Pre/Power Amplifiers

The intent behind these flagship amplifiers is clear enough: 'We wanted to evolve our state of the art,' confirmed Chord Electronics' MD and Chief Designer John Franks. 'Our latest amplifier topology really began life in the compact Etude that we launched in early 2018. It uses a dual feed-forward error-correction amplifier technology originally conceived by Essex University Emeritus Professor Malcolm Hawksford and later refined by a young Bob Cordell from Bell labs. Of course, it's married up here with our high frequency (switchmode) PSU design, which has itself evolved since the mid-1980s.'

So what has enabled Chord to achieve such high outputs in the Ultima? 'Yes, the Ultima design is the largest and most powerful of our mono amplifiers,' says Franks, 'this particular unit has 64 power FETs that demand our most highly advanced and refined drive circuitry, operated here from boosted ±125V rails. These PSU rails are higher the the ±110V feeding the power FETs themselves, though the latter are 2kW supplies [4kW burst] designed to deliver huge current swings.'

And the cool running – how has this been achieved without significant visible heatsinking? 'By combining the Hawksford/Cordell error amplifier technology with our custom lateral MOSFETs, we've been able to reduce the standing current right down to just a few milliamperes in each pair of output devices. As a result our Ultima amplifiers are just barely warm to the touch when idling.'