Integrated Amplifiers

This model is easily the most capable of Arcam’s integrated amplifiers, its 5th generation Class G rail-switching technology rising to the challenge of reproducing dynamic, music-like signals. The SA45’s 180W/8ohm rating is met at 2x198W with a full 2x323W into 4ohm. However, under dynamic conditions (1kHz/10msec/<1% THD), the PSU has sufficient headroom to deliver 255W, 475W and 805W into 8, 4 and 2ohm loads, respectively, even though protection kicks in to limit its output to 745W/27A into the lowest 1ohm loads [see Graph 1, below]. Distortion is incredibly low at 0.0004-0.0009% over its full 180W rated range (re. 1kHz/8ohm) and 0.0003-0.0014% between 20Hz-20kHz (re. 10W/8ohm). This is more than 10x lower than Arcam’s own specification for the SA45. Add to this very low noise and a very wide 96dB A-wtd S/N ratio (re. 0dBW), the sensible +32.3dB overall gain, a response flat to –3dB limits from <1Hz-75kHz and a 0.02-0.05ohm output impedance (20Hz-20kHz) and this adds up to a very capable amplifier indeed.

The digital section is no poor cousin, even that massive toroidal PSU transformer having no impact on the vanishing low 5psec jitter (all sample rates) and wide 111dB A-wtd S/N ratio (re. 2.5V from the balanced preamp output). Distortion is super-low too, hitting just 0.0002-0.0014% with a peak (0dBFs) digital input before falling back to 0.00007-0.0003% over the top 20dB of its dynamic range [all re. 20Hz-20kHz, Graph 2]. Responses are dictated by Arcam’s choice of four digital filters from the ES9027 SPro DAC, taking it to –0.5dB, –16dB, –5.2dB and –8.9dB/45kHz with 96kHz inputs via the minimum phase, apodising, slow linear and slow minimum phase filters, respectively. PM