Adventures In Audio with Audio Masterclass
Recording Tips: Should I use a capacitor microphone for recording vocals?

Recording Tips: Should I use a capacitor microphone for recording vocals?


You won't get a good recording of anything unless you have a microphone of at least basic professional quality.

The benchmark we like to use is the Shure SM57, which you can buy for around $100 in the USA or €99 in Europe. Anything cheaper than this is unlikely to give good results.

The Shure SM57 is a dynamic mic, meaning that it has a tiny electrical dynamo inside. Sound vibrates the diaphragm of the mic, which in turn causes a coil of wire to vibrate in the field of a magnet. This creates an electric current in the coil, which is used to generate the output signal.

You can indeed use the SM57 for recording vocals, or indeed almost any instrument. It works best close to the sound source because otherwise the output level will be quite low.

But the dynamic mic has a shortcoming… the coil is attached to the diaphragm. This weighs down the diaphragm and makes it less responsive to sound.

So the dynamic mic does not capture fine detail in the sound source. You will hear this most strongly on metallic percussion, which comes out rather more dull than it is in real life.

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The capacitor microphone (also known as 'condenser microphone') works by a different principle. You can learn more about this in the Audio Masterclass Music Production and Sound Engineering online course.

The important point however is that the diaphragm does not need to have a coil attached to it. It is therefore lighter and more able to capture the fine detail of sounds.

Capacitor microphones also have internal amplifiers, so the output signal is generally stronger than dynamic mics.

The odd thing is that although a capacitor mic is more accurate than a dynamic, it isn't necessarily better. You can record a good vocal sound with a Shure SM57 dynamic, or a Neumann KM184 capacitor microphone. The Neumann will need a pop screen.

But to capture a great vocal sound, you need something a little different. What you need is a large-diaphragm capacitor microphone, such as the Neumann TLM 103.

The reason why large-diaphragm microphones exist is that in the past that's the way they had to be simply to work. But as technology developed, more accurate small-diaphragm microphones became popular.

But there is something magical about the sound of a large-diaphragm microphone, particularly on vocals. It's impossible to describe scientifically, but you will know it immediately you start to work with such a mic.

Recordings that once were thin and without substance suddenly become rich and sparkling.

The final finesse is to have a large-diaphragm microphone with a vacuum tube internal amplifier, such as the Neumann M 147. Rich, warm and sparkly – all good adjectives to describe the sound.

You can hear recorded examples of large-diaphragm vacuum tube microphones, and others, in the Audio Masterclass Music Production and Sound Engineering online course.

One last point. Large-diaphragm tube microphones are expensive. But you can get more variation and control in the sound you record by knowing how to position the microphone that you already have correctly.

Microphone positioning is best learned by experimentation, and that costs nothing!

David Mellor

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David Mellor