An Archival Grade Phono Stage

What was originally intended to be a simple RIAA add-on for the Makua Preamp has quickly spiraled into the quietest and probably most versatile phono stage ever built.
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MC/MM input stages are optimized for current noise and voltage noise respectively. Unlike the more common arrangement of an MC head amp feeding into the MM stage, the two stages are fully independent, realising an equally short signal path for both. Input gain is switchable in 5dB steps over a 40dB range. Input resistance and capacitance are individually switchable. Available EQ settings cover practically all known cutting curves ever used, including most 78RPM.
All settings are software controllable, either on the fly using a PC or tablet computer or directly stored under the preset buttons. And since the preamp can route any input through the phono stage, only one is needed even if you have multiple turntables and elements connected.

Performance

  • Input noise (MC): 0.35 nV/rtHz
  • Input noise (MM): 0.9 pA/rtHz
  • Sensitivity: variable from 30 uV to 5 mV
  • THD, IMD: not measurable
  • RIAA conformance: +/-0.1 dB.

Available time constants

  • t1: 200, 250, 318, 400, 450 us
  • t2: 50, 64, 75, 100 us
  • bass shelf: 14, 18, 20dB