Moving Coil Orthophonic Loudspeaker Performance?

[Rexophone]

I was reading through the Victor Service section of Look for the Dog when I noticed the Moving Coil Orthophonic Loudspeaker. I am curious which Victrola/radio combinations used these and how much better they sound than the slightly earlier Orthophonic Loudspeaker Units (previous page in the book). I am familiar with the earlier Orthophonic Loudspeaker Unit which is basically an orthophonic diaphragm and spider connected to a Radiola 100-A cone speaker driver. This driver uses a balanced armature which has limited thrust and eventually lost out to modern moving coil speakers by 1930. In contrast, it seems that the Moving Coil Orthophonic Loudspeaker is, indeed, a moving coil driver with the potential for greater bass response, limited only by the deflection constraints of the orthophonic diaphragm.

Although I don't have a Victor that uses either of these electric drivers, I do have a Orthophonic Loudspeaker Unit that luckily has the same connector as a regular reproducer. I occasionally connect it to my Credenza and a modern FM radio (through an impedance matching transformer) just to see what that big horn and orthophonic diagram can do. Even with the limitations of the balanced armature driver, the results are very impressive. In my spare time, I plan to connect the setup to a audio generator to measure how low the orthophonic combination will go. That has made me curious about how much better the Moving Coil Orthophonic Loudspeaker might work. Has anyone compared two machines with these different drivers? Does anyone have a moving coil unit to play with?

Steve

[Uncle Vanya]

The moving coil units were used only in the very scarce 10-51, and (perhaps) in some Auditorium Orthophonic installations. These unit s are rare, and are seldom fiuns in usable condition due to a pot metal inner frame.

I understand that some of these units were offered to dealers in late 1927 and 1928 to upgrade any slow selling 9-40 and 8-60 machines in stock. I know of one 8-60 which is so equipped. I have not heard it play, and I do not believe that it has been electrically restored.

[Rexophone]

Thanks. That makes sense. I'm not surprised that the moving coil units are rare. I never realized they existed until I was looking up the service information on my non-moving coil unit.

Steve