Powered speakers. Ones with the power amplifiers built into the speaker. Not to be confused with active speakers, which have the power amplifiers built into the speaker. What?!
Yes it can be confusing. The terms active and powered are often interchanged, sometimes by audio companies who should know better. The approaches are similar. Both take on the job of matching the power amplifier to the speaker, which can make a big difference to sound quality. Both also mean fewer boxes in your system – no more external power amplifier(s). There are, however, key differences that matter. Let’s have a look.
It’s all about the crossover
The job of the crossover, an electronic ‘filter’ found in virtually all types of speaker, is to split the signal into different frequencies. It then sends low frequencies to the woofer, mids to the midrange driver and high frequencies to the tweeter. For two-way speakers the bass and mid driver are combined, the crossover only splitting the signal two ways.
Whether a speaker is powered or active depends where the crossover sits: before or after the power amplifier(s).
Powered speakers are like a normal (passive) speaker in this respect. The signal goes to the power amplifier, which boosts it. It’s then sent to the crossover to be split up. From there it goes to the individual drivers.
There’s usually one channel of power amplification per speaker. With powered speakers that sits inside the speaker. The benefits are that we don’t have to choose the amplifier, and there are fewer boxes to accommodate.
Active speakers differ in that they put the crossover first. So the signal gets split into the different frequencies before going to the power amplifiers. Amplifiers, as in plural. There’s usually one per driver, tailored to its specific needs. The most obvious aspect being power rating – bass drivers need a lot more power than mid / high frequencies.
Historically, splitting the frequencies within the active crossover – processing the signal – was done in the analogue domain. Increasingly though it’s digital. The speaker is fed a digital signal from a streamer, CD player or computer. Or an analogue signal from, say, a turntable, that’s converted to digital before hitting the crossover (assuming the active speaker has an analogue-digital converter – not all do).
The crossover – effectively a small computer – can then process the signal. And it can do far more than just split it into different frequencies. Equalisation (EQ) can be applied for example, boosting some frequencies, cutting others. Ideal if you want to tailor the sound to your room (some active speakers have room-correction software built in). Or maybe the phase needs adjusting to ensure the sound from the different drivers reaches the listener at exactly the same time. Etc etc.
Once processed, the signal is converted to analogue and sent to the power amplifiers. The boosted signal then goes to the drivers.
The possibilities are relatively endless, limited only by budget and the skills of the software developers. Look at the trickle-becoming-flood of active speakers with streamers built into them for example. Such as KEF’s LSX II that provides a complete solution in just the two speakers. No other boxes at all. £1,200 sounds a lot until you realise just how much they do.
Kef LSX II active streaming speakers
Are powered / active speakers appropriate for the HiFi Starter?
Yes, they can be an attractive option.
Powered speakers basically simplify things for the listener – no need to choose an amplifier. They also take up less room overall – fewer boxes. Just remember that at least one speaker will need mains power. Sometimes both.
Active speakers build on this by tailoring the power amplifiers even more closely to the drivers. Don’t underestimate that benefit. Modern-day actives add in DSP capabilities (digital signal processing) to improve sound quality. Or go the whole hog with a complete system built into just the two speakers.
Downsides? Cost is one, actives in particular tend not to be cheap. Although assembling an equivalent separates system would probably cost more. Upgrading, as and when the urge strikes, is also more difficult. Everything is built into one box.
Complexity is another potential issue, particularly if sophisticated DSP is involved. The challenge for manufacturers is to simplify that complexity through good design. They’re onto it, some doing better than others. So do check out the whole usability thing when looking at active speakers. It shouldn’t be seen as a showstopper though.
And that’s about it. Given the benefits, we intend to review active and powered speakers at HiFi Starters. Let us know if any are of particular interest to you (email@example.com). So far we have our eye on Adam Audio’s new A Series, whose launch we attended recently (report coming soon). KEF’s LSX II and Q Acoustics’ M20 are also on our radar.
Triangle Borea active
Q Acoustics M20