If you’ve put together a sound system for a flat panel TV recently, you’ve probably been tempted to try out a soundbar. Don’t, writes Anthony Grimani.

Soundbars seem like a great idea. They’re sleek, compact, high-tech and look like a great companion for a thin TV. Assuming you’re also conscientious about good sound, you’ve probably wondered if they deliver the kind of performance that will make you and your clients happy.

Unfortunately, things look better than they sound when it comes to soundbars. In fact, I liken a soundbar to two rugby teams trying to play a match on a tennis court. Let me explain.

A soundbar typically consists of three sets of transducers (maybe a few more if it’s trying to do simulated surround); one each for the left, centre and right channels. Each set is sometimes configured in a classic horizontal MTM array, with two woofers or flanking a tweeter. All nine of these transducers have to fit in a cabinet that’s a few centimetres tall by a few centimetres deep and perhaps 100-150cm wide. This is less than ideal for several reasons.

First, the speakers are way too close together to produce any kind of imaging or soundstage. Ideally, the left and right speakers should form a 45- to 60-degree subtended angle from the listening position. So, roughly speaking, if the soundbar is 100cm wide, you should be 150-200cm away from it.

I’ll bet you’re not sitting that close.

When you smush the speakers so close to each other, you get no separation; the soundstage collapses into a giant mono blob. If you don’t believe me, get a test disc and try playing pink noise which cycles through the LCR. Not much difference, huh?

Second, horizontal MTM arrays exhibit significant comb filtering (regular deep notches in the frequency response due to transducer interferences) and ragged overall frequency response when you get off axis. Thus, unless you’re sitting directly on-axis with the array, you get poor intelligibility and a swooshy, mushy character to the sound. With a soundbar, it’s impossible for even one person to sit on axis with the MTM arrays for all three channels. The most you could do is one. You might get decent sound from the left or centre or right, but the other two will sound bad.

The third reason requires a little background information on how soundtracks are mixed. In many cases, mix engineers put the same sound in more than one front channel. This could be something like a phantom centre image for music or a sound effect they want to emphasise in a certain way. With the LCR speakers so close together producing the same sound, you get bad comb filtering between the three speakers. It’s the same concept as before, just expanded across all three arrays instead of within one.

Fourth, the cabinet volume is not great enough to support any kind of significant low frequency reproduction. Assuming the soundbar has three channels in it, each one gets one third of the total volume of the soundbar. It’s not enough to produce frequencies below about 150-200Hz. While you can add a subwoofer, you’re asking for trouble trying to get a good blend. Placement will be challenging, as the subwoofer is playing frequencies high enough to localise it. Plus, you’ll be dealing with all kinds of resonance issues that further restrict where the subwoofer can go.

So, to summarise, you’ll have giant mono sound with no separation or imaging, poor intelligibility and poor frequency response, and no dynamics or bass. It’s just a big, confused, jumbled mess – like those two rugby teams on a tennis court!

Yikes. That’s a pretty grim outlook for soundbars. Is there an alternative?

There are some things you can do to improve matters. Since you’re going to end up with mono anyway, it would actually be better for soundbar manufacturers to just concentrate on making very good monophonic sound. Instead of three MTM arrays, sum the LCR channels and send them to one horizontal configuration consisting of a larger woofer, midrange and tweeter all lined up. A two-and-a-half way MTM (where the second midrange is rolled off on the top end) accomplishes the same thing.

If the crossover network is steep and well-designed, you can eliminate the bad comb filtering and off-axis frequency response errors. The sound will be much cleaner, more detailed and easier to understand. Cabinet volume will increase as well, because that one set of transducers will have the entire soundbar in which to operate. You can expect much-improved bass response as low as 80Hz, which makes integration with a subwoofer much easier. If you’re really determined to get stereo separation, there are some additional alternatives. One is to use the soundbar just for the centre channel and route the left and right to hidden in-wall or in-ceiling speakers. It’s not perfect, but it does give you a wider soundstage. There are also soundbars with the left and right speakers on the ends of the soundbar firing sideways, out-of-phase. These still don’t produce great imaging or bass response, but at least you get some spaciousness without the ugly comb filters. It’s theoretically possible, too, that you might go with one of those giant 250cm wide TVs where the soundbar is wide enough with enough volume to produce pretty decent LCR sound. But I have to ask… if you’re going with a TV that big and expensive, is a soundbar really the best you can afford for sound?

A final alternative would be to split the soundbar in half, put one piece on either side of the TV, and go with a left/right phantom centre set up. This gives you some separation and soundstage without quite as much comb filtering. Centre channel dialogue will still have problems off axis, as it’s coming equally from the left and right, and the small cabinets will have lots of trouble with bass. Fortunately, the speakers can now be vertical MTM, which provides some much-needed directivity in the midrange plus wide horizontal response. One bit of advice if you go this route: Avoid products which have special transducers built into the left and right for a so-called ‘centre channel’. These are entirely unnecessary and add an extra layer of complexity and issues. Configuring the surround processor for no centre channel will automatically route the centre sounds to the left and right very effectively, eliminating the need for anything extra in the speakers themselves.

Yeah. I wish I had better news, but soundbars aren’t great any way you slice it. They may look cool, but they don’t have the sound to match.

Obviously a real sound system is the ultimate solution, but I’ve mentioned some other things you can do. Ultimately, they’re going to sound better than a soundbar and produce results that will make your clients – and you – much happier.