Usable range of feedback loop?

Started by ashcat_lt, November 19, 2010, 03:01:05 PM

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ashcat_lt

Before I get around to wiring it up and actually messing with it, I'm looking for insight from folks with practical experience.  I guess the real question is:  "what's the best pot value for a feedback looper?"

I've seen different schemes with different values - 250K, 500K...  I've got these, I've also got some 100Ks.  I find myself wondering what the actual useful range is going to be.  Do you always turn it up past halfway?  Do you never turn it all the way up?  Do you have trouble zeroing in on the "right" value?  Would a smaller pot (maybe with a limiting resistor?) give better fine control?

I suppose it depends on what effect(s) you've got in the loop.  Please hit me with your experiences, opinions, anecdotes, and recommendations.

Also, a tip, which probably isn't exactly unique or new:  It's possible to forgo the usual toggle which engages the feedback by scraping or cutting the resistive track at the "low end" of the pot.  Then, turning it all the way down turns it off.

Hides-His-Eyes

Is it not an issue of the impedance of the pedal?

R.G.

Unfortunately, this is a question without a single answer other than "it depends". What works well for some pedals may not work with other pedals. Any similarity is accidental, not a law of nature.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

ashcat_lt

First, I'd like to make sure that it's clear I'm talking about one of these True Bypass Looper w/Feedback that we see around from time to time.  I'm not talking about feedback internal to a particular pedal circuit.  Not sure if that was clear from my initial post.

Second, I guess I know that it's going to depend on the pedals in the loop, what I actually want to get out of them, and probably which constellation Jupiter is in at the time.  I'd still like to hear about people's specific experiences.

R.G.

Quote from: ashcat_lt on November 19, 2010, 07:10:42 PM
First, I'd like to make sure that it's clear I'm talking about one of these True Bypass Looper w/Feedback that we see around from time to time.  I'm not talking about feedback internal to a particular pedal circuit.  Not sure if that was clear from my initial post.
It wasn't, but that doesn't matter much. Whether the input is inside or outside the pedal is of interest only if you're wondering whether the feedback is inside or outside the input and/or output buffers, if any, that the circuit has.

For well designed modern pedals, there is a convergence on high input impedance for the pedal, generally 1/2 M or over, and low output impedance, generally 50K or less, but there are many, many counterexamples to those trends, especially in older pedals.

QuoteSecond, I guess I know that it's going to depend on the pedals in the loop, what I actually want to get out of them, and probably which constellation Jupiter is in at the time.  I'd still like to hear about people's specific experiences.
Collecting anecdotes is certainly an OK thing to do. Just remember that they are anecdotes, random bits of storytelling. They may provide you with some starting points, but it will depend on your pedals and whether the moon is in the seventh house or not.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.