Feedback Loop Question...

[tommy.genes]

I had mentioned this in my BassThru Build Report thread, but I wanted to pose the question to a wider audience.

I also tried to be a bit fancy and added a feedback loop as shown below. Problem is, it doesn't work. There is no noticeable difference in sound at most settings of the pot, except when the pot is all the way up. Then, instead of getting maximum feedback, the effects loop is completely bypassed and a clean sound (no effect at all) is heard. Any ideas as to why this is happening? This seems to be how all the other feedback loops I've seen work.

-- T. G. --

[runmikeyrun]

I had the same problem building feedback loops.  They just don't work with some effects, period.  It's all trial and error.  I plan on taking mine to Guitar Center or someplace like that and trying it on all the pedals to see which one works best.  I have an uglyface and a PT-80 delay and it doesn't really work on either of them, it just makes a really high pitched squeal.  I tried it on our guitarists' boss PH-2 phase shifter and i got some really cool old school computer sounds out of it (think TI-99 or early commodore 64 games) but i haven't been able to find one cheap enough for my tastes.  

I suggest building one separately and trying to find an effect that works well with it.  A good idea was suggested to me by Ansil, he said to rig up a tremelo with a gate and have the tremelo trigger the gate which would basically turn any crazy noises on and off very rapidly.  Sounds like a very interesting concept.

[ExpAnonColin]

Depends on the gain and impedences of the circuit.. if the circuit sees a big load, or a straight ("max position") path, it will go with the straight path and nothing will go into the pedal under certain conditions.

-Colin

[tommy.genes]

I had the same problem building feedback loops.  They just don't work with some effects, period.  It's all trial and error.

Depends on the gain and impedences of the circuit.. if the circuit sees a big load, or a straight ("max position") path, it will go with the straight path and nothing will go into the pedal under certain conditions.

Interestingly enough, I did inadvertently get feedback once with the same effects chain I'm using right now. I had experimented with using an A/B/Y box and a DOD 240 Resistance Mixer to get a clean/effects blend before I built the BassThru. It had volume problems (effects were added on top of the normal clean sound, which made it too loud) so I stopped using it, but it did provide an unintended feedback path that made me want to incorporate one into my BassThru.

I guess I'll just have to experiment with various impedences, possibly putting a fixed resistor in line with the pot. Or else I could put a buffer in the feedback path so that signal only flows one way, but that seems overly complex. Hmmm...

-- T. G. --