Aquaboy way too much feedback

[pietro_moog]

hi guys.
i'm having a hard time trying to calibrate my Aquaboy.
it seems to work, but (i've already build another with the bajaman layout and that one was very nice)
it has way too much feedback.
with delay and feedback in the middle position it starts to get crazy.
i checked and delay is 1M.

have this ever happen to you?
do you have a suggestion?

thanks

[stecykmi]

check the feedback pot, C30 and R31.

[madbean]

Please refer to section (vi) in the Aquaboy documentation which explains how to adjust for less feedback.

[gtr2]

You can raise the value of r31.

It's also easier to calibrate with an audio probe at pin 3 or 4 on your bbd with the repeats pot turned fully counterclockwise.

Josh

[pietro_moog]

nice, thanks.
but there's one thing i don't get. i built 2 versions on this schematics, with the same components.
one works beautifully, the other get crazy feedback. (pots are fine)
what i'm getting is that every  v571  is different from each other and needs particular values?

[gtr2]

You'll have to experiment with the value for r31 and find the one that works for you.  Socket it and try something higher than the 22k that you have there.  Maybe something in the 30k-40k range?

Josh

[pietro_moog]

nice. i tried 33k (low), 39k (still low), 47k (high), so now i think i need 43k.
however, my repeats are distortiong so i think i'll try an higher values for R15.
(like 56k, i have it and i've seen it suggested from someone)

but i still don't get why those mods.
ics are so inconsistet?

[gtr2]

Been there done that...  Look in the modification part of the post, there are also schematics changes attached.

http://www.madbeanpedals.com/forum/index.php?topic=1553.0

Here's my battle if your bored...

http://www.madbeanpedals.com/forum/index.php?topic=1246.0

These things just need more tweaking.  If it was easy everyone would be doing it. 

Josh

[juansolo]

I had the same problem with mine. Stuck a pot in place of the resistor. maxed the feedback, then tweaked the pot until I got it just on the edge of going mental. Took a reading (in my case 78.3), teepeed a couple of resistors, stuck 'em in and it's sorted.

I end up doing this with every delay I build. Gives you maximum feedback without it getting into self oscillation.