My Beginner Project: Parallel Loops

[mjaskula]

I am a beginer preparing to do my first project. I was considering the beginner's project in the other forum, but I'm more interested ing the following project:

I'd like to make a parallel looper similar to those offered by Loooper. The initial version would have two true bypass (with led) loops that wouls run in parrallel. So you would be able to use Effect A in parallel with Effect B, or either effect in parallel with a clean sound. And of course with both loops off you would bypass the entire box. There would be a knob that would mix the the two effects, all the way to one end would be one effect, all the way to the other end would be the other effect, in the middle an even blend.

Additional features that I would like to include down the road include a toggle switch that would change the parallel loops to series. I wouls also like to be able to control the mix via an expression pedal. Both of these features would come later, after the initial version is working.

Does a project like this already exist? I'm sure I could make a series 2-loop bypas box very easily. My problem lies in blending the parallel signals. I'm not sure how to do this correctly. I've done some limited research and it seems like this may not be a trivial task. Also is there anything I need to know about splitting thee signals?

I would love some advice on this project from some of you veterans. Is this too complicated for a beginer? Arre there good resources available for this type of project?

Thanks for any help you can provide.

[petemoore]

Check out the Simple Mixer at AMZ. You'll need something like that or that to mix signals.
 I built a Splitter Blend with a treadle pedal for mixing parallel loops...works great...its at runoff groove.
 I think the Juggler article at GEO may have info on the parrallel/series efkts chain switching. Seems like you could draw something on paper that uses a DPDT or two for this. Possibly ~couple jacks and routing cables?
 Fir Bypass LED's I'm going with the 3PDT's for the simplicity...

[mjaskula]

Thanks for the references, I looked into them a little bit. I should be able to look a lot more next week.

The Splitter Blend looks like it does what I want it to. I was envisioning this as something fairly simple, is it? It looks complicated, I thought it might be possible for this to be a passive box, cause it's just routing signals. or does the blending require that it use those IC's?

Do you think this is a good project for a beginner? Or should I try that clean boost first? Anything I should watch out for?

Thanks for your help.

[B Tremblay]

The IC and FETs are necessary to eliminate the impedance voodoo that can occur when passively mixing in parallel.

The entire process could be simplified using two dual op-amps, rather than just the one, but my concern at the time was the potentially harsh sound of an overdriven IC versus a possibly less offensive-sounding overdriven FET.

I wish it was as simple as splitting your signal with a Y cable and then bringing the effects' outputs back together with another Y!

The Splitter-Blend could stand to be re-designed, possibly from scratch, but it should be able to meet your needs.

[mjaskula]

Thanks for the info B.

Can you explain impedance 'voodoo'? or point to a good low-level article on it.

Also can someone tell me if this 'Splitter Blender' is a good first project? Will I be overwhelmed? Should I try the NPN boost first?

Thanks for all the help guys.

[moosapotamus]

A better first project might be something simpler, like a Bazz Fuss. But, if you're feeling ambitious...

I built this to use with my bass rig. It only has one effects loop that runs in parallel with the straight signal. Controls are for wet/dry balance and overall output level.

http://www.moosapotamus.com/paraloop/paraloop.htm

Probably not too big of a deal to add a second effect loop if you wanted to. You'd just have to work out how you'd like the level & balance controls to work. Myself, I'd probably go with three separate volume controls (clean, loop1, loop2).

I don't know about impedance voodoo. But, my impression is that the main problem with trying to do this sort of thing passively is feedback. There is nothing to keep the output of one signal from feeding back into the other signals. If you want to try something cool to get an idea of what happens, get a fuzz pedal and connect a 1M pot from the output to the input, wired as a variable resistor. :shock: You need an active circuit if you want to keep that kind of chaos under control. :wink:

~ Charlie

[B Tremblay]

I agree with Charlie that the Bazz Fuss is a better "first" project; the Splitter-Blend doesn't even have a layout available, which can be daunting for a beginner.

The impedance voodoo I mentioned was the interaction between say, a fuzz face and a wah, when passively placed in parallel.  Since both effects like a certain impedance source driving them, the interaction caused both effects to sound weak.

By isolating the looped effects, the impedance interaction is effectively eliminated.

Unfortunately, I can hear that something's wrong better than I can diagnose and explain it, so looking in the archives or FAQ for impedance discussions would be a smart move.

[mjaskula]

OK I think I will do the NPN boost from the beginners forum for my first project.

I'll also search the forums to look for more impedence information when I start working on this parallel looping project. You guys can expect that I will begin asking questions again when that time comes. Thank you all for the usefull informations and recomendations.

One more question, I assume that a layout is the specific arrangement of parts on the perf board? what is entailed in making a layout? Is it just looking at the schematic and parts and deciding on the best positions for them? Would it be easy for someone who has made it to look at their board and draw up a quick picture to scan?

thanks for the quick resonses.

[mjaskula]

Myself, I'd probably go with three separate volume controls (clean, loop1, loop2).

Would you do this because it's easier to make or easier to use? I hadn't thought of this option, it seems very flexable. I imagine it will be more difficult to build.

It looks like to get exactly what I want I'm going to have to design my own schematic based on those you guys have provided as reference. Sounds fun and difficult. And will probably be more feasable after my first project.

Thanks.

[B Tremblay]

One more question, I assume that a layout is the specific arrangement of parts on the perf board? what is entailed in making a layout? Is it just looking at the schematic and parts and deciding on the best positions for them?

There are some basic considerations of space (obviously smaller is better), but the actual component placement can often follow the schematic.  Aron has some great examples and the RunoffGroove perfboard layouts also illustrate this method.  I usually keep the positive power bus along the top, negative at the bottom, input on the left, output on the right.  On higher gain pedals, it is a good idea to keep the input and output as far apart as possible, but usually if you follow the schematic layout, you'll be fine.

[moosapotamus]

Myself, I'd probably go with three separate volume controls (clean, loop1, loop2).

Would you do this because it's easier to make or easier to use? I hadn't thought of this option, it seems very flexable. I imagine it will be more difficult to build.

It looks like to get exactly what I want I'm going to have to design my own schematic based on those you guys have provided as reference. Sounds fun and difficult. And will probably be more feasable after my first project.

Thanks.

Yeah, I would do it that way 'cause I think it would be more flexible. Also, with three signal paths to deal with, how would you wire a balance contol?

It wouldn't be too tough to design. If you look at the ParaLooper, you'd just have to sort out the wiring for the output pots.

~ Charlie