Thinking about maybe starting from scratch. But something along the lines of a “JC Morrison” driving a 45. yeah, it’s maligned design for the 300 B. Maybe rightfully so, but I’m curious to see how much it can be optimized and used with an easier to drive tube like a 45.
6922 also works very well on lower plate voltage. 40v B+ sounds great but i needed more swing so I used 125v
I am going to try 6j1 at 30v B+ for phono.
I am going to try 6j1 at 30v B+ for phono.
Theoretical discussions.
If you use 6SN7 at about 2mA, the Rp about 10-12kOhm, the recommended plate load is 20-24k.
On this load the voltage drop (Rload*Ia) about 40-48V.
If you use 30V, 2mA operating point (with 20k load), the bias about -0.2V, the B+ about (30V+40V) 70V.
The grid driving MUST BE capable A2 mode, so must to push to grid even few mA current.
The estimated output swing about 32Vpp .... with not so little distortion.
BTW what's the goal of using 6SN7 in A2?
If you use 6SN7 at about 2mA, the Rp about 10-12kOhm, the recommended plate load is 20-24k.
On this load the voltage drop (Rload*Ia) about 40-48V.
If you use 30V, 2mA operating point (with 20k load), the bias about -0.2V, the B+ about (30V+40V) 70V.
The grid driving MUST BE capable A2 mode, so must to push to grid even few mA current.
The estimated output swing about 32Vpp .... with not so little distortion.
BTW what's the goal of using 6SN7 in A2?
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There is also a 12SX7 , a 6SN7 variant with 12V heaters only and with specs and curves for low voltage operation.
Although Tung-Sol claims "specially designed for low voltage" it also lists the same high voltage data as for any 6SN7.
Although Tung-Sol claims "specially designed for low voltage" it also lists the same high voltage data as for any 6SN7.
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