V-FET 2SK79 SRPP stereo preamp board based on Yasui design w/matched 2SK79 !

Description

This is the bare PCB of an audiophile grade pre-amplifier, based on a legendary conponent, SONY's V-FET 2SK79. The pre-amplifier is wired in SRPP configuration, based on the design by Mr. Yasui Akira of Japan.
Background : Yasui Akira was a prolific contributor to Japan audio magazine MJ the last 50 years. He sadly left us in February 2020. In memory of this audio guru, a great promoter of  DIY audio designs for half a century, we actualized this design with our layout effort. The design adhered closely to what Yasui had published in MJ. We have included a volume control on board to make the preamplifier a more integrated design.
2SK79 is an unique small signal V-FET ( or SIT) manufactured by SONY in the mid 70's of last century. V-FET is renowned for their triode-like characteristics. By chance we obtained a limited stock and matched the devices to offer a limited quantity of matched set for this board.
Deliverables :
1. SRPP PCB one piece ;
2. Idss matched 2SK79 two pairs.
This listing is just for the bare board and 2SK79 four pieces. The assembled board is for reference only.
There is a wide spread of parameters in 2SK79 manufacturing, and we are only able to match a quad set from each 30-40 individual pieces.
Supply voltage : 30VAC- 36Vx1 AC 200mA
PCB dimension : 182mm x 122mm.
Frequency response : 40Hz - 300KHZ +/-0.5dB ( 4.7K loading, 1uF output coupling cap.) ; 20Hz - 300KHz +/-0.5dB( 4.7K loading, 10uF output coupling cap.)
PCB thickness : 1.6mm, 2 oz ( 75um thickness !!) copper deposition. Gold flushed surface.
In order to maximize the performance, we do not put solder resist on the board surface, to minimize the effect of plastic in the audio path.
We do air shipping worldwide at US.00. We welcome combine shipping.