Power amplifiers mono — Chord ULTIMA 3

The ULTIMA 3 is a 480 W mono amplifier in the Full Size range of Chord Electronics, where it replaces the SPM 1400 MKII. Chord launched it as part of its 30th anniversary celebrations with a new circuit topology taken from the range-topping ULTIMA, offered at a lower price. Chord describes it as a thoroughly modern amplifier for the high-resolution age. Each unit is hand built in Britain, as with all Chord full-size and Reference amplifiers, and cover runs for 5 years.

Key specs that matter

Into 4 ohm the output rises to 1,000 W RMS. THD is 0.005%, noise is better than -84 dB and gain is 30 dB. Frequency response is -1 dB between 0.2 Hz and 46 kHz and -3 dB between 0.1 Hz and 200 kHz. Input impedance is 100 kOhm for both input types, with 0.04 ohm at the output. Consumption is 2,500 W at full power and 10 W in standby. Fitted with Integra legs, the case is 18 cm tall, 48 cm across and 36 cm from front to back, and side blocks reduce this to 15 x 42 x 36 cm. Weight is 22.4 kg.

Engineering and use context

The MOSFETs are proprietary Chord parts operating in Class AB, and their bias is of the sliding type. Error correction follows a dual feed-forward scheme. Power comes from an HF switch-mode supply, the whole circuit is fully balanced, and heat is removed by convection, so there are no fans. John Franks designed the remodelled fascia, a 28 mm slab of CNC-machined aircraft-grade aluminium. The recessed spherical polycarbonate power button is lit in standby and in operation, and lighting can be dimmed with a discreet switch concealed in the vertical split of the front panel. On the rear are one XLR inverted input, one XLR non-inverted input, one gold-plated RCA inverted input, one gold-plated RCA non-inverted input and a 12 V trigger input. Two pairs of gold-plated high-current speaker terminals support bi-wiring. The finish options are Jett Black and Argent Silver, and buyers choose stackable Integra legs in Jett Black, Argent Silver or Nickel, or a highly polished black acrylic side block.

Pairing

A stereo system requires two ULTIMA 3 amplifiers, one per loudspeaker. The inputs in inverted and non-inverted form allow a source signal in normal or reversed polarity on both connector types, and the trigger input lets the pair switch on together with the source electronics.

Alternatives

Chord's ULTIMA 2 is the next mono amplifier up, rated at 750 W RMS into 8 ohm and 1,305 W RMS into 4 ohm.