Version Description:
Version 1: Without main filter capacitor (finished product)
Version 2: With British Noreva main filter capacitor (finished product)
Version 3: With a mixed array of Chemi-Con + Nichicon main filter capacitors (finished product)
Version 4: Bare PCB with heatsinks
This preamplifier main amplifier is designed with reference to the circuit principles of the Golden A-100 (Ultimate Upgraded Version).
The input and output stages of the main amplifier are each designed with a JFET-based bipolar buffer to enhance the input/output impedance matching of the main amplifier.
The main amplifier circuit is designed with a symmetrical top/bottom shoulder structure overall, consisting of three parts:
Input stage: Employs a dual input, dual output (commonly known as a dual-differential circuit) bipolar-Wolfman amplification configuration. It uses N/P-JFET matched pairs for dual-differential amplification, forming a FET/BJT Wolfman configuration for signal amplification. Powered by DC ±15V.
Voltage amplification stage: Uses low-noise BJTs to form a symmetrical Wolfman amplification circuit. Powered by DC ±24V.
Voltage amplification output stage: Employs a BJT constant-voltage Wolfman circuit for signal amplification. Powered by DC ±24V.
To make the main amplifier's output signal more stable and reduce the impact of DC drift on the subsequent amplifier, a dedicated LF353 op-amp is used for automatic output DC offset zeroing and precise DC servo control.
Power supply uses an independent dual-channel configuration:
AC: 24V - 0 - 24V
AC: 24V - 0 - 24V
It uses a class A parallel regulated power supply widely recognized by enthusiasts as the main power source, followed by multi-stage electronic filtering and RC filtering to supply power step-by-step to each circuit stage.
Finished board dimensions: 190mm X 196mm X 45mm (height)
Sound characteristics: Strong sense of stereo imaging, quiet background. Highs and mids are delicate, midrange is clean and clear, bass is full and powerful.
Transistors used in the finished board (matched/screened):
Power Supply: IRF9610, A940 // C2703, A1268 // C3200
BD139-140, TL431, ROHM LEDs, ON regulators
Input Buffer: J74 // K170 // A1268 // C3200
Main Amplifier Input Stage: J74 // K170 //
A1266 // C3198 (or A970 / C2240)
Voltage Amplification Stage: A1266 // C3198 (or A988 // C1841)
Voltage Amplification Output Stage: A1275 // C3228
B647 // D667 (or A1145 // C2705)
Output Buffer: J74 // K170 //, A970 // C2240 (A1268 // C3200)
Servo Op-Amp: LF353
The main filter can accommodate 4 large capacitors with a diameter of 30mm, or an array of 24 small capacitors with a diameter of 13mm.
Enthusiasts purchasing bare PCBs or kits will receive: circuit debugging methods (the finished board is debugged before shipping) and circuit schematics.
No additional documentation will be provided beyond the above, as none exists.
As long as component parameters meet requirements and installation follows the PCB silkscreen, perfect sound will be achieved. If difficulties are encountered, prompt communication is available.
Special Notice:
Enthusiasts without knowledge of electronic components or assembly skills are advised to order the finished board or contact the store for a custom-finished unit.
For more details, please refer to the color diagram annotations or consult customer service.
Special Reminder:
Components may vary based on market availability, but quality standards will not be lowered.
For details, please check the store's published "Dynamic Information" promptly.
Dynamic Information:
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