Preamplifiers

PrimaLuna ProLogue Premium Stereo Tube Preamplifier

ARTICLE INDEX

The Design

Compared to the PrimaLuna 3 Preamplifier, the Premium has a bit more gain and is about 50% heavier due to the larger power supply transformer. It uses four 12AU7's instead of two 12AU7's and two 12AX7's. Both use two 5AR4 rectifier tubes for full-wave tube rectification. There are two power transformers in this preamp, making it dual-mono.

The preamplifier operates in Class A bias, and does not use global negative feedback.

The connections on the rear panel are all gold-plated brass and very high quality. There are four sets of RCA inputs and two sets of RCA outputs. A tape-out loop completes the configuration. The AC receptacle is grounded.

A very elegant remote control comes with the preamplifier. It is long and slender and has basic functions. It is obviously intended for use with a CD player, and the only functions that apply to the preamp are the volume control and mute button.

There are several protection circuits in this preamplifier. (1) The BTI (Bad Tube Indicator) lamp near each power tube will light up if the tube fails; (2) PTP (Power Tranformer Protection) cuts the power if the amplifier overheats; and (3) OTP (Output Transformer Protection) activates if there is a major amplifier circuit failure.