Getting past the mystique of ribbon microphones, when one looks inside the microphone’s outer case, the device can look shockingly simple. Essentially, at the heart of every ribbon mic, is a thin piece of corrugated aluminum suspended loosely between two magnets connected to a transformer. That encompasses the basic design.
However, as you might expect, the devil is in the details. The way the ribbon element is tensioned and tuned, its size and thickness, the type of corrugation and the materials in front and behind the ribbon all have a huge impact on the sound and tonality of the microphone.
What’s a Big Ribbon?
At AEA, we tune virtually all of our ribbons to 16.5 Hz — the same frequency that RCA used to tune their classic RCA 44 model beginning in the 1930s. In fact, all of our figure-of-8 pattern microphones share the same exact ribbon element as the RCA 44 series.
This is important because tuning is a critical sonic element in why all of our microphones sound like they are in the same family — though each microphone has a very different personality. Even the techniques that AEA’s engineers use to tension and test the ribbons in our mics date back to the RCA days.
The Big Ribbon Sound
So what difference does this 16.5 Hz tuning make to users of our microphones?
For AEA, our tuning is what sets us apart as a company and makes our sound unique. One of the reasons that the tuning of our ribbons is so low is that the lower the tuning of the ribbon, the more bass content will be captured. Our ribbons are tuned lower than human hearing so they capture low end below the sub frequencies.
This makes our ribbon mics perfect for capturing instruments such as kick drum, toms, bass and other instruments that have a large amount of low-frequency content. Our ribbon mics have such a low resonant frequency, that almost no other microphone on the market captures as much low end.
Bigger — is — Better
Along with the tuning, the length of the ribbon matters — a lot. At AEA, we use “Big Ribbons,” our way of differentiating a large 2.35 by 0.185-inch by two-micron pure aluminum, low-tension ribbon element just like the ones used by RCA.
AEA ribbons offer important advantages. Ribbon microphones operate linearly above their resonant frequency, unlike condenser or moving coil transducers, so the resonant frequency of a good microphone design should be as low as possible. The longer the ribbon, the lower the resonant frequency can be.
Most other ribbon mics are tuned much higher, sometimes within the range of human hearing. Ribbons with a tuning as high as 60 Hz or 70 Hz do not sound like they have as much low end as ribbons that are tuned lower.
The ribbon has to move twice as far for every drop in octave as it vibrates within the magnetic gap. Thus, a longer ribbon will allow for further movement back and forth. This results in the ribbon handling louder sound sources and higher sound pressure level (SPL).
The sound from 16.5 Hz tuned large-sized ribbons means that the mic’s sound is smooth, natural and free from any of the uncomfortable resonances that condensers can exhibit. The result is a sound that many engineers say is astonishingly close to what their ears hear while actually standing in the studio.
All AEA mics are ribboned in-house at our shop in Pasadena, California. Each technician goes through extensive training to make sure that every mic is made to the same standard. It requires finesse and a very steady hand to make sure that the ribbon is perfectly applied and tensioned to 16.5 Hz. After the process, the mic is auditioned to make sure it sounds correct to a trained ear. Then the frequency response and sensitivity are tested and recorded.
AEA achieves the classic RCA sound though this 16.5 Hz ribbon tuning. It is what differentiates our sound from others building ribbon microphones today.