Home Theater 101: Act III

A continuation of our Home Theater 101 Series

Previously, we covered the Room itself and looked into TVs and Projectors and are now ready to put the A in A/V. Some thoughts you might be hearing go through your mind are; How do I make sound decisions when there are so many choices? Do I really need all those speakers? Which setup is right for me? How future-proof will all this be? Can I do it in stages or do I have to do it all at once?

Sound System Basics

Sound is critical to a movie. Per George Lucas, "The sound and music are 50% of the entertainment in a movie". Despite this, most consumers spend $500-$2,000 on a tv and maybe, maybe $100-$200 on some kind of sound system, usually a cheap soundbar of some sort. To demonstrate how critical sound, both sound effects and the music are, watch some rough behind the scenes bonus material of your favorite films and ask yourself if you could sit through that for 2 hours and still get the same level of enjoyment from the movie. Ever heard of John Williams? Can you hear the theme from Jurassic Park or Superman or Star Wars in your head? Darth Vader's Imperial March? Sound is seriously important.

Thinking back on your visits to a commercial movie theater, the sound was there. You could feel it. The theaters in the business of making money spend big bucks for sweet sound systems. They also partner up with the likes of THX and Dolby to ensure that they are up to the task of delivering the sound as the filmmakers intended. So, listen up, we're gonna figure this part out together.

*Surround Sound Fundamentals

Modern movie soundtracks have multiple channels of information beyond just simply left and right. The basic surround sound source material is in 5.1, or six total channels; 1. Center 2. Front Left 3. Front Right 4. Rear Left 5. Rear Right 6. Subwoofer (this is the .1 in the 5.1). By not at least having this type of setup, you are choosing to sacrifice something, as a 5.1 surround sound setup is truly the minimum for surround sound. Ideally, you would want all the 5 speakers to be identical. The reason for this is so that as the sound moves around the room, you cannot distinguish any differences in the sound signature, thus helping to preserve the illusion of the surround sound effect. This is hardly ever the case for a few reasons. There usually isn't room for the center channel speaker that lives below a screen to match to the left and right front speakers. So, center channel speakers are usually a modified version of the two main front speakers, designed to lay flat. If they use the same drivers (or internal speakers) they usually do a good job of preserving that sound signature. The rear speakers also receive a lot less sound information and so do not necessarily justify the cost of the bigger main front speakers. They would also be more difficult to mount on walls being full-sized.

*7.1 and Beyond

The latest high-definition movies are encoded to make use of more speakers. The basic 7.1 adds two more surround rear speakers. These are placed nearly directly to the side of the main listening position. They help add realism, especially when sound occurs to the side and/or transitions from front to rear and rear to front.

But wait!, that's not all. New formats such as Atmos and DTS:X make use of even more speakers. These audio codecs, are exciting because they are not channel specific in the same way previous 5.1 and 7.1 setups work. In the traditional 5.1 and 7.1, the mix on say the disc, had each channel already laid out and dedicated with the necessary sounds. All your system had to do was send that info to each speaker. Atmos and DTS:X are no longer locked down to the channels, rather they include information for sounds that are dedicated as 'objects' of digital data that include where in a 3D space they should be coming from. This information is processed by a compatible sound system and sent to the correct speaker(s). This allows the system to decide how that works best with the number and position of speakers in each room. This change is a big deal and can add a whole new level of realism.

How many more channels? Actually that's kinda up to you and your specific setup. But you will see these extra channels added on to the decimal numbering system. So, 7.1 upgraded to add 4 new speakers on the ceiling becomes 7.1.4 or, if only two were added to a 5.1, then it would be 5.1.2. Did we say ceiling? Yes! That's where the majority of these new sound channels get used. Remember, Atmos and DTS:X have objects of sound to be located in 3D space, so that means, front to back, left to right, and now up and down. Although 'down' is not really below the lowest speakers, usually defined by the front speakers. So, now if a helicopter flies overhead, it doesn't just sound like is whizzed past you from front to back, but now goes over your head as it does so.

*Soundbars

The single most convenient upgrade is to add a soundbar. (Honestly, no one can agree if it's sound bar or soundbar, anyways back to the topic at hand) A lot of TV manufacturers would like to sell you one. They are a decent way to upgrade from built-in speakers, but they have some limitations. The speakers are usually quite small and thus can be limited in their dynamic range, especially for larger rooms. Also, the left, center, right separation is locked down since they are all part of the same unit. They may or may not come with rear speakers. It doesn't matter how trendy and flashy the lingo, you will not be fooled much into thinking a speaker in front of you played a sound 'behind' you. Rear speakers were invented for a reason. Some come with a subwoofer. The laws of physics are laws, they are not relenting. Asking tiny speakers to rumble you is just not going to happen. A subwoofer adds the lowest frequencies and the punch and energy required of modern movies and games. Depending on your situation, this might be your only choice. Be sure to try and get the unit with a full complement of subwoofer and rear speakers to extract the most from your setup.

*Soundbar Alternatives

If high quality sound is important but, you can only fit/afford something like a soundbar, there could be another way. This is a two-channel solution, that could offer greater enjoyment, especially for listening to music. There are small amplifiers (often referred to as desktop amplifiers), about the size of the box your smartphone came in, that can process digital signals coming from your TV (and can feature other connections, bluetooth, aux, USB, a remote control, and some even a separate subwoofer output for 2.1 setups). These can be connected to a high-quality set of speakers of your choice. If music is important and improving the sound of your TV would be a serious bonus, this could be the solution for you (TechMyAV staff are fond of this setup for a living room). The amp will usually run about $100-$150, and a decent set of speakers $50-$200.

*A/V Receivers and Component Systems

An A/V receiver is generally the best way to go. They are more robust, flexible, feature packed, and configurable than almost anything else out there. They'll usually end up being the heart and soul of a system. They can be the most expensive initially as well. This is because you are buying the brains and amplifier as a receiver unit and then you must add in the cost of the speakers and a subwoofer. On the flip side of that coin, they can be the cheaper way to go in the long run. By having all separate components, you can upgrade and/or replace each item as needed rather than starting all over. As the name also implies, they process both sound and video. They can also add a lot more connectivity options than that of your TV or Projector, and often can take the amount of wires going to your TV/Projector down to a single HDMI cable. They can have advanced processors for decent video upscaling support as well. Most include support for the latest sound codecs such as Atmos and usually have apps for mobile devices to act as a remote control, dramatically simplifying the often overwhelming remotes. Some can be setup to power two different zones or rooms, example: 5.1 in the living room and 2 on the back patio. They can stream directly from various sources (usually just audio sources, think Spotify). They can connect via Bluetooth and wifi, and have many, many other features depending on the model.

Choosing the right receiver is not really as daunting as you might think. To get the process started, you must first decide on the potential maximum number of speakers you would want to run. This quickly narrows down your choices. For example, most support up to either 7.1 or 5.1.2. Going beyond to say (9.1) 5.1.4 or even (11.1) 7.1.4 will not only narrow down the choices further, but could bring the price up quite quickly. Again, with separate parts to the A/V and sound system this can also be done in stages. You could go with say a 5.1 setup, then when deciding to add the ceiling or height channels, upgrade the receiver and purchase the additional speakers, while leaving the rest of the 5.1 system as-is. Once the number of channels is decided upon, determine a rough budget from the options available.

Other features to consider would be how well it can drive the speakers you will have. Most speakers and receivers fall within a certain range of characteristics that will all be compatible with one another, but minimum impedance must be considered. We won't go all nerdy here, but the lowest listed impedance is the most critical factor. Most receivers will work with 6/8 ohm and above speakers. Some may work with 4 ohm and above. That will be listed from the manufacturer. Do not try and use speakers that fall below the receiver's lowest impedance rating. Ever. The design of the amplifier requires that it sees some resistance to help control the flow of all those wild electrical juices. Going below, or introducing too little resistance, will let them juices flow unchecked and can be the equivalent of sticking your fingers in an electrical outlet, something will end up hurt, damaged, or broken. So, before cannibalizing those speakers that came with your old home theater in a box, pay attention to the ohm ratings.

*Speakers

These used to be like the large flat screens of yesteryear. Today, you aren't seen as "into movies and shows" unless you have some large screen display at home. Decades ago, this was the same but in speakers and Hi-Fi systems. While speaker technology has improved year over year, it really hasn't fundamentally changed in just about a century. Electrical signals are usually converted into electromagnetic work that vibrates or moves a membrane to create sounds. Even most cheap speakers do enough to at least let you know what is going on. Human voices vs instruments can usually be determined quickly enough on cheap audio devices. That's still no excuse for ignoring a major part of a film or game. The experience is utterly transformed when going from built-in speakers on a tv to a full multi-channel surround sound system that delivers clarity, impact, emotion, and a sense of realism that moves you away from a couch in a living room to the world created by the entertainment you are enveloped in. Life is short and our time is precious. If you decide to use that time to enjoy a movie or binge watch an amazing series, then simply put, life is too short to waste on poor audio.

Center Channel speakers are often the unsung heroes of a true home theater. Nearly everything that takes place on the screen in front of you will require audio to go along with it. So, it makes sense that the speaker that is in-line with the screen gets the most sound. The biggest job it has is delivering dialogue. A well-balanced center channel is not too boomy, projects human voices evenly throughout a listening space, and fits within the space restrictions of your setup. It resides just below (or behind a compatible projector screen) the display and as close to it as possible so that it seems the voices are coming from the actors on screen. It should either look really good or be practically invisible, according to your design tastes.

Main Left and Right speakers can be large stand alone units used for both music and movie listening or can be smaller 'satellites'. They often get a lot of the music during shows and a lot of the impactful special effect sounds as well. They should be about the same height as the center channel and evenly spaced to either side. Again, if music is critical give them a little extra room in the budget and they'll treat you right.

Rear speakers will see a lot less information sent to them in comparison to the main front speakers. They should be slightly above the listening position. They should also be small enough to mount on small stands or on walls to help with positioning.

Height and ceiling speakers should be considered too. Most height speakers are on-ceiling or in-ceiling. There are others that can be mounted up high and above the front speakers as well, if ceiling speakers simply cannot be done in your current setup. They should all be able to produce nearly a full-range of sound and have excellent sound dispersion patterns. They can be more labor-intensive to mount, but with object-based surround sound hitting mainstream sources, these are quickly becoming more critical and worth the effort. If your ceiling is flat, but you don't want to install anything in/up there, there are also reflecting speakers for Atmos that can rest on top of your main front speakers and 'bounce' sound off that ceiling to your ears to help add the sense that the sound was from above and not in front of you.

Subwoofers are a lot fun. They play the lowest frequencies the other speakers simply cannot handle. They are self-powered as well. The receiver has an amplifier for the rest of the speakers but, the subwoofer gets a signal and amplifies its own larger speaker. They should play loud and low enough to fill up your room and just high enough to cover any of the sounds the smaller speakers shouldn't and can't handle. The A/V receiver will almost always be the device that determines which frequencies get sent where. Bass frequencies are quite a bit less directional, meaning our hearing cannot always easily identify where the bass is coming from. Combine that with say the crack of a rifle being sent to a surround speaker while the subwoofer plays the grumble and you'd think the shot came from that smaller speaker. This is a big help when placing the subwoofer in a room. Usually, you just need to provide a few possible locations for the sub to live, take a listen, and choose the best spot. Most of the time it lives up front, somewhat close to one of the main front speakers. Subwoofers only play about a 6th or 8th of all the frequencies we can hear, but provide at least 50% of the sound energy. A good sub will bring a smile to your face.

Wiring should be considered as well. In a serious theater setup, wires are all ran to each speaker in its ideal location, through walls and ceilings and all hidden too. That can add up to being a lot of feet of wire and possibly a professional to assist. If running wires is not your thing, there are solutions out there to help you. Flat wire exists to help run along walls and baseboards and can be painted to match the walls to help hide them visually. There are even wireless solutions. Wireless speaker technology really hasn't hit its full stride yet and for some the term can be even a bit confusing. There are very few true wireless speakers that need to be charged up, the rest have the signal sent wirelessly while still needing to be plugged into a power outlet. Still, they may be an option to be explored. The basic idea is that spending a few hours to install things properly and run all those wires will be well worth it when it comes to the near countless hours you can enjoy from the completed setup.

*A note on setting all this up: many mid-tier and high-end receivers come with a setup microphone. Once it's all hooked up, you plug in the microphone and the receiver plays some test tones. It analyzes what the microphone picked up and sets the frequencies, sound level, and timing delays for each speaker. It can even warn you if it detects a wiring issue. These are the one of the greatest time savers and help you get the most out of all the money and time you just spent on installing this equipment.

*Watts and Power Ratings

One of the black eyes of the audio world is the marketing departments and their obsession with stating ridiculous power ratings. Most respectable companies either never engaged in this or have long since given up on it. Claiming one system is better than another because of its massive thousands of watts of max power is silly. Maximum power ratings are absolutely worthless. It's the equivalent of claiming a vehicle's top speed is thousands of miles per hour because if it were sent into space, that's the speed it could reach. What does that have to do with anything you might care about when buying a car? Nothing. So when looking at speakers and amplifiers and receivers, concern yourself with just a few things. 1. The receiver's/amplifier's RMS rating at the ohms/resistance of your speakers. 2. This RMS (average output) rating should at least fall well within your speaker's range of power, generally best toward the upper-end of that spectrum. Example: a receiver with a 130 watt per channel RMS rating at 8 ohms will work great for a 8 ohm speaker that operates between 50-200 watts. If you have a choice though, a more powerful amplifier than the speaker is actually better. Preventing the speakers from blowing up is a simple click of the volume, but more importantly the amplifier will not approach its maximum designed work load. As amplifiers push themselves harder, more distortion to the signal is introduced. And that kind of signal distortion is yucky and no fun.

*Summary:

We took a brief look into some of the sound system items you'll need to know when going for that home theater experience. Like with all of these Home Theater 101 series of posts, there is a lot more than can be covered and we will strive to cover them in future posts, but for now hopefully you are seeing the kinds of things that should be considered when building a home theater. Up next, Sources. What good is a home theater if you have nothing to watch and play?

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