Phono Preamplifiers

First tested over 15 years ago [HFN Sep '07] and then again three years later [HFN Apr '10], the two-box Decade phono preamp has been on a journey of evolution. This new 'Jubilee' model includes the enhanced PWX II LC power supply together with upgrades to the component selection generally, and to the passive eq network in particular. The latter now bears comparison with the costlier Silver Cube model [HFN Jul '15] although the Decade's 'hallmark' technical features, including its super-low distortion of <0.001% [20Hz-20kHz, see Graph 2] and extended HF response of ±0.1dB/300Hz-100kHz [see Graph 1] are retained in the Jubilee. As before, this Lehmannaudio phono stage already has a sub-100Hz bass roll-off that reaches 20Hz/–0.8dB (7Hz/–3dB) before the subsonic filter option kicks-in at an early 110Hz/–1dB, dropping to a low 20Hz/–7.5dB and providing a full 17dB attenuation at typical sub-bass warp frequencies [dotted trace, Graph 1]. Unless you're hosting large-cone reflex-loaded speakers on a lightly suspended floor, the LF filter will likely be left off.

Again, Lehmannaudio's specifications rather under-value the technical performance of the Decade Jubilee which offers impressive 'real world' A-wtd S/Ns of 86.9dB (MM) and 77.5dB (MC) together with higher input margins than quoted. In practice the rated 36dB/46dB (MM) and 56dB/66dB (MC) gain options arrive at +35.4dB/+45.1dB and +56.1dB/+65.7dB, respectively, while the maximum 45mV (MM) and 4.5mV (MC) inputs in 'high gain' mode are a more generous 50mV and 4.6mV. The clipping limits in standard gain mode are 151mV (MM) and 14mV (MC), the former yielding a solid +30dB headroom if used with a 5mV/1kHz MM pick-up. Finally, residual noise is a low –93dBV (22µV) and maximum output a very high 8.7V. PM