We built this city on silicon!
Just thought this board looked a bit like a city with towers, houses and roads. In fact it’s a very-low-noise balanced-input audio amplifier with active ground-control (to Major Tom?) and RIAA filters for playing vinyl records. Records are not cut with a flat frequency response; the bass is reduced as is the treble so that the cutting / etching of the track stays within physical bounds. Playing a record requires the reverse filter at 3180us (50Hz low pass), 318us (500Hz high pass) and 50us (2120Hz low pass).
And yes, there was a deliberate decision to colour coordinate the components as long as quality wasn’t compromised – much like what I’ve done to Phoebe and Chloe recently. In fact, for Phoebe, Chloe and this PCB, colour choice has forced higher quality components to be used.
I call it creative OCD art and it gives me great satisfaction! Horowitz and Hill were not wrong with the name of their classic book.
Thanks again to the fab folk at Ragworm for producing the PCBs.