Too Many Room Treatments?

You’ll hear it from just about anyone you care to solicit feedback from that “the room” is the most important thing when it comes to sound quality. Ok, maybe not the most, but it will definitely make the top 5. There’s a lot of reasons for this, which I’m assuming you already have heard at some length as audiophiles are nothing if not pedantic, but the long and the short of it is that your room can really fuck up the sound of that expensive rig of yours.

The question that doesn’t really get asked very much is how. Well, let’s take a second and talk about that.

First is bass. Chances are, your room is a hot mess when it comes to bass. Sound propagation down a room travels in waves, and waves, when the intersect, can either reinforce or undercut each other. These are “room nodes” and they’re bad.

Now, high frequency waves are little. That is, the distance crest-to-crest is relatively short. So, while room nodes will occur, they tend to not be terrifically detrimental and are relatively easy to work around (ie, move your head). Low frequency waves are much larger, so the nodes they create are, well, larger.

This is bad because over/de-emphasizing certain frequency ranges can radically skew the music. If you ever read someone’s review that mentioned the words “boomy”, “thin”, or “muddy”, chances are, they have a room node. Let’s hope that wasn’t a speaker review.

Now, the good news is that this sort of thing is easy to treat, even if it’s pretty much impossible to cure.

First step, your friendly neighborhood acoustical product purveyor!

The grand-daddy of the group, Acoustical Sciences Corporation, has been selling their iconic TubeTraps for far longer than I’ve been into audio. There’s an excellent chance that when you say “bass trap” to the old-timers in your local audiophile clique, ASC’s TubeTraps are what these guys think of first. Why? Well, they used to be everywhere — because they actually work. Strategically sticking a pair of appropriately sized TubeTraps into the corners of the room, and presto! All your bass are belong to us! Ok, fine, it’s not that simple, but it was a big step forward.

RealTraps is probably the other gorilla in the acoustical treatments market segment. Using panels instead of tubes, the RealTraps were arguably more spouse-friendly than the big tubes.

GIK Acoustics is a more recent panel-maker, and the one I currently use in-house due to their more … ah … user friendly pricing.

Ok, so, enough background.

The folks at RealTraps and GIK have very similar products and so it’s not surprising they have very similar approaches. They boil down to this: get as much acoustical absorption as you can afford.

The reasoning is this — the effects of the panels (or Tubes) is cumulative. To really keep the bass waves in check, you need to attenuate them wherever you can. In the corners of the front wall, behind the speakers. Between the speakers, along the front wall. Directly behind your speakers. In the rear corners. Directly behind the listening position. First reflection points on the sidewalls. First reflection points on the ceiling. Second reflection points on walls and ceiling. Add as necessary to “tame” the bass boosting humps and attempt to fill in the yawning chasms of the bass nulls that are (always present) in your room. And presto, you’re done!

So, that’s what I did. I have GIK Monster Bass Traps in the front corners. I have 244 Bass Traps sitting on top of those. I have a pair of 244s directly behind each speaker, stacked. Another Monster sitting in the center of that front wall. Two 242s on each side wall, for first and second reflection points. One Monster directly behind the listening position. I even have a pair of panels of dubious origin that I grabbed from my local dealer Jeff at Command Performance A/V, to mount on the ceiling over the listening position and at the reflection points (they’re pretty big).

All set up, it’s like sitting in a padded cell.

I’m able to get a reasonably flat response curve all the way down to 20Hz, but that’s with my Velodyne SMS-1 making final adjustments. Without it, I have at least two large nulls, one at 40Hz and another at 63Hz. Without room treatments, I have about 8 nulls and half as many peaks, so something is going right with all this.

But one thing that wasn’t, was soundstage. You know, the ability for a speaker to realistically create a sense of space that extends deep and wide. With the treatments, the soundstage had fine depth and excellent precision, but it wasn’t terribly wide and certainly nothing like what I heard at Command A/V. Moving some treatments around, and adding four 2’x2′ diffusors on top of the panels next to and directly behind the speakers, however, completely opened up the sound stage.

Which is interesting. Apparently, all those absorbers were killing the ambiance.

This brings me to an aside. Both Acoustic System International and others sell little bell-like things that, when strategically placed throughout your room, dramatically enhance soundstaging. And other things, apparently, but the main benefit is creating this sense of room-filling ambiance. Putting aside the whether they work, which I have no real reason to doubt, and their price, which is non-trivial, these little resonators work in many ways like diffusors, where the goal is break up the sound waves so that they don’t all gang up on you (nulls, nodes, &c), get lost in the soundstage-killing absorption that the acoustic folks are telling you to go get, or arrive at your ears in anything like an orderly fashion that might confuse the timing (and the perception) of the actual non-reflected speaker signal. In short, they make your room sound bigger than it is. The Resonators do the same thing, they add back in some “acoustical energy” (ie, they ring at some specific frequency, or set thereof), which might help to add to the depth, height, and width of the soundstage your speakers are creating (assuming that the frequencies that can be “resonated” are those actually in the music being played — which is why you should use a variety of metals, not just one). It’s like adding surround sound to your two-channel — those little bells are like mini-tweeters, and now, they’re all over your room! Yes, it’s totally artificial, but you have to admit, it’s a clever ruse nonetheless — and most users swear by them. I mean, hell, you never see those things on AudigoN. Oh, and don’t forget, they do tend to add that whole Buddhist shrine thing to your listening room, which, as we all know, is entirely appropriate.

Which brings me to my recommendation. Don’t get too much of this absorption stuff. Yes, your room is very important to your system’s over-all sound quality. And yes, you probably need more than you think. But … be careful. Yes, you’ll be able to enjoy the un-muddy and precise imaging your reviewer told you about, but go overboard following the advice of a someone who won’t be hanging out in your listening room and you may be radically limiting all that those expensive speakers of yours were designed to do in the first place.

Which brings up a corollary recommendation. Before you swap out gear, and especially speakers, fiddle with your room treatments. Do you have diffusion anywhere in there? Do you like little bells? Try some. Diffusion that is. I haven’t gotten around to the resonators, myself, so I can’t recommend them (or not).

Which brings me to another aside. When you get your consult from that very earnest sales person looking to stuff your room full of acoustical treatments, diffusion gets recommended for the rear walls only. Maybe the ceilings, if they’re a bit high. Never for the front wall or the first reflection points.

Screw that. Reflection points can be good, especially if your room is a bit narrow, like mine. How about directly behind the speakers? Or next to them? Try it. You might be surprised at how good everything sounds. Again.

By the way, the kind folks at ASC have asked if they could send me some of their TubeTraps for review. The ones that do both absorption and diffusion. Woohoo! Talk about timing! Stay tuned for that ….

About Scot Hull 1062 Articles
Scot started all this back in 2009. He is currently the Publisher here at PTA, the Publisher at The Occasional Magazine, and the Executive Producer at The Occasional Podcast. There are way too many words about him over on the Contributors page.