Speaker digital calibration - the audio gamechanger

October 07, 2021

The idea of using electromagnetic force to create sound by moving a membrane is almost 100 years old. In the early days audio amplifiers were weak and made a few watts of power. Therefore speakers had to be huge to make enough sound pressure to be usable. As for fidelity - let’s just say that everyone’s jaws dropped if they could discern that music was playing or that a voice could be understood to say something. Nowadays amplifiers have become tiny and deliver more power than ever. Due to advances in material sciences even small loudspeakers can move a lot of air, if the amp can make them. What about fidelity? Sadly, the expectations haven’t moved much beyond the old days. But it shouldn’t be the case - read on to learn why!

Always be compensating

Traditionally speakers consist of three components:

  1. The loudspeaker units - they turn electricity into moving air your ears hear
  2. The enclosure - keeps everything in its right place and helps playing bass
  3. The filtering circuit - prepares the audio signal so that it works correctly with the other two components

During the 100 year period since the inception of the moving membrane loudspeaker, all three have seen some innovation. The loudspeaker units themselves are now computer modelled and membranes often use space age materials like metal alloys, ceramics or composite material sandwiches. Even small speakers can move enough to generate low frequency sounds. The enclosure seemingly has seen the least amount of innovation as it’s still just a “box” which holds together the other components. Again the largest leap forward in enclosure design has been offered by computer assisted design which can tell what shapes impact the sound in the least offensive ways. Modern materials like cast aluminum, carbon or wood composites can be used to make all kinds of shapes. However manufacturing these shapes is rather expensive, so the mainstream speaker usually uses an MDF box with some kind of surface finishing so it looks nice.

Filters are where things get interesting. A simple filter consists of electronic components which divide up the signal so high frequency content reaches the tweeter and everything else gets played by the woofer. In a 3-way system there’s extra circuitry to feed the mids to the mid driver. To get the best sound of an approach like this very high quality loudspeaker drivers are required so they play close to the mathematical ideal. The reality, however, is that ideal drivers exist only in manufacturer sales brochures and designers need to wrangle with physics to stay within a certain budget. Even then effects like manufacturing tolerances are rarely accounted for, unless we’re talking about very high end speaker systems.

With the advent of digital audio it was found out that filtering can be done in the digital domain where filters can be designed close to their mathematical ideals and they can be made fairly complex without using extra electrical components, if there’s enough processing power available. Initially the technology was picked up and widely used in live sound for cinema and concerts. They have little limitations in terms of processors and other gear and traveling speaker kits always need fine tuning once they’re set up in a new location. Next came studio monitors. In serious studios sound quality is paramount as engineers need to hear exactly what they’re doing without speakers standing in the way. Now microprocessors have become powerful and affordable enough that digital audio processing has found its way into consumer sound systems. Every Klear LAYLA soundbar has a digital signal processing (DSP) unit which divides the signal to each speaker. However there’s a secret ingredient which is rarely found even in high end speaker systems.

Extreme measures

Early DSP units just copied to a letter what their analog predecessors did. This approach isn’t a bad start, however DSP can do a lot more! The key is actually measuring, before trying to fix stuff. Here are three key aspects of getting it right:

  1. Know WHAT to measure
  2. Know WHAT to correct
  3. Have enough processing power

Having a high enough resolution measurement of a speaker’s performance means that you can in one fell swoop correct the major flaws found in the three of its main components - the speaker drivers, the enclosure and the filter. And what’s more - measuring every speaker that comes from the assembly line, like it’s done for the LAYLA soundbar, removes any deviation brought upon less-than-perfect manufacturing tolerances. Therefore you get performance similar to companies which cherry pick parts for extra tight matching.

This technique isn’t uncommon in high end studio monitors like Genelec, Kii or Dutch & Dutch, however it’s quite labor intensive, so in consumer audio it’s rarely used. Even high end audiophile speakers often rely on manufacturing tolerances to deliver great sound and forego custom calibration. Here at Klear we decided to finally let every listener in on what they’ve been missing out on.

Tune up for what?

So, technically it’s all impressive, but what about, you know… the sound? The main aspect of any speaker system is the frequency response which incidentally is the main characteristic digital calibration corrects. Frequency or tonal response basically tells whether the speaker changes its loudness, depending how high or low the tone of the sound is. Ideally a speaker should treat all sounds equally and calibration makes sure it does.

An imperfect tonal response messes up a speaker timbre - sounds become skewed, bass booms and overpower mids, treble causes unpleasant ear fatigue. Get rid of coloration and all you’re left with is the music or the sound of whatever film you’re watching. This calibration also tends to extend the bass response of the speakers in question, so don’t be surprised when you get more oomph than you expected!

Calibration is done on both left and right channel of the speaker, so you get superb channel matching. This means that the stereo image is distinct and stable. Sounds won’t float around the phantom stage unless the recording calls for it. If something’s centered, it’ll sound like it’s coming from the center channel even if there are only two speakers. The overall effect is such that most people rediscover their favorite music and enjoy watching movies at home now that there’s a sound system that matches the clarity of the TV. All it took was 100 years of innovation!

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