time and attention do you give to reverb? Probably not enough. Adding reverb is like adding another instrument to your mix, in some cases taking up as much or more space than another player. Before we dive in to how you can improve the sound of your ‘verb, let's quickly revisit the main parameters of a typical reverb (hardware or software).