Chord Ultima Pre 2/Ultima 2 Pre/Power Amplifier Lab Report

Lab Report

In common with the Ultima Preamp [HFN Feb '19] the Ultima Pre 2 offers six levels of overall gain: 'x0.5', 'x1.0'... 'x2.5 and 'x3.0' amounting to –0.3dB, +5.3dB, +9.9dB, +12.1dB, +14.0dB and +15.4dB, balanced in/out, respectively. Maximum output level is 10V regardless of gain (so the input overload is a marginal 1.7V in the x3.0 gain setting), from a 96ohm source impedance, while the 'useable' range of its 99-step volume control is ~53dB. Optimum channel balance, in our sample at least, was achieved at the 1 o'clock position (12 o'clock yielding a L/R channel error of 0.65dB). Intriguingly, the A-wtd S/N ratio is significantly improved over the Ultima Preamp's 83dB (re. 0dBV) at 96.6dB while distortion is lower, and lowest in the x3.0 gain setting where 0.0002-0.0023% compares against 0.0003-0.0085% in the x0.5 mode [black vs. blue trace, Graph 2]. Regardless of gain, the Pre 2's response is flat to within ±0.1dB from 1Hz-100kHz.

The partnering Ultima 2 monoblock did not quite make its continuous 750W/1305W 8/4ohm power rating – 690W/1285W was nearer the mark at <1% THD – but the three ±110V PSUs operating in parallel delivered a magnificent 810W, 1590W, 2963W and 4850W into 8, 4, 2 and 1ohm loads under dynamic conditions [see Graph 1, below]. At 1kHz/8ohm, THD increases very gently with output from 0.002%/1W, 0.003%/10W and 0.0035%/100W up to just 0.0045%/600W. THD increases by a factor of ~20x at 20kHz, reaching 0.008%/10W [red trace, Graph 2]. Output impedance increases from a low 0.018-0.020ohm (20Hz-1kHz) to 0.09ohm/20kHz and 0.91ohm/100kHz, and the response rolls gently away at HF to –0.23dB/20kHz and –2.95dB/100kHz (10W/8ohm). PM


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 69.6A


THD vs. freq. for Ultima Pre 2 (1V out, x3.0 black trace; x0.5 blue) vs. Ultima 2 (10W/8ohm, red)

Continuous power (<1% THD, 8/4ohm) 690W / 1285W
Dynamic power (<1% THD, 8/4/2/1ohm) 810W / 1590W / 2963W / 4850W
Output imp. (20Hz–20kHz, pre/power) 96-100ohm / 0.021–0.093ohm
Freq. resp. (20Hz–100kHz, pre/power) +0.0 to –0.1dB / +0.0 to –2.95dB
Input sensitivity (for 0dBV/0dBW) 1035mV (pre) / 93mV (power)
A-wtd S/N ratio (re. 0dBV/0dBW) 96.6dB (pre) / 77.7dB (power)
Distortion (20Hz-20kHz, 1V/10W) 0.00018–0.0021%/0.0007–0.08%
Power consumption (idle/rated o/p) 90W/1080W (23W, preamp)
Dimensions (WHD, Pre/Power) 480x173x355/480x180x670mm
Prices (pre/power amp) £12,500/£18,360 (each)

Chord Electronics Ltd
Supplied by: Chord Electronics Ltd
01622 721444