What’s the Deal With Class D?

Cambridge Audio’s new all-in-one player, Evo, uses revolutionary Hypex NCore Class D amplification. Until Hypex NCore changed the game, Class D amplification was about compactness and electrical efficiency – but Hypex NCore also offers obvious superiority where clarity, resolution and outright musicality are concerned.

It’s a big part of what makes Evo such an enjoyable and convincing listen, but there are still a few misconceptions about Class D in the audio world. We understand – it's our first time using Class D too. Our CX separates, for example, use tried and trusted Class AB amplification.

We asked Francesco Bettucci, our Senior Electronics Engineer, to clear a few things up. Francesco joined Cambridge Audio five years ago and before that worked for 10 years designing and producing tube amps. He says: “It's true that in the past, Class D wasn't a good solution. It was often associated with cheap products. Now, it can perform like Class AB in every aspect.”

What’s the Deal With Class D?

Can you tell us a little more about Class D amplification? 

The first thing to know is: the D was chosen just because it's the next letter in the alphabet...

You mean it doesn't stand for digital?

No, it doesn't! Class D is not digital. Class D was born decades ago as a way to improve the efficiency of amplifiers. Traditional Class AB amps are not very efficient, from thermal and power perspectives. Class D was the solution to improve that, however the performance wasn't ideal. 

But technology has moved on, there are improved semi-conductors out there and new technologies have been developed, so nowadays we can have Class D amps comparable to Class AB in terms of specs. Obviously we don't just care about specs – we also care about sound, so we listened to a number of solutions and we picked the one that we deemed best. 

Evo uses a Hypex Ncore module – what made it stand out?

Hypex have developed their own way to further improve Class D, working mainly on the feedback loop. That's what distinguishes Hypex from other manufacturers, because it's their proprietary technology. 

This means that they achieved very low output impedance, no resonance at high frequencies, like many other Class D amps – this means there are no artifacts in the high frequency range. It also achieves extremely low distortion comparable to the best Class AB amps.

The listening sessions confirmed that we prefer this solution to others.

Tell us more about those listening sessions, how have you made sure Class D can drive a wide range of speakers?

We have a range of speakers from other manufacturers that we can use for listening sessions, as well as different tracks and different types of music. That [gives us] multiple conditions, that should cover pretty much all the ways that a customer would listen. 

Thanks for your time, Francesco!

Evo is available now. Order online or find a local dealer via our website.