Vintage

If, as we suspect, Crimson Elektrik rated its CS-1204 variant at 65W/8ohm then this is not unrealistic: our sample delivered 2x75W/8ohm and 2x110W/4ohm with 103W, 165W, 65W and 31W available under dynamic conditions into 8, 4, 2 and 1ohm loads at <1% THD [see Graph 1, below]. The maximum 5.7A current rather limits the amplifier's ability to drive tougher sub-4ohm loads, but distortion is kept in check to the tune of 0.008%/1-20W, 0.012%/50W and 0.035% at the rated 65W (all 1kHz/8ohm). That's through the midband, of course, while at the low/high frequency extremes THD increases to 0.016%/20Hz and 0.035%/20kHz [all 10W/8ohm – see red trace, Graph 2]. Overall gain is sensibly modest at +31dB while the A-wtd S/N ratio is a fine 89dB (re. 0dBW) and the 'DC-coupled' response stretches out from 2Hz-65kHz (+0.0dB/–1.0dB into 8ohm).

The partnering CS-1200M preamp offers a full +19.5dB gain and, assisted in no small measure by its outboard ±15V DC PSU, very low levels of noise – the 95.5dB A-wtd S/N ratio (re. 0dBV) giving many modern preamps pause. Distortion is also vanishingly low at 0.00006% (yes, four zeros!) through the midband, increasing to just 0.0009% at 20kHz [black trace, Graph 2]. The frequency response, however, is influenced by volume position, so the ruler-flat ±0.01dB (100Hz-100kHz) realised at full output rolls away to –0.4dB/20kHz and –4.3dB/100kHz at –6dB below full output. The lack of volume buffering does not affect the inbuilt bass roll-off, however, which is –3dB/20Hz and –30dB/3Hz. Finally, capacitive coupling across the complex PCB causes a steady shrinking of stereo separation with frequency from 90dB/20Hz to 60dB/1kHz and 35dB/20kHz. PM