Aikido and Tetra Phono-Stage PCBs and Kits

Despite predictions to the contrary, spinning black vinyl by the warm glow of vacuum tubes persists. In spite of the popularly-held belief that both LPs and tubes are dead, long dead—most believe that the vacuum tube died about 50 years ago and that the LP record died 25 years ago at the birth of the CD—both tubes and LPs grow more popular with each coming day. Tubes refuse to fade to black and solid-state audio gear is still embarrassingly being advertised as sounding tube-like; and Marantz once again sells turntables and new records are pressed daily.

Adding the Aikido topology to a phono preamp makes perfect sense. The Aikido’s low distortion, noise, and output impedance, without the use of negative feedback—all are desirable attributes in a phono preamp.

The Tetra phono stage combines the Aikido-All-in-One's power supply with the CCDA topology, a combination that allows an excellent tube phono stage to be made easily and inexpensively. The Tetra uses only four tubes, not the eight tubes that the Aikido phono stage requires. And it holds two power supplies, one for the high-voltage B+ and a low-voltage regulated power supply for the heaters. The high-voltage power supply is unregulated, but uses cascading RC filters to smooth away ripple. Of course, the power supplies require an external power transformer(s) with two secondary windings, one high voltage for the B+ voltage and one low-voltage for the heaters.