The LT1115 operational amplifier from Linear Technologies* with low impedance feedback exclusively boosts the phono signal level for 40/60 dB withultra low noise and distortions to line level and gives the first RIAA stage equalization with 75µs deemphasis.
A frame grid dual triode performs the signal conditioning: The first system is connected as grounded grid amplifier and gives in addition to the levelshift an extra 25 dB amplification for the following 2 stage passive RIAA equalization.
The second system of the dual triode is used as a low impedance cathode follower output stage.
Thanks to this special circuity the tubes do not need any screening caps and can be mounted visible on top of the enclosure.
This is your opportunity to build yourself such a noble and absolute lowest-noise tube phono preamplifier on a smooth evening.
* Lowest noise operational amplifier available on the world market in DIP-8 package