The circuit design is modified based on the Conrad John and the values are adjusted and optimized. The input stage uses 12AX7in common cathode, whereas the output stage uses 12AT7.The signal paths of this PCB layout are designed in symmetry for both channels. Dedicated power rails, ground, and signal paths, altogether are taken into design considerations so that all are to minimize the parasitic, cross interference, and influence of RFI.
·One 12AX7 and one 12AT7 vacuum tubes.
·Voltage gain: 26dB
·Frequency Flatness: 20-20KHz (+/-0.6dB)
·S/N Ratio: >94dB
·THD: 0.057% @Vin = -10dBm and 1KHz
0.087% @Vin= -6.4dBm and 1KHz
·Input impedance 1MΩ
·Output impedance 3KΩ
·Two single-ended and two single-ended outputs.
·Symmetric layout design and signal paths with minimum parasitic.
·Dedicated ground and power rails layout design.
·Two large reservoir decoupling capacitors for power rails.
·Power requirements: one 260V (10mA) DC, and one 12.6V (0.5A) DC.
·PCB dimension: 184mm (W) x 112mm (L)
·PCB thickness: 2.4mm, double layer, 2oz copper.
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