Canor Audio Virtus I2 Integrated Amplifier Lab Report

Lab Report

While Canor suggests that its two pairs of KT88s will deliver 2x40W, in practice the maximum output is 2x35W into 8 or 4ohm via the 8 and 4ohm taps, respectively, at 1% THD. Relaxing the test conditions to 5% THD only yields 2x37W, unlike some lower-feedback tube amps where distortion and power increase hand-in-hand. Under dynamic conditions there's a little extra headroom to support 37W/8ohm (via the 8ohm tap), 37W/4ohm (via the 4ohm tap), and 32W/2ohm and 24W/1ohm also via the 4ohm tap [see Graph 1, below]. With a maximum current delivery of 4.9A (10msec/1ohm at <1% THD) the Virtus I2 is clearly best partnered with sensitive speakers of >4ohm impedance. Power in Triode mode is typically half that in UL, and the Virtus I2 remains 'on trend' with 2x19W into 8 and 4ohm.

Distortion can be lower in Triode mode, but not always, as the amplifier achieves a minimum midband figure of 0.0025% in UL and 0.013% in Triode mode [all re. 1W/8ohm – see Graph 2 below]. The generalised increase at low frequencies is a function of the output transformers and is expected, as is the increase to ~0.1%/20kHz. Canor's output transformers, and feedback, ensure a very uniform 0.6-0.63ohm output impedance and extended response that is flat to within ±0.25dB from a remarkable 5Hz-100kHz. The 'real life' amp/speaker response will be influenced by the swings in speaker impedance but the Virtus I2 is generally less susceptible than most tube amps here. Overall gain is a sensibly moderate +31dB (so ~0.5V input will raise the full 35W output) and noise is very low, leading to a very wide 93dB A-wtd S/N ratio (re. 0dBW) – this is top-end solid-state territory! PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 4.9A


Distortion versus frequency versus power output (1W/8ohm, Ultralinear, black; Triode, red) and (10W/8ohm, Ultralinear, grey; Triode, orange)

Power output (<1% THD, 8/4ohm) 35W/19W / 35W/19W (UL/Tr)
Dynamic power (<1% THD, 8/4/2/1ohm) 37W / 37W / 32W / 24W
Output imp. (20Hz–20kHz/100kHz) 0.605-0.625ohm / 2.19ohm
Frequency resp. (20Hz–20kHz/100kHz) +0.15dB to –0.0dB / +0.25dB
Input sensitivity (for 0dBW/35W) 80mV / 500mV
A-wtd S/N ratio (re. 0dBW/35W) 92.9dB / 108.3dB
Dist. (20Hz-20kHz, 10W/8ohm, UL/Tri) 0.021-0.38% / 0.065-0.39%
Power consumption (Idle/Rated o/p) 220W / 250W (1W standby)
Dimensions (WHD, with ears) / Weight 435x170x485mm / 26kg
Price £7500

Canor, spol. s r.o.
Supplied by: Signature Audio Systems, UK
07738 007776