Still don't know

At your risk. But here is some light. It was decided to try Cinema Engineering EQ 4031-B. If memory is correct it can be seen on a documentary of Motown in the recording studio? Anyway, a Shure SM58 was connected directly to it. Then the output of the EQ directly to the Sony TC-D5M mic preamp in mono mode. Male singer to mic distance was the usual 24in, mic axis 30 degrees above head, towards nose. Surprisingly it worked although there is attenuation in the EQ. Of cource there was some hiss as the Sony recording level control had to be cranked up to maximum sensitivity. At EQ setting out, or both bass and treble controls to 0 the vocal sound was the usual muddy bass due to room acoustics, equal loudness curves, voice effort curves etc. As soon as the bass attenuate control reached -12db (at 100Hz?, bearing in mind that according to Audio Cyclopedia-Tremain, frequency response, attenuation starts at around 1KHz). (Monitoring was in real time trough Sennheiser HD-580 reference headphones while singing.) At -12dB the male voice quality was crispy clear and amazing, reminding of any greatly produced song. Say for exaple Could this be Magic - Manilow. Then a Pleiades one stage K117 JFET mic booster preamplifier was connected just after the mic, before the EQ, using a Canford input transformer and a Neutrik red jack with transformer inside as output transformer. There was no hiss as the cinema Eng EQ was more appropriately driven. Amazing sound again at -12dB low attenuation. The sound really sparkled when boosting also 2 to 4dB at 10kHz on both previous setupss. Then everything was disconnected and the SM57 was tried feeding directly the Sony TC-D5PRO. Again muddy, unclear, prominant mi8d bass, giving the impresion that someone is singing indide a very small space. Then a Pleiades (175mH:175mH) inline bass correcting transformer was insirted between mic and pre. Bass was much better but the mid bass still muddy. Then insited of this transformer a Pleiades (130Ohms,20mH) high pass filter was connected between the mic and pre. Now the vocal sound was much better with definition in mid and high frequencies but still not as good as using the Cinema Eng EQ in the bass register. When cascading both inline filters still the sound was not as good and worse in the mid. So winner is Cinema Eng EQ 4031-B, second best Pleiades (130Ohm,20mH) bass correcting high pass filter. At this point it was realised that the Pleiades (130Ohm,20mH) is a shelving filter of a different frequency than the Cinema Eng. Could a Cinema Eng equivqlent EQ or filter, possibly same schematic too be built inside an XLR to XLR adaptor? WHere is the Cinema Eng schematic?