Hi Johan,
I guess it depends upon the tuner and the manner in which he or she prefers to do things. I have had a fellow over the years that tuned each rank with an electronic device, and another who used a tuning fork for A-440, and tuned the Principal rank from that. After that rank was itself in tune, then he tuned the rest of the ranks, by ear, to the 4' pitch of the Principal rank.
I much prefer the results of the latter - the finished tuning is warmer when done "manually" (starting with a tuning fork) and not so sterile like when the electronic device was used. Oddly enough, the organ as a whole, stays in tune better when the pipes were tuned by ear, at least for my particular church instrument.
I guess it depends upon the tuner and the manner in which he or she prefers to do things. I have had a fellow over the years that tuned each rank with an electronic device, and another who used a tuning fork for A-440, and tuned the Principal rank from that. After that rank was itself in tune, then he tuned the rest of the ranks, by ear, to the 4' pitch of the Principal rank.
I much prefer the results of the latter - the finished tuning is warmer when done "manually" (starting with a tuning fork) and not so sterile like when the electronic device was used. Oddly enough, the organ as a whole, stays in tune better when the pipes were tuned by ear, at least for my particular church instrument.