HomeTheater 101: Surround Sound

Posted in FAQs & Guides,Home Theater by Michael Pica on the May 10th, 2007

Last Week I talked about what to look for in a high definition display. This week I’ll expand on the discussion covering the most important part of a home theater experience; Surround Sound. Once again I pose the question: Do you know what goes into making an awesome home theater experience?

Surround Sound
I’ve always voiced my opinion that the sound system is the most important part of home theater experience. This goes beyond just personal preference though, there are some very important reason that one should put more time and money toward the sound then the picture. Pictures are nice but you’re eyes are fairly easy to impress. Your ears are actually more more discerning and you’re likely to notices flaws in the audio long before you’ll notice flaws in the video.

Beyond discerning ears a good sound system will last you much much longer then a good display. Modern displays all use very new technology. Even the oldest of TV tech only goes back 50 or so years, audio technology has been around a whole lot longer and there are no real signs of it changing anytime soon. This is important because it means that we’ve had all that time and billions upon billions of dollars going into refining the technology for the absolute best quality at the absolute lowest price.

Home Theater in a Box:
Over the last five years “Home Theater in a Box” systems have dramatically increased in popularity. In general these systems are total trash. Consider this: Noise is nothing more then a vibration, more specifically the noise you hear from speakers is really a vibration of air. Now, if you have some little 2in speaker 10ft away from you in the corner of a room how well do you think that speaker is capable of vibrating the air? Lets replace it with a fan of the same size; do you think you could feel a breeze from that distance? You’d really have to crank up the power just to reach an adequate volume. At that point the speaker is running out of it’s optimal range and rather then producing accurate vibrations it is instead just pushing the air as much as it can just so you can hear something. Even worse is if the amplifier providing the power doesn’t have enough to even provide it with a clean signal nevermind the speaker properly reproducing what it’s getting. Things can deteriorate pretty fast.

Another thing to watch out for with these systems is proprietary connectors and inseparable components. Some of the cheaper systems will integrate a DVD player into the amplifier, or use a proprietary connector for the speakers instead of good old speaker wire or banana plugs. These can dramatically limit what you can do with the system and is usually done as a cost cutting measure. Any system with a DVD player integrated into the amplifier should be avoided like the plague. A lot of big box stores will give these systems away for free with the purchase of an HDTV, there’s a reason they can do that; you get what you pay for.

The small cube systems can provide a decent sound experience, but only in the proper environment. Really the only place you should be using one of these systems is in a very small office or cubicle. Originally this is what these systems were designed for. This also fits into my mantra that you should be spending at least the same amount on your sound system, if not more, than on your display. Considering you’d spend between $150 to $300 on a computer monitor that would put you right in range for an appropriate cube based system. Home Theater FOR a Box would be a more accurate representation of what these systems actually offer.

Where to start?
So if you’re not going to just buy some all in one package in a box where do you start looking? It might seem a little overwhelming at first but really it’s pretty simple. Audio can essentially be broken down into three main components pre-amps, amps, and speakers. Pre amps mess around with the signal they change it’s form add effects, and do other stuff, amplification takes that signal and, well, amplifies it. And then speakers take that amplified signal and reproduce it in a form we can actually hear. Most of the time the pre-amp and amp are wrapped up in one unit called a “Receiver” most often these also have basic AM/FM radio functions as well (which is where they get their name). It’s not until you get into the really high end equipment that you should start worrying about buying independent amp and pre-amp units. Receiver units are usually good for those of you spending less than $10K on your surround sound setup. But before we consider a receiver we should consider speakers.

You should choose your speakers first because when buying speakers you need to take into account your goals in terms of the kind of things you’ll use them for (movies, games, music, etc.) as well the size and dynamics of your room. The job of the receiver is really to bridge the gap between your source material and your speakers. Half of what you look for in a receiver is being able to meet the requirements of your speakers.

Choosing the right speakers.
A lot of choosing the right speakers has to do with personal taste, you can read comments about a pair sounding too harsh or too boomy or lacking midrange, or lacking punch, or having warmth or good imagery etc. but what really matters is what sounds good to YOU. First and foremost never buy speakers you haven’t heard, take a CD or DVD you know and love to the store, pop it in the player there and see what it does for you, does it sound right? Does it sound good? As discerning as your ears are they’re also picky and what might sound good to someone else might sound like trash to you, and visa versa. Unlike a display which has a definitive resolution, contrast ratio and easily adjusted colors speakers are much more the subject of opinion then facts and most can’t be adjusted to compensate.

One of the most important factors to choosing a speaker is content. The type of speakers you’d pick for music are completely different than the type of speakers you’d pick for surround sound in movies or games. Determine which one is more important to you as that will be the driving force for where you start looking (and what you bring for testing). The reason the choice in speakers is different comes from the differences in goals between Surround Sound and Stereo sound. In a Surround environment you have numerous speaker and each speaker should produce sounds distinctly. That is to say that when a noise comes out of the left front speaker you can instantly identify it as originating from the left side of the room and like-wise for the other speakers and their locations. The audio imagery comes from the source material and the speakers need only spread their sound just wide enough to overlap from one to the next to reproduce the image. In a Stereo environment you want the audio to come at you as a “wall of sound”. This means that you really only have two speakers and those speakers should produce a very wide, full, and much less discrete image. Some positional imagery will still exist but to a much lesser extent. Stereo imagery is meant to be more like a concert hall where having two channels provides some depth and dimension to the sound but not necessarily direction.

In short speakers designed for stereo playback don’t make good surround sound speakers because they’re too full and don’t provide enough directionality, meanwhile surround sound speakers aren’t good for stereo playback because they are too directional and the resulting sound feels weak and sterile. Most audiophiles interested in both types of audio will keep two sets of speakers, one for stereo playback and one for Surround Sound playback. There are also companies that make speakers with switches that allow you to flip a switch to tune them for Stereo or Surround playback (though I’ve personally never really cared for that). Determine what type of listening is more important to you. You can build your system for varying degrees of both, but know that they are competing goals so pick the setup that represents what you’ll be using them for the most.

Size does matter
I don’t care what some Bose advertisement says about big sound from a small package. I’s mostly crap. That doesn’t necessarily mean that bigger is better but the size of the speakers should reflect the size of the room. When speaking about size I’m referring to the size of the enclosure. In general the size of the drivers is representative of the range of sound they’re capable of reproducing. I would not recommend getting anything less then a 2-way speaker, this doesn’t mean two drivers this means the the incoming signal is split in two ranges to (high and low) and then set to two sets of drivers. Smaller speakers will only have one driver per range but others might have redundant drivers for one or both ranges. Larger and more expensive speakers might also be split three ways.

Multiple drivers in the same range will often help produce accurate sound at higher volumes which can help drive sound through larger rooms. Three way speakers use each driver for a smaller more specialized range of sound which can help reproduce sounds more accurately. The size and shape of the enclosure has a lot to do with sound reproduction too. These aren’t hard fast rules to speaker selection though, you really need to listen to the speakers yourself; and don’t shy away from turning them up. It’s always good to know how a speaker reacts when it’s put under hard conditions.

If you have smaller to mid sized speakers for your front mains you’ll want to get similar speakers for your rear satellites. If you have larger speakers for your front mains you can get away with using smaller speakers for your rear satellites. Though it’s important that all of your speakers match. I high recommend getting all of the speakers from the same brand, preferably the same line. The reason is that the speakers help each other form a complete image; in surround sound environments objects and people walk around the room. Speakers can vary greatly in tone, and react differently to different sound ranges. if you speaker’s aren’t all matched then you run a very high risk of the sound changing as it moves around the room.

Lets use footsteps walking around the room as an example. If your speakers aren’t matched as the footsteps move from one speaker to the next they might get louder or softer giving your ears the impression that the person is moving closer or further away, even if that’s not the case. Also tones could change which would give your ears the impression that the person is stepping on a different type of material even if that’s not the case.

There might be some slight difference in speakers depending on their use. For instance most of the sound is driven through the front left and right speakers so these should have the most dynamic range of sound, the center channel is mostly used for on screen speech so it should have a very strong and accurate mid range and the high range so be soften slightly to prevent harsh “sh” sounds in speach. The rear satellites usually just add ambiance to the front speakers as well as provide rear sound effects like ricocheting bullets or muffled screams from people off screen, so these don’t need to have as much of a dynamic range as the fronts. If you buy in the same brand and in the same family of speakers then these speakers are all likely to use the same drivers and similar electronics as a result the frequency response and tonality from speaker to speaker will be generally consistent with slight tweaks to allow them to produce the kinds of sounds they’ll be used for the most. If you don’t go with the same family but the same brand you should see if the speakers use similar drivers. If you go with different brands you should definitely consider listening to them together to ensure that they match. Sub woofers are exempt from this rule as they are are a completely different beast from the rest of your speakers.

While we’ve talked about “speakers” we’ve neglected the sub-woofer. It’s usually a good idea to go with a sub woofer that includes it’s own amplification. Not very many receivers provide amplification for sub woofers and where a sub uses a substantially larger driver it often requires two to three times as much power then your amp provides on any one channel. There are some considerations with a subwoofer as well. Ported woofers (and ported speakers too) will be capable of louder volumes and deeper ranges, however it gets these things at the cost of accuracy, low sounds will lose a lot of their punch. I personally prefer a completely enclosed sub woofers and speakers, your tastes may vary, again, listen to them yourself and make a decision.

Size again makes a difference in the sub woofer world. In general the larger the sub the deeper noises it’s capable of making. But the larger the sub the more difficulty it has with higher frequencies. Basically the sub not only needs to produce low end noises but it needs to pick up where your other speakers leave off. If your speakers are too small and your sub woofer is too big there will be a very noticeable gap in the sound, lower then the speakers can handle but higher then the sub woofer can handle. It can vary from sub to sub based on the design of it’s enclosure but I’d recommend getting a sub woofer with a driver about twice the size of the largest driver in your other speakers. So if your front speakers have 8in drivers go for a 15in sub. if your front speakers have 6in drivers go for a 12in sub and so on.

To get an appropriate amount of rumble out of your sub woofer I’d recommend getting one that is a minimum of 1in for every 20 square feet of room. So if your room is about 15ft by 15ft -> 15ftx15ft= 225sqft -> 225/20 = 11.25 So a 12in subwoofer would be ideal. You can also use this to determine the size of the speakers you should consider. meaning that at least your front main speakers should have 6in drivers (half the size of your sub). Sub woofers are “non-directional” meaning their noise is so low that you can’t determine it’s origin. This typically remains true if you have a sub woofer sized appropriately for the room; however, if you go to small you and your guests will be able to audibly locate the sub woofer every single time, which is bad, very very bad.

Now that you’ve got your speakers all picked out you’ll need to bridge the gap between your source material and your speakers. This is the easy part. First you’ll need to look at your sources. What kinds of connections do they recommend? Are they using Toslink, coax, separate analog plugs, HDMI? What kinds of data is being sent over those connections? Dolby Digital, DTS, Pro Logic, TrueHD? Ensuring that your receiver accepts Dolby Digital and Pro Logic IIx through toslink and analog stereo plugs respectivly will ensure that 100% of console games on the market can connect to your Receiver in the best possible way. If you watch a lot of DVDs you’ll want to ensure it supports DTS for the few discs that do support DTS; it’s nice to have. And if you want to ensure that you can play all of the new high def audio formats from blue laser discs you’ll want to ensure that it fully supports HDMI 1.3 (though there aren’t any receivers on the market that do that yet).

Research the equipment you’ve got and the equipment you plan on buying, find out what they all recommend using. You should also ensure that your receiver has enough inputs to handle all of your devices, if you have an excessive number of devices you’ll need to get an external switch (though that’s a topic for next week). One thing you should ALWAYS get is pre-amp inputs. this is future proofing your receiver by allowing you to connect a separate pre-amp device. If some new device comes out tomorrow using a new technology that your receiver doesn’t support you’ll likely be able to buy a stand-alone decoder and feed it into your receiver through the pre-amp inputs, it’s future proofing your purchase.

The second half of choosing the right receiver is making sure it can work with your speakers. Look for the receiver’s power rating in Watts. Many will advertise “peak” or “max” performance and 99.9% of those numbers are complete marketing BS. the only number that matters is the Watts “RMS” (root-mean square). If you can’t find the RMS listed for a receiver don’t buy it because the manufacturer obviously doesn’t want you to know (which almost always means it’s bad). Your speakers should tell you what they recommend for power and what their peak power is. You’ll want to make sure the RMS of your receiver fits comfortably in the range of the recommended power and max power. Below or above that range and not only will you get weak, crappy sound and distortion but you risk damaging your speakers.

Anything else on the receiver is fluff and personal prefrence. Receivers have their own tonalities to them and again that changes depending on which speakers you’re using them with. Listen to a receiver before you buy it, and if possible listen to it with the speakers you’re considering as well.

What brand should I get?
Receivers don’t need to be the same brand as your speakers. Actually I usually recommend getting different brand speakers then the receiver as companies usually only specialize in one or the other. I’d shy away from any brand that requires you to use their receivers with their speakers. I’d also recommend shopping in a specialty store as opposed to a big box store. Most of what is sold in the big box stores is crap designed to sell fast and be replaced often. Find a good boutique where the employees know the equipment, if you’re not listening to them in a listening room then you’re not really listening to them. If the store doesn’t even have listening rooms don’t shop there.

Like displays I’d recommend not paying attention to the brand name and just going by sound. Audio is a very unique market where it’s fairly easy for someone in their garage to just start making speakers. I’ve seen homebuilt stuff that goes for half the price of brand name equipment and just blows them away quality wise. There’s something to be said for hand crafted speakers tuned carefully by hand because the guy just loves audio as opposed to something that’s been mass produced as fast and cheap as possible to help boost their bottom line. Don’t count out the little guys.

How much should I pay?
I’d recommend setting aside as much if not more for your surround sound system as you did for your display. If you spent $2K on your display, set aside a minimum of $2K for your surround sound setup. In the grand scheme of things display technology is still very old fashioned. We look at a moving photograph, it’s flat and small and not at all immersive on it’s own. Not until we have stereo vision and virtual reality will we have truly immersive video technology. Sound on the other hand is already there. We can emulate entire 3D worlds and environments with sound alone. With a good system if you close your eyes you’re there, and you didn’t even need a display to have that experience. You could be using an old crappy 25in CRT display but if you’ve got the right surround sound the experience becomes vivid and full.

Most people neglect the sound system or cheap out by buying some crappy home theater in a box just so they can hear the occasional bullet behind their head. It’s not surprising, sound is hard to sell you cant show someone sound in a paper advertisement, it’d be difficult to describe a sound in a review, and unlike displays you can’t line up sound systems next to each other on a shelf in a wide open store and have them accurately produce what they’re capable of. If you get anything out of this just know that cheaping out on your sound system is the worst thing you can do when building a home theater.

That doesn’t mean that you need to buy all your stuff at once. One of the beauties of a piece built system is that you can build it up over time. Start with a receiver and a quality set of front main speakers. Down the road add some rear speakers and a center channel and then a little further down the road finish it up with a sub woofer. You can do this because unlike displays good speakers can last a very long time. You might replace your display every 5 or so years but if you get a good quality set of speakers you’ll be passing them down to your children. Receivers are a little different because the decoding technology changes over time as do the types of inputs but good speakers can last you a lifetime.

I hope you enjoyed part 2 of this 3 part series on building a home theater. Be sure to check back next week where I’ll cover other considerations such as cables, placement, tuning, and supporting devices.

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2 Responses to “HomeTheater 101: Surround Sound”

  1. thax Says:

    Excellent work, I can’t wait for next weeks article.

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