Усилители мощности стерео — Ayon Audio Ayon Crossfire EVO Delta PA

The Crossfire EVO Delta PA is a two-channel tube power amp from the Austrian maker Ayon Audio, derived from the Crossfire Evo Delta integrated amplifier. It is a single-ended pure class A design using directly heated triodes, with four AA62B output tubes from Ayon's own production. Ayon bases its single-ended power triodes on the WE 300B. Compared with the integrated version, the power supply, tube regulator and amplification and driver circuits were redesigned, and Ayon trimmed the gain stages for a shorter, more direct route.

Key specs that matter

Rated output is 2 x 50 W for 4 or 8 ohm loads. Frequency response runs from 8 Hz to 35 kHz at 0 dB. Input impedance at 1 kHz is 100 kOhm, and a full-power S/N figure of 98 dB is given. There is no negative feedback of any kind. Inputs are a single RCA and a single XLR socket, with no volume control, since this is a pure power amplifier. The chassis measures 52 cm in width, 42 cm in depth and 25 cm in height, and the unit itself weighs 52 kg, with a shipping weight of 62 kg.

Engineering and use context

Ayon notes that single-ended amplifiers are more sensitive to power supply aberrations than push-pull designs, so this one uses three separate insulated low-noise power transformers, each in a damped, RFI and EMI shielded case. Dual chokes filter the supply for the AA62B tubes and a second pair serves the input and driver stages, while a 5U4G tube regulates the supply. Each stage of amplification has its own isolated supply, with soft-start regulated DC for the heaters. An AC line filter, large electrolytic storage capacitors and in-rush current limiting are fitted, and the sequenced power-on cycle takes 1 minute. Bias is fixed automatically and shows on a mV-scaled analogue instrument. A protection circuit guards the tubes and the electronics. Transistors, followers and buffers are absent from the signal path, and discrete wiring is kept to a minimum. A wide-band output transformer is used, sealed in an anti-resonance compound. A star earth point is combined with dual grounding that the user can switch. Tube sockets have beryllium-copper spring pins made for Ayon. Hand assembly, better ventilation and engraved panel text mark the anodised case, which sits on aluminium feet that absorb resonance, and an illuminated logo, with black or chrome as finishes.

Pairing

Ayon says that the AA62B output tubes deliver high peak current and high voltage and that the amplifier can also handle awkward speaker impedances. A separate preamp feeding either its single-ended or balanced socket is required.

Alternatives

Among its EVO stereo power amplifiers Ayon also lists the Triton EVO PA.