Premier Guitar

A 5.1 Surround Sound Primer

September 9, 2008

On Track
Five audio channels, plus a LFE (low frequency effects) channel, complete the 5.1 surround sound setup.
This month we’ll jump off the neck a little bit and talk about some music technology that’s becoming more and more relevant as we move towards the big switch to DTV (digital television). When February 17, 2009 rolls along, all analog broadcasting is scheduled to stop. But what does DTV have to do with us PG readers, you may ask? Well, a quick flip through any cable, satellite or fiber network will reveal an increasing number of channels broadcasting in 5.1 surround sound.

On my Verizon FIOS network for example, there are not only concert channels (such as FUSE HD) that are produced in surround sound – sports networks, nature shows, movies and entertainment programming have all begun featuring multichannel content. In addition to network shows (and even commercials), most DVD’s, Blu-rays and video games are also delivered with surround audio. So let’s step behind the scenes and see what it takes to get started doing surround sound production.

The term “5.1” is a common one that signifies discrete Left Front, Center, Right Front, Left Surround, Right Surround and LFE (Low Frequency Effects) channels. The “5” represents the five main speakers and the “. 1” represents the LFE channel, which is played back by your home theater system’s subwoofer. The reason it’s “. 1” is because it only plays back a fraction (the lows) of what a full range speaker would.

Dolby Digital, also often referred to as AC-3, is the most common delivery method of 5.1 surround sound to the consumer. Much information about this can be found on their site, dolby.com. For the millions of consumers who have home theaters hooked up to their digital cable boxes, when a show broadcasts in Dolby Digital, their receiver will clearly indicate so. On my Onkyo, you can hear it “click” into surround mode and “Dolby D” (Dolby Digital) appears on the display. Suddenly, the sound comes out of all my speakers, making stereo sound as dull as black and white TV. On many DVDs and Blurays, you might have to navigate to the audio menu to choose the Dolby Digital 5.1 mix.

You should know that Dolby has a competing format called DTS (Digital Theater Systems). First appearing in 1993 in the movie Jurassic Park, it’s an option on many DVDs and Blurays, but television networks broadcasting in surround only do so with Dolby Digital, not DTS. However, standard DTS retains the same layout as a 5.1 Dolby Digital signal (L, C, R, LS, RS, LFE). There are also formats such as Dolby EX and DTS ES that have 6.1 mixes, but just know that 5.1 Dolby Digital is the defacto “standard.”

For those who want to create surround mixes, you will need five speakers and a subwoofer, as well as an audio system capable of 5.1 mixing. Most modern DAWs can easily handle surround sound (Logic, Digital Performer, Nuendo, Pro Tools HD, etc.). If you’re mixing on a console, you will need either a surroundcapable one or at least six routable Aux outputs. The P&E (Producer & Engineers) wing of the Recording Academy recommends having five speakers of the same type. Much information can be found on this and more (such as mixing suggestions, etc) in their easy-to-read PDF document:

grammy.com/pdfs/recording_academy/producers_and_engineers/5_1_rec.pdf

Most of the work I do in surround is mixing for either 5.1 HDTV broadcast or concert DVDs/ Blu-rays. The tracks are individually mixed just like stereo, but “spread out” into the speakers, creating a much wider soundfield. Note that I’ve also had to deliver music cues I’ve composed for trailers or commercials in surround, so it’s not just limited to shows or concerts.

But how do you record surround? Well, like most other things, there is no right or wrong answer. While there are surround microphones available (such as the Holophone), you can use traditional mics to capture multichannel sound. For example, with an acoustic guitarist in a room, think about miking above their head or out in front of them. I rely on a pair of Earthworks omnis to capture the room, then often place them equally in both the front, left/right and surround speakers. The sense of space is truly amazing, especially with a fine instrument (and player, of course).

With an electric, you can use a close mic the cab, but add another mic up and out in the room. When mixing in surround, take that room mic and place it in the rear surround speakers. Drums and percussion are especially easy to capture in surround, simply by adding additional mics “around” the kit and mixing as such in 5.1.

But you don’t have to use additional mics to create surround. You can creatively use delays, reverbs and panning to spread the tracks out in the 5.1 environment. Some programs, such as Logic, even include multichannel, surround ready reverbs and delays for just such a job.

The important thing is to think about how you can deliver an experience that stereo cannot. By doing some research and practicing, you can open your ears up to a whole new way of mixing. While the above information is just a place to start, it hopefully spurs you on to learn more about surround sound production. Next month, we’ll dig a little deeper into this topic, so stay tuned.


Rich Tozzoli
is a producer, engineer and mixer who has worked with artists ranging from Al DiMeola to David Bowie. A lifelong guitarist, he’s also the author of Pro Tools Surround Sound Mixing and composes for such networks as Discovery Channel, Nickelodeon and National Geographic.