5 out of 5
Graham Slee Proprius Monobloc Power Amp
Free UK Delivery
Graham Slee Proprius Monobloc Power Amp
The Graham Slee Proprius Monobloc power amplifier delivers 25 watts into 8 Ohms (RMS) and 45 watts into 4 Ohms.
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 suitable 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 equipped with its own volume control meaning it can be used 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".
Who is Graham Slee?
Graham Slee is a small, enthusiastic manufacturer of realistically priced, high-performance phono stages and headphone amplifiers, designed and built by hand in Yorkshire since 2003. Very positively reviewed by the UK and international magazines, demand for these products has been overwhelming as the world's hifi enthusiasts can't believe the performance on offer for the price asked.
| Power output (rms) measured | 26 Watts into 8 Ohms; 45.5 Watts into 4 Ohms (ref 1% THD+N at 1kHz) |
| Power bandwidth at rated power into 8 Ohms | 10Hz - 47kHz (-3dB), 20Hz - 25kHz (-1dB) |
| Power bandwidth at rated power into 4 Ohms | 12Hz - 40kHz (-3dB) |
| Total harmonic distortion and noise at 8 Ohms | 100Hz: 0.043%; 1kHz: 0.047%; 5kHz: 0.061%; 10kHz: 0.085%; 20kHz: 0.125% |
| Total harmonic distortion and noise at 4 Ohms | 100Hz: 0.066%; 1kHz: 0.071%; 5kHz: 0.094%; 10kHz: 0.129%; 20kHz: 0.181% |
| Signal to noise ratio in dB | "A-weighted": 87dB; 22Hz-22kHz "Q-pk": 80dB |
| Bias type | Class Ab; Bias current: 60mA (approx.) |
| Input sensitivity for rated output | 575mV rms |
| Short circuit protection | Fuse and power supply shut-down (short circuits should be avoided to prevent component stresses) |
| Fuse | F2A 5mm x 20mm (glass "quick-blow" fuse rated at 2A) |
| Power supply | 48V DC, 120 Watt - self adjusting to AC mains 100V - 240V, 47 - 63 Hz; IEC cord supplied |
| Size (approx.) | Amp W105 x H55 x D205 mm; Power supply W65 H40 D170 mm |
UK Delivery
Providing your item is in stock, the order is usually dispatched within 24 hours. Postage and packing is completely free for orders over £99*. Out of stock items will be dispatched as soon as they become available, which can take between 4 to 21 days
UK Delivery orders are sent via our couriers' DPD Local on a next-day-delivery service and usually take between 1 and 3 days.
Local Delivery
Certain manufacturers disallow mail order for their products, however a local delivery may be possible.
We offer a local delivery service for a large number of our products. After your order has been placed, a member of the Hifi Gear team will contact you to arrange a convenient date and time for your local, personal delivery.
Click & Collect
We offer a free ‘Click & Collect’ service on all items. As soon as your order has been completed and is ready for collection a member of our team will be in contact with you. Orders can be collected from our store at 11 King Street, Hereford, HR4 9BW.
Please use this link to find more detailed delivery information or contact us for more details
