This week we have been building lots of little transformer moxes to match vintage 30 ohm ribbon mics to modern mic preamps. Correct impedance matching can deliver a +12 dB increase in level without noise penalty or loss of frequency response, which is welcome for many older microphones. Here is how a Reslo RV microphone behaves with and without the transformer:
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| Frequency response plots for Reslo mic with and without an impedance matching transformer |
They are suitable for many old microphones including the following:
- Reslo RBL and RB 30 ohm models
- Melodium 42b
- Grampian ribbon mics (including GR1/L and GR2/L)
- Cadenza ribbon microphones (wired for low-Z use)
- RSA & Selmer ribbon mics
- STC 4033
- Altec and Western Electric ribbon microphones