Pre/Power Amplifiers

Fortunately, when developing its custom SMPS, Constellation was not tempted to radically alter the ‘jewel’ in its amplification crown – its exclusively N-Type MOSFET-based output modules. Here, instead of using one power amp stage comprising multiple complementary transistors, each Revelation 2 Stereo employs two NPN-only modules in a balanced bridged configuration [see inset picture]. Also, as in its earlier amplifiers, Constellation’s Revelation 2 Stereo has three inputs, including traditional RCA and ‘Balanced’ XLRs in addition to a second XLR that services its proprietary ‘Direct’ option. In practice, both ‘Direct’ and ‘Balanced’ are balanced, but the former omits the company’s J-FET line stage module, making use of the higher output voltage capacity of the partnering preamp.

This J-FET input stage adds a further +13dB gain to the Stereo, bringing the total to +25dB, but it’s not a given that the sound of the power amp will necessarily improve by cutting this input buffer from the signal path. Why? With the Stereo in full ‘Balanced’ mode, the Preamp will run at lower gain just as the Stereo’s J-FET stage may arguably provide better balanced ‘signal conditioning’ to drive the N-channel FET output modules. In this latest amplifier, measurable differences in either distortion or S/N ratio between ‘Direct’ and ‘Balanced’ are very slight indeed, although the response in ‘Direct’ is now flat to within ±0.1dB from 1Hz-100kHz. Personal preference will doubtless be informed by your choice of source, preamp and loudspeakers. PM