Duo-Beta - Duo-Beta/S - Duo-Beta plus-X
An optimum amount of NFb applied on top of an original, distortion-free amp circuit and servo NFb applied to the DC subsonic region do the best and cause the least harm. The result: smooth, clean reproduction of mid-to-high frequencies and tight, articulate bass response.
With the Duo-Beta/S circuitry, this acclaimed concept is farther deepened and intensified by means of mighty, stable power supplies.
The power supply section has to be stable and low in impedance. But it is also confirmed that in actuality an audio amp having such powerful power supply tends to accompany a "suppressed feeling" in reproduced sound or a lack of subtile nuance in expression. This is solely attributed to compulsory stabilisation by means of excessive damping at the feedback circuit of power supply section. The "plus-X" made compatible both stable power supply and extensive sound reproduction.