[MrFixr55]

Hi Gang,

Mancave, if the radio plays loud and proud, this proves out all of the amplifier section except the phono preamp. Try injecting your Bluetooth audio right at the phono-radio switch by either using jack with internal disconnect or adding another switch at the junction between the plate coupling capacitor of the phono preamp and the radio/phono switch. IMHO, this is the correct junction to add a "line level" or "aux" input anyway.

The reason for the extra stage of amplification for the phono is because this unit uses a magnetic pickup, whose output is much less than that of a ceramic pickup. The output of a magnetic pickup is somewhere between 5 and 20 mV except for some of the really early Victor horseshoe heads. The output of a ceramic or crystal cartridge is between 500mV and 3V. (Many portable phonos of the 40s and 50s employed a crystal cartridge with an output between 1 and 3V and only 1 tube, usually a 117L7 output tube / rectifier or a 25L6 output tube and a selenium rectifier. If your Philco used a crystal or ceramic pickup, the extra stage of amplification and the transformer would not exist. The advantage of a magnetic or the Philco "Beam of Light (BOL) pickup is much greater fidelity and lower distortion.

The output of a Bluetooth, MP3, etc. is usually over 1 volt, and this will "rail" a phono preamp designed for an input between 10 and 100mV. In addition, phono preamp stages usually provide a level of equalization that is not appropriate for another input such as TV, MP3, Bluetooth, CD Player, Computer, etc.

Hope all of this helps!