An SF-12 cannot be upgraded to SF-24 specification. Although the SF-12 and the SF-24 share the same transducer assemblies and have similar sonic characteristics, they are two very different microphones. The impedance matching transformers that are integral to each model are very different electrically and physically. The SF-24's active electronics will not work with the SF-12's transformer set, and the transformers will not fit in the SF-12's slim housing. The large housing of the SF-24 is designed to accommodate the bigger transformers and provide magnetic shielding for them as well as provide the room needed for the active electronics circuit boards. The cost to make all of this work with an existing SF-12 would economically and physically unfeasible.