Arcam SA30 Network Attached Amp Lab Report

Lab Report

Tested in 'Analogue Direct' mode (bypassing the input AK5552 ADC) the gain of the SA30 is as high as many MM phono stages at +49.2dB, though this reduces slightly to +47dB when the line input is digitised at 192kHz/32-bit. The SA30's response is not appreciably different in 'Direct' or 'digitised' mode, the former extending down to –0.3dB/1Hz and up to –0.25dB/20kHz and –4.6dB/100kHz. The 192kHz ADC cuts this off at –10dB/87kHz and –30dB/92kHz. Noise is exceptionally low and the A-wtd S/N ratio some 10dB wider than average at 94.5dB (re. 0dBW) while distortion is also a low 0.0003-0.002% (20Hz-20kHz, 10W). Distortion is fairly constant between 1-10W before rising with output to 0.001%/30W, 0.002%/50W and 0.0035% at the rated 120W/8ohm. In practice the SA30 delivers 2x145W/8ohm and 2x220W/4ohm with the Class G power amp supporting peaks of 190W, 339W, 247W and 130W under dynamic conditions into 8, 4, 2 and 1ohm loads [see Graph 1, below].

Testing the digital stage via the pre outputs is limited to 1.1V because the power amp remains in circuit and, even unloaded, still clips. At 1V/0dBV output, the ESS9038K2M-based DAC stage offers a 104dB A-wtd S/N ratio and minimum 0.00035% THD over the top 10dB of its dynamic range [see Graph 2]. Jitter is suppressed to ~50psec via all sample rates while the rejection of alias images, the amount of pre/post ringing on transients, and the frequency response(s) all depend on your choice of filter. With 48kHz files 'Apodising' gives –1.0dB/20kHz; 'Min. Phase Slow', –5.2dB/20kHz; 'Min Phase Fast', –0.2dB/20kHz; 'Linear Phase Slow', –3.7dB/20kHz; 'Lin. Phase Fast', –0.2dB/20kHz; 'Corr. Min Phase', –12.3dB/20kHz and 'Brickwall', –4.2dB/20kHz. PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 11.4A


Distortion versus 24-bit digital signal level over a 120dB range (1kHz, black; 20kHz, blue)

Continuous power (<1% THD, 8/4ohm) 145W / 220W
Dynamic power (<1% THD, 8/4/2/1ohm) 190W / 339W / 247W / 130W
Output imp. (20Hz–20kHz, Pre/Amp) 226ohm / 0.071-0.090ohm
Freq. resp. (20Hz–20kHz/100kHz) +0.0 to –0.25dB/–4.6dB
Digital jitter (USB / S/PDIF) 50psec / 55psec
A-wtd S/N ratio (DAC/Amp) 104.1dB (0dBFs) / 94.5dB (0dBW)
Distortion (DAC, 0dBFs/Amp, 0dBW) 0.0015–0.002% / 0.0003–0.002%
Power consumption (idle/rated o/p) 41W / 408W (2W standby)
Dimensions (WHD, each unit) 433x100x323mm / 12kg
Price £1995

Waterbeach, Cambs
Supplied by: Arcam (Harman International Industries Ltd)
01223 203200