Phantom power is required for any recordings using condenser microphones. It provides a necessary boost to the power so that the microphone can successfully capture the audio.
Does phantom power work through a ¼ inch cable?
Phantom power is exclusive to XLR cables due to the specific order of the contacts that are made when they are connected. For this reason, phantom power will not work with a 1/4 inch cable. The tips on ¼ inch TRS cables come into contact with the ring and sleeve, which leads to unpredictable results.
Although it is certainly not advised to use phantom power with anything other than an XLR cable, there are more layers to this topic than appear at first glance.
Indeed, using +48v phantom power with a ¼ inch cable will produce some results, even if they are undesirable. In this detailed article, we’ll discuss why phantom power doesn’t work with these cables, and what would happen if you tried it.
- If you are unsure what phantom power is, be sure to check out this article.
Phantom Power & Cable Types
To understand why phantom power only works through an XLR and not a ¼ inch cable, it’s important to establish what phantom power is, and the purposes that it is used for.
Phantom power is exclusively used with condenser microphones.
These devices are commonly used for recording vocals, acoustic instruments, and drum overheads. Condenser mics are considered to be the most detailed options for recording, due to their ability to capture the slight nuances of a voice or instrument.
Because the predominant purpose of phantom power is to aid the recording process of a condenser mic, we must explore how a condenser works to understand why phantom power only works with XLRs, and not with ¼ inch cables.
Condenser microphones work using a process called variable capacitance.
This process starts with sound waves entering the microphone and causing the diaphragm to vibrate. The diaphragm of a condenser mic is usually positioned in front of a protective metal plate.
When the diaphragm starts to vibrate, it causes fluctuations in the distance between itself and the back-plate. This movement causes the capacitance to be altered.
This is significant because it leads to the acoustic variations to be converted into minute electrical impulses. These electrical impulses are too quiet to be received by the recording device and therefore require amplification.
Phantom power provides that amplification. It is therefore a vital part of the recording process using a condenser microphone.
One word of warning if I may! Don’t ever connect phantom power to a Ribbon Microphone or you will fry it!
Phantom Power Compatibility With 1/4 Inch Cables
So, what does this tell us about phantom power’s compatibility with ¼ inch cables? Well, the only cables that are ever used with condenser microphones are balanced XLRs.
¼ inch TRS and RCA cables are used for line-level devices like instruments or preamps.
These devices do not require phantom power if they are subjected to it, the damage could potentially occur due to the unnecessary surge in power that is sent through them.
Using phantom power with a ¼ inch cable would be completely unnecessary, and there are no instances when it would be required for recording or playback.
From a purely physical standpoint, using phantom power with a ¼ inch cable would not work due to the way the contacts on TRS cables work. When this cable is connected, the connector tips come into contact with the ring contacts and the sleeve. This leads to unpredictable results when phantom power is added to the equation.
That’s the reason why most good quality audio interfaces have separate inputs for balanced XLR connectors and unbalanced ¼ inch cables.
The phantom power is sometimes exclusively applied to the correct inputs, to minimize the chance of it being used with a ¼ inch cable, which could result in irreparable damage to the line-level device.
Connecting an unbalanced TS cable would cause one line to be shortened when subjected to phantom power, while the other would remain unaltered. This consequently would result in the bias voltage rising, which the connected equipment would be then affected by.
If an audio interface applies +48v phantom power to all of the inputs, it should still be safe to connect a ¼ inch cable. The balanced inputs and unbalanced inputs should be used correctly, however, to avoid any issues from occurring.
- The table below shows the differences between XLR and ¼ inch cables.
|XLR||¼ Inch Cables|
|Used for recording with microphones||Used for instruments & recording devices|
|Always balanced||Available as balanced or unbalanced|
|Compatible with phantom power||Incompatible with phantom power|
|3-pin connector||Single connector with a ring|
Why Is Phantom Power Necessary?
We’ve covered the main reasons why phantom power does not work through a ¼ inch cable, but why do we need phantom power in the first place?
Would it not be more efficient if all audio cables used the same power source, and could be plugged into any type of input?
Perhaps, but unfortunately, all audio cables operate in different ways, even though they all essentially achieve a similar end goal. Phantom power is often designated as +48v, as this is an increase in power that it produces.
- If you have wondered what 24v Phantom Power is, check out my article here.
Phantom power was originally designed to provide power to condenser microphones without the need for external hardware.
In the formative years of recording, tube mics were often accompanied by large and bulky power supplies, and phantom power was invented to remove the need for such devices.
Phantom power is essentially a method of transmitting the required voltage of DC electrical current through an XLR cable. Without it, there would not be enough voltage present to power the internal amp of the microphone, and its diaphragm, so it would be rendered useless.
Line-level devices, such as an electric guitar, for example, don’t require phantom power, or a balanced signal to operate.
This is because they are low-voltage devices and wouldn’t benefit from the boost that phantom power provides. This also further reinforces the reason that phantom power doesn’t work with a ¼ inch cable – it simply doesn’t need to!
When phantom power is active, the DC electrical current is transmitted through the inner wires of the XLR cable. It then produces the exact amount of voltage that is needed to power the condenser mic.
Condenser microphones have active electronics, which make them compatible with phantom power. The phantom power also carries out another vital function which is required on a variety called “true condenser” mics. The more common type is known as electret condensers.
True condenser microphones, in addition to needing the +48v boost for their internal amp and diaphragm to function properly, require another boost in voltage to polarize the inner transducer element.
Phantom power is very useful because it can provide the necessary power to carry out both of these functions simultaneously.
A line-level device that uses a cable with a ¼ inch cable does not require either of these boosts to function, and therefore the phantom power is incapable of working correctly when used with them.
Check out this video for more information on phantom power and 1/4 inch cables.
Phantom Power & TRS Patch Cables
¼ inch TRS patch cables are commonly used for routing rigs. These cables are the exception to the rule and are capable of transmitting audio and phantom power from one source to another.
Nevertheless, there are reasons that XLRs are preferred for use with phantom power sources over their TRS ¼ inch counterparts. The main reason concerns the lack of electrical shorting.
An XLR cable has a 3-pin connector. Two of these are audio pins, while the third is a ground pin. The two audio pins are the same length as each other, while the ground pin is slightly longer.
This is relevant because it means that when the connection is made using an XLR cable, it is grounded before the audio circuit, with the phantom power added in, is complete.
The equal length of the two audio pins means that they connect at the same time, and this removes the chance of electrical shorting occurring.
On the other hand, ¼ inch TRS connections have what is known as a sequential design. When the TRS connector is plugged into an input, this causes the top of the connector to come into contact with the sleeve, then the ring, and finally, the tip of the jack.
This staggered connection causes electrical shorts to occur whenever the ¼ inch cable is connected or disconnected. The flow of phantom power is then adversely affected, too.
Can you use phantom power with dynamic microphones?
No, dynamic microphones do not require phantom power. Although using them with it turned on is unlikely to cause any damage, it may result in unwanted noise being present in the output.
Can you get balanced XLR to Jack cables?
Yes, you can get cables that have an XLR connector at one end, and a ¼ inch jack connector at the other. These cables are indeed balanced and are commonly used for connecting monitors to an interface.
Take a look here on Amazon to see an example.
How long can XLR cables be?
XLR cables can stretch up to 100ft before their signal strength is compromised. For this reason, they are used for live performances at festivals or in large arenas where long cable runs are inevitable.