When using condenser microphones for recording or live purposes, phantom power is essential. It provides the required voltage boost so that the condenser microphone can operate effectively.
Does phantom power increase volume?
Phantom power simply provides power to condenser microphones, but it does not increase its volume. By sending the required DC electrical current through the XLR cable, it powers the microphone’s internal amp and diaphragm, without increasing volume.
One could argue that without phantom power, a condenser microphone is incapable of capturing a sound.
Therefore, it provides the possibility of volume but doesn’t increase the dynamic output of the sound source. In this comprehensive guide, we’ll dissect the topic and gain an understanding of how phantom power operates without increasing volume.
Phantom Power And Increased Voltage
Phantom power and condenser mics are intrinsically linked.
Without the +48v boost of phantom power, these microphones are unable to operate at all. Although there is no increase in volume caused by these increases in power, it serves vital functions for recording music or live performances.
Condenser microphones operate based on variable capacitance.
Another name for them is capacitor microphones. This simply means that they have a diaphragm that is vibrated by sound waves and is stretched across a backplate. The vibrations of the diaphragm cause alterations in the distance between it and the backplate.
These fluctuations cause the capacitance to change significantly.
To complete the process, the variations in acoustics are then translated into electrical impulses which have to be amplified before they are outputted from the condenser microphone. This process of amplification is more commonly called phantom power.
I have written an article that describes exactly what phantom power is. You can read it here.
This is where the question of whether phantom power causes the volume to increase becomes a little complex.
Speaking purely from a technical standpoint, it could be argued that the amplification caused by phantom power is causing the volume to increase. However, the alternative is that there is no output from the microphone whatsoever, so although there is an increase in volume it is relative to silence rather than an initial, measurable volume level.
If, for example, you used phantom power with a dynamic microphone, it wouldn’t cause an increase in volume.
This is not advised because dynamic mics do not require the boost in voltage to run properly, but the principle is useful when answering the question of whether phantom power increases volume.
Indeed, it is likely to create additional noise, but the volume is unlikely to be affected. Likewise, line-level instruments won’t receive an increase in volume when subjected to phantom power and are actually at risk of being damaged by it in some cases.
Phantom power is commonly accompanied by +48v or P48. It was originally designed to power microphones that used large external power supplies.
Tube microphones, which were the most popular type when recording techniques were still being discovered, were difficult to maneuver due to the bulky power supplies that accompanied them.
So rather than inventing phantom power to increase volume, the original pioneers were more concerned with convenience. By using phantom power, they no longer had to lug around the large external power supplies that were required to record with tube microphones.
Nowadays, phantom power is included in the vast majority of audio interfaces, mixers, and other recording devices. Often you can specifically send the phantom power to certain channels so that it only affects the microphones it is intended to be used with.
If you were to attempt to use a condenser microphone without phantom power, it would be rendered useless. The inner components and processes required to boost voltage and amplification to function at all.
You can however get 24v Phantom Power. I have written an article on this. You can read it here.
The Technicalities Of Phantom Power
To definitively answer whether phantom power increases volume, we must understand exactly how phantom power is used and how it operates.
Phantom power could be defined as a method of providing power to microphones that require additional electricity to successfully operate.
As I previously mentioned, the most common variety of these microphones are condensers. Dynamic microphones, like the popular Shure SM57 or SM58, do not require additional power and therefore operate just fine without the +48v boost.
- How phantom power does its job is quite ingenious, and involves multiple processes. It makes use of the multiple inbuilt wires in a balanced XLR cable, to provide the necessary voltage to mics that require it, whilst attempting to avoid those that do not.
Despite the majority of phantom power being provided at 48 volts, other voltages are sometimes used. 12 and 24-volt phantom power is used in the construction of acoustic guitar amps, for example.
Again, regardless of the voltage, it would be incorrect to argue that the phantom power is causing an increase in volume.
It is providing the necessary voltage for the device to operate in the first place. So it is a platform within which volume can exist, but it doesn’t cause it to be increased.
The different levels of phantom power are unlikely to harm a condenser mic.
Most microphones can operate over the voltage range of 12-48 volts. It is, however, common that manufacturers recommend that 48 volts is the optimal amount of phantom power required, and some microphones may encounter minor issues when used with 12 or 24-volt phantom power.
I should also mention that you should avoid using phantom power with ribbon microphones are you will quickly fry it!
Also, check out this video that discusses ribbon mics and phantom power.
The table below lists common audio devices and whether they require phantom power:
Phantom Power Considerations
In addition to condenser microphones, some preamps and DI devices can also be powered by phantom power. Again, it will not cause there to be an increase in volume when used with these devices.
Many of the devices that can be powered with phantom power will not function with the lower power versions of 12 or 24 volts.
This issue is also reflected in the amount of current that is provided by the source of the phantom power, such as a mixer or audio interface.
The majority of condenser microphones only require a few milliamps, which can be supported by most mixers and interfaces. However, other devices like preamps and DIs may require more current to successfully operate.
Tube microphones are an example of these high-current devices. Unlike condenser microphones that receive an adequate current increase from the inbuilt phantom power in a mixer or interface, tube mics often use their dedicated supply to ensure that they receive adequate power.
Does Phantom Power Increase The Volume Of A Dynamic Mic?
In the majority of cases, it is perfectly safe to connect a dynamic microphone to an input that is subjected to phantom power. With that being said, there may be some issues encountered. These issues don’t include an increase in volume, though.
Some ribbons microphones, which are commonly used to record guitar amps and drum overheads, as discussed earlier can be damaged by phantom power. This is especially common if a cable has been incorrectly wired, and can cause irreparable damage in some cases.
One practice that can minimize the risk of microphones being damaged by the increased voltage of phantom power, is to always ensure that you plug the mic in before turning on the phantom power.
You might have noticed that when you turn on phantom power with a microphone plugged in, there is a sudden pop sound that is sent through the speakers. This sudden increase in volume can, in some cases, cause damage to the speakers.
It’s also a good idea to be careful when using line-level devices, such as instruments, with phantom power turned on. Keyboards or effects pedals may be damaged by the increase in voltage, and phantom power is not designed to interact with these device’s inner circuitry.
A good way to protect devices from the sudden increase in volume and voltage caused by phantom power is through isolation.
Using multiple D.I boxes in your signal chain allows you to isolate devices that don’t require it, from the phantom power, and therefore protect them from potential damage.
Although phantom power doesn’t cause an increase of the general volume level, the audible pop that it causes when you turn it on is in fact a sudden dynamic spike, that could be very loud if the monitors are turned up.
You can learn how to stop speakers popping by reading my article on this subject here.
Do USB mics need phantom power?
USB microphones do not need phantom power. They get sufficient power from the USB connection with the computer. It simply receives the audio, converts it, and outputs it back through the USB cable into the computer.
Can TRS connectors carry phantom power?
TRS cables cannot carry phantom power, because their contacts do not mate simultaneously. This could cause the connection to short when it is plugged in. TRS devices should never require phantom power to operate.
What are condenser mics predominantly used for?
Condenser microphones are versatile and used for multiple recording purposes. The most common use is for recording vocals because they provide unrivaled attention to detail. They are also used to record guitars, drums, and piano.