Blend pot in an effects loop?

[Fastocker]

Hey all, I built this switching box for my Echoplex EP-3 and it works fine --- left and center switch operate the Echo ON/OFF and PLAYBACK functions of the EP-3 while the right switch is simply a Send/Return loop so I can switch the Echoplex out of the signal path if desired.





I used a wiring diagram from the Beavis site for the loop portion but now I'd like to add a blend pot to the loop to blend the echo (wet) signal to the clean (dry) signal.  I'm thinking turn the pot all the way to the left for dry signal, all the way to the right for wet signal and, when in the center, you'd hear 50% dry and 50% wet.

Does anyone know of a wiring diagram (or Vero layout) for this configuration? 

Thanks!

[oldhousescott]

Check out the FX mix circuit on the first page of this Mesa schematic.

Blue Angel

Depending on the output impedance of whatever you're driving your switchbox with, you may need to increase the value of the pot to 100k, 250k, etc.

[Fastocker]

Thanks, oldhousescott --- that one's a bit hard to read and a bit over my head as well.

I found these and was wondering if any of them would fit the bill:



--- or ---

[stecykmi]

It depends if you want an active or passive blend knob. That Mesa schem uses a pot so it's passive, but it does have a gain stage afterward to make up for any loses.

The circuits you've posted seem to use a transistor as a buffer (ie no gain). This is to prevent loading, which basically just means sending a strong signal to next part of the circuit.

the blendimum has a funny configuration, I would go with the other.

Keep in mind I have no idea what it is you're building since I'm not familiar with the circuit.

[Fastocker]

What I've built was a true bypass looper as shown in the diagram below from Beavis Audio --- this is for the right BYPASS footswitch on my pedal only (ignore the other two).  In my case the send and return would go to the INPUT and OUTPUT of an Echoplex tape unit but you should be able to use it with almost any effects pedal.  I'm simply trying to add a blend control in there to allow me to dial in the mix of wet and dry signals if possible.

If you go to the Loooper site and click on custom options, the Blend Pot is the fifth item down:

http://www.loooper.com/

[oldhousescott]

Here's the Mix pot applied to your diagram:

[attachment deleted by admin]

[Fastocker]

Thank you, Sir!  Will give that a try.

[Effectsiation]

Hey man, can you report back on if that worked out for ya? I'm thinking about something similar.

[Fastocker]

Nope, never did get it to work unfortunately.  I tried installing the pot as oldhousescott described but there was a big signal loss so I figured there needs to be some sort of active circuit in there to restore/maintain the signal strength.  I also tried the Blendimum vero layout but couldn't get that to work either.

Frustrated with this because I can't find a schematic or layout to do this.  Here are a couple of pedals available that do what I'm looking for:

[jkokura]

Working on this one guys. Layout will be available once I've gotten the board in and I've checked that it works. If it doesn't I'll let you know.

Jacob

[Fastocker]

Thank you, Sir --- much appreciated!

[jimmybjj]

this might be what your looking for

http://www.runoffgroove.com/splitter-blend.html