Active vs. passive speakers: Which is right for you?

You may have read about active speakers and thought to yourself “Isn’t every speaker system active? After all, it’s the part of my audio setup responsible for turning electrical signals into sound.” Well yes, that’s true, and has been ever since reproducing music changed from a needle in a groove amplified mechanically by a large acoustic horn, to using electronic amplification – that happened back in the early years of the 20th century. By the 1920s, these amplifiers were driving speakers we might just recognise today, with an electromagnetic ‘motor’ moving a diaphragm, or cone, to move air and thus produce sound.

It was when speakers moved on from a single driver to reproduce full-range sound and started using separate units to deliver different parts of the audio frequency range, that the direct connection between amplifier and driver was broken by the introduction of a crossover network, designed to distribute the frequencies to the drive-unit to which they were best suited.

What are passive speakers?

The typical attribute of a passive speaker is that it requires an external source of amplification to function and that it has a non-powered passive crossover. The crossover, in a two-way speaker for example, filters out bass from the feed to the high-frequency tweeter and removes the treble to the midrange/bass driver. This enables each drive unit to operate within its intended parameters: feeding high treble to a large bass driver will impair the high-frequency sound quality, while heavy bass delivered to a delicate tweeter driver will cause it to malfunction and eventually fail.

More about crossovers

The ‘unwanted’ signal filtered out in each section of a crossover is dissipated as heat, meaning it loses some of the signal coming into the speaker before it’s fed to the drivers. Yes, that’s something of a simplification, but the fact remains that a passive speaker receives a full-range signal from the amplifier, and the unwanted energy removed by each of the filtering stages needs to go somewhere – some very large speakers, designed to handle high amplifier power, even have design strategies to conduct this energy away to avoid heat building up within the speaker, which can affect the performance of the crossover itself.

To an extent, then, passive speakers of this kind, while representing the mainstream of most speaker design to this day, are something of a compromise: yes, they need multiple drive units to fully reproduce the complete audio frequency range – some may have drivers for very high treble, treble, midrange, bass and very low bass – but this also means they need crossover networks of varying complexity to split up the incoming signal. And that compromise – the matching of drive units to crossover – is something that’s been refined over many generations of speakers and decades of research and development, with engineers adjusting the sonic characteristics of drivers to enable the use of the least invasive crossovers, meaning less components and thus less loss of signal. Let’s look at the differences between passive and active speakers.

What is an active speaker?

Active designs move the crossover network ahead of the amplification, which is now built into the speaker itself, along with the active crossover circuitry. The signal from the rest of your system is split by powered crossover electronics using active filters to output the various frequency bands, and ensure the drivers are working in their optimal ‘comfort zone’. The signal is then fed to separate amplifiers for each group of drivers or, in some cases, individual amps for each drive unit. Yes, this means more amplifiers are needed, but the benefits include the ability to tailor each amplifier to the needs of the drive unit it’s powering.

A speaker may use a high-powered amplifier for its bass section, where larger, heavier driver diaphragms need more energy to move and control them, while the treble section, with its exceptionally light diaphragms moving the air with relatively tiny movements, are best served by a less powerful but nimbler amplifier section. That also explains another benefit of active speaker systems over a conventional passive speaker/external amplifier setup: in an amplifier delivering full-range music signals, the demands of heavy bass can swamp delicate midrange and treble signals, leading to a lack of focus when there’s a prominent bassline, for example. By splitting the signal before amplification, each section of a speaker is always being driven correctly for the demands of the music signal.

Active or passive?

That’s not to say that passive speakers – which, to reiterate, account for the majority of designs available – are in any way a poor relation of active designs. Indeed, the state of speaker design is so refined, and the understanding of how speakers, crossovers and drivers work together so closely investigated with the latest analytical tools, that today’s conventional passive speakers deliver outstanding results when driven by high-quality source components and amplification. So active speakers, while offering definite theoretical benefits over passive designs, are by no means a universal solution for all systems.

Active or passive: which is right for you?

Aside from those benefits of active speakers, it’s worth noting that such designs are basically closed systems, as all the amplification is built into the speakers themselves. So, if you think you may want to upgrade your amplification – or your speakers – at a later date, it’s important to realise this will involve changing the whole active speaker system. For inveterate system tweakers, therefore, a conventional system of passive speakers driven by an external amplifier will offer greater flexibility.

Simplify your system with active speakers

However, taking the active route does offer practical advantages, not least in its ability to simplify a system setup and declutter your listening room. For example, with the amplification built into each speaker, it can be connected to a preamplifier via simple interconnect cables – or, even simpler, fed directly from any source component with a volume control, such as a streamer or network audio player.

Thus, the ‘box count’ is reduced, and the domestic acceptability of the system increased at a stroke: a streamer to play music from Internet services and a pair of speakers is all you need for a complete music system. Add in-app control for your streamer, and all you need have visible are the speakers: the rest of the electronics can be hidden away out of sight for a neat, clean look – without compromising performance.

Wireless active speakers

Let’s take things a stage further: having all the amplification in the speakers makes active designs an obvious route to one of Hi-Fi’s holy grails – the wireless audio system. Build wireless connectivity into the speakers using a hideaway ‘hub’ to which conventional audio sources can be connected (and which also handles streaming functions), and you do away with the need for speaker cables, while freeing up your options for placing the speakers in your room. OK, you’ll still need mains power for each of the speakers but effectively all the audio part of the system is entirely wire-free – the old idea of a stack of black boxes connected to speakers by cables running round the room is gone.

So, while some high-end active speaker systems operate using external crossover devices feeding multiple amplifiers connected to specially designed speakers with multiple runs of speaker cable – yes, more black boxes and more wires – the true advantage of active speaker design is perhaps best seen in the freedom afforded by wireless technology. Namely that you get superb quality, thanks to optimised matching between amplifier and speaker drivers, and all the scintillating detail and power of true high-end Hi-Fi, all in a system as convenient to use as it is stylish in your room. And that’s the true breakthrough made possible by wireless active speakers.