Pre/Power Amplifiers

The flame in YBA's Passion duo is undoubtedly provided by the AMP650 which has two outputs – direct (the lower 4mm speaker terminals) and via a series inductor network (upper 4mm terminals). Power output meets the 200W/8ohm spec. at 2x223W/8ohm with sufficient in reserve to accommodate peaks of 252W, 460W, 650W and 628W (protected) into 8, 4, 2 and 1ohm loads at <1% THD [see Graph 1]. Distortion is a very steady 0.07% from 1W to 50W/8ohm but increases thereafter to 0.1%/80W, 0.2%/130W, 0.4%/180W and 0.75%/200W (all 1kHz), and at HF to 0.12%/20kHz (10W). The response is very extended into the low bass at +0.2dB/1Hz up to –0.2dB/20kHz and –3.3dB/100kHz but noise, from the frame transformer is quite high, reducing the A-wtd S/N ratio to just 70.5dB (re. 0dBW).

The partnering PRE550A offers a maximum +6dB gain, with distortion from 0.0001-0.001% (20Hz-20kHz) and a ±1dB bandwidth extending from 3Hz-98kHz (–0.05dB/20kHz). Noise is low and the A-wtd S/N wide at 93.8dB, the maximum 18.9V balanced analogue output delivered through an 80ohm source impedance. The digital board, based on a pair of CS4398 DACs offering 99dB of stopband rejection, peaks at a massive 9.1V output and delivers a resolution good to ±0.3dB over a full 110dB dynamic range. Distortion is 0.001-0.023% (20Hz-20kHz, 0dBFs) and falls to a minimum of 0.0001-0.0005% between –10dBFs and –30dBFs over the same frequency range [see Graph 2]. The response holds to a very flat ±0.03dB (20Hz-20kHz) with 44.1kHz/48kHz media, rolling gently away to –2.1dB/45kHz and –12.2dB/90kHz with 96kHz and 192kHz media, respectively. Jitter is impressively low at <40psec for all sample rates. PM

Continuous power (<1% THD, 8/4ohm): 223W / 336W
Dynamic power (<1% THD, 8/4/2/1ohm): 252W / 460W / 650W / 628W
Output impedance (20Hz–20kHz): 0.023–0.041ohm (<140ohm, pre)
Freq. resp. (20Hz–20kHz/100kHz): +0.0 to –0.2dB/–3.3dB (–1.1dB, pre)
Distortion (20Hz-20kHz, pre/power): 0.00013–0.001%/0.065–0.11%
A-wtd S/N ratio (re. 0dBV/0dBW): 93.8dB (pre) / 70.5dB (power)
Digital Jitter (48kHz/96kHz): 40psec / 25psec
Power consumption (idle/rated o/p): 35W / 625W (14W, preamp)
Dimensions (WHD, pre/power): 430x118x412/430x178x397mm
Price (pre/power): £6750/£5750