Фонокорректоры — Trafomatic Audio LUNA

The Luna is a valve phono stage in two chassis from Trafomatic Audio of Serbia. Its main technical point is the way it applies the RIAA curve - through a passive LCR equaliser built from inductors, capacitors and resistors, a method Trafomatic describes as very rare because of its complexity and cost. The circuit runs in single-ended Class A with no global feedback, and the supply lives in a separate chassis from the audio circuit.

Key specs that matter

Gain is 45 dB for moving magnet cartridges and 70 dB for moving coil cartridges. The moving magnet input presents 47 kOhm, and the moving coil input can be set to 10, 20, 50 or 100 ohm. Noise and hum are rated at minus 78 dB, output voltage is 1.0 Vrms, and the RIAA curve is followed within plus or minus 0.4 dB. Both the balanced and unbalanced outputs have a source impedance of 660 ohm. Four C3g valves, a Siemens type made for the German Post, are wired in triode mode. The two chassis together measure 400 x 310 x 85 mm and weigh 10 kg. Power draw is 60 W, and the unit can be supplied for 100, 117 or 240 V mains at 50 or 60 Hz.

Engineering and use context

The signal path contains two valve gain stages with the passive LCR network between them. Moving coil signals first pass through Lundahl LL1941 step-up transformers, which use amorphous cobalt cores and Cardas copper wire, so the extra gain for low-output cartridges comes from magnetics rather than an additional valve stage. Two interstage transformers and two line output transformers complete the chain, giving transformer isolation at both the input and the output. Trafomatic uses no capacitors anywhere in the audio chain except the silver mica parts inside the RIAA network. The external supply combines a low-induction toroidal transformer with two high-inductivity chokes made in house and Mundorf MLytic HV electrolytic capacitors. Both cartridge inputs use RCA sockets, while the output is offered on XLR as well as RCA.

Pairing

Thanks to the XLR output, the Luna can run a balanced cable to the next line stage, and the RCA output remains for unbalanced equipment. Moving coil cartridges of low output can be used on the coil input because the Lundahl step-up transformers supply the extra gain, and the selectable load lets the owner match the setting printed in the cartridge specification.

Alternatives

Trafomatic Audio also offers the Evolution Phono One, a single-box solid-state phono stage built on OPA2134 operational amplifiers with 40 dB MM and 64 dB MC gain.