Soundsmith Zephyr MIMC Star Cartridge Lab Report

Lab Report

Depending on where you look – the website, downloadable 'manual' or engraved on the bottom of the Zephyr MIMC Star's wooden case – the suggested tracking force varies from 1.8-2.0g, 1.6-2.0g and 1.8-2.2g. I performed all my tests at 2.0g where this 'moving-iron' pick-up tracked like a high compliance moving-magnet, successfully navigating the 80µm groove while keeping hold of the top +18dB modulation (315Hz lateral cut, re. 11.2μm) at just 1.4% THD. Indeed, compliance is rather higher at 16/20cu (vertical/lateral) than Soundsmith's rated 10cu which, combined with the high-ish 12g bodyweight, suggests the MIMC Star is best suited to low/medium effective mass arms.

Output is also a little under the rated 0.4mV at 338µV (re. 1kHz/5cm/sec) but channel balance is within tolerance at 0.5dB. Stereo separation meets the >28dB specification at 1kHz while the 'Ultra Low Mass' stylus is securely mounted on its sapphire cantilever to achieve a slightly high 26° VTA. More important is how you arrange the ~60dB gain required by this pick-up without slugging it with a low impedance MC phono stage – a standard 100ohm load produces a broad loss of presence/treble amounting to circa –6dB/20kHz. So, either pick the highest gain setting available on your MM input or use an MC stage with selectable loading over 1kohm. Here the MIMC Star realises a flat and extended response with good lateral/vertical symmetry and a useful +1dB lift from 3-12kHz [Graph 1, below]. Stereo distortion reflects the extended HF response [dashed trace, Graph 1], the unequalised figure amounting to 3% at 1kHz/5cm/sec (0dB) and RIAA equalised from 0.5-15% (lateral) and 1.9-12% (vertical) across 20Hz-20kHz at –8dB [see Graph 2, below]. PM


Freq. resp. curves (–8dB re. 5cm/sec) lateral (L+R, black) vs. vertical (L–R, red) vs. stereo dashed


Lateral (L+R, black infill) and vertical (L–R, red) tracing and generator distortion (2nd-4th harmonics) vs. frequency from 20Hz-20kHz (–8dB re. 5cm/sec)

Generator type/bodyweight Moving-iron / 12g
Recommended tracking force 18-22mN (20mN)
Sensitivity/balance (re. 5cm/sec) 338µV / 0.49dB
Compliance (vertical/lateral) 16cu / 20cu
Vertical tracking angle 26 degrees
L/R Tracking ability 80μm / 80μm
L/R Distortion (–8dB, 20Hz-20kHz) 0.5–15% / 1.9–12%
L/R Frequency resp. (20Hz-20kHz) –0.9 to +1.3dB / –0.7 to +1.4dB
Stereo separation (1kHz / 20kHz) 31dB / 18dB
Price £1999

Peekskill, New York, USA
Supplied by: Signature Audio Systems
07738 007776