Question about the ROG splitter blend

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Question about the ROG splitter blend

Postby Yonatan » 11 Apr 2012, 14:48

I'm interested in buildling a blend pedal. I was looking at the other "blend" threads, and one of the ones I'm interested in is the ROG (http://www.runoffgroove.com/splitter-blend.html), but I have a few questions about this circuit:

1. It looks more versatile than a simple blend dry/wet signal blender, since it has 2 parallel effects loops, so how would this circuit be used to just blend the dry signal with a single wet signal? I'm guessing it would be:
- Guitar -> In
- Send 1 -> Return 1 (to connect the dry signal)
- Send 2 -> Effect(s) Chain -> Return 2 (for the wet signal)
- Out -> Amp

2. Looking at the schematic, why is there a transistor placed before the OpAmp stage after the GREEN return, but not after the RED return? My only guess is that is somehow is needed for getting the phase inverting option to work.
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Re: Question about the ROG splitter blend

Postby B Tremblay » 11 Apr 2012, 16:12

The FET buffer provides a high impedance input for the phase reversal network.

I use a normally closed jack for the Send of the Red channel so that when no plug is inserted, the Red Send and Return are connected.
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Re: Question about the ROG splitter blend

Postby Yonatan » 11 Apr 2012, 18:55

Thanks for clarifying, I think that I found my next project. This thing sounds incredibly useful. Time to start ordering parts :)

By the way, how do you accomplish this trick?

B Tremblay wrote:I use a normally closed jack for the Send of the Red channel so that when no plug is inserted, the Red Send and Return are connected.


I know how plugging something in can create a connection (like using a stereo jack for the input of an effect to complete the power circuit, for example), but how can something be wired so that plugging something in to the jack breaks the connection? Or is this just a special type of jack that I need to order?
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Re: Question about the ROG splitter blend

Postby B Tremblay » 11 Apr 2012, 19:51

Yonatan wrote:Thanks for clarifying, I think that I found my next project. This thing sounds incredibly useful. Time to start ordering parts :)

By the way, how do you accomplish this trick?

B Tremblay wrote:I use a normally closed jack for the Send of the Red channel so that when no plug is inserted, the Red Send and Return are connected.


I know how plugging something in can create a connection (like using a stereo jack for the input of an effect to complete the power circuit, for example), but how can something be wired so that plugging something in to the jack breaks the connection? Or is this just a special type of jack that I need to order?


Yes, you need a normally closed jack. Here is an illustration and diagram:
http://gaussmarkov.net/wordpress/parts/ ... and-plugs/
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