This transformer came out of a faulty Beyerdynamic M260.

Beyerdynamic M260 transformer

I was surprised how roughly the primary coil is wound – it really looks like it has been done by hand. Perhaps it is to minimise parasitic capacitance, although that is not usually such a big problem with low impedance windings as they only have a few turns.

In this case the short was located and the original transformer was repaired, but that is not always possible, and sometimes a rewind or replacement is required.

Some of the Beyerdynamic  ribbon mics, such as the M500 and some models of M260 have a ‘built in’ high pass filter. This is done by manipulating the transformer inductance, allowing some of the bass frequencies to pass to ground. Some people like this, but others (including myself) prefer a full frequency response.

Xaudia B-series (top) and Beyer transformer (below)

Xaudia now produce replacement full-range transformers for repair or upgrade of Beyer and B&O mics. The B-series transformers use a larger core than the originals, but still fit neatly inside the mic. They can be supplied in any desired ratio, and have lower DCR specs than the originals, which gives better noise performance too.