We get a lot of readers contacting us asking about room treatment and so in an ongoing series of articles David Shevyn of GIK Acoustics talks us through practical room treatment for your hifi listening space.
The subject of room treatments is often a hotly contested topic within the hifi Community with two basic camps: those who believe treatments are the best investment they have made because the results provide audible detail they did not even know was possible, and those who think acoustic panels will not make an improvement so they attempt to resolve issues via other means.
The challenge is to help people understand why they should consider treating their room in the first place. I was recently following a thread on a popular hifi forum where members were invited to post pictures of their two-channel listening rooms, show off their gear and room set ups. What instantly struck me as I browsed through 250+ submissions was not only did very few of the rooms have any type of acoustic treatment whatsoever, but very few were also making the best of the room.
So why would you need to acoustically treat your room in the first place?
One of the most basic phenomena of room acoustics – and what most people are familiar with – is echo or reverb. If you’ve ever walked around an empty house and you can hear every footstep and voice, that is echo / reverb and you will almost certainly come across it in everyday life. Ever been to a restaurant where you can hardly hear your dinner companions due to the noise of other dinners, the kitchen, the sound of people’s knife and forks, etc.; that’s echo / reverb too. Echo / reverb is not the only sound distortion caused by the acoustics of a room. Did you listen to your equipment in a hifi shop but upon getting it home discover that the bass is too boomy, or perhaps there are notes missing from the recording. That is the acoustics of your room affecting your listening experience. Lack of detail or a sense that the stereo imaging is not balanced, all of these things can be affected by the room and position you are listening in.
To demonstrate this, we played a short piece of music in our test room and recorded what we heard. We then treated the room and played the same piece of music again. The same equipment was used, the same recording, the same room, the same listening position, the only difference was room treatment.
With the first recording, you can hear the echo in the room. The instruments are not distinct and smear into one another. Overall it was confusing to listen to. In the second recording where the room was treated, the difference is instantly apparent. The echo is gone. The bass is tighter and punchier. The different elements of the recording can be heard separately and the overall sound is much more enjoyable.
For my first article on Room Acoustics we are going to look not at how to treat your room (we will cover this in a later article) but how to set up your room. Proper set up has a huge impact on the acoustic issues you’ll encounter in your room. Some acoustic issues are strictly due to positioning and can only be solved by setting up properly. Moreover, finding the best speaker and listening positions in the room will help you get the most out of your equipment and acoustic treatment in the space.
- Where to set up your system – In most cases, you want to orient yourself so that you’re facing the shorter wall, with the longer walls on your sides. This orientation gives greater flexibility for positioning your speakers and listening position, and also gets you farther from harsh rear wall reflections. The rear wall being the wall directly behind your listening position. Put simply, you want to get as far away from the rear wall as possible; as many nulls (a loss of a certain frequency) and peaks (too much of a certain frequency) are created here.
- Where to place your listening position – The rule of thumb is to experiment with the listening position at about 35% – 40% of the way into the room from the front wall (or the same distance from the rear wall for a theatre and some two-channel rooms). This range avoids the biggest dips and peaks from room modes. You want to avoid being in the centre of the length of the room, and you want to avoid being closer than a few feet to any room boundary.
- Speaker Placement – Speaker positioning can be tricky business, and it can take a lot of trial and error. However there are some general guidelines that can help expedite the process. Usually you want the speakers to be equidistant from their respective sidewalls if possible. If the left speaker is three feet from the left wall, you want the right speaker to be three feet from the right wall.
Standard Speaker Layout for Two-Channel Stereo
Many manufacturers recommend keeping speakers away from a wall if at all possible. However, this is not always the best piece of advice. In fact, for most small rooms placing the speakers right up against the front wall is the absolute best position as it avoids any cancellations and peaks in response due to reflections from the front wall. This phenomenon is known as Speaker Boundary Interference Response, or SBIR for short. In general you should avoid having your speakers anywhere from 12” to 30” from the front wall, unless you treat directly behind the speakers.
I would typically recommend putting speakers on dedicated stands as it gives more freedom to find the best positioning, and also helps decoupling the speakers from a resonating surface.
In my next article, we’ll examine treating the room itself. Should you have any questions about room setup for your particular space, feel free to contact Hifi Pig and we will assist in finding solutions for your particular scenario.
David Shevyn is the General Manager for GIK Acoustics-Europe and helps advise on over 5,000 different rooms each year.
If you have any questions with regards room treatment, or any other aspect of hifi, then get in touch and we’ll get industry experts to answer your questions.