Mini Mixer, do I need that cap and resistor?

[bbmonster]

Hi, after reading info about the mini mixer at http://www.generalguitargadgets.com/diagrams/mixer_sc.gif, the suggestion was to place a buffer in front of the input. So as I bread board the mixer and put buffers in front of two inputs, I ran out of a few parts, the .1uf capacitor and the 100k resistor after the 10k pot for 2 inputs (more specifically C3, C4, R7, R8 from the schem). Those inputs, I placed a buffer in front of them. Just out of curiosity I tried to fire it up to see if it works, no big surprise it doesn't.

So my question is, how important are those parts to the circuit, resistor and capicator? Also, would I need the .1uf capacitor after the input pot if there is a buffer in front of that input? The buffer already has that 10uf capacitor before its output.

I know the answer lies in just bread board the whole thing and experiment but I need to mail order the parts which takes a few days because I'm not about to spend $1.79 for one capacitor at Radio Shack. So any help from the top of your heads is very much appreciated.

Thanks.
-Bernard

[Mark Hammer]

You need the .1uf cap to block any DC coming from the earlier stage.  You need the 100k resistor to set the gain of that signal in ICa.  If R5-9 = 100k and R9 = 100k, then gain = 1.  If R5-8 = 0 and R9 = 100k, then gain = you-can't-count-that-high.