Edcor WSM vs UMM vs PCW

[OneRoomStudio]

Does anyone know anything about the differences between these series? Other than the different core sizes and physical dimensions, the published specs are the same.

-They're all 0.5W
-They all use M-6 29 ga grain-oriented steel lams
-They all use nylon 6/6 GF-30 bobbins
-They all have a published frequency response of 20~20K Hz., <1dBu and a THD of <0.05% @ 1K Hz.

WSM = EI50 (0.50" x 0.625") Core
UMM = EI38 (0.375" x 0.375") Core
PCW = EI63 (0.625" x 0.5") Core

WSM and PCW have the same size cores, just oriented differently, and UMM has a smaller core.

I'm assuming the larger cores would lead to higher inductance and therefore lower distortion/roll off at low frequencies compared to the smaller core, but that could be wrong.

Anyone else know anything about these?

 

[OneRoomStudio]

The WSM and PCW are good line transformers. Some people use them as mic input. They are not too bad, just placement can be an issue because of lack of shielding. Sound close to UTC A series.
the Umm is an unbalanced isolation transformer for killing ground loops.

Thanks!

Edcor describes the UMM series in the same way as the other two ("1/2W balanced or unbalanced line matching transformers"). What makes you say they are supposed to be used as unbalanced isolation transformers?