Refering to the attached schematic, I am wondering if there's a fraud with this circuit.
The value of R14 is 47K in the above schematic. I just feel that it is rather weired having such low impedance at the 12AT7 grid. It reflects the same impedance to 12AX7's plate load. I am wondering if it was a mistake in the design or not. The plate load resistance of 12AX7 is about 70K. The plate load resistor should be 3 times of the plate resistance which is approx 210K. If we load it with 47K, surely it would have higher distortion. May be that's what the designer wants. Please correct me if I am wrong.
I have changed the R14 to 500K and C51 to 0.1uF. It improves the quality and dynamic of the sound dramatically.
I wish I could have the Tube CAD software to check this out.
The value of R14 is 47K in the above schematic. I just feel that it is rather weired having such low impedance at the 12AT7 grid. It reflects the same impedance to 12AX7's plate load. I am wondering if it was a mistake in the design or not. The plate load resistance of 12AX7 is about 70K. The plate load resistor should be 3 times of the plate resistance which is approx 210K. If we load it with 47K, surely it would have higher distortion. May be that's what the designer wants. Please correct me if I am wrong.
I have changed the R14 to 500K and C51 to 0.1uF. It improves the quality and dynamic of the sound dramatically.
I wish I could have the Tube CAD software to check this out.