Vintage

For once 'CD Direct' really does have a measurable impact on performance, not only bypassing the bass/treble controls (which are far from 'flat' in their default '0' position) but also the loudness control and L/R balance slider. There is only a 0.1dB difference in overall gain (+44.2dB) with CD Direct engaged or defeated but a difference of 1dB in A-wtd S/N (90.4dB vs. 89.5dB re. 0dBW). With CD Direct, the response is flat to within ±1dB from 4Hz-77kHz (–1.6dB/100kHz) but, defeated, shows a bass shelf of –1dB from 200Hz down to 10Hz, and a –0.25dB plateau out from 3kHz-60kHz. Distortion is more significantly influenced by output level than 'CD Direct', increasing from a low of 0.0015% at 1W/8ohm to 0.011%/10W and 0.022%/20W before stabilising at this level up to the rated 70W/8ohm power output (all at 1kHz). Implying a drift from low power Class A to Class A/B at a few watts, this trend of THD vs. level is more marked [black trace, Graph 1] than the increase in THD vs. freq. [see Graph 2].

While legacy schematics suggest a similarity in the FA860's output stage with that of stablemate Marantz's PM-50 from the same era, in practice the PM-50 had the edge in output, delivering 2x91W and 2x155W vs. the FA860's 2x85W and 2x130W into 8 and 4ohm loads, respectively. Both amplifiers readily exceeded their 2x70W/8ohm and 2x105W/4ohm rating but only the Philips model used electronic/relay speaker protection to limit output to 275W/16.6A into 1ohm loads [see green trace, Graph 1 below]. Output under dynamic conditions was otherwise well served by Philips' dual-mono PSU arrangement, producing 113W, 189W and 265W into 8, 4 and 2ohm loads (1kHz, 10msec, <1% THD). PM