Pure Vinyl™ High Impedance Dual Differential Preamp Test Prototype

Differential (Balanced) Preamp Test Prototype and Measurements

(Above) Prototype of high impedance preamp for MM or MC cartridges

Measurement scale is in inches

(Above) Prototype of low impedance preamp for MC cartridges

(Above) Low impedance preamp with power source (two CR-123 Li batteries)

(Above) Ortofon Kontrapunkt b MC cartridge, mounted on turntable, for testing above preamps.

(Above) 1/3 octave RTA measurement of differential (balanced) preamp noise spectrum, single channel. Frequency span 2.5 Hz - 20 kHz. Preamp was connected to cartridge (installed on turntable). Note that 60 Hz / 120 Hz "hum" is undetectable.

(Above) 1/3 octave RTA measurement of preamp noise spectrum, single channel, with inverse RIAA equalization applied.