![]() They work fine, woofer pumping that was excessive becomes insignificant. Then there are subsonic filters that operate usually after the RIAA stage, typically these have a slope of at least 12dB per octave, better is 18dB, and begin to work at around 30Hz, note that the bottom bass note for orchestra and electric guitar is 40Hz. ![]() Cart resonance frequency is under our control and this is one of the factors that cart-to-arm matching addresses. The solution? LPs are out of our control, we have to use what we find. Most modern amps can reproduce this stuff so it arrives at the speaker woofer and if the combination of three factors is unfavorable you get massive woofer cone flutter. The result is a big subsonic ripple waveform sent to the input of the preamp and power amps. Third the RIAA curve puts 20dB of gain, the maximum, right where this same band of subsonic ripple exists. Secondly, the arm and cart have a resonance at very low frequencies and this resonance band contains the frequencies of the disc surface ripple. The frequency of ripple is around 0.5Hz to 10 or 20Hz, that is, subsonic. ![]() ![]() The source of trouble is a threefold combination of factors.įirst LP pressings, even high quality ones, have surface ripple many times larger than the width of a groove, take a look sometime at the surface of an LP against some backlight. What it lacks in the flexibility of additional MC cartridge support, it more than makes up for in sound quality. The Rega Fono MM, now in its 5th incarnation, is frequently touted as one of the best phono preamps in the affordable to mid-range category. Taking some round number off the chart above there is 20dB max gain at LF in the regular RIAA and 15dB in the IEC version. Price: 445/220 MM/MC: MM Gain: MM: 41.4 dB Subsonic filter: no. ![]()
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