The pipe is then tuned and voiced to produce a given note. The tuning can be done in different ways: by cutting the top of the body of the pipe until the achievement of the desired note, or through the incision of a tuning slot on the back top of the body with a flap or an adjustable roll. Regarding the tuning, each flue is tested on a "voicing chest": a small organ where there are some flues already tuned and whose frequency is compared with the ones in construction. Every single step is crucial in order to get a flue that gives a good sound, from the alloy used and to the measures that have to be strictly accurate according to the canons of standard stops or to the instructions of organ builder. The welds need to be perfect not only for a matter of aesthetic but also because a bad weld could hide a small hole that would affect the sound of the flue. The final part of tuning is crucial not only because we can find out if the flue has been made in workmanlike but mainly because the organ builder is facilitated in the assembly of the instrument, since he has  just  to finish the voicing giving his personal stamp.