Q Acoustics explains – What is the difference between Active and Passive speakers?
Active speakers – Passive speakers – Powered speakers What are the differences between the active, passive and powered speakers? Which is best?
Doesn’t matter if you’re listening to music on a big stereo system, getting into a film soundtrack as you watch TV, or enjoying some tunes while wearing headphones – the sound you’re listening to is being produced by speakers. Everyone understands that.
And everyone understands that the speakers, no matter if they’re tiny ones inside some in-ear headphones or great big ones at either side of the Wembley Arena stage, are the final part of a chain. There will be a source of sound at the beginning of the chain, and then a specific process to get actual sound from the speakers at the end.
Getting loudspeakers to produce a sound – ideally a faithful, accurate, enjoyable sound – can be done a few different ways. And if we’re talking about a music system in your home, you have three reasonably distinct ways of going about it. You can use passive loudspeakers, or active loudspeakers, or powered loudspeakers.
How do speakers work? What are the differences between different type of
loudspeakers? Which sounds best?
Well, it’s like this.
The process involved in getting sound from a speaker is, broadly speaking, the same in every case. First of all, you need a source. The source can be any player of music-storage software, whether that’s a turntable with a vinyl record on it, a CD player with a disc in its tray, or a smartphone with a Spotify app and access to the internet.
Then the source sends the signal/the information/the music to a preamplifier. The preamplifier tends to be used to switch between different sources, and to adjust the volume of the sound that eventually comes from the speakers.
Once the preamplifier has done its thing, the signal needs to be amplified to a level at which it can make a pair of speakers, in turn, do their thing. This is the power amplification stage – and once the signal gets sufficient oomph from the power amp, it then passes through a crossover filter network. A crossover filter network splits the amplified signal into high frequencies (to be sent to the speaker’s tweeter) and everything else (to be sent to the mid-bass driver). If the speakers have more than two drivers, then the crossover filter network will divide the signal three ways: treble, midrange, and bass. The crossover network (which is incorporated into the loudspeakers) does not need to be supplied with power to do its job – and neither do the loudspeakers to do theirs. All the electrical impetus is coming from the power amplifier that’s positioned ahead of the speakers in the signal path. And if your speakers, and their crossovers, aren’t powered, then you’re listening to a passive system.
Things are a little different with active speakers. Once the signal leaves the preamplifier, it’s sent to a powered (or ‘active’) crossover filter network, which splits the signal according to the number of drivers each speaker has. As well as an active crossover network, each driver in an active speaker has its own dedicated power amplifier inside the speaker cabinet – so that’s at least four, and maybe six, power amplifiers per pair of speakers.
Powered speakers are a kind of halfway house between passive and active designs. They have a single power amplifier driving each cabinet’s drivers, fed by a passive crossover network.
Pros and Cons to each arrangement – And which speakers should you buy?
The most obvious ‘pro’ of passive speakers is cost. Because their cabinets aren’t filled with costly electronics, they tend to be much more affordable. Of course, that’s partly because the power amplification is happening off-board, before the signal reaches the speakers – and there’s a cost attached to that, naturally. It’s also safe to say that a lot of people like to periodically upgrade their systems or, at least, try out other components. In a passive set-up, you can try different loudspeakers without having to change their amplification too.
As far as downsides go, the biggest gripe about passive systems concerns the relative length of the signal path. All of that complicated information has to travel a long way, along lengths of speaker cable, from the power amplifier to the crossover network inside the speakers – which increases the chances of distortion or information loss along the way. Of course, you can mitigate against this by using high-quality speaker cable (at additional cost, of course) – but nevertheless it’s at this stage your signal is most vulnerable. You don’t have to be any kind of deep thinker to realise the ‘pros’ and ‘cons’ of an active set-up are more-or-less the reverse of the passive. An active system has extremely short signal paths from crossover to power amplifiers to speaker drivers – not much opportunity for signal degradation there. And very often the power amplifiers inside active loudspeakers will have been optimised to work well with the specific units they’re driving.
But of course an active pair of speakers looks expensive in the showroom, because they’re so packed with technology. And an active set-up doesn’t give any opportunity for mixing and matching – if you’re bitten by the desire to upgrade, then everything (speakers, amplification, the lot) has to go. It’s also worth bearing in mind that even the best speaker manufacturers may not have the ability to build the best power amps – they may even buy them off-the-shelf from third-party suppliers.
Again, powered speakers are somewhere in the middle. Because they’re not as complex as active speakers, they’re generally more affordable. And they have that nice short signal path that lots of listeners crave. But because they incorporate amplification into the speaker cabinets, you don’t so much ‘upgrade’ them as ‘get rid and start again’. And while one power amp per speaker is naturally more affordable than two or three, they may not be the finest-quality amplifiers the money will buy.
So you’ve some fairly fundamental choices.
Do you like the long-term flexibility (and relatively low initial outlay) of a passive system, even though you’ll need to budget for proper speaker cable too in order to give it a fighting chance? Do you fancy the uncompromised engineering rigour of a multi-amplifier active speaker system, even though a) it’ll seem expensive and b) it’s not really upgradeable? Or do you think the ‘powered speaker’ option is the most sensible balance to strike?
At least you can be sure of one thing. No matter the path you decide to go down, you know Q Acoustics is ready to make sure your investment brings you all the audio excitement you deserve – for years to come.
Source: Q Acoustics