Pännäri Revenge JFET RIAA -kit for MM cartridge

The popular tube RIAA designed by Mauri Pännäri is continued as discrete JFET implementation. The original instructions for the connection have been published as an article on audiovideo.fi (In Finnish) and refined on UralTone as a construction kit. The preamp is housed on the same Hammond 1455 series case, this time in a smaller version with a tube version.

Mauri Pännäri, the designer of the circuit: "This fet connection, implemented without a long feedback, has lived with me for almost 40 years in different experimental versions, mainly as two-fet implementations. After my last experiments and measurements, I ended up with the three-fet version presented here, where the 2120 Hz (75us) turning point has been implemented with the current supply principle on the drain of the first fet. This way, the possibility of overdriving the treble end is eliminated at the same time. Here, the bass end is also linearly amplified to the same output level. The drain also has a so-called Neumann time constant, which can be removed if desired. The next, high-impedance stage with its input produces a linear amplification of approx. 20dB and gives for passive bass correction at the rear (+20dB/20Hz ref 1 kHz) a constant impedance input. The third stage, still high-impedance in its input, is linear with approx. 20dB gain and determines the overdrive margin, approx. 20dB (ref 1 kHz/3 mV in). In the last two stages has been used so-called source degeneration (insurmountable source resistance), which gives the gate control voltage leeway and produces a bit of local feedback."

The building kit is available in two versions, adapted to either the MM box or the MC box. The kit includes a carefully selected and mathcated NOS JFET kit, a copper-plated circuit board and the best possible parts. The Hammond 1455 case and the 24V power supply suitable for connection are sold separately. A connection diagram and parts list are delivered with the set. Illustrated construction instructions can be found at: https://en.uraltone.com/blog/pannari-revenge-jfet-riaa-kit/

Links to products not included in the kit:

• Hammond 1455 -enclosure
• Meanwell 24V adapter
• 24V / 1.5W adapter
• 24V / 2.5A adapter