GlassWare Audio Design
Thanks for supporting the Tube CAD JournalNEW! Aikido Phono-Stage Printed Circuit Board
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.
Aikido Phono-Stage is a stereo phono preamp that uses two Aikido gain stages per channel and passive equalization in between. Only 9-pin pin tubes, such as the 6AQ8, 6BQ7, 6DJ8, 6CG7, 6FQ7, 6GM8, 12AT7, 12AU7, 12AV7, 12AX7, 12AY7, 12BH7, 12BZ7, 5751, 6922, 6072, ECC99...
The gain is dependent on the input tubes used, with 12AX7s yielding the highest gain and the 12AU7s delivering the lowest. Each Aikido gain stage roughly develops a gain equal to half the mu of the input tube used; thus, a 12AX7 develops a gain of 50 (or +34dB). The passive EQ forces a -20dB insertion loss.
Choose between a blank PCB (with 12-page user guide) and a full PCB kit that includes everything needed to the populate the board. (The above photo shows my own Aikido phono preamp and the kit only includes the PCB, standoffs, and parts required to fill the board. But who know, I may be offering the rest soon enough.)
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.
Aikido Phono-Stage is a stereo phono preamp that uses two Aikido gain stages per channel and passive equalization in between. Only 9-pin pin tubes, such as the 6AQ8, 6BQ7, 6DJ8, 6CG7, 6FQ7, 6GM8, 12AT7, 12AU7, 12AV7, 12AX7, 12AY7, 12BH7, 12BZ7, 5751, 6922, 6072, ECC99...
The gain is dependent on the input tubes used, with 12AX7s yielding the highest gain and the 12AU7s delivering the lowest. Each Aikido gain stage roughly develops a gain equal to half the mu of the input tube used; thus, a 12AX7 develops a gain of 50 (or +34dB). The passive EQ forces a -20dB insertion loss.
Choose between a blank PCB (with 12-page user guide) and a full PCB kit that includes everything needed to the populate the board. (The above photo shows my own Aikido phono preamp and the kit only includes the PCB, standoffs, and parts required to fill the board. But who know, I may be offering the rest soon enough.)
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. The PH-1 PCB holds two Aikido phono-stage preamplifiers, with each phono preamp holding two Aikido gain stages with a passive RIAA equalization circuit in between. Thus, one board is all that is needed for stereo unbalanced use. The boards are six inches by eleven inches, with ten mounting holes that help to prevent excessive PCB bending, while inserting and pulling tubes from their sockets. PCB include 12-page user guide booklet. |
