adding a dry control to any circuit

[fatfoohy]

I know this is definitely a noob question, but i tried searching and failed extremely hard.  How can i add a dry control to circuits without an input buffer? would I have to add an input buffer and then tap the dry signal after that. I am pretty much a noob when it comes to some of this stuff, so a good schematic and a healthy description would really help me. Just fyi i am looking to put it in a jordan bosstone and a nurse quacky.  Thanks in advance!

[GibsonGM]

I would definitely go with an input buffer (splitter).  There's a JFET one over at AMZ, link at the top of this page. 
If you just tap off the input signal, you can get some pretty weird interactions going on.  A buffer will ensure that the circuit 'sees' the same signal that is going out to the output.   
Don't forget to take phase into account, just in case the phase changes...that can also introduce some odd effects if there is a large enough shift.

[fatfoohy]

alright, so i've got the schematic, so where exactly should i tap the signal? I would assume right after the buffer, correct? and can you explain phase to me? thanks for your help

[GibsonGM]

Well, my man, there are a few different ways to go about this.  Personally, I would consider adding a buffer between my input and the 'real' input of the circuit, and just 'fanning' the outputs.  Simply split the buffer output into 2, one feeding each circuit leg (the 'real' one and your new one).   

You might use a series resistor in each leg just to keep things nice (to avoid interactions with the input capacitance of each stage - try like 1k to 10k and adjust if needed).

Phase:  if you had a specific project and could post a link, someone could tell you if phase will be an issue.   If you take an AC signal and run it thru something like a transistor, depending on how it is set up, you might be inverting the signal...making it 180 degrees out of phase from how it looked at input.  If you then mix that with the dry signal, it will cancel itself and you'll have no input (and yes, no output, so it's theoretical, but you get the drift...).  Degrees of phase difference can produce odd effects (one of them being the phase pedal which we all know and love!). 

Basically, you can tell if you look at a schem. if you are going thru an inverting stage, then another one (which = same phase as original), then another inverting to output (which would mean an inversion).  So you  might need to add something like a unity(ish) gain output stage somewhere to adjust the signal.   I would try the whole thing out and see what it sounds like before I'd worry much about it...something like that will just come with learning more about reading schematics. 
Every R/C filter you go thru yields a 45 degree phase change, too.    This is part of what makes amps/pedals unstable, and is VERY complex for the beginner (and not so beginner, lol).   I suggest experimenting, then asking ?'s if you get in trouble.  Feel free to post a schematic, maybe this will be interesting?

~MJP