Stereophile review.
Sidebar 1: Soundsmith Zephyr MIMC phono cartridge
The Soundsmith Zephyr MIMC ($1499.95) is a new cartridge that uses much of the technology of the Soundsmith Sussurro ($4799.95), which Michael Fremer raved about in the March 2012 issue. Like all Soundsmith cartridges, the Zephyr MIMC uses what's usually called a moving-iron design, but which Soundsmith designer Peter Ledermann prefers to call fixed-coil. Ledermann makes a persuasive argument about the superiority of fixed-coil over moving-coil cartridges, lower moving mass being the major factor (footnote 1).Like the Sussurro, the Zephyr MIMC uses Soundsmith's Dynamic Energy Management System (DEMS), designed to neutralize unwanted vibrations. The Zephyr MIMC is a low-output (0.4mV) device intended to be used with high-gain phono preamps, the type normally used with MC cartridges. (MIMC stands for Moving Iron for Moving Coil.) A unique aspect of Soundsmith cartridges compared to other high-end designs is that they can be completely rebuilt for 20% of the original price. Thus, if/when its stylus wears out or its cantilever is damaged, you can have your Zephyr MIMC rebuilt to as-new condition for $300. In these days of electronic appliances that cost more to fix than to buy new, Soundsmith's policy is most welcome. The load recommended for the Zephyr MIMC is 470 ohms or greater. My Convergent Audio Technology SL-1 Renaissance Black Path Edition preamplifier has a transformer-based MC section with an output impedance of 4k ohms, but this value can be changed with paralleled plug-in resistors. I discussed the load issue with CAT's Ken Stevens, who suggested that I try the Zephyr first with no plug-in resistors, an arrangement that he said worked well with most MC cartridges, though he admitted to having had no experience with low-output MI/FC cartridges such as the Zephyr MIMC. He sent me a collection of plug-in resistors and suggested that I try all of them. Using the formula he provided for calculating the total parallel resistance (R1 x R2/(R1 + R2), with R1 being 4000 and R2 whatever is plugged in), I compared the sound with: 1) no plug-in resistors (ie, 4k ohms); 2) plug-in resistors of 500 ohms (total 444 ohms, just under the recommended minimum of 470); 3) 1k ohm (total 800 ohms); and 4) 2k ohms (total 1333 ohms). My favorite was 1333 ohms, which produced the most neutral tonal balance; in second place was no plug-in resistors, or 4k ohms; and 444 ohms sounded rather thin.—Robert Deutsch
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