Fx-loop mod for boss DD3

[searoad]

Merry Christmas!!
need some help!!
i love my Fx-loop-added rebote2, so i followed this thread to mod DD3 for my friend.
his is version 3 of DD3...almost all smd there, and i thought it is a little different from yours.
the wiper of feedback pot connects to a cap directly then goes back to the mainboard, see here.
i added the TRS jack here, and i got the problems:
it has pops, the "first delay sound" isnt effected, and the feedback got self-oscillation very easily whatever any kind of pedals i put in.
i read the directions again it seems you all connected Fx-loop between node 11 and cathod of C26, not anode i connected. scheme.
does it make all the trouble? or it is the same as yours?
thanks for any help or idea!
it was delayed for a Xmas present, i hope i can fix it before New Year.

[tommy.genes]

I did the mod on an old DD-2, which corresponds directly to the schematic you are using. I inserted the TRS jack between node 11 of the small VOLUME BOARD and node 11 of the larger EFFECT BOARD. In my version, those two points were connected by a grey wire, so it was fairly straight forward to cut that wire at the effect board, solder it to the TRS jack, and then add a new piece of wire from the TRS jack to the effect board. As you noted, this means that my TRS jack falls between the wiper of the feedback pot and the "-" terminal of C26.

Now it sounds like the newest DD-3 has a different layout, with C26 or some other cap relocated to the volume board. I'm not sure exactly how your finished mod looks, but it is conceivable that some energy is being stored in C26 (or whatever cap is attached directly to the feedback pot) that is released in the form of an audible "pop" when another pedal is plugged into the loop, or when a pedal in the loop is switched on or off. Another possibility: the pop you hear is generated not by the delay, but entirely by pedals in the feedback loop. The pop then gets repeated by the delay pedal.

Beyond the popping, it sounds as if your mod is - in fact - behaving properly. You will not hear the feedback effect until the second repeat. The note you play comes straight through the pedal (the "clean" signal), the first repeat comes straight off the delay line, and the second repeat is actually the first one that had to pass through the feedback loop and receive the effect. Also, in the un-modded pedal, the fact that the feedback loop results in decaying repeats as opposed to runaway oscillation is because the feedback signal is attenuated by the feedback pot, as well as R31 and R33. If you put any kind of "gain" pedal in the feedback loop, this could push the feedback signal up to or beyond unity gain, causing the repeats to get louder each time, until the delay is oscillating.

This is pretty complicated to put down in just a few words, so feel free to ask more questions. I will also be travelling for few days, so I may not respond right away.

-- T. G. --

[searoad]

Thank you!!
this clarifies very much. ill experiment asap.
wish you have a wonderful trip!

[searoad]

i found lots of keeley-modded sound clips here↓ by mrbluetone
http://www.soundclick.com/bands/pagemusic.cfm?bandID=190415
including some use the loop function by DD3.
very cool!
and i heard the loop-effected delay start at 2nd repeat again.
however he put some fuzz in loop chain.
maybe need to control level and feedback knobs well.

ps. i tried to combine the loop of DD3 and loop of rebote2 with memoryman, 3 delay at one time.
of course it sounds bad and nothing spacial....just an experiment.