Hi again,Torbenh,and everyone at the list,thank you very much for your time and help. The solution came after copy from the fst-1.7/ardour build folder: - the SC* files : fst-1.7/ardour/SConstruct to the build directory of ardour-0.99 and fst-1.7/ardour/gtk_ardour/SConscript to the ardour-0.99/gtk_ardour build directory -the vst directory created during the compilation of fst-1.7 and the fst.h file to the build directory ardour-0.99/libs/ardour . After try your advice,It did'nt work giving diferents error messages. I tried again as the first time ,wihtout copying fst.h to /usr/local/include and the last error : /libs/ardour/audioengine.cc:32:17: error: fst.h: No such file or directory libs/ardour/audioengine.cc: In function 'void _thread_init_callback(void*)': libs/ardour/audioengine.cc:87: error: 'fst_adopt_thread' was not declared in this scope scons: *** [libs/ardour/audioengine.o] Error 1 scons: building terminated because of errors. /made me think that scons was looking for fst.h at libs/ardour/ folder inside the building place. After this ,a similar error looking for vst/AEffect.h file in the same place: / libs/ardour/fst.h:26:25: error: vst/AEffect.h: No such file or directory libs/ardour/fst.h:58: error: expected ';' before '(' token libs/ardour/fst.h:89: error: 'audioMasterCallback' has not been declared scons: *** [libs/ardour/audioengine.o] Error 1 scons: building terminated because of errors./ after copy that folder everything went fine. The next step I did was create /usr/local/lib/vst folder and put inside the vst.dll files,but launching Ardour as root is needed the first time,due to the write acces of that folder.After this I open some vstfx that work with very good performance (ambience reverb and nomad factory free sweeper) Thank you very much and best wishes from Spain. Saludos. Cheers. -- Carlos.