Pre/Power Amplifiers

Hegel's dry wit is illustrated by the very precise '2x303W into 8ohm' specification for its H600, a figure met in practice at 2x315W and 2x600W into 8/4ohm, respectively. These numbers are largely unchanged from the outgoing H590 flagship [HFN Oct '18] as is its near-identical dynamic prowess of 327W/8ohm, 641W/4ohm, 1.24kW/2ohm and a huge 2.30kW (48A) into 1ohm [see Graph 1]. The +32.9dB gain is unchanged but despite this common 'gain/power' envelope, the H600 has been fettled for lower noise – and a wider 93.3dB A-wtd S/N ratio – alongside a very different distortion profile. The H600 has higher THD into lower loads, but the trend is otherwise very linear from 0.0057%/1W to 0.0045%/10W and to 0.003%/300W (all 1kHz/8ohm). THD increases slightly at LF (0.007%/20Hz) and HF (0.01%/20kHz/10W) with only a slight further increase up to 100W/8ohm. Response is flatter too – now just –0.11dB/20kHz to –0.8dB/100kHz/8ohm.

The H590's AKM AK4490 DAC is replaced by an ES9038Q2M converter on the H600's digital PCB, although Hegel's preferred choice of minimum phase filter type is retained, offering a 75dB stopband rejection with no (acausal) pre-ringing. Tested via the fixed (2.43V) line out, the response 'shape' shows a mild but consistent HF lift with all sample rates, reaching +0.2dB/20kHz, +0.75dB/45kHz and +1.7dB/90kHz (and +2.0dB/80kHz) with 48kHz, 96kHz and 192kHz media, respectively. THD is 0.0002-0.0013% (20Hz-20kHz) with peak (0dBFs) digital inputs and falls to a minimum of 0.00009-0.0004% over the top 30dB of its dynamic range [see Graph 2]. Again, the 107.3dB A-wtd S/N ratio is a marked improvement over the H590 and jitter is almost entirely suppressed to <5psec at all sample rates. PM