US Patent 2,034,872 “Phonograph Reproducer” Published 2022/10/17 at 503 × 800 in Things I learned on Phono EQ curves, Pt. 4 ← Previous Next → source <cite><a href=httpspatentsgooglecompatentUS2034872Aen>Phonograph Reproducer<a><cite> US Patent 2034872 Arthur C Keller 1936