Усилители мощности стерео — Ayon Audio Ayon Crossfire EVO PA

The Crossfire EVO PA is a single-ended stereo power amplifier from Ayon Audio, developed from the Crossfire Evo integrated. Compared with that model it gains a completely redesigned EVO generation power supply, a tube regulator and new amplification and driver circuitry, and its gain stages were optimised for the shortest signal path. Ayon groups it with the Triton Evo PA and the Crossfire Evo Delta PA among its EVO stereo amplifiers.

Key specs that matter

One AA62B per side does the work, a directly heated single-ended triode that Ayon manufactures itself and bases on the Western Electric 300B. Operation is pure class A with 0 dB negative feedback of any kind. Output is 30 W per channel into 4 or 8 ohm loads, and the frequency response spans 8 Hz to 35 kHz at 0 dB. Input impedance is 100 kohm at 1 kHz while the full-power noise figure is 98 dB. As a pure power amplifier it has no volume control and no remote, and the rear panel carries one RCA and one XLR input. The chassis measures 52 x 42 x 25 cm (width, depth, height) and weighs 45 kg net, with a 55 kg packed weight.

Engineering and use context

Ayon argues that single-ended designs are more sensitive to power supply disturbances than push-pull amplifiers, so the Crossfire EVO PA uses two separate low-noise insulated power transformers, housed in damped RFI and EMI shielding, and total isolation between input and output stages. The AA62B tubes run from a dual choke filtered supply, the pre and driver stage has a dual choke of its own, and a 5U4G rectifier tube forms part of the tube-regulated supply. Each amplification stage has its own isolated supply, filament voltages are regulated DC with soft start, while mains line filtering, large reservoir capacitors and a soft in-rush circuit sit ahead of it all. Power-on sequencing lasts one minute. The bias system is auto-fixed and an analogue meter with a mV scale shows the bias current. Ayon winds the output transformers itself, built for wide bandwidth and sealed with an anti-resonance compound. The signal path is free of semiconductors, cathode followers and buffers, and a switchable dual grounding system uses a central star earth. The anodised aluminium chassis is non-magnetic, hand assembled and comes in black or chrome.

Pairing

Ayon says the amplifier can also manage difficult loudspeaker loads, but the modest output of a single-ended triode is best matched to efficient speakers such as Ayon's full-range Black series. A preamplifier with balanced or single-ended output is needed to set the level.

Alternatives

The Ayon Crossfire EVO Delta PA is the heavier stereo version with four AA62B tubes, 2 x 50 W and a 52 kg chassis.