Pre/Power Amplifiers

Despite the SA 8.2 employing a very heavyweight linear PSU/MOSFET amp, its power output, distortion and response is remarkably similar to that of AVM’s compact integrated CS 8.2 amplifier with its switchmode PSUs and Pascal S-PRO2 Class D modules [HFN May ’17]. In practice, the SA 8.2 delivers 2x235W/

8ohm and 2x435W/4ohm with sufficient headroom to support 240W, 472W and 913W into 8, 4 and 2ohm under dynamic conditions [see Graph 1]. However, the SA 8.2’s extra ‘beef’ is clearly revealed in its substantially higher 1.45kW/1ohm output (38.1A at <1% THD) and, because of its direct-coupled terminals, the vanishingly low 0.003ohm source impedance maintains its –0.17dB/20kHz to –2.4dB/100kHz response regardless of variations in loudspeaker load impedance. This is where AVM’s SA 8.2 has a distinct edge over the spine-friendly CS 8.2!

By the same token, and bearing in mind the PA 8.2’s tube output card is the same 803T-based preamp option offered for the CS 8.2, there are also very similar parallels in performance. (The DAC card option was not installed in our sample, but it is reasonable to expect it to mirror the performance of that fitted to the CS 8.2 reviewed last May.) The preamp’s source impedance is low for a triode stage at 45ohm and the maximum 6.5V output is more than sufficient to drive the SA 8.2 with its 1.5V/230W input sensitivity. The response is ‘milder’ than that of the SA 8.2 at –0.3dB/10kHz, –1.2dB/20kHz and –11.6dB/100kHz but the A-wtd S/N ratio of 88dB (re. 0dBV) is wide enough. THD [blue trace, Graph 2] depends as much on tube matching as the circuit design – here achieving a consistent 0.002-0.005% through the right and 0.003-0.009% via the left. PM

Power output (<1% THD, 8/4ohm): 235W / 435W
Dynamic power (<1% THD, 8/4/2/1ohm): 240W / 472W / 913W / 1.45kW
Output imp. (20Hz–20kHz, pre/power): 45ohm / 0.003–0.004ohm
Freq. resp. (20Hz–100kHz, pre/power): +0.0 to –11.6dB / –0.03 to –2.4dB
Input sensitivity (for 0dBV/0dBW): 148mV (pre) / 97mV (power)
A-wtd S/N ratio (re. 0dBV/0dBW): 88.0dB (pre) / 88.5dB (power)
Distortion (20Hz-20kHz, 1V/10W): 0.003–0.008%/0.00014–0.005%
Power consump. (pre/idle/rated o/p): 20W / 105W/640W
Dimensions (WHD Pre/Power): 430x130x355/435x250x420mm
Price (pre/power): £9995/£12,450