Surround sound may be a specialty format for album production, but it’s become the norm for film and TV. Here’s what you need to know to prepare your mixes for the screen.
For surround mixing, monitoring is critical. NARAS recommends five matching speakers and a subwoofer. Shown is BiCoastal Music�s front setup with left, right and center speakers.
Figure 1: A 5.1 surround panner in Logic Pro
Producer, engineer and composer Rich Tozzoli has created surround mixes for artists ranging from Blue Oyster Cult to David Bowie and is the author of Pro Tools Surround Sound Mixing (Backbeat Books). His music can be heard on channels such as Nickelodeon, VH-1, The Discovery Channel and The History Channel.
It's no secret that music creators have more technological tools than ever before at their disposal. But while this makes it possible to create finished product from home and project studios, it also means that potential clients expect that the work they receive be as close to perfection as possible. In a tight industry, the more you understand about how your music will be used, the better you'll be able to meet the demands of the marketplace. One area that's been around for a while, but is certainly becoming more relevant to the average musician, is surround sound production.
While there are several types of surround formats with channel offerings up to 7.1, surround 5.1 is the most common configuration. But what exactly is 5.1 surround, what gear do you need to handle it, and how can you use it to enhance your music? With the explosive growth of high-definition television and Blu-Ray, as well as the continued success of video games and DVD’s, composers can deliver surround audio to wide variety of platforms. Let’s examine the current market and dig into a few terms, tips and tricks that can help you get started.
Currently, the most common form of surround sound available to the mass of consumers is Dolby Digital. Also known as AC-3, it is now a matured technology, having first appeared on the market back in 1992. Technically, it’s a lossy audio compression system (some data is removed to make file smaller), which means that in addition to providing the consumer with a surround experience, it takes up less space on any delivery medium such as cable TV and DVDs. A quick flip through your TV will reveal an ever-increasing amount of programming coming at you in Dolby Digital. From concerts and nature shows to 5.1 commercials, surround is becoming far more ingrained in the consumer’s ear.
5.1 audio consists of five, discrete fullrange channels: Left (L), Center (C), Right (R), Left Surround (LS) and Right Surround (RS). The “.1” in the term 5.1 refers to the optional LFE (Low Frequency Effects) channel, since it send extreme lows through a subwoofer not one of the full-range speakers.
Note that Dolby Digital can also be delivered in other channel configurations, including mono, two-channel stereo; three-channel stereo with a mono surround; and four-channel stereo with discreet left and right surround. So although it’s still the most common type, when you see the term Dolby Digital, don’t assume it’s always 5.1. (Check out Dolby.com for their 5.1 Channel Production Guidelines PDF, which is full of great information.)
So, what kind of audio files do you need to deliver to a project intended for surround playback? Dolby Digital supports sample rates up to 48kHz, but the new Dolby Digital Plus (also known as E-AC-3), developed for use on Blu-Ray discs and HDTV programming, can handle sample rates up to 96kHz and bit depth of 24-bit. Before you create a final mix, find out what sample rate the project will be.
Note also that Dolby Digital has a competing format called DTS (Digital Theater Systems). It is another type of surround sound and is available as an option on many DVD movies. However, all television shows broadcast in surround are delivered to the consumer in Dolby Digital form—DTS is not even an option. With a typical home theater hooked into a digital cable box, you will see “DD” or “Dolby Digital” light up when your receiver recognizes the AC-3 Dolby stream. Same applies when you select Dolby Digital from the menu of a movie or a video game. Although it’s not a huge part of the music sales markets, some audio-only projects continue to be released in surround format, as well.
So, consumers have many ways of listening to our surround productions: But how do we actually mix it for them? Most of today’s common digital audio workstations let you mix for surround in a variety of formats. Programs such as Cubase, Nuendo, Pro Tools (TDM), Digital Performer, Logic, and SONAR offer the ability to step outside of stereo and deliver surround tracks, even beyond 5.1. For those who don’t use DAWs, you can use any of today’s surround-capable boards such as the Yamaha DM2000 and 01V96, and others.
Whatever you use, there are a few basics you’ll need to understand in order to translate your mixes into surround format. First, you must set up your DAW or console up to output surround sound. For programs such as Logic and Pro Tools, etc, it’s a matter of assigning surround panners and multichannel buses. Figure 1 shows a surround panner from Logic Pro 8, which also lets users open a project for surround.
When working with surround, the monitoring environment is key. For 5.1, you’ll need at least five speakers and a subwoofer. The Producers and Engineers wing of NARAS has released an excellent document with many suggestions for the production and delivery of surround (it’s available as a 68-page PDF at grammy.com/pdfs/recording_academy/produ cers_and_engineers/5_1_rec.pdf). It recommends using identical full range speakers of the same brand and model, plus a subwoofer. It also suggests that you check your mixes on a second speaker system that emulates a home theater. After all, your songs in surround may sound great on the big speakers, but the end product will most likely be heard by a consumer at home with small speakers. In either case, NARAS recommends setting up the speakers to be equidistant from the mix position. A simple trick is to take a piece of string and stretch it to your center channel’s tweeter from your nose. Then move in a circle aligning each speaker’s tweeter the same distance as the center channel. If you can’t make that happen because of your room’s layout, at least try to keep them as close to equidistant as possible. The actual angle of the speaker tends to vary from 110 to 150 degrees, as you can see from the P&E diagram shown in Figure 2.
Everything In Its Place
Surround affords many options for positioning audio, but it can also be a challenge to translate a stereo mix into a great surround mix. A great place to start is to ask yourself what experience you can provide the listener that can’t be delivered with stereo. Gimmicks like wild panning in circles can get old fast, but surround can place the listeners in the center of the music, letting them hear, for example, what a musician hears from the middle of the band.
By taking additional tracks such as drum overheads, keyboards, background vocals and strings, and panning them outside of the stereo field, a mix can envelop the listener in sound. For consumers at home who can’t hear surround, they can still listen to your mix. All Dolby Digital decoders on home theaters and such can downmix, essentially folding your mix down to stereo or mono, depending on the system.
Experiment by simply spreading out the overall image of your production. It’s important to know that you don’t need to record tracks in surround to begin mixing. If you take the tracks in a stereo mix and spread them out amongst the speakers, you’ve got surround.
Surround mixes also give you more options when using spatial effects. For example, you can take a mono acoustic guitar, place it in the left front (like you might already have in your stereo mix) and send it into a short stereo reverb that is panned into the left and right surround positions.
When mixing for surround, however, you must also be aware that not all consumers will have the equipment to hear your mix as it’s intended. That’s one reason that many surround mixers avoid placing a featured element, such as a vocal, in the center channel only (discrete), in case a consumer at home is either missing that channel or has it set up incorrectly. Instead, you can place some in the left and right fronts, with a slightly larger amount in the center.
Bass is another area where surround mixing can get tricky. As with the vocal, you might place some bass in the center channel, with a little in the left and right front. Then you can send some bass to the LFE to provide some extra bottom. Remember, the LFE is a separate, sixth channel in your 5.1 mix, played back by the subwoofer. But also remember that the LFE is optional—some surround producers don’t apply any at all because consumer home theaters often cut the bass (around 120Hz and below) out of those small satellite speakers and send it to the subwoofer anyway.
The final step is to create a final six-channel mix. A DAW like Pro Tools, Logic, SONAR, etc can export a mix in surround (or multi-mono) formats. If you mix with a hardware console, you will need to capture those six channels of audio into a DAW, multitrack hard disk recorder, or onto tape. Working with surround sound is like anything else worthwhile, practice makes perfect (well…better).