This is the Phone Stage, handling both MM (Moving Magnet) and MC (Moving Coil) pickups. The design uses active RIAA compensation. This is untraditional for the EC design which up to this time used passive high-pass and active low-boost. The gain stages are design to handle the active feedback, and note (!!!!!), the active RIAA compensation used SHUNT FEEDBACK. A tough job to calculate but when that was done, it worked wonders !
The line stage section is more traditional, with a normal series feedback line stage. Note the extra buffer on the output.
For both block schematics above, note the roman numbers inside the amplifiers, denoting the particular gain block used.
This drawing show the gain block 3 and 4. Note the completely symmetrical design. The other gain stages also used an ingenious method of utilizing all the current from the last differential stage. Also note the current generators, ever seen something like that ;-) - well - it works ! Check back for more later!
(Also: Details on compensations and other stuff will be described. Don't try to build the gain stage as described above - smoke will arise. Be patient. )