After another revision or two, the final schematic came up and about:
Now we have connectors, power supplies and component values. Also, the schematic suffered some changes - jumpers at the input got thrown out and we have new jumpers bypassing the passive RIAA. This bypass can be used for software based RIAA compensation. Conceivably, a software will provide even more accurate compensation and options for selecting different compensation curves. In that case, we just need a high gain, high accuracy amplifier to bring the signal to the computer input.
Jumpers at the input added complexity to the circuit and prevent us from optimizing layout where it's most critical. The preamplifier still can be easily optimized by replacing resistors/capacitors at the input without detrimental effects on the extremely small signals coming out of phono cartridges.
Even though the schematic is pretty complete at this stage, it is safe to assume that some modifications will take place during bench testing and listening of the built prototypes. (NOTE: In fact, right after posting this I saw that R71/72 and R81/82 will have to change to much lower values and/or R91/92 will need to go to a higher value, otherwise in FLAT mode, RIAA will run in parallel to the bypass resistors.
Ironing wrinkles in a design is normal part of the process, so I decided to leave the original SCH with this note, rather then correct it).
Before we move to printed circuit board (PCB) layout we need to select components (packages), create footprints for every part and associate it with the component's schematic symbol. Once that is done, we will export the so called Netlist, which is a file describing how are components interconnected, along with each component's reference designator (R1, C15, U3....) and footprint name. PCB layout software will then import the netlist, comb its libraries for available footprints (based on the name from the netlist) and pull everything together on the screen for layout to start.
In the next post I will have some interesting links with more reading materials. While we're busy preparing the schematic for export to layout software, you may read some interesting stuff and find more details about the circuitry described in this and previous sections.