Reply To: Backplate without mid-frequency adjustment home › Forums › General Discussion › Backplate without mid-frequency adjustment › Reply To: Backplate without mid-frequency adjustment April 19, 2024 at 12:45 pm #1841 John VParticipant Good catch WillB! According to the schematic I have the zero DB position uses a 5 MH coil. Also, the coil, or coils, are part of the Bass Transformer low pass circuit, assuming I’m reading it correctly. Attachments:You must be logged in to view attached files.