Option:
Inspired by the Accuphase C-3850, this preamplifier circuit is well worth DIY assembly.
The sound signature leans towards the input amplification single op-amp, defaulting to BB/OPA604 (SMD).
You can replace or upgrade it yourself to alter the sound, such as with OPA627, NE/JRC5534, etc.
Added output DC offset nulling circuit with dual voltage/current feedback to reduce distortion.
The output operates in Class A state, serving as a pure preamplifier with a tube-like sound character.
Accurate positioning of vocals and instruments, clear layering and detail, delivering a smooth, refined, and relaxed listening experience.
Dimensions: Length 100mm x Width 100mm x Height 25mm
Power Supply: DC ± Dual 20V to DC ± Dual 24V
Power supply decoupling uses Philips BC 25V 470μF capacitors.
Default resistors are 718 series; contact us if Taiwanese Kun Mao resistors are preferred. For other details, please refer to the images.
Assembled boards require no debugging; simply connect to a DC ± dual regulated power supply.
If adding a volume potentiometer at the signal input, it is recommended to use ≥50K*2.
