Phonostages — Ayon Audio Ayon Spheris Phono

The Spheris Phono is a two-chassis all-valve phono stage from Ayon Audio, the Austrian maker of valve electronics. It works in pure Class A with triodes, uses a single gain stage without negative feedback, and has both single-ended and balanced outputs. It is supplied with a separate Spheris AC ReGenerator that supplies clean mains power to the phono stage. A newer reference version, the Spheris EVO, has since joined the Ayon range.

Key specs that matter

Ayon builds the circuit around 6H30 and 6SL7 valves. There are two RCA phono inputs, each with two load options, and one RCA and one XLR output. Ayon states that the stage works with cartridges down to 0.1 mV output. Maximum output is 5 Vrms at 1 kHz, and output impedance is about 300 ohm. Signal to noise ratio exceeds 100 dB, THD is below 0.1% at 1 V, and frequency response runs from 10 Hz to 80 kHz. The supplied AC ReGenerator delivers up to 300 W at 60 Hz. Each of the two chassis is 500 mm wide, 430 mm deep and 110 mm high, and together they weigh 46 kg. The finish is black and chrome brushed anodised aluminium.

Engineering and use context

The RIAA equalisation is passive, built as an LCR network with super-perm alloy transformers rather than with resistor and capacitor networks alone. Passive equalisation does the frequency shaping without active circuits. Only one coupling capacitor sits in the signal path, at the output, and the circuit runs with 0 dB of negative feedback, meaning the output is not fed back to correct the input. The single gain stage keeps the number of active devices in the path to a minimum. The power supply is valve-rectified, with separate low-noise transformers and triple choke filtering, and it sits in its own chassis, away from the sensitive amplifying circuits. An MC1 and MC2 selector uses relays placed close to the RCA input jacks, so the switching happens as near as possible to the cartridge connection. The valve sockets use beryllium-copper pins, and tantalum precision resistors are used in the circuit. The AC ReGenerator generates a new mains waveform for the phono stage, independent of the quality of the incoming supply.

Pairing

The balanced XLR output connects to preamplifiers with balanced inputs, including Ayon's own valve preamplifiers, and the RCA output to any line input. With its support for very low-output cartridges, low-output moving-coil models can be used without a separate step-up transformer. The two inputs allow two tonearms or turntables to be connected.

Alternatives

The Ayon Spheris EVO is the newer two-chassis reference phono stage from the same maker.