Ribbon microphones often have quite a low output, and so it is important to squeeze every last bit of performance out of the signal chain, particularly when recording quieter instruments. Many older ribbon microphones (and some dynamics too) were designed for a 30 ohm or 50 ohm input. However, most modern mics have a higher impedance and consequently most studio preamps give best performance with microphones of 200 to 600 ohms. Many other ribbon mics were made for use with PA systems, and have high impedance output.

So, if you have an old microphone and a modern recording system, you may not be getting the best out of your signal chain, and there are a few different ways to address this problem.

External matching transformer

The first option is to use an external impedance matching transformer. The advantage of this is that it leaves the vintage microphone intact, and can be used with dual element mics such as the STC4033 and Altec / Western ‘birdcage’ microphones. It is also a good solution for studios with a collection of low impedance ribbon mics, but who only use one or two at a time. These may also be used with dynamic microphones. There is more information about our transformer boxes here.

Transformer re-winds

The second option is to replace the secondary winding of the mic output transformer with one of the desired impedance. This can be done for many (but not all) microphones, depending on the construction of the transformer, and is usually better suited to lower value microphones such as Reslos, Lustraphones and Film Industries mics. Where possible we will keep the original primary winding intact, and re-use the original laminations. This retains the original sonic character of the mic, whilst optimising the output for connection to your studio equipment.

New transformers

A third approach is to replace the internal transformer with a new one. This is useful for modern budget microphones where the original transformer has been made with cost, rather than performance in mind, and for microphones with vintage value, where the transformer can be swapped back to the original at a later date if required.

Our own transformers come in two flavours - vintage and modern. Both are made here in York from components sourced in the EU, and are custom wound for each microphone.

Xaudia type X transformers

The X-series transformers have mumetal laminations and can give an extended frequency response and more bottom end detail.

Xaudia type V transformers

The ‘V’ or vintage series are inspired by classic British ribbon mics, and have a higher iron content than the X -series, and a more rounded, vintage tone.

SAMAR toroidal transformers

We also stock transformers by SAMAR audio design, which are made in the USA, These are a toroidal design with extremely low DC resistance, which gives the lowest possible noise floor. They are very clear and transparent sounding, and available in a wide range of ratios for lowest noise and exact impedance matching - to bring out the very best in your ribbon microphone.

On request, we can also supply and fit transformers by Sowter and Lundahl.

Please contact us for details.

Updated Thursday, 16 February 2012.