Avoiding common mistakes in home theatres
Setting up a home theatre -dedicated or not- is a pretty big project. One that requires planning and researching, but also time for proper set-up. It’s fair to say that mistakes in home theatre set-ups are very common. But why does that matter?
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 as a team. Simply buying good pieces of equipment isn’t enough, and the chain is only as strong as its weakest link.
While we understand that no situation is ideal, that rooms may have multiple uses and that compromises need to be made, some errors are just too sad for words.
We sum up the things you want to do in order to avoid those common goofs so you can enjoy every moment of the precious pennies and time spent.
PLANNING
Make sure gear is appropriate for the room size
While it’s not great to have heavyweight speakers and amps in a small room, you can still work with that.
What you really want to avoid is a low-powered system with low-sensitivity speakers in a large room. Fail to add a correct sized subwoofer to a system in a large room and you are really looking for a poor result.
In a larger room, it may even be necessary to step up from a receiver to separates, and move to speakers that handle more power and have higher sensitivity.
On a related theme, you want to avoid choosing a television or projector screen that’s way too big for your room and seating position. A picture that’s too big loses detail, contrast, black level, and brightness. That said, a video display that’s too small can be even worse. A great calculator to determine what size of screen you need can be found here.
Related to the room issue we would like to get clear on this one:
Fancy Design is not everything.
A bit controversial maybe and it can definitely be a result of a plan to be smart with space, but we really want you to avoid putting your television high up on a wall.
Watching television with your head tilted back becomes uncomfortable unless you’re watching television in bed
The thing to do these days seems to be to put a television above a beautiful fireplace. Think twice before you follow the interior designer in this. It may look pretty in the picture, but it is a rather painful position to sit in for any stretch of time and not ideal for the television itself (Heat, anybody?)
Which brings us to another fancy interior design magazine issue: the all ceiling speaker surround system.
Using round speakers that fire straight down for LCRs (left-centre-right) is just wrong. If you have ever gone to a parade of show homes, you will know that they are everywhere. (To be clear, we are not talking about in-ceiling speakers installed in your kitchen for background music. We are talking home theatre front channels.)
LCR speakers are too important to just sound like the disembodied voice of God (we stole this line from Gene DellaSalla from Audioholics).
LCR’s need to be localized and the average in-ceiling speaker is not really capable of doing a satisfactory job at that, especially if the are not pivoting. For LCR speakers in-wall speakers are the better option. Several brands make it their mission to produce some excpetional architectural speakers.
Match components to one another, or spend a proportionate amounts on each component
Use your budget wisely. We have just one word of advice when it comes to this: plan!
Rather than spending $4,000 on a full-feature receiver with $500 LCRs each, it probably is a much better idea to spend the same amount of money with much better results on a $2,000 receiver and $1,000-each LCRs.
Again, choose the speaker for the room and the application, and then select an appropriate amplifier.
Which brings us to this:
There is actually an ideal order in which to select components.
In the case of a home theater, you probably want to make your screen or video display selection first, even before selecting speakers so you can be sure everything fits properly in the room.
Then, select your speakers, to match the room and your budget.
And lastly, pick your amp (or receiver) to match the speakers.
On the subject of the amp and linked to what we previously discussed about planning your budget: We highly recommend buying the best quality amplifier that works within your budget -whether that be an AV receiver or separates. We highly recommend to focus on quality rather than the latest features. Newer doesn’t necessary mean better and next year will bring a different fancy flavor anyway, especially when it comes to AV receivers.
Check whether power supplies are adequate to run your speakers, even when using 8 Ohm speakers. Remember that an ‘8 Ohm speaker’ is commonly used terminology to express the average load. There is really 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 your AV receiver has pre-outs, consider a separate amplifier for your LCR speakers.
THE FINAL STRETCH MATTERS
Pay attention to room acoustics
You may have the fanciest Home theatre set-up, if room acoustics are not considered, you are not going to have a great experience. Period.
It’s well known that placing your loudspeakers and listening position correctly is the first step toward getting good sound.
It speaks for itself that you want the area between the listening position and the front speakers to be unobstructed if possible in any way. A coffee table is 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.
Correct speaker height at ear level for the LRC channels and giving your front speakers plenty of space to ‘breathe’ are crucial steps in getting room acoustics right. We dedicated a blog on speaker placement previously, so you may want to refer to it here.
The main concern when it comes to room acoustics in small room is handling the bass frequencies. We are talking about early (first) reflections and low frequency behavior which is dominated by resonances and associated standing waves.
All rectangular rooms have a deep bass null at the halfway points – halfway between the front and rear walls, halfway between the left and right sides, and halfway between the floor and ceiling. Therefore, the worst place to sit is exactly halfway back in the room, with your ears halfway between the floor and ceiling.
A lot is said about room acoustics and the treatment it requires to deal with these nulls and bass management in general. You probably have noticed that advice can be fairly conflicting. Part of the reason for this is that acoustical designs for commercial movie theatres, concert halls, recording studios and large rooms in general are also applied to a small home theatre rooms. It is hardly possible for a home theatre to sound like a concert hall if it tried, so just transferring one advise to the other is a stretch at the least. We are talking plain physics.
So what do you do?
Recent research into the matter seems to favor less treatment than previously advised. While there may indeed be need for bass traps in certain situations, the current trend is to tolerate a certain level of sound reflection to make the sound feel ‘alive’.
Also, consider that bass is really difficult to control in small rooms and you need a lot of bass traps to tackle them effectively down to the lowest frequencies.
The latest research shows that you can accomplish the same thing as low frequency passive room treatments by deploying multiple subs. Multi-subs properly placed will smooth out room modes and give you better seat to seat consistency for bass. We have been going on about the benefits of multiple subwoofers in the past and research seems to reinforce this.
That said, this does not mean there is no need for bass traps at all. You definitely want address things like hardwood floors and non-symmetrical rooms for instance.
Take advantage of equalization but don’t rely on it like it’s gospel
No room is ideal and all speakers and all rooms can use some help. There is no argument that equalization helps to compensate for room and speaker response issues (mostly below the room transition frequency around 500Hz).
But…while a good room EQ system can do wonders, don’t automatically trust all the settings that your auto-EQ gives you.
Room EQ has the potential to be hit and miss. We can think of occasions where it has improved sound from a truly bad loudspeaker but we have also seen it degrade the performance from a truly good loudspeaker.
Remember that two ears and a brain are much more discriminating than a computer program without knowledge of the room and the speakers.
So like the weather forecast: please use it. It is there to help you, but don’t forget to look out the window before ditching the rain jacket.
We have a blog on room EQ in the pipeline for next week.
So…
Bottom Line: Plan well, ignore what looks hip and trendy and put the effort in addressing room acoustics.
Try to adhere to these tips so you get the most performance out of your gear, and the maximum enjoyment.
Source: My Home Theater, Audioholics, SVS, Definitive Technology, Auralex, Hunecke, Roomeqwizard, Sengpiel Audio