Mixing grounds and switching in a parallel distortion box

[wavley]

The problem is that since the other two Tubescreamers are being buffered by the standard Tubescreamer buffer I believe I want the impedance of the rangemaster buffer to be some what similar to the others, or does this matter? Could I just get away with throwing an inverting op amp stage before the Rangemaster?

I don't see why not, you're using the pickup simulator which works great in my Fuzz Face after a buffer.

[ianmgull]

That's what I was thinking. Can anyone recommend a fairly simple (low parts count) INVERTING buffer? Ideally one using bipolar NPN but I'll settle.

[wavley]

What about the beginner project with a trimmer or set resistor for the volume?  I'm pretty sure you can turn it down to unity.

[ianmgull]

So I was reading up on buffers and I came across this:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/buffer.html#c4

And realized it is exactly what I need. I know enough to know I don't know about the parts values though. I figure I don't want to do much filtering at this stage so I'd guess the in/out caps could be 1uf? Does anyone have any suggestions for the resistors? I really have no idea where to begin.

[ianmgull]

Ok so in the absence of any idea of what I'm doing regarding the transistor buffer I guess I'll try a simple op-amp stage like this:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/opampvar.html#c4

Again, I'm not sure about the resistor values so I'll start with two 100k resistors. I looked at the begginer project and even considered a LPB-2 after realizing it was inverting but decided against it for the sake of simplicity.

[ianmgull]

Please help!!!    I'm stumped!!

Assume I'm going to use the inverting opamp buffer below. I know for the gain to be -1, I need the resistors to be equal. I also know the value I choose will affect the impedance. Beyond that I'm not sure what a good starting point is.



Also, I assume I need input and output caps. Assuming I don't want to cut any audiable frequencies what would a good value be? (Forgive the noob questions. I know how to calculate this if it is a typical RC filter but not in this situation).

[Quackzed]

I think if you omit the resistors entirely, it will be fine. or use 10k's to be on the safe side...