The dreaded Phantom Power

If you have already thought about having a condenser microphone, you have already heard about Phantom Power. But do you know what it is used for? In this post we will demystify it! We will speak about how it emerged, functioning, tips of use and we will also explain why it is so feared.

The radio station is one of the oldest means of mass communication. Over the years it has developed a lot and, in spite of this, many imagined its end with the arrival of the Internet. But contrariwise, the online media made the radio even more powerful.

Today, you can start a radio station in a traditional or virtual way. The main difference noted as of the start is that there is less bureaucracy involved in mounting an online radio.

To function, it suffices to choose the streaming platform that you prefer and which fulfills your requirements. They will have all support to place your programming on the air. Furthermore, the online radio station is cheaper and has potentially greater reach.

Another clear point of difference is the type of equipment which each one requests. The online radios require less equipment, which makes the process more feasible.

But one piece of equipment which cannot lack in this modality is a good quality microphone, because it will make a lot of difference to the result.

The condenser microphone

Despite not being new technology, there are still many sound operators who  have real fear of working with condenser microphone, which require resources of  Phantom Power.

Many believe that there is a risk of burning out other equipment, or giving the user a shock, which will cause some damage or interference, among many other notions.

To understand this resource, and eliminate once and for all these queries, it is necessary to understand the original functioning of the microphones.

How do the microphones function?

The microphones can be divided into two types, which differ by the construction of the capsule: dynamic and condenser.

The dynamic microphones have the same manufacturing principle as a loudspeaker. When the sound is emitted, it attains the diaphragm, which moves a coil that existis around a magnet, generating a voltage which imitates the sound conditions captured. This voltage is conducted through the cables to the soundboard which reproduces and amplifies it.

But in the condenser (or electret or also capacitive) microphones the construction is different. There are two very thin layers which are fastened very near to each other. This is also the reason that the condensers are much more fragile than the dynamic microphones.

One of these layers plays the role of diaphragm, capturing the sound, and with the variation of the distance caused by the sound waves over the layers, the voltage varies in a similar way. As the layers are polarized, certainly there is the requirement of there being energy, which needs to be supplied in some way.

Besides the polarized layers, the condenser microphones have a small pre-amplifier circuit which is used to increase the level of the signal sufficiently so that it is transmitted by the cables. And this small circuit also requires energy to function.

Knowing this information, we come to discover the possible sources of energy for the condenser microphones, which can be batteries, 9V batteries or Phantom Power.

Phantom Power

Phantom Power is a DC energy supply source for microphones and equipment which requires energy to function. It is called like this because there is not an obvious external power supply source for the microphone. The power supply source is invisible as the mixer send voltage to the wires in a remote way.

The professional soundboards usually have this very useful resource, which can be driven by one or more switches. Often Phantom is supplied up to 48V, and the condenser microphone uses only the quantity of energy necessary for its functioning, and discards the remainder without there being any loss.

To the Phantom Power can function correctly it is necessary that there is a balanced system, i.e., a double coaxial cable (balanced cable), with two internal conductors plus a mesh (positive, negative and ground), and also a balanced connector (3 pins, XLR or P10TRS).

The voltage is sent by the conductors (both are “positive” for Phantom) and returns by the mesh (always “negative”). In soundboards which have XLR connectors for inlets of MIC and P10 for LINE, Phantom is only enabled in the XLR connectors of the channel, even though P10 TRS connectors are used in LINE. Certain microphones can be supplied by Phantom Power or by cells/batteries, generally with the energy source being selected by switch.

The main problems presented in the use of Phantom Power in truth are related to the cables which, if they are badly done (poorly welded, too many shorts or outside standards required), can generate noise and even burn out the equipment.

The history of Phantom Power

Since the presentation of the telephone with rotating dialer in 1919, power supply Phantom Power was already used. With the launching of the first transistorized microphone in the world, Schoeps CMT20, in 1964, the commercial use started. Schoeps CMT20 functioned with power supply from 8 to 12V.

In 1966, the studios of NRK Norwegian Radio Corporation presented Neumann, a new type of transistorized microphone, KM84. At the time, the radio already had a system of 48V batteries for emergency lights, so this power supply was used for the microphones, later becoming the standard audio voltage.

How to connect and disconnect Phantom Power and avoid risks?

An important tip for using Phantom Power is that the microphones must be connected before the resource is activated, otherwise problems can occur. This happens because, if we connect the microphone to a cable already supplied by Phantom (therefore there is energy) there can be sparking, as occurs when we connect an electrical appliance already connected to the energy socket.

Certain appliances are very fragile and this sparking can cause the microphone or soundboard to burn out. Thus, the correct way is to do all the connections of the cables and only at the end activate Phantom Power. And at the end, first turns the Phantom Power off, wait approximately 1 minute (until the residual energy disappears) and then disconnect the microphones.

Another very important tip is to ensure that the Phantom Power option of your soundboard is disabled if you use a dynamic microphone. Connecting dynamic microphones in connectors with Phantom Power active will very likely lead to the device burning out.

Nobody need be afraid of using Phantom Power, but it is essential to know how to use the resource correctly. If we know the principles of functioning and use cables within the standard, there is no risk, and the benefits of using the resource will be many!

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About the author

Luiz Silveira

Luiz Silveira is a specialist in digital marketing and a radio, music and technology enthusiast. With a decade of experience, he aims to help radio stations better position thenselves on the internet.

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