Integrated Amplifiers

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