1. B

    Neumann UM57 From Scratch

    Hi, Just wanted to post this info now that my mic is actually working!!! I made this replica of a Neumann UM57. I did everything except the power supply. It took three months and it works great! It's very transparent and extremely sensitive. I chose this mic because the schematic was...
  2. P

    plug-in input transformers in tube PA?

    I have a Bell Sound 5630 tube PA amp I am restoring. It has 3 XLR mic inputs, which are each wired through an octal socket on the chassis before going to the first preamp stage. The sockets are marked (on the chassis and the schematic) as "Low impedance input transformer socket". They currently...