With the release of our powerful new active music system, the LS50W, we thought it might be a good time to take an in-depth look at some of the technology that makes the LS50W such an incredible product. The LS50W is a high-end digital music system that allows you to play music from an amazing variety of formats and over the next few weeks we're going to take a look at the technology behind the product.


Music is energy and vibration and capturing that energy and vibration and playing it back as faithfully as possible is what the home audio industry is all aboutKEF LS50 Active Music System (or should be). Our sole mission at KEF is to reproduce the energy and vibration sent to our speakers from whatever source, as faithfully and honestly as the source allows. With the active LS50W music system, we’ve taken the next step and matched the amps and converters as perfectly as possible to the already outstanding LS50 acoustics.


To kick us off, we’ll start with a basic primer on how digital music happens.

* * * 

The energy and vibration of music, once captured by a microphone (or a cable) is either going to be recorded on to tape or converted to digital information to be stored as a file. In this piece we’ll focus on the digital.


The electrical impulses captured from the musical instrument are then sent to a device called an analog-to-digital converter (ADC). Simply, the ADC samples the frequency (and amplitude) of the musical signal at a set rate. Once the signal (or entire song) is converted to binary information (1s and 0s) it can then be stored as a digital file. We covered the operation of an ADC in How An ADC Works (Blog - KEF Tech November, 2013)


But as we drill down and look into the technology a little deeper than the original piece mentioned above, take whatever song you’re thinking of right now and freeze it in time – that’s what an ADC does. The resolution of the sampled music comes from what we do with this singular slice of time.


The amount of samples we take of this singular second of music is called the sampling rate. With Red Book CD (the standard for CDs) we take 44,100 samples of this second of music, and subsequently 44,100 samples of every second. This equates to a sampling rate of 44.1kHz (or 44,100 samples per second). Obviously, the more frequently you sample the more information you retain (to a limit – there comes a point where you can’t gather any more information), so it stands to reason that a sample rate of 96kHz will sound better but not as good as 192kHz (considered high-resolution). Pro audio recording typically samples at a rate of 192kHz (4 times 48kHz which is the broadcast standard for video applications).


But wait! There’s more…


It’s not just the amount of samples we take, but the amount of that information that we store that also makes a difference in how a digitized song sounds. That’s where bit depth comes in – the deeper the bit depth (larger the data word) the higher the resolution.


Red Book CD uses a bit depth of 16-bits. The broadcast video standard for audio, as well as files considered high resolution is 24-bits. Dynamics are particularly affected by bit depth, and by adding those extra 8-bits of data our ability to maintain the dynamics of a musical passage is greatly enhanced. If you listen to music that is not very dynamic you’ll have a hard time hearing the difference between 16- and 24-bit (this also speak to why popular music in the mp3 and lo-res file age purposely de-emphasized dynamics in the production – we weren’t listening to it so we couldn’t hear it anyway).


There’s also another problem – storage. We increase the resolution of the file from 65,536 possible data values (per sample) to 96,000 when we jump from 16- to 24-bit, but on the downside we also increase the size of the file thirty-two times! This allows you to store significantly fewer high-res songs (especially on a mobile device) than lo-res files.   


That’s where digital compression comes into play. In order to fit as much music in as small a space as possible we learned how to compress the digital file – basically by removing data that is not absolutely necessary to the coherence of the song. The basic notes and sounds will still be there but the lift and dynamics are removed. Through ear buds or a tiny little speaker on a portable device you’ll probably not notice the missing stuff, but when you listen on a system capable of recreating your music as close as possible to what the artist intended you will definitely notice the missing bits.


All of this has absolutely nothing to do with bit rate, which is the speed with which we digitally transmit information (from your computer through your router to the LS50W for example). Bit-rate is the capacity of a digital transmission system to transmit date: The higher the bit-rate the more cohesive your music or video will be when you are streaming.


So, there’s a really basic primer on how digital audio works, with a few buzz words thrown in. You can love your music no matter how you listen to (or at what resolution), but you can love your music even more when you take advantage of everything today’s awesome technologies have to offer.