What Makes a Great Soundbar?

July 12, 2021

Soundbars and smart speakers are some of the more recent offerings in the speaker department. It’s largely the need for a convenient sound reproduction device that has birthed the soundbar. Back in the old days CRT and projection TV’s were large enough by themselves to house a decent sound system. Nowadays especially with the advent of OLED screens, their thickness has shrunk considerably which means bad news for the built in sound system. You can’t cheat physics - speakers need enclosures with some internal volume to play nice and loud. Most of the time the sound that comes even from very high quality OLED or LCD screen built-in speakers is very much not in-line with the picture quality. For those, not having space for a dedicated speaker system, the soundbar is a nice option to get respectable sound from an unobtrusive piece of equipment. In this article we’ll look at the main ingredients which make up the average and above-average soundbar.

The box

Or the “enclosure”, as acoustic engineers call it. Oftentimes with speakers it’s more important to know the characteristics of the box than what’s in it. Throughout the ages the most common material for speaker box building has always been wood of some kind. While timber is pretty decent both structurally and acoustically, it’s prone to warping when exposed to the environment and it’s costly to source and process.

Just like most electronics these days, many soundbars, especially in the budget segment are made from plastic. While plastics themselves can be used for speaker enclosures with good success, thin plastic walls will resonate audibly. You can check a speaker enclosure by knocking on it - a good enclosure should feel hard, sturdy and the decay of the knock should be very short. Most soundbars will do badly in the knock test due to an enclosure that resonates and thus muddles up sound with unwanted coloration.

A good compromise is treated wood materials like MDF and particle board. They’re cheaper than pure timber, hold up better to environmental changes and are easy to process with machining. Our Klear LAYLA soundbar uses an MDF enclosure to both battle resonances and to look nice. This material can be machined in many shapes that are both eye and ear friendly.

The speakers

Most speakers use the same principle to make sound - a coil submerged into a permanent magnetic field moves due to changes in electric current it conducts. The coil is then connected to a speaker membrane which couples the vibrations better to the surrounding air. All of this moving structure is suspended, so it can only move back and forth, without wobbling sideways. While a single loudspeaker driver can be designed to play almost the whole audible spectrum of sound, it’s usually better to use dedicated speakers for high and low frequencies. Some lower quality soundbars use so-called full-range drivers, however they never are truly full range and project high frequencies in a very narrow angle.

As most soundbars are convenience driven audio products, they don’t exactly use the best drivers out there. Lower end offerings make do with a couple of low quality full range drivers. They’re ok for casual TV watching, however to have any resemblance to quality sound a soundbar needs dedicated tweeters and woofers. The light dome diaphragm of a tweeter does two things that help tremendously - allow reproducing higher pitched sounds and radiates them in a wider angle, so the optimum listening position can be larger.

The LAYLA uses a high quality tweeter for each channel and the low frequencies are handed over to top mounted woofers. For lower frequencies directivity doesn’t matter as much, so top mounting is used to save precious space on the front baffle. The low end is augmented by passive radiators - speaker cones which resonate due to powered drivers moving. Such a solution is usually reserved for higher quality offerings as most use ports to increase the bass response. Passive radiators behave much better at higher SPL’s and don’t have the characteristic chuffing sound that plagues many speakers.

The electronics

A powered speaker like a soundbar needs at least three electronic ingredients to play sound - the amp, the filter and the input board. Amplification has come a long way since the advent of speakers and nowadays class-D amps can be made both tiny and powerful. A 100W amp can be made as small as a thumb nail and they will even sound pretty decently, provided the implementation is done smartly.

The input board takes whatever you feed into the soundbar and converts it so that the amp can amplify the signal. Our take is that burdening a speaker with software bells and whistles is a sure way to make it obsolete faster. Therefore LAYLA just has the fundamentals so you can connect your TV or play music through Bluetooth from your phone. Keep the smarts in your TV, so your soundbar can freely serve you up quality tunes even for decades to come.

Electronics which run filters usually do two things - they divide up high and low frequency sounds so they reach their respective drivers and filters also try to correct the tonal response intrinsic to the loudspeaker driver and enclosure ensemble. Depending on how well it’s designed, a filtering circuit can make or break any loudspeaker including a soundbar. The filtering circuit used in the LAYLA soundbar uses real world measurement data to correct the final tonal response for impeccable timbre. Each unit that leaves the factory goes through our lab for a tune-up, so they’re all performing beyond their natural capabilities once they reach our clients. The method is usually reserved for higher end studio speakers, however we decided that you deserve to hear what near perfection sounds like.

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