Quoted from GRUMPY:Is it really necessary to step up to 50 volts? Did you try it on 20 volts and it was weak?
https://www.pinballlife.com/index.php?p=product&id=708
This knocker you can chose from 2 different coils and the 23/800 coil maybe sound good at 20 volts. Just an idea to make the wiring easier.
I got two knockers one for Stern Jurassic Park and one for iron maiden. Jurassic Park sounds good but iron maiden is extremely loud any ideas?