Improved Marantz 7-tube preamplifier circuit

The principle is shown in the figure below. This circuit uses 12AX7 for two-stage amplification, followed by a 12AU7 cathode follower as a signal buffer. As we all know, the Marantz 7-tube preamplifier is famous for its sweet mid-range, but its analytical power and high and low extension are poor. In view of the shortcomings of the traditional Marantz 7-tube preamplifier, some adjustments have been made to the selection of coupling capacitor capacity and the selection of negative feedback loop. The improved Marantz 7-tube preamplifier has a certain extension and sense of strength for high and low frequency reproduction, but the mid-range is better.