Graham Slee Proprius Monoblock Power Amplifiers – Silver

Here we have a pair of Graham Slee Proprius monoblock power amplifiers. Small neat and compact these units come in very good fully working condition and are supplied in original factory packaging along with power supply units, mains cables and our usual three month warranty.
Graham Slee Say….
Real class-AB discrete transistor amplifiers made small. 45 watts into 4 Ω; 25 watts into 8 Ω. With rugged 15 amp 200 watt output transistors the Proprius drives even the most difficult of speakers.
With volume controls that go all the way, these power amps can be driven by a separate preamp by parking the volume at full — or their own volume controls can be used in a minimalist system driven by a fixed output source.
As a stereo pair the volume controls can be used to balance the stereo image if there’s no balance control anywhere else.
Bi-amping, tri-amping, and surround sound will benefit by using the Proprius volume controls, allowing you to easily adjust the tonal balance and/or audio image placement.
Power amps don’t have to be brutish – they can be neat and compact as the Proprius shows – and at only 20.5 cm deep by 5.5 cm high by 10.5 cm wide, the Proprius is definitely neat and compact.
Cool running doesn’t always require dark, drab and dusty heat-sink fins – clean lines are possible as the Proprius heat-exchanger case shows. It doesn’t overheat even when used for long intervals at maximum output.
Easy to connect and get up and running, the Proprius can be used with “single-ended” and “balanced” sources using the same single input XLR socket.
Connect power supply to the “48V” connector – both signal and power connectors are locking – and attach the speaker cable: the speaker terminals accept 4mm plugs; 8mm spades; or bare wire to 4mm diameter.
The Proprius power amplifiers can be used free-standing wherever you want, or mounted on the back of speakers, making them into “powered monitors”.
The last thing we want is to be repairing the things we make – it’s so counter-productive.
So that should give you a clue to why the Proprius power amp has a number of features which make it reliable.
We don’t want it to break when you forget yourself, and although we don’t advise on you being reckless, we did lots of naughty things ourselves to test the reliability of the Proprius.
Knowing we were going to do this; we made the power devices as rugged as we could – yet we also needed them to be gentle-giants to resolve all the subtleties contained in your music.
Take a look at the giant output transistors bolted to the heat-exchanger chassis in the above shot. They’re rated at 200 Watts; 15 Amps and 260 volts! They can stand 40 times more power than Nyquist’s power amplifier theorem states is necessary.
It means we don’t need to employ a protection circuit which is always meddling with your transient highs.
Instead, it’s intelligent remote power supply can detect when things are getting out of hand when it immediately shuts down and restarts when the problem goes away. But that’s not going to be during normal listening.
And then we added the final “failsafe” – a fuse (just in case).
Technical Specifications:
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
Dimensions (approx.): Amp 105 (W) x 205 (D) x 55 (H) mm; Power supply 65 (W) x 170 (D) x 40 (H) mm