Power amplifiers mono — Octave Audio Jubilee Mono Ultimate

Octave Audio of Germany describes the Jubilee Mono Ultimate as the most sophisticated amplifier design in its portfolio, and it sits in the Jubilee line alongside the Jubilee 300 B and the Jubilee Preamplifier. Each chassis carries eight KT 170 output valves and delivers 440 W into 4 ohms, and a stereo system uses a pair of units.

Key specs that matter

Octave quotes a frequency range of 10 Hz to 80 kHz. Harmonic distortion stays below 0.1 % at 10 W into 4 ohms, and Octave rates noise at -103 dB. Gain through the RCA input is 28 dB, with an input sensitivity of 1.5 V. One RCA and one balanced XLR input are fitted and selected by a switch, next to a pair of speaker binding posts that accept banana plugs or cable lugs and a 12 V DC trigger for remote switching. Each chassis is 750 mm high, 280 mm wide and 484 mm deep, and the weight is 78.0 kg. In the US, two units cost USD 142,500.

Engineering and use context

The central part of the Ultimate version is an oversized ultra broadband output transformer, newly developed to extend the power bandwidth and the bass range. Its speaker windings use multi-wire technology to reduce skin effect. Four custom transformers are used in total - the output transformer, a separate heater transformer and two line transformers for the power section. Bias can be set independently for each output valve and is shown on a display, and power preselection works in two stages, low and high. The protection system includes soft start electronics with inrush current delay and a circuit that guards both the device and the output valves, plus an eco mode that reduces consumption. The casework is available in silver or black, and the middle section can be specified in Makassar wood or in stone finishes including black granite, blue granite, slate and rainforest.

Pairing

The selectable XLR and RCA inputs let the amplifier take a balanced or single-ended feed from a preamplifier, and the trigger allows both monoblocks to power up with the rest of the system. Octave offers the Jubilee Preamplifier in the same line as a matching control unit, and its HP 700 SE line preamplifier also provides both XLR and RCA outputs. With its large power reserve, the amplifier is intended for loudspeakers that need high power, including low impedance designs.

Alternatives

The Octave Jubilee 300 B is another Jubilee monoblock, using three 300 B triodes with a selectable output of 15 to 30 W.