Dangers & Solutions - Audio Phantom Power + Demo

cool cool i'm dave rat and let's talk phantom power phantom power is a really an interesting and cool uh tool to use it's a voltage that we can send down mic lines to power up various things like di boxes and condenser microphones i've seen it used for other things you can use uh i when i designed the sound tools sniff xlr snipper sanders i designed it around a phantom power type circuit uh you can actually use phantom power to test mic lines uh the sander unit actually creates a 12 volt phantom power that can be used to power 12 volt phantom bikes typically phantom power is 48 volts at least when it first came out but there are phantom power units that are 9 to 12 volt there's 24 volt and 48 volt so there are some lower voltage phantom power sources typically a 48 phantom power source will power anything but due to like operated portable units or whatever a lot of times it's difficult to create 48 volts or it used to be so they made various phantom power devices that will run on lower voltages i remember first buying akg c451s and there was a 12 to 48 you know phantom power or 48 only version all right so um phantom power has some uh mysteries and misconceptions as well um so and also there's some interesting stuff about phantom power that even those of you that are well-versed in how it works and what it does um that you might find interesting phantom power is 48 volts 48 volts is fairly high it's almost half the voltage of 120 wall voltage that would shock somebody conversely it's very low current so it's very it's it's more like getting a shock from rubbing your feet on the carpet or a balloon the electrostatic it's got very low current so it won't hurt you but it can be felt and some people are more sensitive to it than others and miswired snaking systems or there can be situations where if something's wired improperly and you get that 48 volts to your lip you'll definitely taste it and feel an electric shock there i've been called in to on two different occasions to um resolve people getting shocked do i got a call to the roxy once and went down there and messed found some falls in the snaking system but that's all beside the point let's go ahead and look at phantom power here so i've got a little setup we've got a little gopro up here that's running hopefully you can see a good amount of what's going on i've got two mixing boards um both capable of creating phantom power and then they're tied together through this sound sound tools cat box which has got an out to this mixing board out to this mixing board and then an input which would be like a mic going to both consoles so let's first of all start with looking at phantom power so i'm going to unplug one of the consoles let that dangle down there and i'm going to turn on the meter and i've created an xlr to banana plug to go right into the meter and let's go ahead and turn this on and we should see the phantom power show up there and there it is it should be approximately 48 volts 47.4 is good enough and uh it doesn't the thing about phantom power doesn't need to be exactly 48 volts it's basically um it puts out 48 volts but the various units would drag it down lower and they're meant to operate on much lower voltage so it's a very it's a high voltage low current and it drags down and the way this cable is wired is there's the ground is here this black one and this blue wire which you may or may not be able to see is on pin two and this red wire is on pin three and if you look we have 48 volts between the ground and pin three for 47.7 we have 47.7 volts between ground and pin 2. and if we look at between pin 2 and pin 3 we see no volts at all and that's really important and let's go ahead and look at some pictures here that i do with my high quality artistic skills uh the way phantom power is uh outputted is the console input which it's going backwards right the console input your microphone input to the console phantom power is sent out of that in reverse so it's going the wrong way down the mic cable there's no real direction but it's being sent back to the mic the opposite direction that the mic signal comes and pin one is ground and there's no voltage on it or it's the reference of 0 volts pin 2 and pin 3 both have 48 volts on it so we saw that we saw 48 volts between pin 1 and pin 2 and we saw 48 between pin 1 and pin 3 but if we measure between pin 2 and pin 3 they're both at 48 volts there's no difference between them so we don't measure any voltage differential so there's no voltage offset alright so then that would then go down your mic cable here and show up at your microphone so the microphone pin one has zero pin two and three both have 48 volts as i just showed on the meter there let's go to the next one inside of a condenser mic um we have the ground or the reference for all the circuitry inside and then it takes it and it splits this out into two different directions one it has the it grabs the 48 volts from pin 2 and pin 3 through usually a pair of resistors that are equal in value and connects them together and uses that as a 48 volt source that can then be uh utilized to power various circuitry inside the mic the little preamp that and any other filters and stuff and eq or whatever else is going on in that mic that's using the phantom power as the as a voltage source or as the current source additionally there is the output of the microphone the signal and you have the in polarity signal which shows up on pin two on a properly wired mic you have the outer polarity signal that shows up on pin three and though you generally there will be a capacitor or something that blocks the 48 volts from going this way and so this circuitry here is powered by the 48 in the ground and then outputs the signal back down and sends that back down the other way one of the beauties of electricity is you can run voltages in differing directions especially dc and ac so you could have an ac signal on a pair of wires and a dc voltage on those wires and you can separate them out and you can combine them together and utilize those independently and that's what phantom power does all right so that's kind of a simplistic version of what we're doing with what the condenser mic is doing grabbing the phantom power off those um pin two and three in relation to ground and sending the signal down two and three back to the mixing board the mixing board conversely it creates a phantom power it puts the phantom power on and it does a separation as well so when the signal comes in it is pulled off and goes through some capacitors that present prevent the phantom power to get to the circuitry and it's amplified and done up and there's a special circuit that injects the phantom power onto those lines all right so let's go ahead and look at what happens now what happens if we plug in so let's go ahead and we looked at a condenser mic so let's plug in a condenser mic so what we'll do is plug in the sennheiser ksm105 and i'm going to plug that into there now it's plugged into a y cable i'm going to leave this y cable on there but basically it's just coming in here these are just dead ends right now so we don't really need to worry about it and we'll plug that in oh we are going to worry about that so what we're going to do is we're going to plug that onto here and we're going to look at the phantom power this right here is there we go there's our 48 volts okay that 47 points slowly rising again not a big deal so now what we're doing is we are the phantom power's showing up here it's going into these adapters and it's only going to the meter now watch what happens when i plug the microphone in i plug the microphone in it should load this down slightly see now the current draw the microphone has dropped the phantom down to 35 volts um not a big deal these mics are designed to that phantom power has specifications if it's designed properly 35 it can run in 48 volts a starting point and it can drop lower than that depending on mic cable lengths um the mic is designed to be able to utilize a wide range of voltage in there but we do see a drop in voltage when the mic is put on and we can listen to it two two two hey hey hey and the mic works all right let's see what can we do let's talk about dynamic mics now so now i unplugged we got a 48 volts back if i take a dynamic mic we've got 48 volts people what happens when you plug a dynamic mic into this 48 volts it doesn't need it will it hurt it well the way a dynamic mic is basically set up whether it has a transformer or it's the coil of wire is very similar the console puts out 48 volts on pin 3 and pin 2 in relation to ground or pin 1. and inside the dynamic mic is pin between pin two and three and the most simple of mics like an om-7 that has no transformer it goes to a coil of wire which is the voice coil of the diaphra attached to the diaphragm submerged in a magnetic field and that's it and then when the sound moves that diaphragm that voice coil moves back and forth the magnetic field and the magic of electricity is if you move a coil of wire immersed in a magnetic field it will generate electricity and so this will generate electricity and it will show up on pin two and three as and they will be equal and opposites of each other um so it's just really simple if it's a mic with a transformer in it it'll operate almost exactly the same there'll be a coil of wire that then goes to a transformer which is a coil of wire near another coil of wire and then that coil of wire will be connected across pin two and three and there might be some other stuff in there but pretty much that's the whole rundown now will 48 hurt this well a minute ago we measured that we had 48 between pin 2 and pin 1 and 48 between pin 3 and pin 1 and we had 0 volts between pin 2 and pin 3. well if there's 0 volts between pin 2 and pin 3 then there's no voltage being put across this coil and that's okay that's great if we were to use an unbalanced cable to power a dynamic mic with phantom power on that unbalanced cable and shorted pin one to pin two now we would be putting 48 volts across this coil um there's not a lot of current there but that would not be good for uh for the microphone for the dynamic mic and you can actually hear that if you plug a dynamic mic into phantom power and the cable has a short in it or it's a unbalanced cable you'll actually hear the diaphragm pop and actually we could do that i don't mind um putting a pop through some of these mics i got enough of them so let's go ahead and first of all what we'll do is we'll plug a dynamic mic we'll look at the meter we'll see if it does anything the meter doesn't change at all it doesn't drop at all and i'll listen to mike and there's no pop um let's see what would be the easiest way to do a pop um probably to short something out i'll have two okay so now what we're going to do is let's see what happens when we have a poorly improperly wired cable so i'm going to use these meter probes to create a pin too hot i mean an unbalanced cable and listen for this i'll get up close so you can hear it that sound is actually the diaphragm of the mic acting like a speaker and going bam and slamming against the magnet there you can see that it clips the microphone all right i don't recommend doing that to microphones and as it can damage them especially delicate mics like a sennheiser 441 with a really delicate coil or ribbon mics you can destroy them blow that ribbon into pieces so it's not generally a good idea to put phantom power onto dynamic mics but phantom powered is designed such that a properly wired system it's in good condition with nothing wrong with it there is no negative effect directly from phantom power again having phantom power on dynamic mic if the cable is slightly crackly you'll hear that voltage it can cause issues so i don't recommend it but it won't and if everything's working right it won't hurt the mic alright so enough on powering dynamic mics with phantom power let's go on to take a look at a more complex setup here we have a house console generating phantom power a monitor console also generating phantom power and a stage box the question is if i turn phantom power on in this console and phantom power on this console what's going to happen here so we've checked phantom power let's go ahead and look at that we will look at the phantom power here on the meter and there we have 48 volts i'm going to get my condenser mic back before we put the condenser mic up now what i'm going to do is i'm going to turn phantom power off on this console i'm going to plug in this console oh that one's not muted i'm going to plug in that console and i'm going to turn phantom power on let's see unplug that one and turn phantom power on here and there we have it so now we're powered phantom power off of this console okay so this is our front of house console and now we're going to decide are we going to power off the monitor console or the house console well before we even decide that let's take a look at what happens when i plug the monitor console in we're powering off the front of house console now at 46.6 volts a little variation no biggie but now what happens when i plug the monitor console in the phantom power from the front of house console is being loaded down by the monitor console the monitor console is actually impacting the phantom power source there again it's not that big of a deal we're 38 volts but optimum we'd have something closer to 48 depending on the power draw of the mic we've already lost some energy just by plugging in the monitor console but the final power is not on on the monitor console and now the big question is what happens if we turn the monitor the phantom power on on both consoles at the same time will 48 plus 48 equal 96 or will 48 plus 48 equal 48. well for this test let's go ahead and pull out a neumann u89 because uh if we're going to do something test with you something expensive to do it with and we'll plug that in let's um plug it in hot and bad boom now here we saw the phantom power drop from 35 down and then it's come back up again too close to where it was before even a little higher which is interesting okay so now we've got the mic let's go ahead and test that two two two two two two two two two two yep yep and we have power mission control all right what happens if we turn phantom power on both consoles it's climbing and boom we got 46 volts and let's see what it sounds like 2 2 2 2 2 2 2 2 and we are all good uh what happens if we unplug the mic with the two phantom powers what happens we go to 48 volts so with both consoles on i'll turn one off i'll turn the other one off i'll turn the first one on and i'll turn the other one on 48 volts from two different sources gives us 48 volts because those sources are in parallel with each other um and when two voltage sources are in parallel the voltage stays the same but the current increases and the current has allowed us to supply a more stable voltage to the microphone here's a example of that with two nine volt batteries um if you connect the pluses together and the minuses together the output will still be nine volts and this is something you can test at home with a meter if you want to the whole concept the voltage will double and it'll hurt microphones is based on the wiring of series series wiring where you would take the plus of one battery and hook it to the minus of the other so you'd have zero volts and the minus the plus would be nine volts and you'd send nine volts to the minus of the other one and they would add another nine and end up with 18. so it would be possible to create a 96 volts a 96 volt source with this by hooking them up in series assuming that they're isolated enough but that's not what's happening okay so that's pretty much it the general uh the overall view is that there's really no good reason not to use phantom power from both microphones stable from both consoles stabilize that voltage source keep in mind that phantom power does not pass through isolation transformers they so if you do have isolation transformers and iso split you're going to want to phantom from whatever console is hardwired to the mics and not the one that's on the other side of the transformers now the phantom will not hurt transformers again they're designed in such a way just like the inside of a dynamic mic so that when you have 48 volts on both sides of that coil of wire there's zero volts drop across the coil and it won't have any damage of the transformer it won't cause any audio quality loss it won't hurt anything all right well that should just about do it i thought was pretty interesting i knew the outcome of the 48 volts in parallel and i've been doing powering from multiple sources whenever possible what i was surprised to see is i had not measured this before and saw that one console was loading down the phantom power of the other console that would increase as well if you had three consoles or if you've got two consoles and you're going you're splitting into a record feed and maybe the transformer there the transformer won't put a load but if it's not a transformer into the record feed you have another direct input those will continue to load down that phantom all right well hopefully this is interesting and helpful and cool cool i'll do another video soon [Music] hmm [Music] you

Channel: Dave Rat

Views: 13,304

Rating: 4.9878421 out of 5

Keywords: Dave Rat, Pro Audio, Rat Sound., Pro Sound, Live Sound, SoundTools, Rat Sound Systems, Audio Engineer, Soundtips, Pro Sound Tips, Pro Audio Tips, Phantom Power, Phantom, Power, 48 volt, Condenser Microphone

Id: _8UTGcuAtd0

Length: 23min 15sec (1395 seconds)

Published: Tue Sep 01 2020

Reddit Comments

[u/adamminer]

Also noteworthy: he replies to every comment

[u/curbstyle]

dam Dave is ripped

[u/AudioShepard]

Damn upvote the shit outta this one. Big if true.

[u/notasabretooth]

Is he saying I can't yell down the shout at the monitor engineer when they forget to hit 48V anymore?

[u/finishedlurking]

yes i clearly remember dave telling me that 23 years ago. I've never had a problem double assigning phantom in all those years

[u/sublime_cheese]

And here I was thinking that he’d be talking about a Hip album.

[u/Kryzm]

Damn, this was super helpful. Definitely going to binge all his videos.

[u/Jonnymak]

The reason I want to make sure that no one but me send phantom power is because I have a couple of ribbon mics and I've had some equipment die when phantom power was sent to it.

I do not trust someone on another console, especially if it's a festival situation to run phantom power unless we have a proper conversation beforehand.

[u/alexelder]

This question just popped in to my head and then I saw this video in my feed. This is great.