02-24-2013 01:55 PM
Hello, just need a few questions answering regarding building a feedback looper, the more i've looked into it the more interesting variations i've discovered but given my lack of in depth knowledge i need some advice about how to go about building it.
Basically i'd like to build an UTTER STUTTER style feedback looper, one that gives that cool tremolo like effect. http://www.youtube.com/watch?v=VJR3hRmkWl8
Does anyone know how i'd go about building a pedal like this? The other thing i noticed from this video is that, unlike most other feedback loopers i've seen, there seems to be a fairly well balanced mix between the effects as they would sound normally and the feedback loopers craziness. I'd like a feedback looper that i could use live, whilst still having 50% of my normal guitar sound coming through and the other 50% coming through the feedback looper and going mad in the background. Would this require a blend knob or is it all or nothing with these things? Apologies if this makes little sense, it's indicative of my confusion.
Thanks a lot
02-24-2013 05:21 PM
Well, you can use an LFO circuit to control an opto-coupler that modulates how much feedback you're getting. Basically, the parts that aren't overwhelmed by the feedback loop you've created would be the normal sound of the pedal because it's varying the ammount of feedback with a variable resistor. So, it might very well be going from full feedback to almost none depending on how you have it set.
Anotehr way to do that would be with an LFO controlling a transistor switch, i suppose which would be making and breaking signal as it gets signals from the LFO.
As far a blending between the two...you'd need two of the same pedal, really. As you suspected, you can't have a clean blend on feedback. Youcould have the illusion of it having a clean portion because of a stutter effect, but really it's either feeding back to varying degrees or it isnt. If you split your signal to two pedals, however, one with no feedback (straight through to a mixing stage) and the other with a circuit like what i described, you could blend between the twosignals in parallel.
Of course, this alsodepends on what type of pedal it is. Delays and reverbs and stuff of that nature will be able to get part of their signal fed back to them and not necessarily start oscillating until it gets over unity gain. Some pedals will also have an input an output that are out of phase and you will create negative feedback instead of positive.
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