KEF has recently begun shipping the LS50W Active Music System: a product we are really proud of because of what it does and how it does it. The LS50W is more than just a powered speaker, and it’s more than just a wireless speaker – it’s an entire music system designed for the many ways people listen to music. With a product this powerful and this advanced there are always going to be questions, so over the next few weeks we’re going to give you an inside look at the technology behind the LS50W. 

There are FAQs available for detailed answers to commonly asked questions, but this post will attempt to explain and answer some of the most common questions about the amazing LS50W Active Music System.


Maintaining the World Renown Performance of the LS50 In An Active Package

Pretty much anyone can take an amp and a DSP, stick it in a speaker box and call it an active speaker, it’s not that challenging and companies do it all the time. The challenge is to take a speaker with a world-wide reputation for sonic excellence, like the passive LS50, and turn it into an active music system while preserving the sonic integrity of the original. To do that while making the active version an amazing sounding speaker in its own right is an engineering feat your run-of-the-mill speaker company simply can’t accomplish.


Problem #1: Preserving the Iconic Image of the LS50 While Designing the Next Generation Music System

The passive LS50 was designed to produce an incredible amount of full-range music in an enclosure that would normally be reserved for middle of the pack KEF LS50Wbookshelf speakers. The next goal was to add amplification and all of the assorted electronics needed in a fully active music system without changing the look and finish of the original, or adding unnecessarily to its size and weight all while keeping the price in a reasonable range.

This meant adding 230 watts of amplification to each channel, a DAC, a custom Digital Signal Processor (DSP) and the circuits required for streaming and Bluetooth operation, not to mention the necessary power supplies, without significantly changing the size and weight of the product.

  • • LS50 Passive: Weight=15.8 lbs each, Dimensions=11.9" x 7.9" x 10.9"
  • • LS50 Active: Weight=22.5lbs each, Dimensions=11.9" x 7.9" x 12.1" 

We added 7.3 lbs and a mere 1.2” to the depth of each enclosure and came up with a music system that approaches our esteemed Reference 1 in performance.

The LS50W Active Music System is powered with a dual-mono bi-amped configuration, with separate power supplies for each amp, four separate DACs and a customizable DSP that allows you to configure the sound to suit your particular room and listening tastes.


Problem #2: Connectivity

Thanks to some incredible technical leaps and bounds over the last few years, people can now listen to music in an amazing variety of ways, and more to the point, the average listener will listen across several platforms consecutively, so a music system capable of keeping up with the demands placed on it is an absolute necessity. There are tons of products on the market that accomplish this, but very few that accomplish it in a manner that upholds the traditions of audio quality KEF has worked to achieve over the past 55 years.

With that in mind, a listener can use the LS50W Active Music System to stream via their local network, Bluetooth, direct from a turntable or CD player via either a standard RCA connection or an optical connection, or from a computer or other device via a USB connection.

This doesn’t mean the LS50W can do everything – no music system can – but it does mean we’ve looked at the most common ways listeners consume music and we’ve provided them a platform that is extremely versatile and affordable.


The Difference Between A Wireless Speaker and a Wireless Music System

Wireless speakers abound. They’re small, lightweight, they have no wires, and they sound like, well, they sound exactly like you’d imagine they’d sound. The LS50W Active Music System (the ‘W’ stands for ‘wireless’) is not your off-the-shelf run-of-the-mill wireless speaker (for that matter neither is our Muo, but you get the point). The LS50W is an entire music system – speakers, amps, DSP, equalizers, DACs, pre-amp, transformers, power supplies and enclosures – that just so happens to be capable of connecting to a music source via a wireless connection.

Sometimes customers are a little surprised to find that the left and right channels of the LS50W are connected via a cable – but there is an important reason for this that sums up nicely with one word: performance. We could have had the left and right channels communicate with each other wirelessly, but we designed and built a high-end audiophile-quality digital music system and nothing is more important for quality stereo playback than the integrity of the clock that syncs the left and right channels. If you want 100% phase-correct playback with ultimately pure and precise timing between left and right channels you need to ensure the clocks in both speakers don’t miss a beat (or technically – a cycle) and are reliable. In short, you need to use a wire (in this case a Cat-6 cable) and make sure the length and quality of the interconnection is maintained at a proper specification.

So, yes, the LS50W connects to music wirelessly, and yes, within the system itself there is a wire (and two AC power cables for all of those individual amps and power supplies and things). 

KEF LS50W Block Diagram

What the LS50W Does

The LS50W plays music you have stored on your phone, computer, server, CD, vinyl record, or any other physical storage medium. Keep in mind, the LS50W is best thought of as an old-school stereo system with a fabulous new modern twist – if you want to play an LP you have to have a turntable, and if you want to play a high-resolution music file from your computer you have to have playback software on your computer that will render the file for output to the LS50W. Basically, what you send the LS50W is what it’ll play.

Once the music has been sent to the LS50W – either via an RCA cable from your turntable, via your wireless network, or anywhere in between – the music is processed with our bespoke DSP for optimal performance before being converted to an analog signal where the dual-mono bi-amps produce clean and powerful analog signals for our singularly awesome Uni-Q drivers.


What the LS50W Doesn’t Do

There are two prominent wireless conventions for entertainment devices on the market: Digital Living Network Alliance (DLNA) and Apple AirPlay. Despite what a lot of tech bloggers may tell you, DLNA is the most widely used format in the world today – more devices are available for direct plug and play (uPnP) via DLNA than any other format. Since you can’t drop every single available technology into a product and expect to sell the product at a price people are willing to pay, the choice that makes obvious sense is to have your product aligned with as many devices already in the market as possible. So therefore, the LS50W supports DLNA and doesn’t support Apple AirPlay (directly). This doesn’t mean you can’t stream to the LS50W from your Apple devices, it just means – like with a slew of other audio products on the market today – you have to put a device (such as an AirPort Express) in the wireless signal chain.

Since the LS50W was not intended to be a music system solely dedicated to streaming services, at this time we don’t support direct streaming from Spotify, Tidal, or other popular streaming networks. That doesn’t mean you can’t enjoy those services on the LS50W, it just means you have to connect your service to the LS50W with an extra step. This is more or less a matter of how each streaming service approaches its business model, and like all other technologies in this day and age, those approaches are bound to change, but for now, a life (audio?) hack or two is necessary.


Here’s the Deal


The LS50W’s five different connection options pretty much ensure every standard way of listening to music is covered, although some users on non-DLNA platforms or users with unique file formats such as DSD may have to take an extra step in the connection process.

For about $700 more than the price of the passive LS50 we have designed a product with a DSP and amplifiers that are custom tuned to the enclosure and Uni-Q drivers; you’d be hard-pressed to put together a system of pre-amps, DACs, amps and DSP power at the LS50W's level of audio power, quality and connection capabilities for $700.

The LS50W has been designed to fit all of your current music needs with an eye on the future so that the system will evolve as music and technology (and your listening habits and preferences) evolve.


We’ll take a look at some of the other unique features of the LS50W Active Music System in the coming weeks, but in the meantime if you have questions hit up or FAQs or contact us directly.