Pre/Power Amplifiers

Exposure's 3510 preamplifier takes some cues from the earlier 3010S2 model [HFN Dec '14] but its feedback regime is more 'relaxed'. Gain is unaltered at +17.2dB and the A-wtd S/N ratio only 1dB adrift at 93.3dB, but the 3010S2's very low 0.0002-0.0005% distortion is increased to 0.001-0.0024% in the newer 3510 (re. 0dBV, 20kHz-20kHz). The HF response is identical, too, at –0.5dB/20kHz and –7.4dB/100kHz, although the 3510 has a more obvious (sensible) subsonic bass roll-off of –3dB/5Hz (vs. <1Hz in the 3010S2) plus a higher 266ohm source impedance at 25Hz (vs. 160ohm). Trading slightly higher THD in the preamp's 'sound tuning' process is perfectly reasonable as these figures still fall within the envelope of the partnering 3510 power amp.

The latter behaves almost exactly like the power stage from Exposure's 3510 integrated [HFN Nov '21] but with a slightly higher output impedance of 0.018-0.033ohm versus 0.010-0.022ohm (20Hz-20kHz), a slightly flatter and more extended high frequency response (–0.5dB/20kHz to –9.1dB/100kHz vs. –1.0dB/20kHz and –15.8dB/100kHz) and slightly more grunt into very low impedance loads. Both the 3510 integrated and power amp are rated at 2x110W/8ohm and both deliver 2x135W/8ohm and 2x225W/4ohm rising to 170W, 320W and 550W into 8, 4 and 2ohm under dynamic conditions [see Graph 1, below]. Into the lowest 1ohm load the 3510 power amp has a slight edge at 795W (28.2A) versus 760W (27.6A). Distortion has a 'U-shaped' trend vs. output, decreasing from 0.005%/1W to 0.0025%/15W before climbing gently again to 0.005%/70W and 0.008% at the rated 110W (all 1kHz/8ohm). Distortion also increases with frequency, more markedly so at higher output [see Graph 2]. PM