Loop pedal with spillover/bleed?

GuitarTek86 · March 07, 2011, 10:56:05 PM

previously posted in the wrong category....

here's the idea. I want to build an effects loop pedal that when you click back to bypassed signal from the effected signal, the effected signal will spillover natually (IE remaining delays, or reverb). here's the problem. I am a complete noob, and have very little knowledge in electronics apart from wiring guitars, and doing simple mods. can anyone tell me how I can do this? I'm guessing it would be super simple...

on my mis-categorized post, CynicalMan said...

"So, you're trying to make a loop pedal that lets tails from delay and reverb through. For that you need a blender that mixes the dry input and effect return, then switch the dry input so that it goes either to the blender or the effect send. I can't draw a diagram now but I'm sure someone can help you with that if necessary. Also, this kind of post belongs in the building you own stompbox forum. More people watch that forum so you can get an answer more quickly."

Thanks in advance. I have faith in you guys!

vendettav · March 08, 2011, 09:19:33 AM

ahh yeah that Hardwire Delay stuff e

basically what you got was what you need. you need a FX blender. get one from GGG and an FX loop.

Pedal input> switch>A>mixer>pedal output
B>FX^

guess that'll do... Switch is before the A/B so it bypasses the input to one of them.
hope that makes sense

Hides-His-Eyes · March 08, 2011, 10:50:18 AM

Won't be true bypass but not a problem.

You should look at the Echobase circuit which does this but instead of the delay section you'd put your send and return jacks.

slacker · March 08, 2011, 01:13:34 PM

Here's a simple design that should do what you want. I haven't built it yet, but I don't think there's anything wrong with it.

The switch grounds either the dry signal which goes thorough the lower path or the input of the loop. This gives you either the clean signal or what ever is in the loop. When you switch from loop to clean, you get the delay tails or what ever from the loop mixed with the clean. If you use a DPDT switch you could use the other half for a LED.

It could be improved a lot, but it should work fine, I might try expanding the idea into something with more features.

vendettav · March 09, 2011, 03:51:06 PM

^ nice

what would the IC be? LM386?

slacker · March 09, 2011, 04:06:23 PM

The IC is a dual opamp, I'd use a TL072 but virtually any dual should be fine.

GuitarTek86 · March 10, 2011, 06:11:18 PM

thanks a lot for the info guys. still trying to get this to work. it would help if I could read schematics

so what I'm gathering is that you can NOT do this with a simple tpdt toggle, 4 mono jacks, and some wire... right? if anyone has a wiring diagram rather than a schematic, it would do wonders for me since I'm retarded and can't make sense of schematics. haha. thanks again guys. sorry for the total noobtivity on my end...

R.G. · March 10, 2011, 07:08:43 PM

Quote from: GuitarTek86 on March 10, 2011, 06:11:18 PM
what I'm gathering is that you can NOT do this with a simple tpdt toggle, 4 mono jacks, and some wire... right?

Yes. Sorry. It requires active electronics to do it well, not just switches.

slacker · March 12, 2011, 07:32:02 AM

If anyone's interested I chucked the thing I drew above on the breadboard and it works fine. I'm working on a better version that doesn't invert the signal and has the option of tails or no tails, latching/momentary switching and a feedback loop.

GuitarTek86 · March 12, 2011, 10:37:26 PM

I'd love to see what you came up with. I'm going to be building a large loop pedal to true bypass each of my pedals, and this is something I would really like to include in my design if I can wrap my in-experienced mind around it. haha.

GuitarTek86 · March 28, 2011, 10:51:03 PM

anyone build one of these? I'd love to see pictures, since I'm having a hard time making sense of the schematic...

GuitarTek86 · April 07, 2011, 03:53:52 PM

trying to make one of these. I have never plotted a board before. can someone who knows what they're doing confirm that this is correct? I'm sure there's a simpler way, but I'm a n00b. seems like there should be less jump wires...

GuitarTek86 · April 07, 2011, 04:22:36 PM

just realized my ICs are too narrow...

slacker · May 24, 2011, 01:33:56 PM

If anyone's interested I did a vero for this. http://www.eskimo.plus.com/fxstuff/tlboard.jpg

It's slightly different from the schematic I posted above in that it has an extra switch to give you the option of tails or no tails. I haven't built it, but I think it's Ok.

BennyBoop · May 26, 2016, 12:03:15 PM

Hi,

Came across this one a wide search for a useful tool to put in a bypass looper, but the link is broken. Anyone have the last version slacker made on file?

GuitarTek86 · May 26, 2016, 12:16:42 PM

You are in luck, my friend. I have it on my public Dropbox. Here is a link. Let me know if it works for you. I have built it and it works perfectly!

https://www.dropbox.com/s/n1jf01pc8egsalr/SlackersLoop.jpg?dl=0

Mark Hammer · May 26, 2016, 04:27:09 PM

Personally, I think your needs would be best-addressed by a simple pan pedal: a volume pedal that goes from full bypass to full effect as you move the foot treadle. The reason I say that is because you will most likely NOT be satisfied with a single fixed transition time as things "spill over". So now, once you find the need to have a variable transition time, the circuit starts to becomes more complex.

MUCH easier to have your variable transition time be a function of your foot. Assuming no motor limitations on the user's part (and I don't mean that in any sarcastic way - I'm pitching a solution that assumes certain preconditions), transition time is set by how fast you want to move your foot.

Hard to draw with keyboard characters so I'll try and illustrate with a bit of drawing and a bit of your imagination.

- [ R1 ] --x--[ R2 ] -

- [ R3 ] --x--[ R4 ] -

R1 and R3 each take an input. R2 and R4 each feed a mixer. Joining the two points labelled 'x' are the outside lugs of a linear pot. The wiper of the pot goes to ground. Move the pot wiper in one direction and the input resistor and leg of that side of the pot form a voltage divider that attenuates the input signal. When the wiper is at point x then that input signal is dropped down to nothing. The other input resistor and the (now) entire resistance of the pot on the other side of the wiper still provide some attenuation, but that can be compensated for by some gain at the input stage, and perhaps at the mixer stage.

The same circuit could also be used for blending wet and dry.

slacker · May 27, 2016, 12:41:20 PM

Here's a link to the vero layout from the broken link above, it's the same as the one GuitarTek86 kindly shared except it has the component values on it.

http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=52584&g2_serialNumber=1

karis12 · February 07, 2017, 05:23:08 AM

Bumping this for an update request.

Has anyone ever come up with the circuit in question, that does not invert the phase? Thanks in advance for replies.

blackieNYC · February 07, 2017, 06:37:18 PM

Google inverting op amp buffer - you can add the buffer or reconfigure that input to use the inverting input.

Slacker's circuit is nice. I would consider grounding the return (so you don't have unwanted pedal noise coming into your mixer) instead of the send for normal looping operations, but if you're doing a tails thing then do it as drawn.

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Loop pedal with spillover/bleed?