Hi, Andrew, thanks for your advice in not using duplicated objects. I just didn´t noticed that.
Don´t know what happened in the first place but now the original patch I made works great!. You were right.
Here´s the patch.ludo-sample-drum.axp (76.7 KB)
and a picture of the circuit:
It has 6 channels, each of them with a 3.5" connector for the piezos, protected with 3.3V zener diodes and also with a 1M pull-dow resistor.
It also has a 10k trimpot per channel for adjusting sensitivity and a led to show when a sample is triggered.
Finally a button for changing banks upwars cyclically (now working with only 3 but it can be easily change) and a potentiometer for the main volume.
As soon as I have time, I´ll design a pcb and ulpoad the schematics.
Hope this wlll be useful for some one else.