Pre/Power Amplifiers

Not for the first time, we have an amplifier claiming a good few watts – 35W/8ohm in this instance – with sufficient quiescent current in the output stage to maintain all the devices in their 'on' or conducting state. This is Class A. Crossover distortion is eliminated but dissipating those unused amperes develops plenty of waste heat. On more than a few occasions I've been inclined to doubt the boast, but not here where Classé's lateral MOSFET output stage is kept in thermal equilibrium by mounting the devices on what it calls its IC (Intelligent Cooling) Tunnel. The square-section tube is filled with very fine alloy fins that are cooled by air drawn from the front of the amp, exhausting out the rear. On my test bench I measured a steady 48°C air temperature from the vent. Toasty!

Classé has engineered a solution with a very wide open-loop bandwidth and relatively limited negative feedback but it still maintains an astonishingly low distortion out to high frequencies. Distortion is optimally low and consistent with frequency through its 'Class A range', seen [adjacent] between 1W (blue) and 10W (black, 0.00015-0.0007% from 20Hz-20kHz). It looks higher at lower power (0.1W, green, as noise) but only genuinely increases at HF at higher power (100W, red). PM