Phono Preamplifiers

The REF Phono 3SE's equalised response [dashed trace, inset Graph – with 20Hz-20kHz shaded in green] is very flat and extended above 1kHz, reaching out to +0.1dB/100kHz. Below 1kHz there's a gentle bass shelf amounting to –0.45dB/100Hz, –0.7dB/20Hz and –1dB at 4Hz. The other curves on this Graph represent the REF Phono 3SE's playback eq. for RIAA [black] and the earlier Columbia [red] and Decca [green] record-cutting characteristics. The RIAA curve's turnover points correspond to 2.12kHz (75µsec), 500Hz (318µsec) and 50Hz (3180µsec), delivering slightly less HF attenuation and a slightly greater bass boost than the 2.65kHz (60µs)/500Hz/100Hz (1590µsec) constants for Decca and the 1.59kHz (100µsec)/500Hz/82Hz (1950µsec) finally utilised by Columbia (after tweaking the 1940s NAB standard).

The exact points and slopes for the myriad historic eq. standards is still debated, so the overlay between the Columbia [red] and Decca [green] seen here possibly relates to ARC's interpretation of the Decca/US rather than Decca/London curve. So, if you play an old Columbia/Decca 33.3rpm LP with a modern RIAA preamp it'll sound +1.7dB/20kHz 'brighter' and +1.5dB/+2.4dB/20Hz, respectively, 'weightier'. PM