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Phantom power, or 48-volt DC power, is primarily used in the audio industry when recording with condenser microphones.
Most recording devices or mixers have microphone preamplifiers that put out phantom power.
However, phantom power can damage some equipment, specifically any equipment with unbalanced outputs.
We take a look at how you can avoid damage to your equipment from phantom power.
Phantom power is a 48-volt DC power supply used in the audio industry to power active devices such as condenser microphones. If a microphone does not need phantom power, it’s powered through internal electronics instead, which provide the appropriate power and audio signal once plugged into an XLR cable.
So what should you do if your device or instrument doesn’t need an external power source? If you leave phantom power switched on in your audio interface or mixer, will it damage any equipment that doesn’t require phantom power?
Let’s look at the safest ways to use phantom power if required and how to avoid damage to your valuable equipment.
Microphones: Condenser, Dynamic, and Ribbon Mics
Phantom power is mainly used for microphones, so we will look at these first.
A recording studio uses many different types of microphones to capture a rich and accurate sound. Recording engineers often use a mixture of condenser, dynamic, and ribbon microphones, since they each have different unique characteristics and capabilities.
To understand whether phantom power will damage each style of microphone, first we need to know how each is used in a studio setting.
Condenser mics are active mics that require an external phantom power supply to function. It’s a bit like a car without a battery, in that the internal electronics of a condenser mic won’t operate without power. Typically, that power is provided from the mixer or mixing desk by turning on the 48-volt DC phantom power switch.
As a result, condenser mics won’t be damaged by phantom power; they won’t even work without it.
Condenser mics are most commonly used for vocals, acoustic instruments, amplified instruments, drum overlays, and spoken word.
Used most commonly for live performances, a dynamic microphone is a passive piece of equipment, meaning it doesn’t require any external power source. In live performances, no one will notice if you accidentally leave the phantom power switched on when a dynamic mic is connected.
However, when recording in the studio with a dynamic mic, phantom power has plagued recordings with an electronic hum caused by the surge of unnecessary power to the mic.
Whether phantom power can damage a dynamic microphone is debatable.
If it’s a balanced microphone, with both pins of the XLR supplying the same DC voltage, it should just pass through the microphone with a slight hum and some heat dissipation at the worst.
However, damage to your mic could occur if the faulty XLR cable is used to connect the microphone.
Suppose for some reason, the pins on the cable have been damaged. In that case, the power distributed through each could become unbalanced and cause permanent damage to the microphone – or even wreck the mic in some cases.
So, if in doubt, switch off the phantom power when using the dynamic microphone. Some mixers or interfaces even allow the phantom power to be assigned to just a couple of the inputs while leaving the rest unpowered.
Ribbon microphones are a popular choice for recording louder sound sources like drums. They come in two varieties, those that require a phantom power supply, and those that don’t.
The ones which require phantom power are rarer, so you should always check the individual specs of the ribbon mic before connecting it to your recording source.
Leaving your phantom power switched on when using a ribbon mic that doesn’t need it will result in the fragile internal ribbons being stretched, or in some cases, blown or burnt out.In these instances, the additional power can be too much for the ribbons to cope with, often resulting in permanent, irreparable damage.
Again, faulty cables can be a significant cause of damage from using phantom power with these forms of recording microphones. A common mistake many sound engineers or musicians make is cross-patching microphone tie lines, resulting in an unbalanced power feed. Instead, many engineers use patch bays to route their signals and avoid the issue.
Can Phantom Power Damage a Mic?
Nearly always need power to work.
No phantom power is required.
90% of ribbon mics don’t need phantom power.
Used for vocals, drum overheads, and acoustic instruments.
Used for a wide variety of instruments, drums, and vocals. The popular choice for live performances.
Mainly used for louder drums and vocals.
No risk of damage from phantom power.
Rarely damaged by phantom power (but faulty XLR cables can be a problem if they’re unbalanced).
Phantom power will likely cause irreparable damage.
Guitars, Other Line-In Instruments, and Phantom Power
Line-in instruments are also susceptible to damage from phantom power. This includes any guitar, keyboards, or other electrical instruments that don’t need any external power source. The following are examples of line-level gear:
Connecting a line-level device to a mixer or recording desk with the phantom power switched on can result in the internal output electronics of the device being fried.
Most audio interfaces and mixers are now equipped with specialized line-level inputs which should be used with such instruments or devices. Connecting a line-level device to an XLR mic input is not advisable, especially if there’s a chance phantom power is being sent to that input.
How a mixer or interface delivers phantom power is another factor in whether it is likely to damage your equipment.
Some send phantom power to all inputs, whereas other more advanced units may offer phantom power, which can be turned on or off for each input.
If in doubt, always connect line-level gear via a TRS jack, since phantom power is only ever delivered by XLR connections.
Phantom Power and Audio Interfaces
Many professional-grade audio interfaces now can supply phantom power to communicate with as many microphones as possible. In these instances, the audio interface either draws power from an external power adapter or the USB port it connects to.
Phantom power is usually activated via a button on the channel strip. Activating it allows the interface to send phantom power to the XLR inputs.
An audio interface does so much more, though, so don’t assume because you have phantom power on your mixer, you won’t need an audio interface. After all, the audio interface turns your recording into a format your laptop can understand.
Like most line-level devices, an audio interface doesn’t like having a 48-volt phantom power supply applied to its inputs. Some are designed to cope with an external phantom power supply without issues.
However, many will be permanently damaged or “fried”, so we recommend you use some form of protection like a Passive Direct Input box or isolation transformer.
Will Phantom Power Damage Your Speakers?
One of the most common questions about phantom power is if it will cause damage to speakers.
The truth is that phantom power is unlikely to cause any noticeable damage to your monitors since phantom power is applied to the inputs rather than the outputs.
Despite this, you may have noticed a “popping” sound coming through the speakers when you switch on the phantom power. Although the sharp “pop” sound rarely causes significant damage, it’s not doing the speakers any good. The sound of the power surge when you switch on the phantom power can be avoided by ensuring the speakers are turned off before activating phantom power. You should at least turn the volume down to a minimum.
Checking the equipment’s specs is the only sure way to know if the phantom power will cause damage.
Some instruments and line-level devices may be fitted with protective measures to prevent phantom power from causing damage. But this protection will only survive for a short period, so phantom power should be switched off once it’s not needed.
As a rule of thumb, when you connect any single-ended (unbalanced) output device to a balanced preamp, you should ensure that the phantom power is not active on that input.
In general, try to avoid using an XLR cable when plugging line-level gear into any device that employs phantom power. A TRS jack cannot carry the phantom power to the mic and is much safer.
Ribbon microphones are the most likely piece of equipment damaged by phantom power if phantom power is not required.
Most other equipment is rarely permanently damaged. If in doubt, turn off the phantom power when connecting devices that may be damaged by phantom power.
We hope this has answered your questions on whether phantom power can damage equipment, but get in touch if you have any further questions or experiences to share.