Common Mistakes When Setting Up a Home Theater System

originally published: May 13, 2005

Are You Doing It Wrong?

You can make your sound and picture much better just by avoiding these common goofs

To get the most bang for your buck when assembling an audio or audio/video system, it’s important to make each piece of equipment and the room all work together synergistically. Simply buying good pieces of equipment isn’t enough, and the chain is only as strong as its weakest link. While I understand that some audio/TV rooms are multi-purpose and have inherent compromises, some errors are egregious.

Before reading this article also check out our YouTube discussion below for further insights.

 Common Mistakes When Setting Up a Home Theater YouTube Video Discussion

Here are, in no particular order, some of the more common mistakes made when conceiving and integrating a system into a home…

Selecting components in the wrong order

Don’t buy your receiver first. You may be enthralled with a certain receiver because of its features or appearance, but it shouldn’t be your first component choice. Select your speakers first, to match the room and your budget. Pick your amp (or receiver) next, to match the speakers. In the case of a home theater, you probably want to make your screen or video display selection in advance of selecting speakers so everything fits properly. Leave yourself some wiggle room and keep an open mind in case you have to make changes before pulling the trigger.

Inappropriate gear for the venue

Heavyweight speakers and amps might overpower a small room, but I don’t necessarily consider that a bad thing. Overkill is generally good, whether it be wattage, horsepower, pizza, or Nutella. What is inappropriate, however, is a low-powered system with low-sensitivity speakers in a large room. And you can exacerbate that problem by not including sufficient subwoofage. Most often, speakers with a sensitivity rating of 86 dB @ 1 meter will not work well in a 5,000 cubic foot room, regardless of the size of the amplifier. In a larger room, you may have to step up from a receiver to separates, and move to speakers that handle more power and have higher sensitivity. And if your 300-watt 10” sub makes rude flatulent noises during loud passages, it isn’t necessarily the sub’s fault. If you have under-spec’ed a subwoofer for a room, you can compensate somewhat by placing it in a corner where it will couple better and have more output,  but in some cases may sound boomy in a corner. Consider buying multiple subs. Not only will the output be cleaner because each driver and amp is  being driven less hard for a given system SPL, but you can place them strategically in the room to smooth out the room modes. If two are placed laterally on opposite midwalls, they can minimize the null to improve bass in the center of the room where most people place their seats.

As Scotty used to say: "How many times do I have to tell you, the right tool for the right job!"

A pair of vintage JBL Pro III speakers as the main channels in a 6,000 ft^3 theater room?  I don't think so.

Not matching components to one another, or spending a disproportionate amount on one component

Use your budget wisely. Around ten years ago, I advised a dealer who was going to install a nice, full-feature $4,000 receiver with LCRs that were only $500 each. For about the same $5,500, I tried to explain to him that he could achieve dramatically better results with a $2,000 receiver (or budget separates) and $1,000-each LCRs. I can recall another dealer who systematically used expensive, high-end two-channel amplifiers to drive single pairs of inexpensive in-wall speakers in their distributed audio systems (In case that dealer is reading this, I’m not talking about you; I’m talking about someone else). Again, choose the speaker for the room and the application, and then select an appropriate amplifier. To illustrate my point, think of the last time you saw a rough 1984 pickup truck with $10,000 worth of aftermarket wheel/tire/suspension/exhaust add-ons (I live in Southwestern America, and I see this quite often).

A controversial area where I feel people use up too much of their budget is wire. If you’re using a receiver and modest speakers, I see no reason to spend thousands of dollars on speaker wire and interconnects. Just use something good and substantial enough for the distance covered. The lower end products from reputable wire companies seem to work transparently, and there are a few really good budget internet companies with great products and service.

Just this past week I visited with my old friend and brilliant designer Jim Fosgate, inventor of Dolby Pro Logic II, and I got a long demo in his spectacular home theater. Even in a cost-is-no-object system, the preamp low-level output wire he’s using to the tube power amps that are located by the speakers is simple 300 ohm flatwire; the same wire we always used for our FM antenna wire. Jim did extensive measuring and listening before deciding upon cheap 300 ohm wire.

Marantz AV Separates: Processor (top) and Multi-Channel Amplifier (bottom)

Picking a receiver instead of separates

If the budget allows, buy separates, mainly for the separate power amplifier. The amplifier section of most multi-channel receivers is Weak Sauce. Power supplies are usually inadequate, and current-limiting is employed to protect the insufficient output devices. Speakers run on power (voltage x current) and even a modest basic power amp should be able to drive a 4 ohm load. Most of them can drive a 2 ohm load. My 200-watt per channel amplifiers are rated at 375 watts into 4 ohms, and they pump massive wattage into my cottage. Many 100-watt per channel receivers can’t deliver its rated power into 4 ohms with more than one channel driven, and they may shut down or go into protection if driven hard into a 4 ohm speaker. Remember, there is no such thing as a 4 ohm or 8 ohm speaker. The resistance varies with frequency, and a typical 8 ohm speaker might vary from 5 ohms to 18 ohms, depending upon the frequency. If you must use a receiver, make sure it’s rated at least down to a 6 ohm load and you should be okay. Not great, but okay. If you have a receiver with pre-outs, consider upgrading the front three channels by going to a separate amp. If you’ve only heard a receiver on your speakers, you’re in for a shock when you add a separate amplifier.

See: AV Receiver or Separates: Which One is Better?

Ignoring room acoustics

If 50% of what reaches your ears is reflected because you haven’t addressed your room acoustics, do you really think you’re going to hear a $2,000 difference in speaker wire and interconnects? Avoid hardwood floors and other hard surfaces. Treat floor or ceiling reflections with absorption if using hardwood flooring.  Acoustical panels adjacent to the left and right speakers to kill first reflections is optional and depends upon the liveliness of the room and the off-axis properties of the loudspeakers themselves.  Ideally you want a higher percentage of direct sound to reach your ears than reflected, jumbled, incoherent sound. The first thing I’ll do when entering a sound room is clap my hands once, hard (We used to call this “The THX Clap”). This will give me a rough idea of what the room sounds like. I’ve been told by friends that this habit is becoming annoying, and it scares their pets. If you hear long decay, slap echo, or flutter echo when you clap your hands, your room needs work. The decay rate is the rate of decrease of the reflected sound over time; flutter echo is the fast, repetitive echo caused by hard opposing parallel surfaces; and slap echo is a discrete reflection from a hard surface. Flutter and slap must be eliminated; decay must at least be controlled - and always remember to floss…

Editorial Note About First Reflections

If your loudspeakers are well behaved off axis, absorption of the first lateral reflection is optional.  According to the research by Dr. Floyd Toole, In double blind tests most people find the additional spaciousness caused by not absorbing the early reflections to be pleasant.  Early reflections help to fill the huge hole in the frequency response which improves the center phantom image in the sweet spot for two-channel listening.  The idea for killing first lateral reflections originated in pro audio, where mixers found that being in a strong direct sound field made their job easier.  A recent JAES paper confirms this, but goes on to say that mastering engineers prefer to listen in more reflective spaces.  This of course is good, because that is where consumers listen. 

Now, if you want to “kill first reflections” you will need at least 3 inches of fiberglass or solid (not sculptured) foam.  Anything thinner just turns the treble down, degrading sound quality.

Editorial Note About The "THX Clap" Test

To make the "THX Clap" Test more useful, you should have one person stand by the speaker clapping their hands while you sit in the listening area for offensive flutter or slap echo.  The only flutter echoes that matter are those caused by sounds originating at the loudspeakers and heard by people in the audience seats.  What you hear yourself in other areas of the room is irrelevant.  But, is a room too reverberant?  The acid test is speech intelligibility.  Have someone speak from the center channel location (the dialog) and walk around the room, carrying on a conversation.  If it works, you are done, if not, add some absorption, or scattering (scattering makes the existing absorption work harder). 

Nice Room but why is the center channel on the floor?

Objects in front of speakers or poorly placed speakers

Nothing should block a speaker, so move that ficus tree. It hates your Night Ranger and Whitesnake tunes anyway. Another common mistake is having a low table directly in front of the seating, between the listening position and the front speakers. It’s a great place for the chips, dip, and feet, but bad for sound. Direct sound from your speakers mixes with the reflected (delayed slightly) sound off the table, reducing focus and clarity.

I covered this in a previous article about optimizing front LCR speaker placement but a center speaker under a screen with a 2^nd row of seating on a riser = no bueno. Try for correct speaker height in relationship to seating. Your front channel tweeters should be approximately at seated ear level.

A beautiful room in need of a few tweaks to improve sound

Improperly placing speakers on or in furniture

Speakers on shelves must be pulled out flush with the front edge of the shelf to avoid diffraction. Speakers in cavities in shelving units must be surrounded with foam or other acoustical damping material to avoid a nasty, hollow resonance.

Not taking advantage of equalization or relying on it too much

“My speakers are so good that I don’t need EQ!” Right? Equalizing is not “cheating.” Use an RTA app for basic EQ. Audyssey, or something more sophisticated like Lyngdorf RoomPerfect™ (which I employ in my 2-channel room)  can work well.  All speakers and all rooms can use some help, and equalization helps compensate for room and speaker response issues (mostly below the room transition frequency around 500Hz). Don’t automatically trust all the settings that your auto-EQ gives you. EQ settings aren’t always correct, and automatically-chosen low crossover frequencies never take power handling into consideration. Remember, EQ should be used judiciously, and mostly to reduce peaks. Generally, you should EQ down; not up but some of these auto-EQ systems apply boost too liberally which can cause resonances that weren't originally in the loudspeakers themselves.  If you need to boost a frequency by 9 dB somewhere to get a flat response, you have other issues that need to be addressed. Keep in mind that for every 3 dB you increase EQ at a frequency, you are doubling the power used at that frequency. A 6 dB boost will use 4 times the power, and a 9 dB boost will use 8 times the power. If you’re one of those folks who uses the classic “smiley curve” on your graphic equalizer, you must now don “The Shroud of Shame.”

Editorial Note About Room EQ

With no knowledge of the loudspeakers and no knowledge of the room, an omnidirectional mic and RTA can be unpredictable.  Two ears and a brain are much more discriminating.  “Room EQ” is a hit or miss proposition in the audio industry, occasionally improving sound from a truly bad loudspeaker (why did you buy it?) and occasionally degrading the performance from a truly good loudspeaker – an unforgivable sin!  It is a lottery.  Dr. Floyd Toole recently submitted an AES Journal on the topic, including cinema sound, which is in a dreadful state.  The X-curve should be eliminated. 

Seating placed in the center of the room

The worst spot for bass in a room is dead center, which is a huge, deep null if only using a single sub (or single bass source). No amount of equalization can compensate for it which is why two subs properly placed are a must. Make sure your important seating (who cares about your mother-in-law, am I right?) is at least a few feet off from the center of your room. We geeks refer to this as “the money seat.” And conversely, seating against a wall (back or side) will be very high in bass level because of the boundary effect. A boundary creates approximately a 6 dB increase in level of bass frequencies.

A center channel on top of a subwoofer?  Not a good idea.

Not calibrating your system properly

If done by ear, your bass invariably may be too loud. I have recalibrated dozens of systems that were set up by laymen and calibrated by ear, and they always seem to have the bass level up by 10 to 12 dB. The bass sounds bloated, and it masks detail, plus bass headroom is cut. Take the time to properly calibrate your system, including your subwoofer.  Use an SPL meter (C-wt, slow response) and internal test tones as a minimum to balance all of your channels.  It's ok to have your sub channel run a bit hot but let's not make this a car audio competition.

See:  How to Calibrate and Level Match Your Speakers

Running front speakers “full range” or “large” along with subs

Using your big front speakers full range in tandem with subs will yield more bass but proportionally less low bass response. You may have an additional octave of bass extension in your sub compared to your LCRs. Main speakers are very rarely designed for 110 dB output at 25 Hz, plus their placement, usually out in the room away from walls, isn’t conducive to proper bass coupling. Also, removing 80 Hz and below from your LCRs enhances their power handling, reduces their mid-bass distortion by means of lower excursion (and less Amplitude Modulation, and (this is important) frees up more amplifier power to drive the main speakers. Let your subs do the heavy lifting. The Doppler Effect can best be illustrated by the sound of a train whistle as the train approaches; changing in pitch as the train goes by. This is due to the speed of sound plus the speed of the train changing to the speed of sound minus the speed of the train. A vigorously moving speaker cone reproducing low frequencies is subject to Doppler in the higher frequencies.

Choosing a video display or screen that’s waaaaay too big for your room and seating

A picture that’s too big loses detail, contrast, black level, and brightness. But other than that…no problem! If half the picture is in your peripheral vision, you’re missing content. When I hear the term “immersive video” I think back to when I was a kid and I’d sit in the front row of the theater because the picture was HUGE, and I could get close to Kim Novak’s breasts. (I am old? Google her.) I soon realized the best seats were back at least a dozen rows. A 1:1 ratio of screen width to viewing distance is too close. On a related theme, a video display that’s too small can be even worse. Many combination “audiophile/theater” systems feature enormous monolithic speakers the size of grain elevators, flanking a comically miniscule 42” plasma TV.

Try watching the Jet-Li subtitled movie Fearless from the couch in this room 

Visual distractions in a theater

Don’t use light colors for the walls or ceiling, or during bright segments of movies the room will light up like the inside of a supermarket. Also, speakers with stylish high-gloss finishes reflect light from the screen and cause a distraction. If at all possible, move your electronics and their light show away from the video display. Having big separate amps with bright power meters right under the screen is visual clutter, unless you enjoy the nerdgasm of watching the meters dance during the end of “The Phantom Menace.” The best home theaters have light control, and the picture seems to float from a black background.

All In-Ceiling Surround System - this is just wrong on so many levels. Can you count the ways?

All ceiling speaker surround system

Using round speakers that fire straight down for LCRs is wrong, and if you have ever gone to a parade of homes, that’s all you see in million dollar-plus houses. Sound appears to be the disembodied Voice of God, and sounds don’t correspond with the action on the screen. Aimable tweeters are not a solution,  they only redirect the treble. I have heard ceiling speakers work fairly well for an A/V system, though. Most directional cues in music or movies comes from the midrange frequencies; a door closing, a car, a voice, a saxophone, etc. My office is filled with a few drum kits from a past life, so I use three LCRs that are flush in the ceiling, but with their baffles angled at 45-degrees to direct the sound, especially the midrange, towards the seating. My dog will bark wildly at the screen during a Beggin Strips commercial, even though the speakers are in the ceiling.

Video display too high

Watching television with your head tilted back becomes uncomfortable unless you’re in bed or in the hospital- or in a bed in a hospital.  I don’t know how else to say this, but Fireplace!! NO!! I know it’s commonly done, but I wonder what the thinking is behind it…”Know what would look great above that beautiful stone fireplace? A TELEVISION.” Interior designers use fireplaces as the de facto place for flat panel TVs, and I am counting on all of you to help put a stop to this travesty.

Save yourself some chiropractic visits and lower your display.

Placing “bookshelf” speakers on their sides

The term “bookshelf speaker” is from the 1960s when we didn’t care about proper dispersion and imaging. Drivers generally need to be vertically aligned for proper dispersion. This is also true for horizontal center channel speakers, which are almost all a compromise.  Choose one of the center channel designs in the diagram below except for Fig 1.d.  That is a lousy design plagued with acoustical interference for all but the single listener sitting directly in the middle of the two tweeters.  The design in Fig 1.c is the best type of center speaker especially for those sitting more than 20 degree's off-axis. 

Note: The importance of exact timbral match between the front LCR's is a bit overstated.  Most of the on-screen sound comes from the center speaker –  so it's arguably the MOST important speaker in the home theater system.  Don't skimp on this speaker!

Various Center Channel Design Topologies

Adding "super tweeters" to existing speakers

If the speaker designer had intended that you use an additional tweeter, he probably would have included it.  Tweeters need to be designed as part of the original system.  Arbitrary add-ons cannot integrate properly, even if they actually are good, or even better than the original. The desired effect could be emulated simply by boosting the 10 kHz-20 kHz range of your main speakers by 3 dB in your preamp or receiver. Cheap super tweeters are a sonic horror show, and the $1,000 ones add very, very little, if anything. And remember that when you add another tweeter, it interacts with the main tweeter. The distance between the axes of the two tweeters cannot exceed the wavelength at the crossover frequency, or you'll get lobing and cancellations. Even worse, the arrival times of these short-wavelength frequencies (a 9 kHz wavelength is an inch and a half long) will be different, and the treble will be smeared and less distinct. There is very little program material above 12 kHz, and even less above 15 kHz. I did read a marketing statement for one high-end super tweeter that made the claim that response to 90 kHz made bass sound better. I call "horsehockey" on that one.

Not using HDMI

Always use the highest quality means of moving a digital signal from one component to another, so use HDMI whenever that option is available. This is far more important with video, but there can be a subtle sonic difference with audio devices, too.  For one, you cannot get lossless Dolby TrueHD and DTS-HD audio decoding by any other means other than HDMI transmission. If you're stuck using Toslink or Coax, you're also stuck with lossy Dolby Digital and DTS as your top codec choices.

Not displaying video in its correct aspect ratio

Please don’t stretch a 4:3 picture to fill up your 16:9 screen. Just. Don’t. And don’t take a 16:9 movie and stretch it so you have black bars above and below the film, making everyone as wide as Kevin James. (And definitely avoid this if you’re watching “Paul Blart: Mall Cop 2.”)

If you haven't seen Mall Cop 1 or 2, consider yourself lucky 

If what you watch on cable or satellite is displayed in 4:3, it’s a cinch that you’re not watching HD, even though you may think you are. Go into the menu of your cable device or satellite receiver and make sure you have the highest resolution chosen. Most people think they’re watching HD as long as the screen is filled up, and that’s often not the case. If you actually prefer a zoomed or stretched picture, I am respectfully asking you to leave America as soon as possible.

Bottom Line: Do what's right, not what happens to look hip and trendy.

Don’t automatically emulate systems you see in industry magazines and on audio websites, either, because most of them have at least one issue and some systems are just hopelessly ill-conceived. Try to adhere to these tips so you get the most performance out of your gear, and the maximum enjoyment. If you have a difference of opinion with yours truly or you have your own list of system faux pas, please post them in the forum thread. Your input will be helpful to others, and I may actually learn something.