Feedbacker Not Noisy Enough

[aChorusofJays]

Well, I've finished my Feedback Looper is finally finished, and I tried it out last night for the first time properly! What a disappointment.

Here's the schematic I used:




Here's a picture of the final results, then I'll tell you my setup:




I was running an Epiphone SG into a Line-6 DL-4, into a Rat, into the Looper, with an SD-1 and a SmallClone in the loop, then out to a Fender Bluesdriver. Sounds like I should get some crazy sh*t right? Well, I didn't.

Basically, with the Loop and Feedback Loop turned on, with the pot starting at 7-o'clock, I'd get the pre-loop signal with the loop signal creeping in, @ 9-o'clock the Pre-loop and Loop signal are about even, and from then on the pot doesn't really do much.

Other than the expected feedback from having a Rat running into an SD-1, I didn't get anything out of the ordinary. I know chorus effects aren't necessarily the best for loops, but the delay should have done something. Right? Or am I over-estimating the fun this pedal was supposed to be?

[cloudscapes]

sounds like it's wired wrong. every single delay I've ever used, except for the boss DD20, turned int oa sea of insanity in my feedback loopers. chorus went pretty mad as well and started self-oscillating. some distortiosn I've tried actually started beeping when in the loop.

your DL-4, like my DD20, might not be super compatible with feedbackers in general because it's more like a computer inside, rather than having real delay circuitry.

[aziltz]

2 things.  it does seem like its wired right, i would think the pot is used to blend between wet and dry signals, and thats not how it appears to me.

and b, would you want to put the delay in the loop to get more craziness?

[Andi]

Nah - the pot is there to allow a feedback path between send and return of the loop (though in the schematic it's between send and output-when-engaged which is puzzling me).

[ashcat_lt]

I haven't traced it through to be sure if this could cause the problem you're experiencing, but I know those 3 pole switches are pretty easy to misorient.  Are you sure you haven't got it turned 90 degrees?

[tommy.genes]

I had this same problem when I built a feedback looper. You need to look at the feedback loop in both the reverse and forward directions to understand it.

As you turn up the feedback knob, you are lowering the resistance along a path from the tip of the output jack to the tip of the send jack, allowing more of the output signal to feed back into the signal going to the pedals in the loop.

However, you are also lowering resistance along a path from the tip of the input jack to the tip of the output jack via the tip of the send jack (follow along in the schematic, hopefully I'm making this clear). So, as you are trying to increase the feedback from the output to the send, you are also allowing signal to bleed from the input directly to the output. In a way, the knob is acting as a both a feedback and a blend knob simultaneously. In my case, when the feedback pot reached max, all the clean signal passed directly from the input to the output, effectively bypassing the loop entirely.

If you read opinions about feedback loopers on forums like MusicToyz, HC and ToneFactor as well as this one, you will see that results vary wildly among users, or even among different pedals for the same user. I think it has to do with the input impedance of the pedal right after the send jack, and that of the pedal or amp right after the output jack. Your signal is going to choose the path of least resistance, so with some pedal combinations, you will get plenty of feedback and very little clean signal bleed, but with other pedal combinations, you will get just the opposite.

I had an idea to fix this, but never got around to trying it. If you do, please share your results. You could put an emitter-follower or an op-amp buffer into the feedback path to help insure that audio only flows in that direction and not in the feed forward direction. Do a search for SeanM's 90% B. Blender. He used this same idea to prevent a clean blend path from becoming a dirty feedback path, but you could flip it around and use it to prevent a dirty feedback path from becoming a clean blend path.

-- T. G. --

[Taylor]

would you want to put the delay in the loop to get more craziness?

Yeah, the delay's not going to do anything weird if it isn't in the loop.

[aChorusofJays]

So its been a couple of months since I built the Feedback looper, and I've finally gotten a chance to give it a real test-run. I think my favorite right now is guitar - FeedLooper - Whammy - Overdrive(boss) - Amp. I'm getting some cool Oscillation and some wet pitch-shifting, lots of fun!

My only issue at this point is that because of the wiring, I'm getting my original 'clean' signal with my Feedback signal. I'd rather just have the feedback signal exclusively. I've been thinking for about 24 hours about how to rewire this puppy, but my electronics skills are so shockingly inadequate, I'm stumped. Here is a picture of my current wiring scheme.







It's the X-wing style DPDT. Any advice you can give would be great. I know most of you will be able to take one look and just know what is and isn't possible with this setup.  Thanks guys!

[ParlorCitySound]

just giving this guy a bump. I've got about the same problem going on. Trying to but my BYOC fuzz though the loop. I can only hear a slight tonal variation...no chaos.

[Taylor]

So its been a couple of months since I built the Feedback looper, and I've finally gotten a chance to give it a real test-run. I think my favorite right now is guitar - FeedLooper - Whammy - Overdrive(boss) - Amp. I'm getting some cool Oscillation and some wet pitch-shifting, lots of fun!

My only issue at this point is that because of the wiring, I'm getting my original 'clean' signal with my Feedback signal. I'd rather just have the feedback signal exclusively. I've been thinking for about 24 hours about how to rewire this puppy, but my electronics skills are so shockingly inadequate, I'm stumped. Here is a picture of my current wiring scheme.


It's the X-wing style DPDT. Any advice you can give would be great. I know most of you will be able to take one look and just know what is and isn't possible with this setup.  Thanks guys!

Just look at the path you've got going. Your input goes to the 3PDT. When the loop is active, the input is connected to the tip of the send jack, which is connected to the feedback pot, which then is connected to the output. So your input and output are connected, that's why you have the clean.

I can't say I really understand what's going on with your DPDT. The resistor and LED aren't connected to anything? And you have the feedback pot connected to ground, so the feedback pot is grounding the signal going to the send jack? Maybe I'm looking at it wrong, but that doesn' make sense to me.

[Taylor]

just giving this guy a bump. I've got about the same problem going on. Trying to but my BYOC fuzz though the loop. I can only hear a slight tonal variation...no chaos.

Note that not every effect sounds crazy with feedback.  Why don't you post a gut shot of your feedback looper so we can see if you've got any obvious problems? Actually, same for you, AChorusOfJays, that would help diagnose.

[earthtonesaudio]

My advice would be to start over and do a deluxe active version.  Buffered inputs/outputs/phase reversal, the works.

[frequencycentral]

My advice would be to start over and do a deluxe active version.  Buffered inputs/outputs/phase reversal, the works.

+1, been thinking that myself recently while planning my "Loop Computer".