This is a new made preamp – Hybrid Balance Mu-Stage. Dual triode medium gain subminiature tube like 6N16B-V, 6N18B-V, 6N28B-V, 6111, & 6021 etc… can be used. The choice of submini tube is due to its low noise and good microphonic effect.
Features:
- Hybrid (Mosfet + Tube) mu-stage design with full balance at input and output
- Supply voltages: +128V, +59V, -69V and two 6.3V DC – all regulated supply
- Tube biased at about 1.5mA at about 60V plate voltage
- Mosfet IRF710 as Source Follower biased at about 7.5mA
- Gain about mu of the tube, about 20 to 40 times
- Non feedback design and thus tube may need to match for gain.
- Tube can be replacable using IC sockets, the submini tube is first soldered on 8-pins leads and then inserted into IC socket.
FFT measurment:
Update new photo on Jan 3rd, 2011 …..
