Hybrid tube preamplifier is module containing SRPP tube voltage stage and CCS biased source follower based on high voltage MOSFET transistor. CCS is fully discrete bipolar. Both transistors are placed on powerful heatsink.
First stage is the same as in both my fully tube preamplifiers (with cathode follower and White cathode follower) but only difference is that here expensive 6N30P tubes are replaced by more modern components like transistors.
Most of components are SMD type. Only few bigest components are THT. Tubes are mounted on bottom side of PCB to helps
Parameters:
- Frequency response: 2Hz – 1.35MHz to 47k load (2.2uF output capacitor
- Amplification factor: base 10V/V (20dB
- Anode supply: 300V 60mA
- Heater supply: 6,3V 700mA
- Output impedance: ~100R
- Board dimensions: 100 x 100mm
Additional features:
- input resistor divider for gain reduction to desired one
- place for bypass capacitor on cathode resistor of SRPP circuit to increase gain
- muting relay at the output (required external control circuit)
- possibility to change heater style from ECC88 like tubes to ECC82 like tubes
Helps to small board dimensions this module could be used as tube output stage for DACs and CD players (equipped with my HV power supply).
MuzgDIY 
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