DC field effect amplifier 01 using AP500A

This amplifier is a two-channel amplifier. The core device uses the AP500A module. This device is a high-voltage high-speed dual J FET input amplifier
. It has an internal fine-tuning input offset voltage structure and
has automatic zero-adjustment (zero drift less than 90mV) during closed-loop operation. 30dB gain
, while having very small distortion (less than 0. oz%) and very
good voltage frequency response (OHz ~ 500kHz). With a few necessary peripheral
components, a wide frequency response DC power amplifier can be formed. As
shown in Figure 3-18 (only one channel is drawn) o In the picture, AP500A is used as
the voltage amplification stage, and VT1 and VT2 are used as the current amplification stage. The circuit is simple
. The front and rear amplifiers complement each other and are
indispensable The amplification stage uses the familiar VMOS field effect transistor, and its excellent musical characteristics as a
power amplifier
have been recognized by most audiophiles.