Pro Co Rat Input & Output Buffers
Hi, I'm thinking about building a ProCo Rat, and I'm wondering about the input and output buffers. There are many schematics in the internet, and they differ a lot. In some versions you don't have the input buffer at all, and in some versions the buffer transistors have different biasing or different transistors. Some have even BIG errors. Errors with the biasing, errors with the transistor symbols.
Since I have no access to 2N5458 or BF245A transistors I'm thinking of designing my own buffer circuit for the output. Here are the data sheets of these transistors:
I understand that the devices are symmetrical, and that means it really doesn't matter which way you connect the drain and the source. The second thing that catches my eye is that it seems the devices are supposed to be run with negative Vgs voltages, and that at 0 Vgs, the transistor is fully on. In other words the cut-off voltage Vgsoff is negative.
I read somewhere that some guy has made this circuit with different in/out buffers, even with no buffers at all. It's looks like the output buffer is more crucial, since in the latter Rat versions the input buffer was discarded anyway. What would the circuit be like without both buffers? I guess a guitar amplifier shouldn't be that big load... But I guess it influences the LM308 too much?
What do you think?
Also all modding ideas and other comments about the Rat are welcome!