I’ve just made a new reed for my baritone regulator and have gotten A, F#, and D in tune. According to my electronic tuner, G was sharp, so I rushed the bore and placed a small glob of poster putty near the G hole. This has brought it closer to being in tune. If I add any more poster putty, it adversely affects the lower notes, especially F#.
What is odd is that the G comes in tune when I increase the pressure on it (this seems counter-intuitive, since increased pressure generally sharpens the pitch of a double-reed instrument).
Should I try to bring the G in by playing the reed more? The other three notes are in tune, so I really don’t want to modify the reed if I can help it.
As you noted, any adjustment you make to one note affects all the other notes below it. Ronan Browne’s suggestion is to tune the whole reg reed a half-step sharp, and then work all your notes down from there as required.
You can cut a very small crescent-shaped piece of cork and pinch it into the G hole to reduce its diameter. As the flattening effect is greatest with the cork at the top side of the hole you can tune the note by changing the positon of the cork. Of course you have to take care that the cork doesn’t stop the key from sealing properly so it has to sit well in the hole, on the other hand it shouldn’t protrude into the bore either. It is a bit tricky but well worth it in a case like yours.