newbie question about blending (for bass)

[SirPoonga]

I have been looking at the bass paralooper.  I saw a schematic the other day that I forgot to bookmark, I can't find it now.  It was like the paralooper but you blended two effects.  It would work the same as the paralloper if one set of effect jacks weren't used.

I'm wondering why the signal has to go trough op amps and why this has to be a powered circuit?

Couldn't one just split the in signal into two.  Both of those goto a send jack.  The receieve jacks goto lugs 1 and 3 of a pot.  Lug 2 goes to out.  
What would be bad about doing something like that?
Actually, it would probably be better to have two "volume" pots instead of one "blend" pot but the idea is the same.

[tommy.genes]

As for blending two different effects chains, check out the Splitter-Blend at runoffgroove.com.

As for why blend circuits need op-amps, most of them are for buffering and/or protecting against strange impedence mismatches amongst your other pedals, instrument, amp etc. The other important reason is to prevent feedback, which is what happens when a portion of your effected signal bleeds back into the input of your effects. While this can sometimes be a desireable effect, it can get out of control quite easily if not managed properly.

Check out Sean M's B Blender page, which also includes a link to his  90% B Blender design that uses only one opamp. You just have to hope that all your other equipment plays nice, though.

-- T. G. --

[SirPoonga]

That's the schematic I forgot to bookmark, the runoffgroove blender.

Thanks for the info.

I think I am going to start with the runnoffgroove schematic and see how it works for bass.

One of the cool things I will do with a splitter-blender is delay one of the channels a slight bit and make it sound like two basses are being played.

[SirPoonga]

About the splitter-blender ...
I've have to get the parts and breadboard this to see how well it works with bass.  But, let's say it is filtering off some of the low end.  I noticed all inputs have a 220n cap.  All outputs have a 10u cap.  This brings up the question do you need that?  IE, what happens if you removed the green and red send and receive caps?  Most effects have an input and output cap already, so why would one need to be put there?  Could it be possible those caps will rob bass going to the connected effects?

I know, I'm probably thinking to far ahead but I'd like to learn this stuff

[tommy.genes]

From strictly a bass frequency point of view, both the 220nF and 10uF caps (in conjunction with the 1MOhm bias and pull-down resistors) have -3dB frequencies below 1Hz, and both have near-unity gain even at a low B string fundamental of 32Hz. So neither one should significantly suck away your low end.

Of course, that leaves the question: why did ROG choose the values they did, instead of using the same value everywhere?

So much more to learn.  :?

-- T. G. --

[SirPoonga]

cool cool.  BTW, how did you figure that out?  If I learn that it will make life easier   I look at an effect and I always wonder if it will work with bass.

[tommy.genes]

This Link describes it as well as any I've seen. You want to look at the RC High Pass filter in this case.

Just to clarify one possibly confusing point: "frequency" as a musician would understand it is depicted by the variable f, but frequency as a mathemetician would understand it (also called "angular frequency") is depicted by a lower-case omega, which looks like a squiggly w.

When looking at the above link, just remember that:


-- T. G. --