Phono stage AF7-6A6 (Y)

The vinyl version of this preamplifier-corrector has been a long time in the making, as the components were meticulously selected for the most interesting sound. The circuitry is two-stage on the old sounding chassis 766GW with oak framing. In the first stage there is an AF7 pentode, the lamp head is powered by a bridge on D305 germanium diodes and CRC filter. This is a necessary measure to get minimal background. The lamp is excellent, but the choice of copies suitable for the corrector is a torture. They are noisy, or phonated, or sown, as well as there is oxidation of the contact area, you need to solder. However, there is no alternative to the sound of this paw. The output stage is assembled on a 6A6 triode with battery bias, the cathodes of the tubes sit on the ground.

The correction is located in the anode, the design of correction capacitors is based on Anton Stepichev's works, in this case they are precision Y-capacitors wound with copper cores on a wooden frame. Such capacitors catch background very strongly, so they are packed in a copper shield.
It is desirable to design the power supply for such a corrector as a separate external device, but in this case it was necessary to assemble a single-block design. The power transformers in the supply are two from Telefunken 166 receivers, feeding the pre- and output stages separately. AZ11 kenotrons are used in the rectifier. The capacitors in the supply are another good-sounding standard set: bosh, valvo and siemens electrolytes. FRACO electrolytes are installed in the cathodes of the pre-stage. Resistors siemens and BC. Monocore wiring from Telefunken receivers in original insulation. Shielded wires to input/output connectors from Bruel & Kjaer measurement equipment.
The corrector has a very clear and dynamic sound (the merit of the cathodes of the output stage sitting on the ground), and thanks to the input pentode AF7 is heard high musicality, outstanding scale and vigor of the sound.