Graham's Blog Archive

Amplified Loudspeakers

Posted by Graham
October 24th, 2012
Proprius mono block amp Image updated July 2016

Amplified Loudspeakers are nothing new – think about the combo amps electric guitarists use on stage. But amplified loudspeakers – powered or active monitors – are relatively new to Hi-Fi.

What I’m going to explain to you today is new to Hi-Fi. It’s a technique used by studios for a number of years, and it makes a big difference to the way you listen to music.

Look around the internet for what others think about powered monitors for high fidelity listening and you’ll see comments like “there does not seem to be a lot of good active speakers for Hi-Fi” and they’re right! Amplified loudspeakers contain power amps designed by loudspeaker designers and that’s why.

A powered monitor or active loudspeaker can only be as good as the amplifier that’s built into it. If you’ve ever contemplated going down the active loudspeaker route you may have come to the same conclusion that I did. If you could marry together a great loudspeaker and a great power amp you’d get a really great active loudspeaker.

Well now you can!

Doing exactly this was one of my design goals when I sat down to design the new Proprius mono-block power amp. That also answers why the Proprius is a mono-block.

I wanted something small enough to mount to the back of a really good monitor loudspeaker. Class D or class T would not do – this had to be a real class AB amp with liberal bias current – what others call ‘pure class A’. And the Proprius pulled that off.

So what’s the advantage of mounting an amp to a loudspeaker? It has exactly the same advantage the active monitor has – no speaker cables! By connecting at line (preamp) level there are no power losses. But with the Proprius it’s more than that. As a stand alone amp only just launched it’s already received these accolades…

“…Proprius mono blocks were in the same league of performance as Electrocompaniet Ampliwire 180 mono blocks. I’m not joking. It was quite shocking for me, considering the price difference.” “Prototypes of Graham Slee’s tiny mono power amps were also on show, which made a very interesting comparison. Despite the EC amps being several times more powerful, the Slees lost no sense of energy and dynamism.”
“The Proprius is engaging and full sounding even at low levels. It is tremendous and room filling with the volume turned up.”

Now think about its use as a powered monitor amp.

Here’s how it’s done…

Proprius amp mounted to back of speakerThe Proprius is so small it can even be mounted to the back of mini-monitors such as the Harbeth M20 or P3ESR (see photo).

We supply each Proprius with a speaker mounting kit designed so that you can mount it to the back of a speaker, making it easy. Speaker connection is then just a matter of two short wire tails. The Proprius power supply sits unobtrusively at the base of the speaker stand. See more information here.

But there’s more…

Should your speakers be that little bit larger, enough to mount two Proprius round the back, and have two sets of terminals for bi-wiring/bi-amping, then you’ll be able to realize the ultimate in bi-amped reproduction. What’s more, you have the added ability of being able to adjust the volume to either drive unit with the individual Proprius volume controls.

Connecting to your preamp…

Usually you’d need a preamp with balanced outputs to drive a balanced XLR input like the one on every Proprius mono block, but, if if you’re using your Proprius powered speakers near field then the good news is we’ve made some really nice sounding single ended to XLR interconnects – see them here.

And for use at a distance? That’s where you really need a balanced source. That’s why I’m working on the Aria preamp which I hope to launch soon, but I have another trick up my sleeve you’ll really love. Before the Aria launch I’m designing a single ended to balanced converter to enable you to go balanced from any single ended output preamp. Look out also for our balanced audio cables.