![]() For the latter, my phono stages are optimized for a total input capacitance agreeable to virtually all MM cartridges on the market once tonearm and cable capacitance are taken into account.ĭo you offer a PSU upgrade? No. Variable loading inevitably deviates away from optimal rejection of radio frequency interference, increased insertion loss in moving coil inputs, and can increase noise and seriously distort the high frequency response of moving magnet cartridges. This rather tricky subject is soon to be covered in a series of articles on moving magnet and coil input circuitry, but it has been revealed through quite extensive research that variable loading is quite undesirable for 99% of applications. I pulled these items from the FAQ page of Michael Fidler - Classic Audio Ltd.:Ĭan I customize cartridge loading? Absolutely not. I'm not able to give chapter and verse let alone proper technical evaluation, but do hope Mr Fidler and others with proper test gear can properly expand definitively on this.Ĭlick to expand.I thought that this might be of interest (I think that it is well worth the time to peruse his site) This is a MOVING COIL phono stage and for such a type, this one is excellent! The 'sinad' of a vinyl record (*estimated* at various frequencies) could be as high as 65 - 70dB at high frequencies with a new top quality highly profiled stylus and a spotless new record played but once and as low as 10dB or worse down at sub 50hz levels, the midrange somewhere between 20 and 40dB depending on all manner of factors from stylus to the player itself. In a phono stage, we're talking a measurement average level in the groove of 5cm/s, where most 'MM' types give 3 - 5mv output and where MC types are around a tenth of that and sometimes lower, so extra noise is inevitable, especially when the inverse RIAA curve is applied, boosting lower frequencies and reducing higher ones. Input sensitivities of old were in the hundreds of millivolts back in the day (and Hegel and others still abide by that to a degree, hence the higher noise figures from memory due to the gain structure) We're talking audio output levels at 2V upwards as regards dacs and amps, the spectacular results with Class D amps 'helped' by less sensitive inputs needing less gain I understand.
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