Guettler diagram for a Thomastik Infeld Domainant G cello string mounted on rigid supports at a relative bow-bridge distance β= 0.0786. The pre-Helmholtz transient duration is given by the colour of each point at a certain combination of bow force F_b and bow acceleration a. White points indicate an immediate onset of the Helmholtz motion, while black points indicate failed transients (duration of 20 period lengths or more).