The ribbon microphones are, in a way, the obscure and forgotten stepchildren of dynamic mics. However, things were quite different in the earlier days. Ribbon microphones first made their presence felt in the 1920s. During those times, they were the only option available to people.
In the 1970s, solid-state condensers became cheaper and more available owing to the solid-state technology. By that time, tube microphones had already replaced ribbon mics. Even today, some of the designs are still a favorite in studios, such as the RCA 44A.
A variation of dynamic mic
A ribbon microphone is, in many ways, a variation of the dynamic microphone. You’ll see the diaphragm of a dynamic mic attached to a moving coil. It vibrates within a certain magnetic field. Ribbon mics have an extremely thin metal strip, which is most often aluminum. You’ll notice its suspension in a strong magnetic field.
The ribbon provides a similar kind of sensitivity and transient response expected from a condenser. You’ll notice that even with this similarity, the character is wholly different. This is because the ribbon acts as both the diaphragm and the transducer element.
Most of the ribbon mics are passive devices, which means, they don’t have any pre-amplification or active electronics onboard. They connect to a preamp input. The impedance of this preamp input is critical to the microphone’s sound as a result.
There’ll be a change in frequency, particularly on the bottom end, if the impedance is significantly low. This would cause the ribbon to become damped, producing a lowered high-frequency output. You’ll notice a range of useful sounds produced with a change in the frequency response. It could be one of the EQ options in low-frequency.
Let’s understand this with the help of an example. On a source, you’ve got a passive ribbon microphone. Owing to the proximity effect or any of the other factors, there’s too much bass in the sound. In such a situation, you can tailor the sound by reaching for an equalizer. Another option is to plug the microphone into a preamp with a variable input impedance. The impedance setting is lowered.
This results in a reduced low-end response of the mic. The sound produced would be exactly what you wanted. Upon moving away from the microphone, you can minimize the low-frequency boost of the proximity effect.
Active and passive ribbons
You’ll come across a new kind of active ribbon mic in the market today. The onboard electronics in an active ribbon allows the microphone to work to its full potential. This benefits the mic preamp no matter what its input impedance is. Active ribbon microphones have greater consistency in preamps with different input impedances.
They typically possess stronger levels of output when compared to the passive ribbons. Of course, the delivery of sound quality in passive ribbon microphones is fantastic when paired with the right preamp. However, it is easier to achieve that sound quality with active ribbon microphones.
Characteristics of ribbon microphones
Over a period of time, ribbon microphones have built a reputation for being fragile and delicate. This is partly due to its ribbon material, which is extremely thin and suspended in the magnetic gap. Many have no idea how thin is the ribbon. The thickness of the ribbon in Coles 4038 is 0.6 microns. It’s 1.8 and 2.5 or 4 microns thick in AEAs and Royers respectively.
We can understand this better by taking an example of human hair. Typically, the thickness of a human hair is about 100 microns. This means that a human hair is 50 times thicker than the ribbon used in AEA R84. Keeping this in mind, you’ll understand why you must take care of the aluminum ribbon. You must provide strong protection to the aluminum ribbon from blasts of wind.
Most of the engineers are extremely careful with ribbon microphones. They steer away wisely from allowing phantom power to come closer to these mics. Phantom power is used in the electronics of the newer microphones, such as Royer R-122 MKII and AEA R84A. The carbon-nanotube ribbon used in Shure’s KSM313/NE makes it almost indestructible.
Naked RCA 44BX microphone
Ribbon microphones are also well-known for being dark as well as quiet. There is a good reason why they’ve built this reputation. When compared to the modern condenser microphones, the classic ribbon mics have lower output levels. They can sound dark as they’re much more sensitive to input impedance.
The AEA TRP2 Ribbon Pre and RPQ2 Ribbon Pre have the right preamp. CL-Z Cloudlifter or Royer dBooster have an in-line amplifying device. These microphones can work wonders.
AEA Ribbon Pre
When talking about the sonic darkness, there’s a reason why ribbon microphones sound darker. This has to do with the reaction of the ribbons to waveforms produced by different frequencies. This implies, in simple terms, that ribbon microphones are more affected by lower frequencies than the higher ones. This results in a smooth roll-off.
A decrease is essential in output at higher frequencies with shorter waveforms. The benefit is that ribbon microphones take EQ quite efficiently with all the high frequencies even if muted slightly. One can easily bring them out. It is important to remember that this is not the case with all ribbon microphones.
The applications for ribbon mics
You’ll find a great deal of detail in ribbon mics. Yet, these mics are not oversensitive. This is, perhaps, one of their greatest attributes. This is the quality that allows them to gather the nuances of closer sources. While doing so, they remain isolated from off-axis sound and room noise.
This quality makes ribbon mics perfect for choirs or guitar cabinets in larger spaces. In such settings, the sound level entering the mic’s back is significantly lower.
One of the most useful and fascinating aspects of a ribbon microphone’s design is its directionality. Ribbon mics are all naturally bi-directional. However, they lack bi-directionality if designed otherwise. This gives them a figure-8 polar pattern. The sound waves coming from the thin ribbon element can’t move it. The figure-8 directionality has almost endless applications.
Ribbon microphones were a favorite among the hosts of television and radio talk-shows for a long time. The reason was that a single microphone could pick both sides of the conversation. The sides of the microphones point towards the audience.
A unique quality of non-linearity is, by far, the most fantastic aspect of ribbon mics. A ribbon microphone produces a sonic output that has a greater accuracy. If you want your recordings to sound completely natural, these mics would be the best choice.