Pre/Power Amplifiers

While the stereo version of the 3510 power amp [HFN Nov '22] behaves almost exactly like the power stage from Exposure's 3510 integrated [HFN Nov '21], the newer, Mono version of this established chassis shows a distinct evolution. Not only has Exposure embraced a fully balanced input stage but this and the power output circuits are now fully DC-coupled, the latter governed by electronic thermal and over-current protection. As a result the 3510 Mono has a response that's flat to below 1Hz (the AC-coupled 3510 Stereo rolls off below 20Hz, reaching 4Hz/–3dB) while stretching out to 20kHz/–0.4dB and 100kHz/–6.3dB. Distortion is much reduced over the 3510 Stereo, achieving 0.0005-0.0028% over its rated 100W range while the 110W-rated Stereo model hovers between 0.0025-0.008%. Versus frequency, the 0.0016-0.018% distortion recorded for the 3510 Stereo (re. 10W, 20Hz-20kHz) falls to 0.0006-0.0055% with the 3510 Mono [see Graph 2, below], but it is the reduction in noise that marks out this new version. This is a phenomenally quiet amplifier that takes the 89dB A-wtd S/N ratio of the 3510 Stereo and pulverises it with a massive 100.0dB (both re. 0dBW).

But what of power? Again, there are differences, for while the Mono and Stereo (and Integrated) both deliver 135W/8ohm and 225W/4ohm, under dynamic conditions we see the impact of that new protection regime as the Stereo's 170W, 320W, 550W and 795W (28.2A) are traded for 160W, 305W, 530W and a reduced 310W (17.6A) into 8, 4, 2 and 1ohm loads, respectively [see Graph 1]. So while the Mono chassis is cleaner, quieter and reaches down deeper, it's the Stereo model that has the raw grunt to drive the very toughest of speaker loads. PM