Feedback Looper

[scheffehcs]

Hey, looking to see if anyone has built or has a layout for a feedback looper. I’ve heard a phase inverter is handy, any other bells and whistles I could throw in there? Maybe a boost circuit?

 

[Nacht]

Just wondering what you found and if you build something?
I'm starting to look into making a feedback loop pedal.
Thanks

 

[coltonius]

Here's a layout for the Devi Ever Eye of God. No bells or whistles, just typical Devi insanity. You can omit the eye if you want something more 'standard'.

 

[Feral Feline]

Beavis' simple Flooper is the classic, I like his one with a little more control though, such as the Beavis-one in the article at the bottom of this post.

There's the Ohnoho's "Utter Stutter" which IIRC combines a feedback looper with a tremolo.


As for bells and whistles on a flooper...

Here's a few ideas I've messed around with for the FFFX Super-Flooper, use what you like but maybe you'll be inspired and come up with some of your own twists.

stompers:

ON/OFF (bypass)
FLOOP
100%WET ie DRY KILL 
+ MOMENTARY for DRY KILL or FX so dry continues while fx cuts in/out vice versa
STUTTER
ON-OFF ANTI STUTTER — have this patch-bay wired so it can do the whole signal or just the effect
ANTI-STUTTER [ this is greatly simplified to just two stomps now]
FX LOOP SIDE INSERT FLIP-FLOPPER
WARP!

KNOBS:
- Wet
- Dry
- DRY Gain
LEFT SIDE FeedBack
RIGHT SIDE Feedback Vol


AND MAYBE ...
BuffNBlend stomp & knob


DON'T forget HPF & LPF ! These don't have to be toe-controlled, could be small 9mm switches.
LPF on CLEAN
HPF on FX

Other considerations:
A limiter/compressor for after the feedback section of the Flooper, to help tame volume jumps and squeals
A GGG Translocator to swap in/out additional effects into the flooper such as a Hard-Chop tremolo (Vox Repeat Percussion), a Bitcrusher or similar or Escopedo's LoFoMoFo, a Parasit sonic reducer something or other
Buffered Bypass option for tails in case you put a runaway delay in the flooper...
Devi's LDR concept has already been mentioned by Coltonius, above, but you could also consider adding a proximity sensor ala ZachVeXx's Probe Wah ...



or via an optical sensor like the robot-builders use:

That way you could control the amount of feedback going through the flooper via a foot, and infinitely more cool than a simple BIG KNOB, or SLIDER that breaks the first time your clumsy-oaf size 13 foot hits it...

https://diyshoegazer.tumblr.com%2Fpost%2F3042080186

 

[scheffehcs]

I never got around to building a feedback looper! Crazy, this post does not feel two years old. Thanks for all the great info y’all, very inspiring. It’s back on my list.

 

[jimilee]

Oh, I gotta build one, now.

 

[Feral Feline]

I forgot to mention, instead of arcade-buttons, just use regular momentary stompers and add the plastic or aluminum toppers.

I have momentary footswitches in DPDT, 3PDT and even 4PDT — they are all much more robust than the arcade-buttons. Kinda doesn't make sense, since a true arcade-button has to withstand constant hammering as people try to defeat the Galaxians, Space Invaders, Centipedes, etc...

Maybe I just got consumer-level "arcade"-buttons... whatever, I think momentary footstompers are better suited to foot abuse and the coloured snap-on plastic covers from Mooer and the like are cheap and easily replaced, or you can spend a little more and get the aluminum ones with the set-screws. Just don't get the clear Lucite ones with set screws, they just break.

 

[Bricksnbeatles]

…they are all much more robust than the arcade-buttons. Kinda doesn't make sense, since a true arcade-button has to withstand constant hammering as people try to defeat the Galaxians, Space Invaders, Centipedes, etc...

Maybe I just got consumer-level "arcade"-buttons...

the arcade buttons on Amazon are pretty bad. The research I’ve done in the past seems To show that boutique pinball and custom arcade cabinet makers use Sanwa, Happ, or sometimes Semitsu brand switches. Each has a slightly different style to them, but they’re all much higher quality than the No-name stuff you typically find online

 

[Nacht]

Just finished mine.
I combined Beavis design with the LDR idea of the other layout and added pots for send and return levels.
Toggle switch removes the LDR from the path.
Swapped the toggle that activates the feedback for a 3pdt stomp with a led.
No pictures of the inside because it's a complete mess lmfao
Really simple raw enclosure, i'm not sure if everything is correct, probably not but it seems to make really weird noises and many settings to choose which is exactly what i was looking for

 

[RobotZombie23]

This is basically the same as Nacht's layout but with a dimmer for the led/ldr. Any Idea on how to add a phase inverter? or other bells and whistles? Feral Feline has some cool ideas in their post but does't show how to do them.

​

I hope this works. I haven't built it yet

 

[pricklyrobot]

There’s a buffer/inverter utility board listed as “coming soon”

Signal Buffer / Inverter - PedalPCB.com

Signal Buffer / Inverter

www.pedalpcb.com

This thread reminded me of one I built many years ago, off of one of the Beavis layouts, but haven’t messed with in a while…


Need to dig this guy out!

 

[Feral Feline]

This is basically the same as Nacht's layout but with a dimmer for the led/ldr. Any Idea on how to add a phase inverter? or other bells and whistles? Feral Feline has some cool ideas in their post but does't show how to do them.

​

View attachment 86879
I hope this works. I haven't built it yet

I don’t understand your diagram, which admittedly could be due to my having had extremely little sleep in the past week.

Nacht’s posted diagram I get, but yours is not similar — at least not to me.

Nacht’s has 2 LEDs wired as bypass indicators for their respective bypass-switches.

You’ve got 3 LEDs, first LED is for the master bypass, which is … yeah, normal.

Second LED is wired to a momentary switch, so it isn’t strictly necessary but why not have fun and have it light up whenever you activate the momentary.

Last LED looks to be set up for the LDR, on a dimmer, I guess to set a constant level of feedback?


Last LED I’m not understanding. I thought the point of an LDR for this sort of flooper-setup is so you can hover your foot over it (LDR being mounted externally) and control the feedback via the amount of light you let hit the LDR.

If you want a set-and-forget level of feedback, you just need the feedback-potentiometer, no LDR required.

The LDR in Nacht’s acts as a variable resistor (potentiometer);
You have audio signal going through your LDR…dimmered-LED

Sorry, I’m completely lost.


If there’s anything in my earlier post you want to add — mods/features such as phase inversion, adding an H/LPF, dry-kill, anti-stutter, etc — I’ll do my best to help integrate it in your build, but first I need to understand it and your goals/objectives.


To reiterate: I’m sleep deprived and viewing this all on my phone instead of my computer.

I know better than to post when sleep deprived, but I still do it.

I’ll come back to this after some zeds and coffee ️ tomorrow

 

[RobotZombie23]

You have audio signal going through your LDR…dimmered-LED

Is it not the same a Nacht's diagram? I looks like the audio signal is going through the LDR on coltonius's layout too

Someone said they don't like the LDR because its inconsistent depending on what room your in. I thought I'd try to make it work different. Maybe an envelope that controls the brightness of the led? or a fader that automatically fades the led in and out that you can adjust the rate?

Would I be able to make this a parallel mixer too? I would be nice to have that and "ON-OFF ANTI STUTTER — have this patch-bay wired so it can do the whole signal or just the effect"

I'll probably make what I have in the diagram (I will be away for a couple days so I can't do it right away) and see what happens.

first I need to understand it and your goals/objectives

I'm just messin' around trying to make nasty sounds with my guitar.

Thanks for your reply

 

[Feral Feline]

Is it not the same a Nacht's diagram? I looks like the audio signal is going through the LDR on coltonius's layout too

…

My foggy sleep-headed posts are worse than drunk-posting.

Indeed the audio is going through the LDRs, Coltonius’ & Nacht’s controlled likely by ambient light, yours by the fixed-LED source — I must’ve been following the path, trying to trace it out.
I think it’ll work, I think my foggy brain was trying to figure out why. From what I can comprehend, the dimmable LED-to-LDR is not doing much that a straight pot couldn’t do. Therefore unnecessarily complex, adding extra parts to potentially introduce fail-points, and added cost,
BUT…!

Add in your ideas about an envelope or having the LED fade in and out via a 555 timer or similar — it becomes an intriguing twist on the flooper concept.

If you put anti-parallel LEDs on the input signal to react to your playing — say a Muff clipping stage or boost driving the clipping diodes to ground —and have the LDR on the feedback path, as you suggested the harder you’d play the more feedback (or vice-versa if you want).

Someone said they don't like the LDR because its inconsistent depending on what room your in.

Yeah, if you dial in the LDR to react to an ambient light source in the lab, then try to use it on stage with a light-show … I know some people have added a clip-on light to their board to have a consistant light source, but the light show may still affect the LDR even so.
With your idea, internal of the pedal, you’re no longer constrained by ambient light — GOT IT! Took me awhile, but I finally get it. I can be slower than molasses flowing uphill in January.

Would I be able to make this a parallel mixer too? I would be nice to have that and "ON-OFF ANTI STUTTER — have this patch-bay wired so it can do the whole signal or just the effect"

Sure. I don’t see why not. I’ll have to try working that out when I get my computer back.


More mayhem mod ideas…
Flickering LED: I’ve got some randomly flickering-LEDs, no extra circuitry needed — just CLR and apply juice. That could be pretty cool, random levels of stabbing shriekback.

I got a few of the little flickers from Electronic Goldmine (they come in red blue amber…I think I got the latter), if they’re sold out and you can’t find them elsewhere I can send you a few, once the postal-strike here, gristmas, and associated backlog has been addressed.

 

[RobotZombie23]

It Works! I sometimes get a ticking from the ne555 I guess? I can try to shield it but I don't care enough to do something about it.

I used a couple guides on youtube to put together a circuit with the ne555. I can adjust the speed of the blink/fade and toggle between fade and blink. It reacted nicely with the Phase II and a couple other pedals once I found a good setting.

For the momentary switch I chose a sanwa arcade button. I have some extra from using them for killswitches in my guitars ala Buckethead. I think it looks cool and is easy to press with bare feet and it shouldn't break... I hope

I haven't messed with it too much but I think I want to replace the Feedback knob with a Log. pot maybe 250k? I just used what I had sitting around. I only seems to do anything at the very end of the sweep
Ignore the Husky glitter in the pics btw

 

[pricklyrobot]

Looks good!

I just make (rough) calculations based on this chart, when pots aren’t behaving as expected/desired. Usually gets me close enough:

 

[jwin615]

A few things for the ticking, if you care to try them.
-Try swapping the ne555 with a CMOS version. They don't dirty up the power line as much as a NE555. They are more limited in their current load ability but running a single LED is probably fine.
-use a 5v LDO to power it separately and run a dedicated ground back to the DC jack.
-run all audio cables away from the 555 circuit, preferably shielded cables.