Dual buffer using a TL072?

[pott]

I'd like to build a box with:

Buffer in
Buffer out

Each buffer with a footswitchable volume pot, to go from unity/off (when the volume pot is switched off or at its minimum) to boost. This way I have a clean boost before, a clean boost after.

Between each buffers/boosts, have an effects loop or two.

So basically I can plug the pedalboard in between two high quality buffers and with one switch, go straight to the amp.

So I'd like to figure out a buffer using a single dual opamp, and each with the possibility of transforming into a clean boost, without having an adverse effect when the loop is turned on and both buffers are right after the other, if possible..?

Thanks!

[David]

Look at R.G.'s Adjusticator on GEO.

[pott]

I have no idea what an inverting opamp is... :s I'm guessing it's where the signal comes in positive and leaves negative or something like that..?

So which of those adjusticators would I need? And would it be possible to get the volume pots to go from unity to boost (say + 20db)? I.e the footswitch would toggle between the boost pot and a fixed resistor for unity gain.

[Ben N]

Not a bad idea, but you need to crawl before you can walk. Google "op amp basics" and start reading. (If you focus on sites with an audio emphasis, youi'll avoid some stuff that you might not see the relevance of.) You will learn that a voltage amplifier is not a buffer, although it does buffer, that a buffer, or voltage follower, is a specialized variety (unity gain) of amplifier, and the difference between inverting and non-inverting configurations. Once you have a basic idea of what is going on, kludging together what you are trying to do out of pretty much standard and readily available building blocks will be a trivial task.

Some other things to consider:
1) There are some effects that don't like to be preceeded by a buffer, such as most vintage fuzzes. You can just put these ahead of your input buffer, but with true bypass switching so they don't load your pickups down when bypassed.
2) There are some effects, like vintage boosters, that work best when they interact directly with your amp.
3) You may already have decent buffers on board with your existing pedals; others can be made to work as buffers in "bypass" mode (check out http://www.muzique.com/lab/tsbuff.htm and http://www.muzique.com/schem/mosfet.htm.

[pott]

Yep I'm already buffered well, with Carl Martin pedals first and last, but used only as buffers for now (they're spares). I just love how they affect my tone straight to the amp. All of the pedals in the middle are true bypass, though by total accident. Most of them used to not be.

Mostly I'm looking for an easy build, some useful thing that'd allow me a bit more flexibility and ease of setup. I don't have any vintage fuzzes or boosters that'd cause me issues.

You're right though I'll do a bit of reading first... I just hope designing a buffer isn't above my head  Thanks!

[Ben N]

Actually, a simple IC buffer is pretty commonplace, check this one out: http://www.generalguitargadgets.com/pdf/ggg_ic_buffer.pdf. Also, there are a couple of articles on buffers at the AMZ site.

And welcome.