Amplificador - Etapas de potencia Monofónicas Graham Slee Proprius PAR
It's a mono-block amp so two are required for stereo. We made it this way for a variety of reasons — one of which allows them to be used remotely at, or fixed to, the loudspeakers for powered monitor performance from your favourite passive speakers — see speaker mount tab. The great thing about mono-blocks is they give you true dual-mono amplification for improved stereo separation.
They're perfect for use with high sensitivity speakers where quality comes before quantity. However, they're not short on quantity and sound louder than their 25 watt rating would suggest, even using speakers as low as 83dB sensitivity — including the Stirling Broadcast/BBC 11 Ohm LS3/5A.
The balanced XLR input works just as well single ended with shorter interconnects so using them side by side like a normal amp isn't a problem — you can find sutable interconnects in our Cables & DIY section.
For remote or speaker mounted placement requiring long cable runs, you'll need a source with balanced outs and our balanced audio cables.
Unusually for a power amp, the Proprius is equiped with its own volume control meaning it can be used direct from a fixed output source. When using it with a control preamp the volume control is put "out of circuit" by parking it at full rotation.
The input is based on the balanced topology by David Birt of the BBC, modified to "all-inverting" making it free of common mode distortion. Absolute phase is accomplished by "phase swapping".