Adding a blend control to a true bypass pedal.

[Shawk]

It already has a 3PDT switch in it and I would like to add a blend control for the loop only when the loop is active so I can blend in my effects to my dry signal without volume loss.

I want it like this:

Full clockwise: 100% wet signal

Full counterclockwise: 100% dry signal

12 'o clock: 50% wet, 50% dry.

Switching "off" on the 3PDT bypasses the potentiometer and loop completely.


How should this be wired in the "send" and "receive" loop?

What ohm potentiometer works best for this?


Thanks

[petemoore]

http://runoffgroove.com/splitter-blend.html
 Actually that's two circuits that work well together.
 The splitter part, well it's nice for getting 'two signals out of one or for driving the signal into two different other circuits like effects or amp.
It does your line like this ---<
 The Blend part is what works like 2 mixer input channels
and takes two sources from the blend [could be two different guitars for amp sharing..etc] takes two sources and mixes them like  >---giving a nice blended output.
  I built the S/B and have the mix pot on a treadle foot pedal.

[Shawk]

Isn't there a way to do this passively?

[smoguzbenjamin]

Passively.... yes if you are willing to accept massive signal loss, major tone sucking and no proper result.

If you want to do something properly, use a little bit of active circuitry. It makes all the difference.

[Peter Snowberg]

Welcome Shawk,

Check out this thread from a couple of weeks ago...
http://www.diystompboxes.com/sboxforum/viewtopic.php?t=19737

99% of the time it takes more than just wiring up a pot (thanks to impedance issues), but add an opamp and it's pretty close.

Best of luck and if you have more questions, please ask.

Take care,
-Peter

[Shawk]

I emailed Dave Boggs at loooper.com and he says that his units with the "blend" option are all passive.


What gives?  :?  :?

[Alex]

You can blend two signals that come from two sources that have the same low output impedance (like two Boss pedals), but if there's any mismatch between the two outputs then the blend control will not work very well or it will work very poorly.

Don't try to blend your dry guitar with a pedal output. You won't like it. It will suck the tone right out of your dry signal.

You will like a buffered blend control MUCH better than a passive control in almost any circumstance.