XA8250 07 is a symmetry complementary double-difference pure Class A amplifier pre-amplifier with separate dual-channels structural, which is especially designed for XA8800MNE.
Input stage adopts TOSHIBA HIfi dynatrons A970/C2240 to constitute symmetry complementary double-difference amplify circuit. It also connects one resistor in serial with the emitter of each dynatrons, which processes current negative feedback, in order to decrease open-loop distortion, stability Operating Point and improve the linear dynamic Range.
The voltage amplifier stage also adopts the complementary push-pull amplifier circuit consists of A970/C2240. The signal have been directly transferred to output stage after amplified.
Output stage adopts the pure Class A push-pull source follow output model consisting of N-type and P-type JFETs, in order to increase dynamic range and decrease output impedance. This measure will ensure the match between the pre-amplifier and other power amplifiers better.
The left channel, right channel and power supply circuit parts are especially designed as separate and isolated. Left and right channel are separately lie at the two sides inside this unit. The power supply lies at the middle, and there is separate 40W high-quality E-type transformer with steeliness shield cover to supply power to each channel. That is to avoid the small signal interfered by magnetic-leak. Power supply filter and decoupling adopt Marcom and America Military-grad electrolytic capacitors. It also adopts optimized grounding, to ensure the high SNR.
In addition, there is extra separate balanced input and output terminals for left and right channels, opening delay indicator and closing mute protection functions.
XA8250 07 is a source follow output Class A pre-amplifier constituted by JFET, in this case, its tone is natural, transparent and with high analysis ability. The sound is balanced in whole frequency parts: exquisite at the high frequency, bright at the mediant, plump at the low frequency.