You can improve the sound of most ribbon microphones by replacing the internal transformer with a Lundahl LL2912, LL2913, LL2914, or LL2915. These transformers are designed specifically for ribbon microphone use and will generally improve both the bass and treble frequency extension, as well as the sonic clarity. Several ribbon microphone sellers and upgraders use these transformers in their premium versions.
The LL2912 and LL2915 are unshielded transformers that can be used to upgrade microphones with narrow bodies, where the bodies incorporate magnetic shielding.
The LL2913 and LL2914 are shielded PC board mount transformers similar to the LL2912 for use where shielding is necessary or PC board mounting is a mechanical advantage.
The LL2913 is internally identical to the LL2912, which uses a cobalt amorphous core. The LL2915 and the internally identical LL2914 use a more traditional mu-metal (permalloy) core, which results in a more vintage tone (more warmth in the upper bass/lower midrange).
Small PC boards for mounting and simplifying the wiring of the LL2913 and the LL2914 are also available. See the picture. See the datasheets for the dimensions to determine which transformer will fit in your microphone.
Turns: 1+1+1+1 : 37
Usage/Comment: Amorphous core transformer, PC mount
Data Sheet: LL2913