Phono Preamplifiers

Phono stages often trade versatility for ease-of-use, obliging users to fiddle with DIP switches to select between the various options. Fortunately, the DIP switches here cater only for input loading/capacitance, so once set for MM and MC they can be shut away behind their little blanking plates. MM/MC and their respective gain options are selected via toggles, with relay muting inside the R35, so changes may be executed swiftly and without speaker-busting pops. Primare claims +42dB, +46dB and +50dB gain for its MM input and +68dB, +72dB and +76dB for MC, values that are closely matched on test at +42.1dB, +46.1dB and +50.2dB for MM and +68.5dB, +72.3dB and +76.5dB, respectively, for MC (all single-ended in/balanced out).

In practice, the lowest MM gain offers a 7.85mV sensitivity (good for high output MMs) with the highest MC gain equal to 0.15mV (149µV – and with a 10ohm load option, ideal for the lowest output MCs). With a huge maximum output of 22V, the R35 carries enough headroom to maintain a +27dB input overload margin with every input setting. The limits of 176mV, 115mV and 73mV (MM), and 8.9mV, 5.6mV and 3.3mV (MC), respectively, are sufficient to accommodate the 'hottest' >18dB groove modulations (re. 11.2µm/300Hz). See boxout, p55.

The RIAA equalisation is also very flat and extended out to 100kHz, its subsonic filter amounting to –0.5dB/20Hz and –6dB/9Hz [see Graph 1]. If you have reflex-loaded speakers then the sub filter should be engaged. Otherwise, the RIAA-eq'd distortion [Graph 2] is very low, with a max. of just 0.0035% and a min. of 0.00035% (20Hz-20kHz). Noise is low too, and the A-wtd S/N ratios impressive at 85dB (all MM gain settings) and 77dB (all MC gain settings). All versatile, textbook stuff! PM