Chord Ultima Pre/Power Amplifier Lab Report

Lab Report

Chord's Ultima preamp offers six levels of overall gain: '0.5', '1.0'... '2.5 and '3.0' amounting to 0dB, +5.6dB, +10.2dB, +12.3dB, +14.2dB and +15.6dB, balanced in/out, respectively. Maximum output level is 10.6V regardless of gain, from a 96ohm source impedance, while the S/N ratio is slightly below average at 83dB (re. 0dBV), a feature it shares with the Ultima power amp(s) with their 79dB A-wtd S/N (re. 0dBW). Incidentally, both amplifiers have a 'smooth' noise floor – decades of lab test data indicating a correlation between amplifiers that show a finite level of 'white' noise and those preferred on listening tests... The preamp's response, meanwhile, is flat to within ±0.1dB from 1Hz-100kHz with the EQ facility disabled, and ±5dB/10kHz and ±5dB/20Hz (all re. 0dB/1kHz) with the HF/LF EQ controls enabled and rotated to maximum/minimum.


Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 74.9A


THD vs. extended freq for Ultima pre (1V out, black trace) vs. Ultima monoblock (10W/8ohm, red)

The partnering Ultima power amp did not quite make its continuous 780W/1400W 8/4ohm power rating – 690W/1305W was nearer the mark at <1% THD – but the 0.2F of low-ESR reservoir capacitance and three ±110V PSUs operating in parallel delivered a stupendous 825W, 1595W, 3041W and 5617W into 8, 4, 2 and 1ohm loads under dynamic conditions [see Graph 1, below]. Into 8ohm loads, distortion is well managed at 0.001%/1W, 0.0012%/10W and 0.0018%/100W up to just 0.004%/600W (all at 1kHz). THD increases by a factor of ~10x at 20kHz, but remains lower overall than the preamp at 0dBV [see Graph 2]. Commensurate with an output impedance that increases from a low 0.016ohm/1kHz to 0.08ohm/20kHz and 0.9ohm/100kHz, the response rolls gently away at HF to –0.7dB/20kHz and –2.9dB/100kHz (10W/8ohm). PM

Continuous power (<1% THD, 8/4ohm) 687W / 1305W
Dynamic power (<1% THD, 8/4/2/1ohm) 825W / 1595W / 3041W / 5617W
Output imp. (20Hz–20kHz, pre/power) 96-99ohm / 0.016–0.090ohm
Freq. resp. (20Hz–100kHz, pre/power) +0.0 to –0.15dB / +0.0 to –2.9dB
Input sensitivity (for 0dBV/0dBW) 1000mV (pre) / 96mV (power)
A-wtd S/N ratio (re. 0dBV/0dBW) 83.3dB (pre) / 78.5dB (power)
Distortion (20Hz-20kHz, 1V/10W) 0.0009–0.11%/0.0003–0.072%
Power consumption (preamp) 22W
Dimensions (WHD, Pre/Power) 480x310x355/480x310x670mm
Prices (pre/power amp): £30,000/£30,000 (each)
Chord Electronics Ltd
Supplied by: Chord Electronics Ltd
02890 279839