Integrated Amplifiers

Courtesy of Copland's substantial PSU the CSA100's power output readily exceeds its rated 100W/8ohm and 180W/4ohm specification at 2x125W and 2x193W, respectively, and supports bursts up to 174W, 320W, 527W and 715W into 8, 4, 2 and 1ohm under dynamic conditions at <1% THD [see Graph 1, below]. Distortion is rather vaguely spec'd at '0.04%' although, in practice, it is impressively flat with frequency while the largely 2nd harmonic increases uniformly with power output from 0.003%/1W, 0.01%/10W and 0.035% at the rated 100W (all into 8ohm). Overall gain of the tube and transistor stages amounts to a sensibly moderate +38.6dB (balanced input) but the A-wtd S/N ratio is slightly below average at 79.7dB. This is a subjectively pleasing white noise rather than hum or buzz, however. Also via the analogue inputs, the CSA100's response is very flat and extended, though there is some 'movement' in HF extension depending on volume position. Best case, the CSA100's ±1dB limits are <1Hz to 100kHz.

Measured via the tape loop (the preamp output leaves the power amp in-circuit), a 0dBFs digital input yields a 2.2V output, the ESS9018S-based DAC stage offering a 105.5dB A-wtd S/N ratio and minimum 0.0013% THD over the top 10dB of its dynamic range [see Graph 2]. Jitter is suppressed to an impressive ~20psec via all sample rates while the 82dB rejection of alias images, pre/post ringing on transients, and the frequency response(s) are all linked to the DAC's default linear phase digital filter. The responses reach out to –0.1dB/20kHz, –0.7dB/45kHz and –2.3dB/90kHz with 48kHz, 96kHz and 192kHz digital files, respectively. PM