The Tetra Sans PS phono stage uses two tube-based gain stages with a passive equalization network in between. The gain stage's topology is the Constant-Current-Draw Amplifier [CCDA], whose low distortion, fairly high gain, and low output impedance are desirable attributes in a phono preamp. The CCDA is a compound circuit that holds a grounded-cathode amplifier directly cascaded into a cathode follower. So what; what's so special about this obvious pairing? Its special status lies in the details.
Combining the Aikido All-in-One power supply with the CCDA topology allows an excellent tube phono stage to be made easily and inexpensively. The CCDA’s low distortion and output impedance, without the use of negative feedback—all are desirable attributes in a phono preamp.
The Aikido phono stage requires a lot of parts, many sockets, resistors, and capacitors. Thus, this kits includes every thing needed to populate the PH-1 PCB, except the eight tubes.
Aikido phono preamp printed circuit board: This FR-4 PCB is extra thick, 0.094 inches (inserting and pulling tubes from their sockets won’t bend or break this board), double-sided, with plated-through 2oz copper traces, and the boards are meticulously and expensively made in the USA. PCB include 12-page user guide booklet.