The FET Evolution
Up to now bipolar transistors have been dominating as active devices in audio amplifier circuits. Bipolars are low-noise devices, but they lack the ultimate resolution in low-level circuits. They also tend to sound “grainy” and irritating at mid and high frequencies. JFETs, on the other hand, offer not just low noise, but also exceptional resolution and natural and transparent sound. No bipolar device, not even the LM394, is coming close as far as resolution is concerned. Some tubes are excellent in terms of resolution, but they can not match the low noise and neutrality of the JFETs.
We have been using JFETs in the input stages of all our audio amplifiers for the last 15 years. However, the second stage always used bipolar transistor. With many years of listening and testing we have found that these bipolars are the limiting factors in terms of the finest resolution. We have therefore replaced all the bipolars with JFETs and MOSFETs in our phono preamp, lineamp and power amps.
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