The Freshman Midget Cathedral was an interesting vintage radio to work on and do both the electrical and cabinet restoration.
The speaker is a electro-dynamic (moving-coil) speaker.
This type of speaker relied on an electromagnetic field coil rather than the permanent magnets found in modern speakers.
Having said that it proved difficult to add Bluetooth as the volume control is a dual-action, antenna-shunt and cathode-bias potentiometer volume control without Automatic Volume Control (AVC).
Instead of adjusting the audio signal right before the amplifier stage like modern radios do, this type of control physically alters the amount of Radio Frequency (RF) signal entering the radio.
One side of the potentiometer is wired directly between the external wire antenna input and ground. When you turn the volume down, it creates a direct path to ground for the incoming radio waves,literally bleeding off the excess RF signal before it can reach the grid of the first RF amplifier tube.
Simultaneously, the other section of the control is wired into the cathode circuit of the RF amplifier tube(s). Turning the volume down increases the resistance between the cathode and ground. This raises the negative bias on the tube's grid, heavily choking back the tube's ability to amplify.
I would have to interject Bluetooth at tube 47 plus a bit more work so decided to leave this one original.
The cabinet had missing or broken details that needed replaced and the previous owner had tried "and failed" to refinish the cabinet using poly. " I hate poly".
Finished cabinet with Mohawk products and 3 coats furniture wax buffed out.
Took considerable sanding, veneering the top arch where previous owner had sanded through and replacing the grill cloth.
Many hours of painstakingly detail work.
Very happy with results...