November’s microphone of the month is a British long-format ribbon that was sold under the names “Lustraphone” and ‘Grundig”.

A Lustraphone-badged ribbon microphone in glorious brushed stainless steel finish

This mic was available in at least three different impedances, and I have come across 30, 200, and high impedance models. Unfortunately the badge often falls off so you don’t always know what you are getting! Most of the models I have seen are finished in a bronze hammerite colour, although there is a deluxe low impedance model which has a gorgeous brushed stainless steel finish. Despite the different badges and finishes, the mics are exactly the same on the inside (transformer aside).

Lustraphone ribbon microphones on the bench

One of the ribbon clamps sits on a spring-tensioned screw thread, which allows fine adjustment of the ribbon tension. This makes tuning the ribbon very straight-forward, and allows the owner a little bit of grace if the ribbon becomes a little stretched over time. This feature should probably be mandatory on all ribbonmics!

Grundig badged lustraphone mic, opened up for service

The magnetic field is supplied by a pair of horseshoe magnets (which unfortunately sometimes age with time, losing their strength). Connection to the rest of the world is made by a balanced three-pin paxolin plug, which are hard to come by now. The middle pin is ground, with the audio on the outer two pins.

Rear connector and original plug.

Fortunately, a male XLR connector can be modified to fit by slicing off part of the barrel.

XLR connector modified to fit the mic.

The long ribbon and motor design gives these mics a full bottom end and a pronounced proximity effect. Here are the frequency plots for three of these mics that we have serviced recently:

Lustraphone ribbon mic frequency plots.

(Thanks to Mark Stevens for additional information).

Update 23/1/12. These microphones were also sold under the brand Pamphonic. One appeared recently on ebay: