Mk113 help

Hi team!!

I have done your mk113 in a proto pcb to have fun, but i dont know why i have a residual noise AT THE END!

Here you have attached a link to listen it on each mode of sound.

mediafire.com/download/ja0c1 … he_end.rar

Please, could you help/advise me?

Thanks in advance!!

Regards
Oriol