hello Lewis,
thanks for the link
Actually I read it a few days ago but I didn't choose the solutions given there because they cause some pitch artefacts when you change loop lenght :(
But I overlooked the solution from fe.
thanks to you and him I can achieve what I need now.
here is a patch where 2 grooveducks with and without fe.nocut~ are used.
BTW,now I am trying to get rid of the granular effect caused by amplitude modulation, it is a never ending story I guess ;-)