Integrated Amplifiers

There’s a lot of technology squeezed into this enclosure but not at the expense of raw speaker-wrestling power. Rated at 140W/8ohm and 250W/4ohm, the R 2500 R actually delivers closer to 2x145W and 2x270W into 8 and 4ohm, respectively, with enough in the tank to support 150W, 275W, 475W and 355W into 8, 4, 2 and 1ohm loads (<1% THD) under dynamic conditions [see Graph 1]. Overall gain is a sensible +33.1dB and the A-wtd S/N ratio clocks-in at a spectacularly wide 100dB (re. 0dBW). Distortion holds true to 0.003-0.004% over the rated 140W power bandwidth (all 1kHz/8ohm) but tracks higher – to 0.02%/100W – under dynamic conditions [again, Graph 1], with decreasing load impedance and with increasing frequency (0.014%/20kHz/10W). Output impedance is a usefully low 0.02ohm, the response is flat to ±1dB from 1Hz-47kHz, and channel separation a wide 100dB through the midrange.

Digital inputs (and CD) are handled by four PCM1795 DACs with the flattest response achieved by the ‘FIR Long’ filter at –0.3dB/20kHz, –1.9dB/45kHz and –5.1dB/90kHz with 48kHz, 96kHz and 192kHz digital files, respectively. The NOS filters are best used with high (96kHz+) sample rate media. Tested at 2V output (vol = 77) from the preamp RCAs, T+A’s R 2500 R offers an above-average 108.1dB A-wtd S/N and low <10psec jitter (all sample rates). Distortion falls to a minimum of 0.00025%/1kHz over the top 30dB of its dynamic range [see Graph 2] while its low-level resolution is good to ±0.4dB over a full 100dB dynamic range. And the meters? They over-read very slightly, so a 10W/1kHz/8ohm output appears as ~15W on the very coarse, logarithmic scale. PM