Ribbon microphone transformer box - 30/50 to 600 ohms.

£75 for one, £140 for a pair. Free UK postage.

Please contact us for details.

Ribbon microphones often have quite a low output, and so, when recording quieter sound sources, it is important to squeeze every last bit of performance out of the signal chain. 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.

So, if you have an old microphone and a modern recording system, you may well need one of our ribbon microphone transformers. This little gadget is designed for interfacing older 30/50 ohm microphones to modern preamp inputs. It contains a high quality Sowter transformer and will give a 12dB increase in level without noise penalty. The transformer is housed in a robust metal enclosure, with silver plated Neutrik connectors.

Here are frequency plots for a vintage Reslo RBL microphone connected to an Apogee microphone preamp. The blue line shows the mic connected directly to the preamp, and the red line shows the increase in level with the transformer in-line (click the plot for a higher resolution version).

The measurements show an increase in level of 12dB across the audible range, with no significant change in the frequency response of the microphone.

Reslo RV microphone (marked “30/50”)

Melodium 42B (click to enlarge)

Other 30 or 50 ohm mics include:

Grampian ribbon mics (including GR1/L and GR2/L)

Cadenza ribbon microphones

RSA & Selmer ribbon mics

STC 4033

Altec and Western Electric ribbon microphones

And many others

We can supply custom transformers for microphones with unusual impedances - please ask about your microphone.

Some user comments on the transformers:

“It's nice to have the [extra] gain from the Altecs when the preamp has nothing more to give.”

Matt Howe, UK.

“The impedance matching transformers have been a bit of a revelation too. I can use them with the different 30-50 ohm impedance microphones I have and they really increase the clean gain significantly. and allow me to make a much more versatile use of them. I love the sound of ribbon microphones on soft acoustic instruments like glockenspiel, toy piano, acoustic guitar, mandolin, etc.. and the transformers allow me to do this with less fear of preamp hiss.”

Santiago Calvo Ramos, Otherdays music

“Hey Stewart, great work on the ribbon transformers. I have tried them out on all of my ribbons and they make a huge difference to every one, boosting level and cleaning the signal. My [Grampian] GR2/M blue label sounds fab. The bigger mics, eg the 4038, varacoustic and especially the EMI have all benefitted loads.”

Mark Stevens, UK

 

Updated Thursday, 16 February 2012.