Integrated Amplifiers

While not in the same league as Chord's massive Ultima stereo power amp and Ultima 2 monoblocks there's clearly some 'trickledown' in the design of the switchmode PSU, FET-based output stage and error-correction seen in this compact Ultima Integrated [see boxout, p65]. There are similarities, too, in the performance 'fingerprint' of the Ultima 2 and Integrated, specifically in their unvarying distortion with power output - the latter, albeit higher than in the '2, but holding between 0.025-0.027% (1kHz, 1W-125W). Versus frequency, distortion is not 'flat' but increases across the band from 0.0045-0.15% (re. 10W, 20Hz-20kHz). The profile [see Graph 2] is quite unlike most conventional feedback-compensated amplifiers which typically have a more consistent distortion from 20Hz to a few kHz then rise more steeply up to 20kHz. The Ultimate Integrated's trend is not only more 'smoothly' correlated with frequency but, again, Graph 2 also clearly shows its consistency with power output.

Talking of which, the Integrated beats its specification at 2x138W/8ohm and 2x257W/4ohm while its 'stiff' switchmode supply regulation means there's no difference under dynamic conditions - 138W, 256W, 448W and 699W are delivered into 8, 4, 2 and 1ohm loads, respectively, [see Graph 1] even though distortion at ~0.015%/8ohm is lower than under continuous conditions. Chord amplifiers have never offered super-wide A-wtd S/N ratios and the Integrated follows suit at 82dB (re. 0dBW) though the 'noise' is an indirectly, subjectively pleasing hiss rather than hum. Finally, the response has -1dB points at 2Hz-32kHz, gently rolling away to -7.1dB/100kHz. PM

Above: Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 26.4A

Above: Distortion Versus Frequency Versus Power Output (1W/8Ohm, Black; 10W, Pink; 75W, Red)

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