MoFi UltraGold Cartridge Lab Report

Lab Report

With a fairly standard tracking force range of 1.8-2.2g suggested for the UltraGold, I performed all my tests at 2.0g where this MC 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 0.5% THD. Indeed, compliance is rather higher at 18/20cu (vertical/lateral) than MoFi's rated 10cu which, combined with the 7.3g bodyweight, indicates the UltraGold is better suited to low effective mass arms. Ironically, the high effective mass of the 10in alloy tonearm fitted to MoFi's own UltraDeck [HFN Jul '19] better suits its 'Tracker' range of MM pick-ups with their lower ~12cu compliance.

Output is a little over the rated 0.4mV at 452µV (re. 1kHz/5cm/sec), channel balance is within tolerance at 0.6dB while stereo separation is a perfectly 'good' 28dB/1kHz (falling to 14dB/20kHz). In most cases you'll be looking at selecting around +65dB gain on your MC phono preamp to optimise output level, S/N and input overload margin (headroom). Driving a >100ohm load, the UltraGold shows a very slight low bass roll-off of –0.9dB/20Hz but the rigid and lightweight boron cantilever, and near-ideal 21° VTA of the Shibata diamond, assists in delivering an extended HF response that rises to +0.8dB from 12-16kHz and achieves –1.7dB/20kHz (–4.6dB/20kHz, left channel). Distortion reflects the extended HF response [dashed trace, Graph 1], the unequalised figure amounting to just 1.9% at 1kHz/5cm/sec while the RIAA-equalised THD ranges from 0.4-11% (lateral), 1.5-9.7% (vertical) and 0.75-7.2% (stereo) [see Graph 2, below]. This is a well-sorted MC that tracks like a trooper... PM


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


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

Generator type/bodyweight Moving-coil / 7.3g
Recommended tracking force 18-22mN (20mN)
Sensitivity/balance (re. 5cm/sec) 452µV / 0.6dB
Compliance (vertical/lateral) 18cu / 20cu
Vertical tracking angle 22 degrees
L/R Tracking ability 80μm / 80μm
L/R Distortion (–8dB, 20Hz-20kHz) 0.5–17% / 0.4–11%
L/R Frequency resp. (20Hz-20kHz) +0.0 to –4.5dB / +1.2 to –1.7dB
Stereo separation (1kHz / 20kHz) 28dB / 14dB
Price £1499

MoFi Electronics
Chicago, USA
Supplied by: Karma-AV Ltd, York
01423 358846