This is a weird one! I just hooked up a 12si alternator, but not sure it's related to this problem.
I have a 68 Camaro and noticed when turning the key to (on) the coil begins to buzz just like a door buzzer? The system is a points type setup with a Lazer II CDI to super coil to accel 37100 dual point distrubutor. I have had this setup since I built the motor years ago. I never heard this buzzing sound before in all that time.
If the coil wire is hooked to the distributor it will sound the same until I unplugged the wire from the dist to the Lazer box. But as mentionjhed it does not have to be hooked up to the distributor to buzz. It also happens intermittenly too? Sometimes it ok and few cranks later the buzzing. The car runs fine though regardless.
I tried a new coil and distributor (exact items) and no change. I replaced the Lazer II wire to the distributor and really pushed the coil wire down into the coil and distributor thinking it could also be not seated all the way into the sockets. After doing this it's quiet again (for now at least).
Also is it normal for when the key is in the on position and you connect the power cable for the coil to fire ounce? I saw a message from Everett on when they went from dn to si they changed the ingitions by adding an extra tab to reduce sometype of feed back? Not sure what it is, but if it happen s agin maybe return it to a dn setup.