Phantom power issues

48 volt phantom power that is common in pro audio mixer mic inputs can kill the sound card in your laptop or computer (and some other devices). Here Dave Rat shows a quick and easy test to make sure you do not accidentally damage your valuable computer.

Don’t Let Phantom Power Kill Sound Cards – Lick Test

This was a funny video with facts and parody. Do not follow the advice to put the plug to your mouth. It is not a good idea.

Anyone else’s tongue just tingle like a 9v test just by looking at this video? I mean, that’s gonna be very unpleasant to say the least to lick 48V DC. Even 9V battery hurts on the tongue.

Phantom power can really damage equipment. It is possible that using an XLR to 3.5 mm stereo plug cable to connect devices like PCs and smart phones can fry the connected devices when phantom power is on. Some devices can take it and some can be seriously damaged. It depends how the audio output is built and protected if it can withstand phantom power or not.

“Phantom power into a laptop or phone! That’s the best way to get rid of DJ’s I’ve heard for ages !”

Phantom power is typically 48V through 6800 ohm resistor. Own resistor for signal + and – sides. You get around 7 mA current from one pin to ground. 14 mA total from two pins.

I have even fried one Behringer UltraCurve device XLR output with phantom power. It cooked some 25V or 35V capacitors from output and nothing else if I remember correctly. Had those been higher voltage and there probably have been no damages due phantom power.

How to avoid frying your equipment?

Ne careful and do not plug things not designed for it to mixer XLR mic inputs. Do not use questionable cables. XLR male to mini jack!?!

Someone is looking for troubles with those. That’s what’s a DI box is made for ?

Some people say that minijack should be banned from real shows. How many times there is a #%$$#% clever dude unplugging them while they are live.

Some people have recommended that don’t connect shield to pin 1, for unbalanced signal connect signal to pin 2 and shield to pin 3. This could on some cases avoid phantom power getting to device, but is not foolproof and can cause other potential issues.

14 Comments

  1. Tomi Engdahl says:

    Q. When used live, how should I protect an audio interface from phantom power damage?
    https://www.soundonsound.com/sound-advice/q-how-to-protect-audio-interface-phantom-power-damage

    I recently worked at an event where the sound engineer blew up the sound card on a computer, apparently because the sound desk it was connected to sent phantom power to all channels. As I have a small gig coming up where I need to run sound from a computer, keyboard player and a drum pad using a small mixer that also sends phantom power to all channels, I don’t want that kind of disaster! So is there a way that one might prevent equipment damage from phantom power?

    Is a DI box the answer, and if so, what type?

    SOS Technical Editor Hugh Robjohns replies: Very few electronic line-level devices (computer sound cards, electronic keyboards, MP3 players, DJ mixers, etc) like having 48V phantom power applied to their outputs! Some are designed to cope, but many will be damaged or even destroyed, so some form of electrical protection is definitely advisable, if only to protect against accidental mis-plugging on a dark live stage!

    A basic requirement is to introduce a means of electrical isolation between the source equipment and live sound mixer, and the conventional options are either a DI box or a ‘line isolator’ box. Both essentially use a transformer to provide the electrical isolation and thus prevent the mixer’s phantom power from reaching the source equipment.

    The main practical difference between these two devices is that DI boxes are designed to transform the unbalanced line or instrument signal down to a balanced mic-level output signal, while a line isolator doesn’t change the signal level at all and so provides a balanced line-level output from an unbalanced line-level source. The choice of one over the other really depends on what signal level the mixer’s mic inputs can cope with, but in most live-sound cases I would generally go with a DI box.

    When working with electronic sources (sound cards, keyboards, etc), a ‘passive’ DI box would be fine (I often use a Radial ProD2, for example), but if you are likely to want to use the DI box with an electric guitar I’d recommend buying an ‘active’ one instead

    An alternative source of extremely good and highly cost-effective active DI boxes is Orchid Electronics: (www.soundonsound.com/reviews/orchid-electronics-di-boxes). Technically, these don’t use an isolating transformer (this contributes to the lower cost and smaller size) but they will still keep the phantom power safely away from the source equipment. I have several and use them frequently.

    Reply
  2. Tomi Engdahl says:

    How Does Phantom Power Affect Microphones?
    https://www.youtube.com/watch?v=qTarfzrCGvI

    Phantom Power does change the sound of your microphone, BUT HOW & is More Power Better, Worse, Too Much, or Not Enough?

    Can Microphones Work with 12v if their Specs Says 48v?

    In this video I test and compare multiple small and large diaphragm condenser and shotgun microphones with both 12 and 48v phantom power and use frequency analysis to find out how phantom voltage affects sound. If you have ever wondered whether phantom power really affects your microphone, this is for you.

    Phantom Power – How to Avoid Damaging Your Microphones
    https://www.youtube.com/watch?v=DZ5AdyreC4o

    Phantom power is used to turn on any condenser microphone such as small pencil condenser mics, and large diaphragm vocal microphones. It is important to understand how to properly use these mics, and how to properly apply phantom power to turn on these mics.

    Reply
  3. Tomi Engdahl says:

    Can Phantom Power Damage Equipment? Here’s The Truth
    https://stampsound.com/can-phantom-power-damage-equipment-heres-the-truth/

    Phantom power is required for recording with any condenser microphone. Most audio interfaces and mixers have phantom power built-in for this purpose. However, dynamic microphones and other equipment don’t need it to function.

    Can phantom power damage equipment?

    In some cases, phantom power can damage equipment. Although dynamic microphones are unlikely to be damaged, sending phantom power to a ribbon microphone can cause permanent damage. It is also advised to turn phantom power off before connecting other equipment like line-in instruments and monitors.

    When recording, many different forms of studio-equipment are used.

    Various microphones, outboard equipment, speakers, instruments, and cables all form a studio setup. Each of these devices has inner components and circuitry that widely differ from one another.

    Phantom power may be safe to use with condenser mics and some dynamic mics, but many of the other devices can be damaged by its presence. In the following article, we’ll examine the equipment’s relationship with phantom power so that you can avoid any disasters.

    Will Phantom Power Damage Your Guitar? (I Tried!)
    https://stampsound.com/will-phantom-power-damage-your-guitar-i-tried/

    Will phantom power damage your guitar?

    It’s highly unlikely that subjecting your guitar to phantom power will cause any damage. Guitars are line-level devices that commonly use unbalanced, TS cables. Phantom power can only be sent through balanced cables – in most cases, 3-pin XLRs.

    Although the chance of your guitar being damaged by phantom power is unlikely, there are some situations where using unsuitable equipment could put the instrument at risk.

    This is because phantom power can only be sent through the second and third pins in a balanced XLR cable.

    Guitars typically use ¼ inch TS cables, which are unbalanced and have a tip-sleeve design rather than the 3-pin design of their XLR equivalents.

    The reason for this is that TS and TRS jack cables which are commonly used for connecting guitars and other live level instruments have contact points that don’t connect simultaneously.

    When you plug a guitar jack cable in, the tip enters the input first, followed by the ring, and then the sleeve. The connection is therefore established one step at a time.

    Conversely, when you plug an XLR cable into a balanced input, each of its three pins connects at the same time. This is why XLR cables can receive the additional voltage supplied by phantom power, while conventional guitar cables are not.

    Leaving Phantom Power On When Recording Guitar

    In theory, the only way that phantom power could damage your guitar is if you connected it to the interface or mixer using a balanced cable.

    All guitars have a jack output, so this would mean you’d need to use a cable that had a male XLR connector at one end, and a TS or TRS jack connector at the other end.

    There are practically no situations where this would be beneficial, however.

    Therefore, you don’t need to worry too much about leaving phantom power turned on. Although it may cause some unwanted noise to be present in your recordings, the chance of it damaging the instrument is virtually nonexistent.

    Reply
  4. Tomi Engdahl says:

    Will it hurt anything to leave the phantom power on? Will it damage my microphones if the phantom power is on and the mics don
    https://www.sweetwater.com/sweetcare/articles/hurt-anything-leave-phantom-power-damage-microphones-phantom-power/

    It will not hurt anything to leave your phantom power on. Most dynamic or condenser microphones that don’t require phantom power will reject it. Ribbon mics are the exception in this situation. Sending phantom power to a ribbon microphone will probably have disastrous consequences. You should refer to the specs of your microphone to be sure it is safe to turn on phantom power before plugging any microphone into an input with phantom power. Never plug line instruments into the XLR input jacks with phantom power engaged. This could damage your gear. You should also make sure to only turn phantom power on after connecting your microphone and turning it off before unplugging your microphone. Doing this will ensure that you don’t get a loud pop through your speakers.

    Reply
  5. Tomi Engdahl says:

    What happens if you put phantom power on a dynamic mic?
    https://www.quora.com/What-happens-if-you-put-phantom-power-on-a-dynamic-mic

    If you’ve got the mic already plugged in, then you can switch on the phantom power and it will do no harm for most dynamic mics (but a ribbon mic, which is a specific kind of dynamic mic, might well take damage).

    If the phantom power is on, and you start plugging microphones in, all kinds of bad things can happen. Always switch off phantom power before plugging microphones.

    However… microphones are a lot more robust these days than they once were. When I was first being trained in video production, the trainer, who was a specialist sound guy, hot swapped the phantom powered Sennheiser shotgun mic.

    “Aren’t you supposed to turn off phantom first?” I said.

    “You’re supposed to. But life’s too short.”

    I’ve been hot swapping video production mics ever since, and not had any problems. Whether I would do that with a U87 is a different matter…

    Reply
  6. Tomi Engdahl says:

    Can phantom power break a mic?
    https://mulloverthing.com/can-phantom-power-break-a-mic/

    Can phantom power break a mic?

    Some ribbon mics (usually used only in studios) can be damaged by phantom power if a cable or the mic is mis-wired. It’s also best to plug microphones in before turning on phantom power. At the very least, doing so while phantom power is active can cause a loud, audible pop from the speakers if the volume is up.

    What happens if you use phantom power on a mic that doesn’t need it?

    Will Phantom Power Damage My Dynamic Mics? A dynamic microphone, like the SM58, does not require phantom power because it does not have active electronics inside. Nonetheless, applying phantom power will not damage other microphones in the vast majority of cases.

    Can phantom power damage pedals?

    No, phantom power can’t do damage to your guitar. The first thing that you need to question is whether you are plugging the guitar in through a XLR cable or not.

    Can you destroy a ribbon microphone with phantom power?

    Ribbon technology can be traced back to the beginning of the previous century. It works with a very thin sheet of metal between two magnets. Many of these microphones in the old days didn’t have an internal transformer. If you hit one of these very rare and old ribbon microphones with phantom power you can destroy it.

    Microphone Technology & Design
    EEVblog #616 – How Microphone Phantom Powering Works
    https://www.youtube.com/watch?v=e5xenXTwAzo

    Reply
  7. Tomi Engdahl says:

    On phantom power:

    If it’s 48v DC supply it’ll need to connect via 6k81 resistors to the balanced signal wires. The pre amp will need DC blocking as well as some diode based clamping to keep charge/discharge pulses to within limits on the input to the preamp.

    Reply
  8. Tomi Engdahl says:

    Could phantom power damage a PC’s speaker output?
    https://www.soundonsound.com/forum/viewtopic.php?t=70885

    Yes, I think you probably could damage the headphone/line drive chip in the laptop.

    This is about the only area where phantom power can cause a problem. Mostly people worry about a non-problem but feeding ~48 volts into things that were never intended to get it is asking for trouble.

    There will be an AC coupling capacitor (though maybe not as you might think be in the ‘hot’ pin) but it will be the ‘wrong way around’ i.e. phantom power will put +V on the -ve end and the voltage rating will be far too low. I doubt any laptops fit 63V non-polarized caps?
    Best solution is a transformer. Is the quality critical? If not a wee 1200 from OEP would do. Or, Amazon do a twin ch earth isolator for about a tenner and you could mod that.

    You could of course put a capacitor in the line. 2.2mfd electrolytic at 63V should do assuming a mic input impedance of 2k and you don’t want a lot of bass? The cap of course should have the +V end connected to phantom power and a ‘drain’ resistor of about 22k connected to the -ve end and ground. But! I still think there is the possibility of a voltage surge and I doubt laptop jacks are protected very well, if at all?

    Yes, damage is a real possibility. A di box is the best solution, or use a separate preamp as you now are.

    Many thanks Dave. Putting any DI box between the mic pre and the PC speaker out would isolate it from phantom also wouldnt it?

    Yes it would but you would still have to be careful how you ‘started things up’ IMHO as a pulse could get to stuff designed to live with just five volts!

    NO spook juice at all as you are now going to do is best of all.

    I don’t know which mixer you are using but does it not have a line input on the channel you are using? On most mixers phantom power isn’t fed to the line input – only the mic input (but it is always best to check in case yours is one of the odd designs where phantom power is fed to both).

    I’ve never come across a mixer where phantom power is applied at the line input stage.

    The title of this post is confusing, my initial thought was ‘No’ because where would the phantom power come from since mixer outputs don’t have phantom power. Closer reading showed that it was the PC headphone output going into the mixer’s mic’ input that was the issue.

    I’ve never come across a mixer where phantom power is applied at the line input stage.
    I can’t instantly recall a mixer like that, although I have a nagging thought that I have reviewed at least one that did
    This one?
    https://www.soundonsound.com/reviews/schertler-arthur-modular-mixer
    This was one of the preamps that had phantom on line inputs
    https://www.soundonsound.com/reviews/trident-audio-s20

    Well I never!!! Having just bought a ribbon mic’ I’m going to have to be careful. The instructions do say not to plug it in until at least a minute after phantom power has been switched off.

    As you say, the vast majority of ribbon mics are absolutely fine with phantom power on the line. I must have hot-plugged hundreds of Coles 4038s over the years and they all worked!

    Reply
  9. Tomi Engdahl says:

    Q. When used live, how should I protect an audio interface from phantom power damage?
    https://www.soundonsound.com/sound-advice/q-how-to-protect-audio-interface-phantom-power-damage

    I recently worked at an event where the sound engineer blew up the sound card on a computer, apparently because the sound desk it was connected to sent phantom power to all channels. As I have a small gig coming up where I need to run sound from a computer, keyboard player and a drum pad using a small mixer that also sends phantom power to all channels, I don’t want that kind of disaster! So is there a way that one might prevent equipment damage from phantom power?

    Is a DI box the answer, and if so, what type? I would also like a good DI box for my guitars too, so can I kill two birds with one stone? And would the DI box help reject interference? Finally, someone told me that phantom power does not run through jack lead connections. Is this correct and would that negate the need for a DI box?

    SOS Technical Editor Hugh Robjohns replies: Very few electronic line-level devices (computer sound cards, electronic keyboards, MP3 players, DJ mixers, etc) like having 48V phantom power applied to their outputs! Some are designed to cope, but many will be damaged or even destroyed, so some form of electrical protection is definitely advisable, if only to protect against accidental mis-plugging on a dark live stage!

    A basic requirement is to introduce a means of electrical isolation between the source equipment and live sound mixer, and the conventional options are either a DI box or a ‘line isolator’ box. Both essentially use a transformer to provide the electrical isolation and thus prevent the mixer’s phantom power from reaching the source equipment.

    The main practical difference between these two devices is that DI boxes are designed to transform the unbalanced line or instrument signal down to a balanced mic-level output signal, while a line isolator doesn’t change the signal level at all and so provides a balanced line-level output from an unbalanced line-level source. The choice of one over the other really depends on what signal level the mixer’s mic inputs can cope with, but in most live-sound cases I would generally go with a DI box.

    When working with electronic sources (sound cards, keyboards, etc), a ‘passive’ DI box would be fine (I often use a Radial ProD2, for example), but if you are likely to want to use the DI box with an electric guitar I’d recommend buying an ‘active’ one instead, simply because the input impedance is usually higher and is less likely to affect the guitar tone in a negative way. Two popular ‘industry standards’ are the Radial J48 and the BSS AR-133. Although initially expensive these devices both sound very good indeed, and will easily last a lifetime; most cheap alternatives don’t and won’t!

    The notion of reducing the signal level through a DI box only to boost it again in the mixer’s mic preamp isn’t ideal, so if the mic preamp has the headroom to cope with a line-level signal (many do), then it might make more sense to use a line isolator box instead, providing a balanced line-level output from a line-level source. My usual recommendation is the ART DTI box, simply because it’s quite affordable and it has a plethora of different connection formats, making it very versatile indeed.

    Finally, there can be a beneficial reduction in interference when using DI or line isolation boxes, but only because placing the box next to the unbalanced sound source means the long cable run back to the mixer will be balanced and thus able to reject interference far better in comparison with running long unbalanced cables directly between the source and mixer.

    Reply
  10. Tomi Engdahl says:

    Can Phantom Power Damage Equipment? (ANSWERED!)
    https://producerhive.com/ask-the-hive/can-phantom-power-damage-equipment/

    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.

    condenser mics won’t be damaged by phantom power; they won’t even work without it.

    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.
    So, if in doubt, switch off the phantom power when using the dynamic microphone.

    Ribbon Microphones
    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
    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.

    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:

    Preamps
    Electric guitars or basses
    Keyboards and synthesizers
    Drum machines
    Outboard FX units
    DJ controllers
    Electric string instruments such as a violin

    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.

    Phantom Power and Audio Interfaces
    Many professional-grade audio interfaces now can supply phantom power to communicate with as many microphones as possible.
    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.
    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.

    Wrapping Up
    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.

    Reply
  11. Tomi Engdahl says:

    Which is More Dangerous? Phantom Power, USB Power or a 9 Volt Battery?
    https://www.youtube.com/watch?v=62ZUDwRKit8

    I will test to see which makes more noise with a speaker, which lights and LED brighter, can melt small wires, is louder when connected to a mic and which tastes the best.

    00:00 Introduction
    00:59 What is Phantom
    01:27 USB Power
    01:55 9 volt battery
    02:07 LED Test
    04:44 Touch Test
    05:22 Speaker Test
    08:06 Wire Short
    10:47 Wired Wrong Into a Mic
    13:07 Eye and Lick Test
    15:35 Summary

    Reply
  12. Tomi Engdahl says:

    Don’t Blow Up Soundcards – Mini Plug Phantom Power Test
    https://www.youtube.com/watch?v=MQSPfjzR7uo

    Here is a quick and easy way to test for phantom on 1/8″ (3.5mm) jacks.

    Phantom can damage some laptops and it is important to make sure there is not phantom on the mini plug when plugging into gear that is not designed to accept it.

    Also, thank you Cassidy for helping with this video!!

    00:00 Introduction
    00:34 Testing Phantom on mini plugs
    01:37 Phantom Test 1 no phantom
    02:06 Phantom test 2 yes phantom
    02:58 Phantom Test 3 Again
    03:24 The aftermath

    Reply
  13. Tomi Engdahl says:

    Which is More Dangerous? Phantom Power, USB Power or a 9 Volt Battery?
    https://www.youtube.com/watch?v=62ZUDwRKit8

    00:00 Introduction
    00:59 What is Phantom
    01:27 USB Power
    01:55 9 volt battery
    02:07 LED Test
    04:44 Touch Test
    05:22 Speaker Test
    08:06 Wire Short
    10:47 Wired Wrong Into a Mic
    13:07 Eye and Lick Test
    15:35 Summary

    Reply

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