I was lucky enough to pick up an old Reslo ribbon mic, like the ones you see in old Cavern Club pictures. I wanted to know your suggestions on what preamp to use. I have Behringer's MIC100 and a Behringer Xenyx 502 two-input mixer, but the sound is so weak! The noise floor is swamping the signal! Can you recommend anything?
Denis McDermott
AEA's TRP two-channel microphone preamp is designed specifically for use with ribbon mics. Its quality is reflected in its retail price. Technical Editor Hugh Robjohns replies: Up until the last decade or so, ribbon mics were, without doubt, the lowest level source you would ever find. Given the physics of the design, that's not surprising. The ribbon mic works like a moving coil mic: a conductor is moved within a magnetic field, and it is that action that generates a current proportional to the sound waves. However, in a ribbon mic there is only one conductor in the magnetic field — the ribbon itself — whereas in a typical moving-coil mic there are many tens or even hundreds of conductors moving in the magnetic field. As a result, the output of a moving coil mic in front of someone talking might be -50dB or so, whereas a ribbon would be about 20dB quieter. Modern ribbon designs are able to use much more powerful magnets, and some also include internal preamps to output a more usable level.
In your case, with a vintage mic, you have a very low-level output which is beyond the capabilities of most budget preamps, hence the weak sound and obvious noise floor.
The American ribbon mic manufacturers AEA produce the only two-channel preamp I know of that's specifically designed for ribbon mics, and it is called the TRP (The Ribbon Pre). I reviewed it for SOS and it is extremely quiet, with more than enough gain for any ribbon mic... but it isn't budget priced. Most classic 'vintage' preamps were designed to accommodate ribbon mics, so they tend to offer higher gains, 72dB being a common figure. So it may be worth looking around for a vintage preamp or a clone design. Another possible solution would be to invest in a microphone step-up transformer, which would increase the level before feeding the signal into a conventional mic preamp. Most ribbons incorporate an output transformer that serves this purpose, and some have user-adjustable taps to allow the impedance and gain to be configured to suit the preamp. It might be worth checking your Reslo to see if there are other output configurations that might help.