Vintage

B&O's first DC-coupled tuner/amplifier identically matches the Beomaster 2400-2 [HFN Dec '19] for raw power output but otherwise delivers a very distinctive technical performance. In practice our circa-1975 test sample sustained a maximum continuous output of 2x35W/8ohm (40W/8ohm, one channel driven) and 2x55W/4ohm with sufficient reserve to sustain transient peaks (1kHz/10msec/<1% THD) of 42W, 74W, 33W and 18W into 8ohm, 4ohm, 2ohm and 1ohm loads, respectively [see Graph 1, below]. Once again, the 4.3A current headroom is modest, suggesting the 2000 is best used with speakers rated at 6ohm and above, and of generous sensitivity.

Otherwise, the 2000 may be DC coupled but its low bass response is actively filtered, falling from –0.1dB/100Hz to –2.2dB/20Hz and –6dB/11Hz, just as its HF roll-off is influenced by the buffering of its volume control. With the volume slider at maximum (35.8dB gain) the response is flattest – reaching –0.2dB/20kHz and –3.8dB/100kHz – while at reduced volume positions (this is gain, not output level) the HF response is progressively muted. Output impedance is also influenced, but even the lowest 0.3-0.5ohm (20Hz-20kHz) will still cause some further response modification in line with the swings in speaker load. Distortion is more predictable, a steady increase in level from 0.016%/1W to 0.045%/10W and 0.09% at the rated 30W/8ohm (all 1kHz), and with frequency to 0.09%/10kHz and 0.14%/20kHz [all at 10W/8ohm – see red trace, Graph 2 below]. Noise is low too at –78dBV – testament not only to the design of B&O's linear power supply but also the elegant circuit layout – all of which secures a worthy 86.6dB A-wtd S/N ratio (re. 0dBW). PM