This is the second article in a series about multichannel audio, also known as surround sound audio. Our goal is to deliver articles that will educate and instruct our readers about the technology and equipment used for multichannel audio and to demonstrate how anyone can get involved with it. The first article in this series discussed the basics of surround sound playback, including fundamental surround sound speaker placement, and provided details about audio codecs. In this article, we will provide the information you need to build a great playback system. The focus is on consumer-oriented playback systems. Future articles will focus on professional playback solutions as well as discuss encoding and decoding by using Microsoft® Windows Media® 9 Series. But first, it is important that your playback system be in shape or nothing will sound right.
To start playing back surround sound files created with the Windows Media Audio 9 codec, you must first install some sort of multichannel input/output (I/O) port on your computer. There are several solutions for this, including a USB port, an IEEE 1394 interface
About Hector and Mike
Hector La Torre is the founder and managing partner of Fits & Starts Productions, LLC. The company has conducted nearly 300 surround sound seminars and is the leading provider of audio seminars in the United States. In another life, Hector was a Boston- and New York-based musician and record producer, former executive director of EQ and Gig magazines, and technical editor of Pro Sound News magazine. Hector La Torre also is an audio consultant and technical writer for the music and recording industry. For more information, go to the Fits & Starts Productions website and the ModernRecording.com website .
Mike Sokol is a live and recording audio engineer with more than three decades of experience in the music field. He has authored more than 1,200 articles for numerous pro-audio magazines over the last 20 years and has published a book on acoustic instrument sound reinforcement. He also owned a computer integration and repair business for 15 years before joining Fits & Starts Productions LLC as a lead instructor, with more than 250 seminars on surround production techniques taught over the last five years. His new book on surround audio is currently being written for publication late 2004. For more information, go to the Fits & Starts Productions website .
(for example, Apple FireWire or Sony i.LINK), a CardBus PC card, or a sound card that supports multichannel audio. Examples include the M-Audio Sonica Theater and Firewire 410 found at the M-Audio website the Echo Audio Mona and Echo Layla 24 (discontinued, but product support is still available) found at the Echo Digital Audio website , and the Creative Labs Audigy and Extigy cards found at the Creative Labs website .
As long as your sound card has at least six analog outputs and the proper drivers for the Windows® operating system, you can decode and play multichannel (5.1 audio). One of the most affordable products is Sonica Theater by M-Audio, shown in the following illustration.
Figure 1. Sonica Theater
Sonica Theater has four stereo one-eighth-inch TRS outputs, enabling up to 7.1 channel outputs from a USB connection. You can use standard, consumer-based, one-eighth-inch speaker connections and powered computer speakers to get started playing back Windows Media Audio 9 surround sound—all for a couple of hundred dollars.
To get the best use out of your multichannel hardware, it's important to use the appropriate drivers. Drivers are programs that help the computer operating system understand which devices are connected to it. Drivers are written by the gear manufacturers with specific tables and specifications describing, for instance, what sort of connectors are used and how to route the appropriate signal to them. An important part of any driver is its user interface, which allows you to set parameters such as volume level and bass management.
The good news is that if you're using a USB or IEEE 1394 interface, driver installation is largely automatic—albeit a bit too automatic at times. If you install the hardware without first installing the proper drivers, the Windows operating system might install a generic driver set for the hardware. That's why, in most cases, you should install the drivers from the manufacturer before you install the hardware. Doing so ensures that you'll get the full functionality of the manufacturer's driver set.
The vast majority of drivers are available from each manufacturer's website. The following links go to the driver download pages for the previously mentioned manufacturers:
If the wrong driver set is accidentally installed, you can correct the problem by doing the following:
Disconnect the hardware.
Open Device Manager, and then navigate to the driver that you want to uninstall. The driver will usually be marked with a yellow exclamation point or a red "X."
For more information about using Device Manager, see Windows Help.
Select the driver, and then click Remove.
Restart the computer.
Download and install the latest drivers from the manufacturer's website.
After installing the drivers, connect your hardware and follow the installation steps. Keep in mind that if you're using an internal sound card, you must turn off your computer, and then install the card by using all static precautions. For USB and IEEE 1394 interfaces, however, you can connect the hardware when the computer is turned on. If you are using a USB device, note that it will draw quite a bit of power from the port so that passive USB hubs might not work properly. Either use an active (powered) USB hub or plug the device directly into a USB port on your computer.
Next, verify that your new hardware is the default device for sound playback. To do so, open Sounds and Audio Devices in the Control Panel, click the Audio tab, and check that the device is listed in the Sound playback area. The following illustration shows what this looks like when using Sonica Theater:
Figure 2. Selecting Sonica Theater as the default sound playback device
The following two illustrations show how to select a Creative Labs sound card as the default sound playback device directly from its setup screen.
Figure 3. Selecting a Creative Labs sound card
Figure 4. Speaker setup for Creative Labs
After you have installed the hardware, you can specify the speaker setup that you want to use in the Windows operating system. In most cases you will probably use 5.1 surround sound speakers, but because the Windows Media Audio 9 codec will accommodate up to 7.1 surround sound, select the configuration you plan to use. To specify the speaker setup, open Sounds and Audio Devices in the Control Panel, click Advanced in the speaker settings area of the Volume tab, and then select the appropriate setup as shown in the following illustration.
Figure 5. Selecting 5.1 surround sound speakers
The next step is to make sure your sound card is running in the proper mode. To do so, return to Control Panel where you should see an icon for your hardware. Again, select the appropriate speaker setup for your actual speaker layout, typically 5.1 surround sound speakers.
The following illustrations show the setup for M-Audio and for 5.1 surround sound speakers and volume levels respectively.
Figure 6. Selecting 5.1 surround sound speakers for M-Audio
If you are using a consumer device like Sonica Theater or the Audigy card, it will have one-eighth-inch TRS stereo output connectors. In this case, you will need Y cables that split the two signals out to separate connectors, as shown in the following illustration.
Figure 8. Example of a Y cable
In most cases, the speakers will have an RCA connection. Take note that you will need active-powered speakers (speakers with an internal amplifier and their own power supply) for multichannel sound cards. These types of speakers are necessary because although most stereo sound cards will drive passive speakers with their onboard, 5-watt amplifier, multichannel sound cards typically have no internal amplifiers.
A good solution is to get an inexpensive active-powered speaker system, such as one of the following:
It is important to arrange your speakers properly. Most multichannel sound cards have some sort of test that lets you send pink noise (a hissing sound) or tone (a single note like a flute) to each speaker one at a time. Your point of view (POV) is always from the listening position, so the front-left speaker should be placed to the left of your computer monitor, the front-right speaker should be placed to the right of the monitor. The surround-left speaker should be just behind your left shoulder, and the surround-right speaker should be placed just behind your right shoulder. Finally, the center speaker should be just above or below the computer monitor. Make sure your speakers are magnetically shielded if you will be placing them within a foot or so of a cathode-ray tube (CRT) display screen. (Flat-screen LCD and plasma screens have no magnetically deflected beams, so stray magnetic fields are not a problem.)
To comply with surround sound standards, the front speakers should be spread about 60 degrees apart (30 degrees each from center), and the surround (rear) speakers about 110 degrees from the center. If you have space limitations don't panic, as you will still get good surround sound as long as your speakers are in the approximate positions. Also, each speaker should be the same distance from your listening position. If one speaker is closer to you than the others, the sound from it will arrive too soon, spoiling the surround sound illusion. Using the center speaker as the central point—about 3 feet away—will result in all speakers being the same distance from you and from each other after you properly angle them at 60 degrees. The subwoofer (also called the LFE, or low frequency effects, speaker) can be placed anywhere convenient because bass frequencies are largely omni-directional. Close to your feet or in a nearby corner usually works well. You can experiment with its placement. The following illustration shows a typical speaker placement.
After you have your speakers in place, the next step is to make certain each speaker is playing back at the proper volume. To do so, return to the setup screen for your sound card and turn on the tone or pink noise, one channel at a time. If your speakers have volume controls, adjust the first one to a comfortable level, and then set the volume for the other speakers to the same level. This is what is known as "level calibration." You can typically calibrate the level with your own ears, but for really accurate calibration you can use a sound pressure level (SPL) meter or real time analyzer (RTA)—audio tools that we will discuss in a future article. For now, set the levels by ear while seated in your chair in front of the monitor. Adjusting playback levels properly lets you hear the original speaker balance that was intended by the engineer or producer.
To ensure that your system sounds correct, it is important to enable bass management (or bass redirection) for both your subwoofer and speakers. If your speakers have a bass management feature, you can enable it for the speakers, which allows your subwoofer to handle the bass for the speakers. Because a small 3- or 4-inch speaker can't produce any real bass, enabling bass management will make the speakers sound really huge; otherwise, playback will sound tinny and small. Some integrated surround sound speaker systems from Creative Labs, M-Audio, and Alesis already handle bass management filtering in the speaker system itself. In that case, we recommend that you turn off bass management in the driver for your multichannel sound card. The easiest way to verify that bass management has been enabled is to play back a stereo music source and check to see if any bass comes from the subwoofer. (Do not use a 5.1 audio source as many surround sound files include bass in the LFE channel, so it won't be possible to determine if the subwoofer is getting bass from that LFE track or from the bass manager.)
Also, we would be remiss if we didn't add a short note about playing music too loud. Having five to seven speakers pointed directly at your ears can achieve volumes approaching concert levels in excess of 100 decibels. Yes, it's fun and inspiring to listen to your favorite musical piece really loud, and in surround sound to boot. But if you notice your ears buzzing or ringing after an extended listening session, you should turn it down next time. Damage to your ears is cumulative and can never be regained, so protect your most valuable listening tools and limit your loud sessions to the occasional sonic reward. There's not much work or enjoyment for a deaf sound engineer.
Finally, you are ready to test your system. You can find surround sound music on the Surround Sound Showcase page. If you want to create your own surround sound music and learn lots more about multichannel audio and music, come to one of our national Fits & Starts seminars, which are free 3-hour workshops that discuss all aspects of surround sound music production. For more information, go to the Fits & Starts Productions website .
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