Specific question on buffer circuit

[diaretto]

Hi, i have a question regarding this circuit and the value of the pulldown resistor (R7) on the output of the opamp. What's its purpose? What's the right value to choose? I see different values being used.

In this (http://coldcrafteffects.net/blog/wp-content/uploads/2013/06/Micro-Buffer-Build-Doc-v2.pdf) document specifies different values depending what pedal (fuzz or not) the buffer goes into. I want to use the pot to raise the impedance of the buffer in case the first pedal is a fuzz.



Thank you!

[antonis]

R7 isn't actually a pull-down resistor (Vol pot serves for that purpose)

It "offsets" Pot's ground and serves for dual purpose..

It protects Op-amp from heavy loading (when pot set at minimum) and also sets output max/min impendance (in conjuction with pot setting..)

[DavidRavenMoon]

If you raise the output impedance you are kind of defeating one purpose of the buffer. It won't be able to drive the rest of the signal chain as well.

You are probably better off putting one of those pickup simulator circuits before the fuzz, assuming it's a low input impedance fuzz like a Fuzzface.

And they tend to interact with the pickup which it can't do with a buffer.

I prefer to just avoid archaic circuits like that. There are plenty of other fuzz and distortion circuits that will work.


Sent from my iPhone using Tapatalk

[antonis]

I prefer to just avoid archaic circuits like that.

If so, then you probably also avoid the use of archaic dictums like:
" A Fuzz with a buffer in front of it shouldn't considered as fuzz anymore ".. 

[karbomusic]

" A Fuzz with a buffer in front of it shouldn't considered as fuzz anymore ".. 

Beat me to it.

[bool]

So a fuzz driven by an axe that's loaded with EMGs isn't a fuzz anymore?

What is it then? A "buzz"? Or a "fizz"?

Seriously; if you're considering adding a "impedance adjustment" pot to your fuzz-friendly buffer, consider also adding a passive "tone control" pot like in the active guitars. Perhaps you'll like it.

[antonis]

So a fuzz driven by an axe that's loaded with EMGs isn't a fuzz anymore?

You've said the magic word..