You often read questions on the Internet like, "Should I use a dynamic microphone, a ribbon microphone or rather a condenser microphone for miking xyz?" Unfortunately, many users still use the term "dynamic microphone" as a synonym for the plunger coil microphone. This is not wrong, because the moving coil microphone IS a dynamic microphone. But a ribbon microphone is also a dynamic microphone. Under the umbrella term "dynamic microphone" we find the two transducer forms of moving coil microphone and ribbon microphone. But what is the difference between them and what are the similarities?

Both have in common that a conductor is moved in a magnetic field.



In the plunger coil microphone, it is a coil that is either immersed in the gap of a permanent magnet (hence the name) or wound around it. The diaphragm moves the coil and a voltage is induced in the coil by the movement in the magnetic field, the rate and magnitude of the voltage change corresponding to the frequency and magnitude of the diaphragm deflection due to the airborne sound. Due to the construction of a relatively thick diaphragm and coil, moving-coil microphones have an inherent inertia in converting sound into voltage changes.


How does a ribbon microphone work?
In the ribbon microphone, an extremely thin and folded aluminum ribbon is moved as a diaphragm between the poles of the permanent magnet. This delicate membrane is extremely sensitive and converts even the slightest air movement into a corresponding voltage change induced in the aluminum membrane. The thin aluminum ribbon hardly opposes the sound and responds immediately.

Both have in common that the induced voltage and the voltage change resulting from the continuous diaphragm excursion are immediately available at the output without the use of further electronics for conversion or amplification. In ribbon microphones, only a transformer is used to boost the output voltage. Unlike condenser microphones, where the change in capacitance of the plate capacitor must first be converted into a voltage change by electronics and this voltage change must be amplified, and where a bias voltage is also necessary in many models, dynamic microphones such as the moving-coil microphone or ribbon microphone do not require a voltage supply.

On the contrary, some of the early ribbon microphones could be irreparably damaged by the application of phantom power if it reached the thin diaphragm through a malfunction. Current ribbon microphones usually have protection that does not allow phantom power to pass through to the ribbon. Nevertheless, it is recommended to switch off the phantom power before connecting a ribbon microphone to the preamplifier.


Sound characteristics of ribbon microphones
When it comes to the characteristics of ribbon microphones, many myths must be dispelled that no longer apply to current models and are more historical in nature. The ribbon microphone is in fact a very old type of transducer.



Ribbon microphones quickly caught on, because the condenser microphones used as an alternative were nowhere near the level of today's technology. Compared to ribbon microphones, they had a very limited frequency response and poor audio characteristics at the time. Ribbon microphones were therefore attributed attributes such as wide frequency response for the time, true-to-life and clarity, and smooth highs. They were simply superior to the condenser microphones of the time. The RCA 44-BX, for example, had a frequency response of 50 Hz to 15 kHz, covering a considerably wider frequency range than the audio transmission and recording equipment of the time could handle.


Typical frequency response of a ribbon microphone - here the beyerdynamic M130.


Ribbon microphones usually have a figure-of-eight characteristic. The diaphragm is accessible from both sides, so that the directional characteristic of an eight is formed. But there are exceptions here as well
( the beyerdynamic M160 with hypercardioid characteristic).


The figure-of-eight characteristic is the typical polar pattern of a ribbon microphone, here the characteristic of a beyerdynamic M130

Ribbon microphones are very impulse-frequent, which is made possible by the extremely thin and light diaphragm. They are by far not as sluggish as their dynamic colleagues from the moving coil fraction.
Ribbon microphones have a pronounced proximity effect, which is accompanied by a very strong bass boost at close range. Depending on the speaking distance, this leads to drastic changes in sound.
The output voltage of passive ribbon microphones is very low compared to moving coil microphones. A good preamplifier is mandatory due to the low output voltage.


Applications for ribbon microphones !

Vocal recording
The smooth roll-off of the highs, a sound that is perceived as "warm" and the very natural reproduction make the ribbon microphone the ideal microphone for vocal recordings. However, precautions must be taken to avoid damaging the sensitive ribbon.
A pop guard protects the ribbon from the dangerous pressure buildup at the diaphragm. Therefore, vocals should be sung slightly past the microphone.
If you record the lead vocals with a condenser microphone, the ribbon is the perfect companion for the background vocals. These are automatically placed a little further back in the mix, but without sounding thin or washed out. Due to its characteristics, the ribbon microphone takes care of the interventions that would otherwise be done with EQ, compressor and reverb.


The Coles 4038 is a sought-after ribbon microphone

Electric guitar
The sound characteristics of guitar amplifiers get along particularly well with ribbon microphones. They lie between the punchy sound of plunger coil microphones and the very airy sound of condenser microphones. The roll-off in the treble, which is inherent in the design of ribbon microphones, benefits the guitar sound. At the same time, transients are transmitted very well. Even with the guitar amplifier, ribbon microphones should be placed slightly outside the 0° axis of the speaker to avoid damage.

Drums & Percussion
The first-class impulse response and natural reproduction also make ribbons a good choice for drums and percussion. A prerequisite, however, is that they be used as overheads with some distance between them, otherwise the high sound pressures would destroy the ribbon. Another prerequisite is a good room, since the figure-of-eight characteristic naturally also picks up the reflections of the room.

Brass
Ribbon microphones are also a great alternative to moving coil microphones when recording a brass section. The natural and warm sound as well as the gentle treble roll-off is especially beneficial for trumpets, which can sound shrill in the upper registers and when played at high volume. Thus, the horn section comes across with decent pressure and fits well into a mix. A higher distance is again mandatory, especially with trumpets. A pop shield and/or windscreen offers additional safety.

 

Last edited: Feb 21, 2022

Ribbon Microphone Forever?

Ribbon microphones do come with their own pitfalls, especially older models with a lower output, which will need a good, clean preamp to raise the gain to a usable level. However, modern active ribbon microphones come with built-in preamps and you can even use them with any preamp you want.

Ribbon microphones are also pretty delicate, but nowhere near as delicate as they used to be. For example, you can’t store a classic ribbon microphone horizontally, since the ribbon will sag. These days, there two things to watch out for:
Generally, ribbon microphones don’t like phantom power since it can burn up the ribbon. Active ribbon microphones are an exception to this rule: these microphones actually need phantom power to work.

Ribbon microphones don’t do so well in windy conditions. So when recording vocals, always use a pop filter and never place the microphone right next to the bass drum port, since it might damage the ribbon.
Have you already got a ribbon microphone in your collection? Let us know why you love it and what you use it for in the comments.

Source: https://www.bax-shop.co.uk/blog/microphones/ribbon-microphones-the-pros-cons/