PREdator, Diff/CF linestage.
The object for this preamp is to keep things simple, with a gain of 10dB, and quite low Zout.
The input stage is a diff-amp, like a LTP. The gain in that stage is about 18dB. The line driver is a cathode follower with a bit NFB back to the inverting input of the diff-stage. Overall gain is estimated to be 10-12dB.
Zout is something like 1/gm (12J5) in parallel with 22k, plus some contribution from the NFB. Perhaps I am going to use ½ 12SN7 instead of two 12J5...
The power supply is also quite strait forward, C-R-C for B+, C-L-C for C-, and DC for heaters. Maybe I will use a solid-state regulator for 12VDC. What are yours experience with regulators (7812 etc) for heaters in preamps?
Any other comments?
Preamp:
Power supply:
The object for this preamp is to keep things simple, with a gain of 10dB, and quite low Zout.
The input stage is a diff-amp, like a LTP. The gain in that stage is about 18dB. The line driver is a cathode follower with a bit NFB back to the inverting input of the diff-stage. Overall gain is estimated to be 10-12dB.
Zout is something like 1/gm (12J5) in parallel with 22k, plus some contribution from the NFB. Perhaps I am going to use ½ 12SN7 instead of two 12J5...
The power supply is also quite strait forward, C-R-C for B+, C-L-C for C-, and DC for heaters. Maybe I will use a solid-state regulator for 12VDC. What are yours experience with regulators (7812 etc) for heaters in preamps?
Any other comments?
Preamp:
An externally hosted image should be here but it was not working when we last tested it.
Power supply:
An externally hosted image should be here but it was not working when we last tested it.
