PLEASE Never Stop doing these videos! After 30 years, you always teach me something that I didn't know, that I should have known, that makes perfect sense, but somehow I feel like I'm an apprentice. That's simultaneously humbling and exciting. And we're talking about Phantom Power of all things!
In all my years of Audio engineering (40 odd)I have never been able to grasp the concept of phantom power workings. This has explained it in the most simplistic form ever. Thank you so much and keep up the great work.
Thanks Dave. I really enjoyed this chat and demonstration. I've been running PA's and doing all sorts of sound for over 40 years and never really understood what was (technically) going on under the hood. In saying that, I always made sure that my pin to pin wiring was spot on and never had any major issues when running condensers with dynamics. Your bench top demonstrations are excellent, and show that the principles do not need a massive rig or console to explain. Keep up the discussion. Cheers ...
For the more technically curious, the actual 48v power supply in the mixer feed each channel separately through resistors, typically 20k ohms or more, so that any difference in the multiple supplies will be dissipated in a small amount of heat, and not damage the microphone or mixer. Even If one or more wires is shorted to ground, like using an unbalanced cable, it will not greatly affect other channels. The only possible damage would be if the microphone voice coil or transformer cannot handle the current. For example , a typical mixer feeds pins 2&3 through 47k ohm resistors, and a typical voice coupled is 200 ohms, so 48v would place about 0.2 volts across the microphone voice coil. It would not be healthy, and would push the coil against the end of its space. It would also generate some heat. The actual damage would depend on the specific microphone. Thanks for the excellent demonstration and keeping it simple.
Thanks again , nice experiment. The loading of the second console un-powered phantom is due to the two , normally 6k8 , resistors used and as you showed us the phantom voltages combine when both on to share the microphone load. The idea of phantom power came from Telephone/Telegraph balanced circuits for either powering up repeater circuits or adding dc signalling to a balanced transmission line. Cheers Dude
I gotta say when you pulled out the Neumann I'm like whaaaaaat. "If we're going to use something to test, let's use something expensive to do it with." Lol. You are hilarious my friend.
Very brilliant explanation. Now, I will not be afraid that my house mixer would not damage the recording mixer even without isolating transformers! Thank you!
I am sure that until now, under no circumstances have I seen an explanation as well structured about Phantom Power as this one, particularly on the question of the interconnection FOH /MONITOR mixers. Thanks, Dave. Keep up your good work. Greetings from Portugal
I'm an electrician industrial for 20 years plus and I love sound and computer networking as hobbies.of which I love doing. I recognised a lot of what Dave was saying,and learned a few new things too..
If I were on the road and had money for all the good things, i would chose you. From the few videos I’ve watched, I’m convinced you might very well be one of the best sound guys out there. That’s a big deal! There are many factors to running sound setups... and knowing you’ve got a person who is a Masterful tech is relaxing I’m sure. Thank you for yet another insightful video.
That's great - nice, simple and clear explanation and demonstrations. Thanks. Another 'danger' case is linking an output of one console to an input of another. I had a repair case when several balanced line outs of a large expensive Soundcraft console had been destroyed due to being connected to the balanced inputs of another console that had phantom power active on those inputs. Some outputs may be protected against damage being caused this way - but for sure not all.
Interesting. Phantom is so low of a current and should not hurt outputs. That said, I have run into situations where activating phantom caused the outputs to distort. Not personally burned outputs though.
Great explanation of the mysterious phantom power! Also like that you explained that AC and DC can both flow on the same pair of wires. Telephones, old Lionel trains and cable TV are some other examples that take advantage of this too :)
Dave , your videos are getting better and better. I just want you to know I really appreciate that you share your knowledge!. Thank you so much!. If you have time can you please review how to fix problems with getting pops or little shocks on the lips when they touch the mic and also noise or buzz from the monitors but not from the mains.
Thanks for taking the time and trouble to do these videos. I learned some things from this one in particular. Even an ol' sound dog like me isn't afraid to admit that I can still learn stuff! Not that it's doing me any good at the moment with nowhere to apply my knowledge, but I remain hopeful.
Many of us share your disappointment from not being able to do live events, Carl. Just hang in there and eventually we'll all be back in action, and probably appreciating what we get to do even more than ever thanks to a shift in perspective from this weird time. Stay strong. 💪🤘🖖
EXCELLENT video as always! My only comment is that this only works IF everything is properly wired and undamaged. You did touch on what happens if a dynamic mic is in the mix and an unbalanced cable is used...BUT what about the possibility of damaging a console's input or the output on a piece of equipment with improperly wired cables, a damaged cable, or some other issue combined with phantom power? I've just been burned by this one too many times...especially when tying into someone else's gear. If it's all your gear, and all properly maintained, perfect! I still much prefer an active or transformer split for some isolation, but that's just me...
Phantom power should be safe for all pro gear regardless of being wired properly. It is limited by 6800 ohm resistors and gear designers should and almost always take into account the potential existence of phantom Computers, semi pro, super cheap and home hifi gear? Not so much, that will often get cooked by ohantom
Great demonstrations thank you! Dave over at EEVBlog invited Doug Ford (from Rode Mics) to explain phantom power and a lot of other microphone design considerations on the EEVBlog channel here on TH-cam. I highly recommend them. (Phantom power is episode #616.)
Nice bass test in the end :D Great info, I guess someone who is an electric engineer would have known this already, but developing an intuitive understanding of electricity is Incredibly hard for some (like me) :)
Two things : Red should be pin 2 (hot) ? And blue pin 3 (Cold) The condenser mic is a Neumann kms105 not a sennheiser kms105😉 And I like your videos Thanks🙏🏼
Great video! There's a lot of information here I've kind of put together over time (sometimes from watching you), but it's great having it all together and verified.
@@DaveRat The pleasure is mine. I've been involved in sound in some capacity since 1996 but in the film industry since 2001 as a boom operator. Completely different world from yours but your knowledge and teachings have helped round out my sound knowledge.
Chiming in late. I've been watching your videos for several years off and on and they're all great and informative. Regarding this video on phantom supplies, there is one legit issue with not using phantom on inputs not requiring phantom. Such as wireless microphone receivers. As you mentioned, capacitors are used to block DC, protecting a mixer's active input circuitry as well as active devices connected. And in a perfect world this works well. However should a phantom powered microphone, wireless receiver (or any direct connected device with active as opposed to passive outputs) be unplugged or plugged in, the voltage change on the capacitors will cause the capacitors to briefly pass the voltage onto the internal circuitry of the mixer or other devices. This can cause a signal spike to be heard in the sound system as a pop. it can also damage microphones or active devices connected. Rule x; never plug or unplug microphones or devices into a mixer, stage box or sound system while phantom voltage is active. Make all connections first then activate phantom. And then there's the occasional bad mic cable causing loud pops in the sound.
I always love your videos. You always break stuff down and show it, instead of just talk about it. I appreciate that. I watch videos of yours on stuff I already know and still enjoy them and pick stuff up. Quick question though, I didn't think DC could pass through a transformer. Isn't that one of a transformers (isolation transformer) uses is to filter DC out?
Not sure of the specific part you are referring without re watching the vid, but... There is a way to pass a DC voltage through a transforme and have it function correctly for ac by tying the centertaps of the primary and secondary together if one leg of the DC was applied to both sides of the primary in relation to ground. The DC would show up on both sides of the secondary in relation to ground. This is how phantom power can pass through transformers designed to pass phantom work
@@DaveRat Well I learned something new. I didn't think it was possible to pass DC. Thanks for the clarification. You're the man. Love your work and passion for audio. I share it.
As always, another excellent video, Dave. You mentioned having first generation (1970's) AKG C-451's that would run on anything from 9 - 52 Volts DC phantom power. The wide range of power options allowed them to be used with field recorders or other battery operated devices or just any console that used a different voltage because there was no agreed upon standard back then. But one less common mic that many engineers are not familiar with is the AKG C-452 which used the same modular head/capsule system but it could _only_ run on 48 Volt phantom power because it was designed and sold shortly after 48 Volts became internationally standardized among manufacturers (1981?). Allegedly the 452 with its modified 48 volts only circuit has a lower noise floor than the 451 but I honestly don't know if that's true.
Not sure if anybody else mentioned it in the comments or maybe you followed up Dave but people often forget that if you are using a splitter box with out transformers but does have ground lifts for one or two of three splits phantom power should come from the split that the ground lift does not lift. When the ground gets lifted it breaks the phantom circuit.
Another home run Dave! Stuff we can use. I would assume that this is a moot point with linked digital consoles -- only one (or a stage box) can actually generate +48V.
@@DaveRat I hope you didn't think I was being sarcastic, I really meant it was useful. I was just thinking about the digital realm and realizing that it's a different situation. Thanks for all you do!
That's an interesting question. Since phantom power is 48 volts on both pins two and three and a polarity reverse only switches to with three polarity reverse makes no impact on phantom power. There are several ways to reverse polarity either by swapping pin 2 and 3 or as consoles normally do after the line is unbalanced putting a polarity reverse opamp or circuit there. Either way phantom shows up on both pin 2 and 3 If you have the time check out my videos on phantom power you may find them interesting I did one specifically on powering mics with multiple consoles
Thanks Dave! Great video! I have only one question, if you would want to create 96V by running two consoles in series (20:30), how would you do it? would you just revers pins 1 and 2 on one console, or am I missing something? Thanks
It would be tough or not easily possible. You would connect pins 2 and 3 or pin 2 or 3 to the ground pin 1 of the other console and then, if at least one console was battery powered or not grounded in any way, you could see 96 volts between the pin 1 of console 1 and puns 2 and 3 of console 2. Basically you would need to wire the phantom powers in series. But if the pin 1 grounds of both consoles were referenced to each other then the 2nd console would just short the 1st console phantom to ground. That would not hurt anything but you would just get 48v
Question please. I have a splitter that itself provides phantom for each channel if needed. In your scenario above, I am assuming that a voltage drop occurs because I have two consoles FOH and monitor not turned on for phantom as I have been relying solely on the splitter source for the power. I don't use enough condensers that I think it would cause too far a drop, but with that scenario, should I be keeping it as I have it or should I have phantom on both channels from both boards as well as the phantom on the splitter. My boards allow phantom to be selected for each channel needed vs powering the entire board. Thanks for the explanation, it makes sense, I just never gave it a thought before 🙂
Thank you so much for sharing your talents and experience with all of us. I have a question. I want to utilize 2 AT4033 large diaphragm condenser mics in my acoustic trio. I also love the sound of our Meinl slap top cajon with passive pickups connected directly. Im told by percussion dealers that phantom power will damage it and our small Bose digital mixer doesnt have individual channel control of phantom power. How can I protect the cajon? Will the low Z output of any passive direct box isolate and serve the purpose? Do I need a specific device? Thanks again!
Yes, the output of a direct box will block phantom. Or use and isolation transformer. Or make a special xlr cable that has 100uf capacitors on pin 2 and pin 3. Phantom won't go through a capacitor.
@@DaveRat Thank you so much! Your approach and egoless attitude are rare and so refreshing in this business. You should write a book or a series. I'm sure they'd be VALUABLE go to resources for all of us. Your knowledge and experience needs to be preserved. Thank you!
We just bought a set of drum microphones for a church. Is it safe to use another mixer just for the drum mics for 48v (both the dynamic and OH condenser mics) and use a send for the snake, traveling to the main house console? Otherwise, I'll have to check the wirings of my dynamic mics and xlr cables one by one if we'll gonna be using a single console where both the drum mics, singers instruments will be plugged in. Thanks in advance Dave! Your videos are always helpful!
Yes, all good with using a drum sub mixer and also, with the SoundTools XLR Sniffer/Sender (I designed it) you can test all your lines in a few minutes or less. Just turn on phantom and plug in the sniffer to each channel on the snake and it will tell ya good or no good. Probably worth having one. th-cam.com/video/bG77DLOTPsQ/w-d-xo.html
Great question. Phantom is supplied from the console to the output XLR of the DI. Where a phantom DI will grab the phantom to power it's internal circuits. The ground lift on a DI is breaking the ground connection from the input ground to the output pin 1. So the input signal is grabbed by the di and outputted on pins 2 and 3 of the XLR and the input is not connected to the output ground. The isolation of the input to the output can be done with electronics or with a transformer then boosted by electronics.
A lot of DIs don't fully disconnect when the ground lift is engaged. Pin one is still connected via a parallel 100 ohm resistor and 0.1uF capacitor. This allows enough current to pass to power an active DI but is enough resistance to reduce earth loops.
Hi, Dave Rat. I was taught BEFORE you plug in a mic with phantom power, you first plug the mic in WITHOUT phantom power engaged, then engage it. and then when it's time to tear-down, you turn OFF phantom power from your console or whatever source is driving the phantom power, then wait about 1 min (for the voltage to go away from the mic / cable) and THEN it's safe to unplug the mic from the xlr. is that wrong?
@@DaveRat I had no idea, thanks for that info! It's been 20 years though for me of doing it this way that I just have to keep on with that program of the way I do it. I was literally cringing when you just plugged in that $3,000.00+ U-89 mic! .... and then unplugged (with the method I was referring to above). yikes! but I hear you, it doesn't bother the mic and as long as your channel is muted while engaging, plugging in / out, you won't experience the pop noises.
Is the ethercon breakout boxes wired T568A or T568B? Would this have something to do with why my ethercon system is not lining up 1 for 1? I wired my whole system T568B.
I love the question! Tell ya what, if you join and you're not happy and they don't respond all your money I'll personally send you a check for whatever they don't refund
Dave, could you do a comparison between active and passive DI boxes? We use both and can't seem to tell a huge difference on the different instruments we use them on. And also, maybe compare against an instrument amp XLR direct out? Thanks!
Thanks for teaching me what a balanced cable is. A question... If the two different consoles are at slightly different voltages, theory tells me would that cause some current flow between the two units. Have you any idea how the two different power supplies cope with that? Obviously, no magic smoke is released! Thanks!
All input and output voltages are either floating or references to ground. Inputs look at the differential between the two hots on balanced lines and the diff between hot and ground on unbalanced. Outputs create the same things. As long at the gear is either isolated through a transformer or other method like being battery powered or references to the same ground as the other gear, all good. Differing ground potentials on non isolated gear causes issues
The one with the higher voltage will be providing most of the current. The internal 6.8K resistors help out with current sharing, so the difference will be small.
nice topic....i have been wonding about it quite a while ago and i didnt found answer, thanks for that another question would be, what will happen if you feed line output signal from one cosole to the phantom powered input of another console?
Sending phantom to electronic outputs can give varied and often undesirable results. Due to the wide diversity of output circuit designs, there is no rule to whether it will have a negative impact, other than avoid it. Phantom can be blocked with a pair of capacitors inline on pins 2 and 3 of an XLR or using an iso transformer
Hi Dave, i have a very basic question - if i have a mixer with just one button to turn off phantom power on the whole mixer and i have a device that outputs line level over xlr, should i put a di-box between the mixer and the line level device to prevent damage or can i just connect the line level device directly to the xlr inputs of the mixer that has phantom power turned on?
It won't damage but some output circuits don't perform well when phantom is applied. I would just test and listen to the device with and without phantom. If you don't hear a difference, then I would not worry about it
I can see that the cats stagebox seems to pass Phantom power. I wanted to know if that same stagebox would be able to pass phantom power across a cat6 cable going into the snake?
@@petetrott7568 I dont try it...i have a prof amp rack in my leaving room aprox 6 channels total 3,8 kw, but i have only one 230v phase of 16 amp's...cant do not test at full power. Here small test xd (Notice: the plops in sound are from the camera that cant handeling the sound pressure) th-cam.com/video/UeJemn-PvZg/w-d-xo.html
If the mixer produces +48V to the pins 2 and 3 it will add up to 96volts reference to the ground. Should the mixer produce a negative voltage for the pin 3 to cancel each out when you connect a dynamic or condenser microphone to it?
Hmmm, that's a bit off. The 48v on pin 2 is referenced to ground and same with pin 3. It is the same 48 volts sent to both pin 2 and pin 3 so if you measure with a meter, which I suggest you do to see for yourself, pin 2 to ground is 48volts, pin 3 to ground is 48 volts and pin 2 to pin 3 is zero volts.
I wonder if there is any microphone response difference if 3 or more consoles drag down the voltage enough? Any pro OB set up I've seen always used an active 3rd split anyway. Would having 3 phantom switches on 1channel triple the current then?
Is there any way to remove phantom power from the output, I have a mixer that has all phantom on or all phantom off? If I run phantom into a passive DI box, will it damage the input device?
Can the phantom power ever damage either of the consoles providing it if the split is passive/not transformer isolated? I would assume the power would travel back up the split into each other. i.e. monitor and FoH console both going into a passive split - I'm just wondering how people get away with passive splits in this case
Consoles that can create 0hatomenpower are immune to damage from phantom power. Most mic preamps are immune to phantom power impacting them. Transformers are immune Most input circuits are immune Some or many output circuits are not immune and will either act strangely or possible be damaged. Except: Mic output circuits are almost always ummune As a rule of thumb, phantom on input circuits, all good, phantom to out put circuits, not good. Passive splits is connecting multiple input circuits to a mic output
I'm a total novice about this topic but I have a question about using drum mics. The typical kit comes with various dynamic mics for close mics on the drum and two overhead pencil condenser mics that require phantom power. Obviously, when using one mixer, you have to turn on the phantom power for the condenser mics but that means it's on for the dynamic mics too. It sounds like you're saying this is ok as long as the cables are good. I was wondering this is the normal, expected way to use these drum mic kits. I haven't found any source that addresses this specific issue. Thank you.
Mosicers allow 6urn8ng on phantom on each channel seperately. That said, if phantom was dangerous to any mic, that would be a huge problem. Phantom is safe for all mics with properly wired cables and phantom is so low power almost no mics can be damaged by it though there are some older ribbon mics that can be damaged by wind, dropping, blowing into them and potentially miswired phantom. Don't worry, you won't ever encounter these or any mic that can be damaged by phantom unless if you break into the vintage mic section of a recording studio.
If you wanted to go from one mic into Y split cable and then onto 2 inputs of the same same mixer ( double patch type thing) Would it be the same as the 2 mixer set up? As I have often thought if doing this one apply 48V to one of the inputs.
Thanks for the vid, could you help me a bit? I have an effect pedal with constant 24V phantom power, will it make any harm if i use it in a chain like this: Condenser mic --> external power supply with phantom power 48V --> effect pedal with constant 24V --> audio interface with turned off phantom power --> pc
Phantom power into balanced outputs should not hurt anything. I have seen some outputs don't like it and either distort or offer reduced output levels when phantom is went to them. Just try it. If it works and sounds ok, roll with it
I wish obvious phantom power indicator lights were standard on all mixers. A pro tip for club engineers is to mark any channel on the tape when phantom is on so when the band is finished the engineer is reminded to mute the channel immediately. Experienced musicians know that they need to make eye contact with the engineer before unplugging a hot phantom powered instrument, but this will inevitably slip by the most seasoned sound engineer, and that painful pop is a real vibe killer. It happens to me occasionally when someone starts chatting with me at the board at the end of a set and I get distracted.
Whilest I personally don't worry too much about phantom 9n or off, I do make sure channels are muted before swapping mics at a gig. And if I see the peak lights flash on a muted mic, there is a good chance phantom is on. Phantom power is about as dangerous as drinking a soda in a car, all good except if things go terribly wrong
What about the use of an unbalanced input cable (i.e., RCA phono jack to XLR) for a line in situation, where pin 3 is tied to pin 1 and pin 2 is the "signal line." Pin 3 tied to pin 1 is shorting out the phantom power of a small console (presuming all on/all off environment). I'm guessing that the internal resistor circuit prevents a dead short of the phantom power, but does it reduce the voltage on the other channels? Still got that XLR to bananna plugs cable? Inquiring minds want to know... ;-)
Shorting phantom on one channel has no impact on other channels. But, since phantom has a seperate 48volts on pin 2 and a seperate 48volts on pin3, running phantom to an RCA will put 48 volts on the input of the RCA unit. Generally not good unless the RCA is capacitor coupled which blocks the 48v
Re one console loading down the phantom from the other, I’ve seen consoles that drag the voltage down to 24 volts. Basically the phantom switch chose between +48 and ground, likely for noise reasons.
It would have been cool if you could have demonstrated with an oscilloscope, just to illustrate how phantom power is basically just a large DC offset. Also (and this is just my personal anecdotal observation), but I've encountered situations where a condenser microphone seems to have a lower maximum SPL on 12VDC phantom power than it will on 48VDC phantom power. I would be interested in your insight - am I crazy?
Yes some mics 48 volt only and some are 12 to 48 volt. On the ones that are 12 to 48 volts I have seen specifications that derate their maximum SPL by 3 to 6db. Pretty sure I recall first seeing it on the AKG c451 12 to 48 volt version.
Great video Dave ...often contemplated these things. Do you subscribe to having phantom both ends of the snake then for voltage stabilities sake and have you ever found a change in practical sound from any condenser that has a phantom fluctuate from 48v to as low as you’ve measured. The one thing I’ve missed is your opinion on what some of these experiments show you about the quality of the sound the different environments make. Was especially interested in your cascading channel analogue vs digital mixer experiments ...there were some raised eyebrows but nothing on the audio aesthetics. Nice one for the videos mate ...what else does one do when there’s nothing to mix
Cool cool. Having the added phantom voltage should at best, just offer slightly more headroom as well as redundancy. The main point is that it does not hurt anything. And ever so slightly could help.
Dynamic mics don't need phantom, condenser mics usually do need it. Some ribbon mics need phantom and some do not. It's like a battery, some things like a radio, needs a battery, and something's like a hammer do not and and something's like an ice box can be powered to cool things and others just keep things cool and don't need power
I’m wondering what happens when you split the mic cables and have two desks both supplying phantom power ? Ps not finished video yet :-) Haha just watched the rest 👍🏻
What if the consoles where on different phases of a 3 phase source, would this cause an issue? What if on outside OB truck was on a generator and then production was house power, would there be potential for a cycle or earth issue?
Ideally all analog interconnected audio gear should tie to a common ground point to avoid ground loops. The phases that power the gear tend not to impact. With fiber and digital interconected gear, this is less of an issue or a non issue
Phase of AC should have zero impact. First off the consoles will be isolated from mains via a power transformer or switch mode supply. So it's like they're on separate phases to begin with in Dave's example. Then all of the ground wires on the XLR allow all consoles to have the same reference. Phase would only ever be an issue if you are referenced directly to mains but that's very dangerous and hence why almost every device has galvanic isolation from contacts you can touch to mains.
Good timing on this one for me Dave. I have a Focusrite 18i20 interface, I run a pair of TRS to XLR cables from its outputs into a snake or inputs on a mixer. I’ve been worried about somebody sending me phantom power to the interface outputs. I doubt the interface outputs are transformer isolated, so because there’s no power on the tip or ring, I should be ok? I’d only have a problem if I was running 1/4” to XLR unbalanced cables, correct? I was thinking about buying or making a two channel transformer isolation box to safeguard against this, but if I run balanced cables I’m ok, unless there’s a problem with the snake?
Avoid running phantom to electronic inputs. Capacitor iso will solve but often electronic inputs don't like the 48 v DC offset that phantom sends and will act strangely
You can test for isolation by checking continuity of the grounds for both the input and the output --- if there is no continuity then they are isolated.
Fantastic vid as usual Dave! Would love to hear your recommendations for study material regarding Power in the live environment. I know i'm not up to scratch on power, and with Universities putting out more engineers, I feel like power is the least understood part of this job. Hope you're in good health! ALSO WHO PUTS SUB ON THE OUTRO OF THE VIDEO?
I don't have good reference for live event power, definitely would be a good thing to find. Lots of stuff to know as well as conflicting regulations depending on country and portable versus fixed wiring.
Typically a differing phase is not an issue. Its when the ground for mons and FOH are different and not tied back to the same place that issues arise. Since neutral is tied to ground somewhere in most, if not all, power systems, loads on the neutral can drag it off of zero volts and possibly drag the ground off of zero volts. Or if there is gear that somehow causes the ground to not be zero volts, that can cause issues if the ground at FOH is differing in voltage to the ground at mons. With digital snakes, this is less of an issue and usually a non issue as long as the ground offset voltages are small. With analog snakes and interconnects, even very small offsets in voltage between the ground at FOH and mons can cause hum and buzz issues. Large ground voltage offsets can be dangerous or deadly.
If we wanted to make a mute on/off switch with a short XLR patch cable to be able to mute any mic of our choice, with regards to phantom power, how will that work? Do we have to disconnect both pin 2 and 3 to prevent phantom power from damaging a dynamic mic?
It should not and is easy to test, just listen or measure the output of one console while plugging and unplugging the other console. Typically a console input will be like 10,000 ohms or so and a mic output will be 200 ohms or so. So, you can drive several consoles with very minimal impact on the mic output level and loading of the mic.
Hey Dave, long-time fan and love the videos! Just to calm the nerves of those in our shop - with what you stated about the current being low, can I assume that if I have wireless mic receivers receiving phantom power that there's not much cause for concern? Thanks!
PLEASE Never Stop doing these videos!
After 30 years, you always teach me something that I didn't know, that I should have known, that makes perfect sense, but somehow I feel like I'm an apprentice. That's simultaneously humbling and exciting. And we're talking about Phantom Power of all things!
Awesome, thank you!
In all my years of Audio engineering (40 odd)I have never been able to grasp the concept of phantom power workings. This has explained it in the most simplistic form ever. Thank you so much and keep up the great work.
So cool and thank you! Honored
Thanks Dave. I really enjoyed this chat and demonstration. I've been running PA's and doing all sorts of sound for over 40 years and never really understood what was (technically) going on under the hood. In saying that, I always made sure that my pin to pin wiring was spot on and never had any major issues when running condensers with dynamics. Your bench top demonstrations are excellent, and show that the principles do not need a massive rig or console to explain. Keep up the discussion. Cheers ...
Thank you Perry
For the more technically curious, the actual 48v power supply in the mixer feed each channel separately through resistors, typically 20k ohms or more, so that any difference in the multiple supplies will be dissipated in a small amount of heat, and not damage the microphone or mixer. Even If one or more wires is shorted to ground, like using an unbalanced cable, it will not greatly affect other channels. The only possible damage would be if the microphone voice coil or transformer cannot handle the current. For example , a typical mixer feeds pins 2&3 through 47k ohm resistors, and a typical voice coupled is 200 ohms, so 48v would place about 0.2 volts across the microphone voice coil. It would not be healthy, and would push the coil against the end of its space. It would also generate some heat. The actual damage would depend on the specific microphone.
Thanks for the excellent demonstration and keeping it simple.
Agreed and I believe the phantom power spec calls for 6.8k ohm matched pair resistors
@@DaveRat thanks, I couldn’t remember off the top of my head.
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Thanks again , nice experiment. The loading of the second console un-powered phantom is due to the two , normally 6k8 , resistors used and as you showed us the phantom voltages combine when both on to share the microphone load. The idea of phantom power came from Telephone/Telegraph balanced circuits for either powering up repeater circuits or adding dc signalling to a balanced transmission line. Cheers Dude
Awesome. Thank you Dave
I gotta say when you pulled out the Neumann I'm like whaaaaaat.
"If we're going to use something to test, let's use something expensive to do it with."
Lol. You are hilarious my friend.
Fun!!
Very brilliant explanation. Now, I will not be afraid that my house mixer would not damage the recording mixer even without isolating transformers! Thank you!
Excellent
Really cool video. Appreciate the intentional fault to show the mic coil popping.
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nice! the more I watch your videos, the more I realize how important it is to get a practical understanding of electrical connections and signal flow.
So cool and yes and thank you!
Great video Dave. You really made it easy for me to understand how phantom power works, especially with the drawings. Cheers for that.
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This is great! Thank you for this video. When I saw the two 9v batteries in parallel, I knew exactly what’s going on.
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I am sure that until now, under no circumstances have I seen an explanation as well structured about Phantom Power as this one, particularly on the question of the interconnection FOH /MONITOR mixers.
Thanks, Dave.
Keep up your good work.
Greetings from Portugal
Awesome, thank you
I'm an electrician industrial for 20 years plus and I love sound and computer networking as hobbies.of which I love doing.
I recognised a lot of what Dave was saying,and learned a few new things too..
Awesome!
Best explanation of this ever. Thank you
Thank you, big smile
i can't get enough of your videos. does the audio engineering rabbit hole get any deeper than this!
Ha! Awesome!
If I were on the road and had money for all the good things, i would chose you. From the few videos I’ve watched, I’m convinced you might very well be one of the best sound guys out there. That’s a big deal! There are many factors to running sound setups... and knowing you’ve got a person who is a Masterful tech is relaxing I’m sure. Thank you for yet another insightful video.
Hell yeah and thank you!
You rock. The deep dive, your personality, and the outro with low freq sweep etc., I love it!
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That's great - nice, simple and clear explanation and demonstrations. Thanks. Another 'danger' case is linking an output of one console to an input of another. I had a repair case when several balanced line outs of a large expensive Soundcraft console had been destroyed due to being connected to the balanced inputs of another console that had phantom power active on those inputs. Some outputs may be protected against damage being caused this way - but for sure not all.
Interesting. Phantom is so low of a current and should not hurt outputs. That said, I have run into situations where activating phantom caused the outputs to distort. Not personally burned outputs though.
Great explanation of the mysterious phantom power! Also like that you explained that AC and DC can both flow on the same pair of wires. Telephones, old Lionel trains and cable TV are some other examples that take advantage of this too :)
Awesome!
Dave , your videos are getting better and better. I just want you to know I really appreciate that you share your knowledge!. Thank you so much!.
If you have time can you please review how to fix problems with getting pops or little shocks on the lips when they touch the mic and also noise or buzz from the monitors but not from the mains.
Yeah, I can do a pop shock vid
Thanks for taking the time and trouble to do these videos. I learned some things from this one in particular. Even an ol' sound dog like me isn't afraid to admit that I can still learn stuff! Not that it's doing me any good at the moment with nowhere to apply my knowledge, but I remain hopeful.
Very cool and thank you!
Many of us share your disappointment from not being able to do live events, Carl. Just hang in there and eventually we'll all be back in action, and probably appreciating what we get to do even more than ever thanks to a shift in perspective from this weird time. Stay strong. 💪🤘🖖
Amazing to get these graduate level info packets from the icon himself.
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EXCELLENT video as always!
My only comment is that this only works IF everything is properly wired and undamaged. You did touch on what happens if a dynamic mic is in the mix and an unbalanced cable is used...BUT what about the possibility of damaging a console's input or the output on a piece of equipment with improperly wired cables, a damaged cable, or some other issue combined with phantom power? I've just been burned by this one too many times...especially when tying into someone else's gear. If it's all your gear, and all properly maintained, perfect! I still much prefer an active or transformer split for some isolation, but that's just me...
Phantom power should be safe for all pro gear regardless of being wired properly. It is limited by 6800 ohm resistors and gear designers should and almost always take into account the potential existence of phantom
Computers, semi pro, super cheap and home hifi gear? Not so much, that will often get cooked by ohantom
Great demonstrations thank you! Dave over at EEVBlog invited Doug Ford (from Rode Mics) to explain phantom power and a lot of other microphone design considerations on the EEVBlog channel here on TH-cam. I highly recommend them. (Phantom power is episode #616.)
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HI i like how in-depth you go on explaining stuff and showing details.
Thank you!
Thanks so much Dave. Love these videos, they're very informative and you're an inspiration to everyone in the industry.
Awesome and thank
Nice bass test in the end :D Great info, I guess someone who is an electric engineer would have known this already, but developing an intuitive understanding of electricity is Incredibly hard for some (like me) :)
Fun stuff to learn!
Thanks Dave for your continued work. Interesting to see the dual consoles experiment with a Neumann haha
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Super explanation. simple and easy
Thank you 🙂
Two things : Red should be pin 2 (hot) ? And blue pin 3 (Cold)
The condenser mic is a Neumann kms105 not a sennheiser kms105😉
And I like your videos
Thanks🙏🏼
Cool cool,
Great video! There's a lot of information here I've kind of put together over time (sometimes from watching you), but it's great having it all together and verified.
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I love your demos Dave. Your channel is one I recommend very often thru mine.
Thank you!
@@DaveRat The pleasure is mine. I've been involved in sound in some capacity since 1996 but in the film industry since 2001 as a boom operator. Completely different world from yours but your knowledge and teachings have helped round out my sound knowledge.
@@SoundSpeeds
A most brilliant video.a superb production.
Thank you Stephen!
Brilliantly thought out and presented.
Awesome and thank you
Good info, looking forward to the zoom meeting tomorrow!
Thank you Neil and see you tomorrow!
Chiming in late. I've been watching your videos for several years off and on and they're all great and informative. Regarding this video on phantom supplies, there is one legit issue with not using phantom on inputs not requiring phantom. Such as wireless microphone receivers. As you mentioned, capacitors are used to block DC, protecting a mixer's active input circuitry as well as active devices connected. And in a perfect world this works well. However should a phantom powered microphone, wireless receiver (or any direct connected device with active as opposed to passive outputs) be unplugged or plugged in, the voltage change on the capacitors will cause the capacitors to briefly pass the voltage onto the internal circuitry of the mixer or other devices. This can cause a signal spike to be heard in the sound system as a pop. it can also damage microphones or active devices connected. Rule x; never plug or unplug microphones or devices into a mixer, stage box or sound system while phantom voltage is active. Make all connections first then activate phantom. And then there's the occasional bad mic cable causing loud pops in the sound.
Totally agree. Phantom applied to electronic inputs or outputs that are not designed for phantom is a common issue. Great points!
I always love your videos. You always break stuff down and show it, instead of just talk about it. I appreciate that. I watch videos of yours on stuff I already know and still enjoy them and pick stuff up. Quick question though, I didn't think DC could pass through a transformer. Isn't that one of a transformers (isolation transformer) uses is to filter DC out?
Not sure of the specific part you are referring without re watching the vid, but...
There is a way to pass a DC voltage through a transforme and have it function correctly for ac by tying the centertaps of the primary and secondary together
if one leg of the DC was applied to both sides of the primary in relation to ground. The DC would show up on both sides of the secondary in relation to ground.
This is how phantom power can pass through transformers designed to pass phantom work
@@DaveRat Well I learned something new. I didn't think it was possible to pass DC. Thanks for the clarification. You're the man. Love your work and passion for audio. I share it.
Awesome! Thank Aaron!
Great video. I learned a lot and will implement using phantom from both mixers on a non transformer isolated splitter snake I have.
Excellent
As always, another excellent video, Dave. You mentioned having first generation (1970's) AKG C-451's that would run on anything from 9 - 52 Volts DC phantom power. The wide range of power options allowed them to be used with field recorders or other battery operated devices or just any console that used a different voltage because there was no agreed upon standard back then. But one less common mic that many engineers are not familiar with is the AKG C-452 which used the same modular head/capsule system but it could _only_ run on 48 Volt phantom power because it was designed and sold shortly after 48 Volts became internationally standardized among manufacturers (1981?). Allegedly the 452 with its modified 48 volts only circuit has a lower noise floor than the 451 but I honestly don't know if that's true.
I remember the c452 maybe was the C452eb. Higher voltage also could help with max headroom.
@Phil Allison very interesting and thank you!
Not sure if anybody else mentioned it in the comments or maybe you followed up Dave but people often forget that if you are using a splitter box with out transformers but does have ground lifts for one or two of three splits phantom power should come from the split that the ground lift does not lift. When the ground gets lifted it breaks the phantom circuit.
this is absolutely correct phantom will not pass with the ground lifts also running phantom to a ground lifted split will not hurt anything
Another home run Dave! Stuff we can use. I would assume that this is a moot point with linked digital consoles -- only one (or a stage box) can actually generate +48V.
Yes and no. Knowing how things work is not that important in optimum situations. And we all don't always deal with optimum
@@DaveRat I hope you didn't think I was being sarcastic, I really meant it was useful. I was just thinking about the digital realm and realizing that it's a different situation.
Thanks for all you do!
@@ToddWCorey1 no, all good and yes, with linked Digi, no need
Awww...this is amazingly COOL !! Thank you Dave, its always pleasing watching your experiments. Keep doing this maestro and let us learn. Cheers \m/
Thank you Sunny!
Great episode 👏 what would happen if both desks had phantom power on but one desk had phase reverse on ?
That's an interesting question. Since phantom power is 48 volts on both pins two and three and a polarity reverse only switches to with three polarity reverse makes no impact on phantom power.
There are several ways to reverse polarity either by swapping pin 2 and 3 or as consoles normally do after the line is unbalanced putting a polarity reverse opamp or circuit there.
Either way phantom shows up on both pin 2 and 3
If you have the time check out my videos on phantom power you may find them interesting I did one specifically on powering mics with multiple consoles
I really enjoy your channel. I’m always learning! Thank you!
Thank you!
wow i was just talking about this last night over a beer/s... thanks for the video
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Finally I have support when I’m arguing with other engineers claiming phantom power is bad for mics that don’t need it
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Thanks Dave! Great video! I have only one question, if you would want to create 96V by running two consoles in series (20:30), how would you do it? would you just revers pins 1 and 2 on one console, or am I missing something? Thanks
It would be tough or not easily possible. You would connect pins 2 and 3 or pin 2 or 3 to the ground pin 1 of the other console and then, if at least one console was battery powered or not grounded in any way, you could see 96 volts between the pin 1 of console 1 and puns 2 and 3 of console 2.
Basically you would need to wire the phantom powers in series.
But if the pin 1 grounds of both consoles were referenced to each other then the 2nd console would just short the 1st console phantom to ground.
That would not hurt anything but you would just get 48v
Thanks Dave.
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High quality artistic skills!! Made my day! And I left TH-cam more informed again.. thanks dave.. ps. Do you have a license?
Licence?
@@DaveRat for those guns! Been working out more in lockdown?
@@lerrynhawke3375 ha! Surfing everyday and made my day!
Awesome explanation!
Awesome and thank you
Thanks Dave, that was brilliant that!
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Thank you Dave , I wonted to connect a 15 too 48 source I'm afraid I hope this is what your covering.
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Great work as always, Dave!
Thank you!
Question please. I have a splitter that itself provides phantom for each channel if needed. In your scenario above, I am assuming that a voltage drop occurs because I have two consoles FOH and monitor not turned on for phantom as I have been relying solely on the splitter source for the power. I don't use enough condensers that I think it would cause too far a drop, but with that scenario, should I be keeping it as I have it or should I have phantom on both channels from both boards as well as the phantom on the splitter. My boards allow phantom to be selected for each channel needed vs powering the entire board. Thanks for the explanation, it makes sense, I just never gave it a thought before 🙂
If your splitter supplies phantom, just use that. The sitter will most surely block the phantom from the consoles so console phantom is not needed
Thank you so much for sharing your talents and experience with all of us.
I have a question. I want to utilize 2 AT4033 large diaphragm condenser mics in my acoustic trio. I also love the sound of our Meinl slap top cajon with passive pickups connected directly. Im told by percussion dealers that phantom power will damage it and our small Bose digital mixer doesnt have individual channel control of phantom power. How can I protect the cajon? Will the low Z output of any passive direct box isolate and serve the purpose? Do I need a specific device?
Thanks again!
Yes, the output of a direct box will block phantom. Or use and isolation transformer. Or make a special xlr cable that has 100uf capacitors on pin 2 and pin 3. Phantom won't go through a capacitor.
@@DaveRat Thank you so much! Your approach and egoless attitude are rare and so refreshing in this business. You should write a book or a series. I'm sure they'd be VALUABLE go to resources for all of us. Your knowledge and experience needs to be preserved.
Thank you!
@@tlb2732 thank you Tony and much appreciated!
We just bought a set of drum microphones for a church. Is it safe to use another mixer just for the drum mics for 48v (both the dynamic and OH condenser mics) and use a send for the snake, traveling to the main house console?
Otherwise, I'll have to check the wirings of my dynamic mics and xlr cables one by one if we'll gonna be using a single console where both the drum mics, singers instruments will be plugged in.
Thanks in advance Dave! Your videos are always helpful!
Yes, all good with using a drum sub mixer and also, with the SoundTools XLR Sniffer/Sender (I designed it) you can test all your lines in a few minutes or less. Just turn on phantom and plug in the sniffer to each channel on the snake and it will tell ya good or no good. Probably worth having one.
th-cam.com/video/bG77DLOTPsQ/w-d-xo.html
Thanks for the video, what happens if you supply phantom to a DI box with the ground lift switch engaged, how does the direct box get voltage?
Great question. Phantom is supplied from the console to the output XLR of the DI. Where a phantom DI will grab the phantom to power it's internal circuits.
The ground lift on a DI is breaking the ground connection from the input ground to the output pin 1. So the input signal is grabbed by the di and outputted on pins 2 and 3 of the XLR and the input is not connected to the output ground.
The isolation of the input to the output can be done with electronics or with a transformer then boosted by electronics.
Thanks!
Cool cool
A lot of DIs don't fully disconnect when the ground lift is engaged. Pin one is still connected via a parallel 100 ohm resistor and 0.1uF capacitor. This allows enough current to pass to power an active DI but is enough resistance to reduce earth loops.
Hi, Dave Rat. I was taught BEFORE you plug in a mic with phantom power, you first plug the mic in WITHOUT phantom power engaged, then engage it. and then when it's time to tear-down, you turn OFF phantom power from your console or whatever source is driving the phantom power, then wait about 1 min (for the voltage to go away from the mic / cable) and THEN it's safe to unplug the mic from the xlr. is that wrong?
Nothing wrong with that plan but as long as you are muted, the mic doesn't care if phantom gets turned on with a switch or by plugging in
@@DaveRat I had no idea, thanks for that info! It's been 20 years though for me of doing it this way that I just have to keep on with that program of the way I do it. I was literally cringing when you just plugged in that $3,000.00+ U-89 mic! .... and then unplugged (with the method I was referring to above). yikes! but I hear you, it doesn't bother the mic and as long as your channel is muted while engaging, plugging in / out, you won't experience the pop noises.
@@coffeehigh420 👍
Is the ethercon breakout boxes wired T568A or T568B? Would this have something to do with why my ethercon system is not lining up 1 for 1? I wired my whole system T568B.
Shoot me an email at daveratsound@gmail.com and will help ya sort.
Great explanation! Thank you for the time you put into these videos!
I love the question! Tell ya what, if you join and you're not happy and they don't respond all your money I'll personally send you a check for whatever they don't refund
Thank you Dave, I loved that demo.
Thank you Ian
Dave, could you do a comparison between active and passive DI boxes? We use both and can't seem to tell a huge difference on the different instruments we use them on. And also, maybe compare against an instrument amp XLR direct out? Thanks!
I will ponder some DI box demos
Thanks for teaching me what a balanced cable is. A question... If the two different consoles are at slightly different voltages, theory tells me would that cause some current flow between the two units. Have you any idea how the two different power supplies cope with that? Obviously, no magic smoke is released! Thanks!
All input and output voltages are either floating or references to ground. Inputs look at the differential between the two hots on balanced lines and the diff between hot and ground on unbalanced.
Outputs create the same things.
As long at the gear is either isolated through a transformer or other method like being battery powered or references to the same ground as the other gear, all good.
Differing ground potentials on non isolated gear causes issues
The one with the higher voltage will be providing most of the current. The internal 6.8K resistors help out with current sharing, so the difference will be small.
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Fantastic video.
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great video...
what about mics with batteries. good or bad?
The best mics don't have batteries but having an onboard power source does not make a mic bad
I've had a few cool mics over the years with batteries.
nice topic....i have been wonding about it quite a while ago and i didnt found answer, thanks for that
another question would be, what will happen if you feed line output signal from one cosole to the phantom powered input of another console?
Sending phantom to electronic outputs can give varied and often undesirable results. Due to the wide diversity of output circuit designs, there is no rule to whether it will have a negative impact, other than avoid it.
Phantom can be blocked with a pair of capacitors inline on pins 2 and 3 of an XLR or using an iso transformer
@@DaveRat thanks, that what I was thinking about it. I didn't try it though I always used active DI box because I was not sure what is gonna happen.
Hey Dave, thanks for this ! greetings from Berlin
Greetings Curtis!
You're a madman Dave! I love it! 😏🤘
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Hi Dave, i have a very basic question - if i have a mixer with just one button to turn off phantom power on the whole mixer and i have a device that outputs line level over xlr, should i put a di-box between the mixer and the line level device to prevent damage or can i just connect the line level device directly to the xlr inputs of the mixer that has phantom power turned on?
It won't damage but some output circuits don't perform well when phantom is applied. I would just test and listen to the device with and without phantom. If you don't hear a difference, then I would not worry about it
@@DaveRat Thank you for the quick response :)
I can see that the cats stagebox seems to pass Phantom power. I wanted to know if that same stagebox would be able to pass phantom power across a cat6 cable going into the snake?
Yes, it will pass phantom and each channel can be individually phantom powered, works just like a 4 channel snake with disconnects.
22:40 Nice sweep of 86hz - 21hz and back at the end... its sound lower but the meter no longer measures. lol
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My computer audio has a 400W JBL sub on it. That sweep really shakes the house!
@@petetrott7568 I dont try it...i have a prof amp rack in my leaving room aprox 6 channels total 3,8 kw, but i have only one 230v phase of 16 amp's...cant do not test at full power. Here small test xd (Notice: the plops in sound are from the camera that cant handeling the sound pressure) th-cam.com/video/UeJemn-PvZg/w-d-xo.html
@@petetrott7568 so cool!
@@JohnvL 👍
If the mixer produces +48V to the pins 2 and 3 it will add up to 96volts reference to the ground. Should the mixer produce a negative voltage for the pin 3 to cancel each out when you connect a dynamic or condenser microphone to it?
Hmmm, that's a bit off.
The 48v on pin 2 is referenced to ground and same with pin 3.
It is the same 48 volts sent to both pin 2 and pin 3 so if you measure with a meter, which I suggest you do to see for yourself, pin 2 to ground is 48volts, pin 3 to ground is 48 volts and pin 2 to pin 3 is zero volts.
@@DaveRat Yeah, i had to draw a picture and do the math and you are absolutely right, couse there’s only one voltage source for both pin 2 and 3.
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Here is a man who has been spending a bit much too long lockdown up at home going "WTF".
Yeah! Finally the time to dive in to all my curiosities!
I wonder if there is any microphone response difference if 3 or more consoles drag down the voltage enough?
Any pro OB set up I've seen always used an active 3rd split anyway.
Would having 3 phantom switches on 1channel triple the current then?
3 should triple the current assuming you have a splitter that passes phantom
Is there any way to remove phantom power from the output, I have a mixer that has all phantom on or all phantom off?
If I run phantom into a passive DI box, will it damage the input device?
A couple of 100uf capacitors, 1 each on pin 2 and 3 will remove 0hantom. But phantom won't hurt a passive di
Can the phantom power ever damage either of the consoles providing it if the split is passive/not transformer isolated? I would assume the power would travel back up the split into each other. i.e. monitor and FoH console both going into a passive split - I'm just wondering how people get away with passive splits in this case
Consoles that can create 0hatomenpower are immune to damage from phantom power.
Most mic preamps are immune to phantom power impacting them.
Transformers are immune
Most input circuits are immune
Some or many output circuits are not immune and will either act strangely or possible be damaged.
Except:
Mic output circuits are almost always ummune
As a rule of thumb, phantom on input circuits, all good, phantom to out put circuits, not good.
Passive splits is connecting multiple input circuits to a mic output
I'm a total novice about this topic but I have a question about using drum mics. The typical kit comes with various dynamic mics for close mics on the drum and two overhead pencil condenser mics that require phantom power. Obviously, when using one mixer, you have to turn on the phantom power for the condenser mics but that means it's on for the dynamic mics too. It sounds like you're saying this is ok as long as the cables are good. I was wondering this is the normal, expected way to use these drum mic kits. I haven't found any source that addresses this specific issue. Thank you.
Mosicers allow 6urn8ng on phantom on each channel seperately. That said, if phantom was dangerous to any mic, that would be a huge problem.
Phantom is safe for all mics with properly wired cables and phantom is so low power almost no mics can be damaged by it though there are some older ribbon mics that can be damaged by wind, dropping, blowing into them and potentially miswired phantom.
Don't worry, you won't ever encounter these or any mic that can be damaged by phantom unless if you break into the vintage mic section of a recording studio.
Great video Dave!
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If you wanted to go from one mic into Y split cable and then onto 2 inputs of the same same mixer ( double patch type thing)
Would it be the same as the 2 mixer set up?
As I have often thought if doing this one apply 48V to one of the inputs.
Yes, I would supply phantom from both and or all console inputs
Thanks for the vid, could you help me a bit?
I have an effect pedal with constant 24V phantom power, will it make any harm if i use it in a chain like this:
Condenser mic --> external power supply with phantom power 48V --> effect pedal with constant 24V --> audio interface with turned off phantom power --> pc
Phantom power into balanced outputs should not hurt anything. I have seen some outputs don't like it and either distort or offer reduced output levels when phantom is went to them.
Just try it. If it works and sounds ok, roll with it
I wish obvious phantom power indicator lights were standard on all mixers. A pro tip for club engineers is to mark any channel on the tape when phantom is on so when the band is finished the engineer is reminded to mute the channel immediately. Experienced musicians know that they need to make eye contact with the engineer before unplugging a hot phantom powered instrument, but this will inevitably slip by the most seasoned sound engineer, and that painful pop is a real vibe killer. It happens to me occasionally when someone starts chatting with me at the board at the end of a set and I get distracted.
Whilest I personally don't worry too much about phantom 9n or off, I do make sure channels are muted before swapping mics at a gig. And if I see the peak lights flash on a muted mic, there is a good chance phantom is on.
Phantom power is about as dangerous as drinking a soda in a car, all good except if things go terribly wrong
Between monitor and foh, do separate mains power/phases create any audible issues?
They shouldn't as long as the grounds and feeds come from the same general source or as long as foh and mons are well isolated.
What about the use of an unbalanced input cable (i.e., RCA phono jack to XLR) for a line in situation, where pin 3 is tied to pin 1 and pin 2 is the "signal line." Pin 3 tied to pin 1 is shorting out the phantom power of a small console (presuming all on/all off environment). I'm guessing that the internal resistor circuit prevents a dead short of the phantom power, but does it reduce the voltage on the other channels? Still got that XLR to bananna plugs cable? Inquiring minds want to know... ;-)
Shorting phantom on one channel has no impact on other channels. But, since phantom has a seperate 48volts on pin 2 and a seperate 48volts on pin3, running phantom to an RCA will put 48 volts on the input of the RCA unit. Generally not good unless the RCA is capacitor coupled which blocks the 48v
@@DaveRat Makes sense. Obviously, a DI box is a better option...
Yes, absolutely
Re one console loading down the phantom from the other, I’ve seen consoles that drag the voltage down to 24 volts. Basically the phantom switch chose between +48 and ground, likely for noise reasons.
Oh my
It would have been cool if you could have demonstrated with an oscilloscope, just to illustrate how phantom power is basically just a large DC offset. Also (and this is just my personal anecdotal observation), but I've encountered situations where a condenser microphone seems to have a lower maximum SPL on 12VDC phantom power than it will on 48VDC phantom power. I would be interested in your insight - am I crazy?
Yes some mics 48 volt only and some are 12 to 48 volt. On the ones that are 12 to 48 volts I have seen specifications that derate their maximum SPL by 3 to 6db. Pretty sure I recall first seeing it on the AKG c451 12 to 48 volt version.
From 22:43. There's a DC offset in the audio. Makes a pop when you pause/play. Are you getting meta on us, Dave?
Interesting and I wish that was planned
Great video Dave ...often contemplated these things. Do you subscribe to having phantom both ends of the snake then for voltage stabilities sake and have you ever found a change in practical sound from any condenser that has a phantom fluctuate from 48v to as low as you’ve measured.
The one thing I’ve missed is your opinion on what some of these experiments show you about the quality of the sound the different environments make. Was especially interested in your cascading channel analogue vs digital mixer experiments ...there were some raised eyebrows but nothing on the audio aesthetics. Nice one for the videos mate ...what else does one do when there’s nothing to mix
Cool cool. Having the added phantom voltage should at best, just offer slightly more headroom as well as redundancy. The main point is that it does not hurt anything. And ever so slightly could help.
Great Stuff,
Is there any Microphone designed for both propose....? out of curiosity..
Dynamic mics don't need phantom, condenser mics usually do need it. Some ribbon mics need phantom and some do not.
It's like a battery, some things like a radio, needs a battery, and something's like a hammer do not and and something's like an ice box can be powered to cool things and others just keep things cool and don't need power
I’m wondering what happens when you split the mic cables and have two desks both supplying phantom power ? Ps not finished video yet :-)
Haha just watched the rest 👍🏻
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What if the consoles where on different phases of a 3 phase source, would this cause an issue?
What if on outside OB truck was on a generator and then production was house power, would there be potential for a cycle or earth issue?
Ideally all analog interconnected audio gear should tie to a common ground point to avoid ground loops. The phases that power the gear tend not to impact. With fiber and digital interconected gear, this is less of an issue or a non issue
Phase of AC should have zero impact. First off the consoles will be isolated from mains via a power transformer or switch mode supply. So it's like they're on separate phases to begin with in Dave's example. Then all of the ground wires on the XLR allow all consoles to have the same reference. Phase would only ever be an issue if you are referenced directly to mains but that's very dangerous and hence why almost every device has galvanic isolation from contacts you can touch to mains.
Good timing on this one for me Dave. I have a Focusrite 18i20 interface, I run a pair of TRS to XLR cables from its outputs into a snake or inputs on a mixer. I’ve been worried about somebody sending me phantom power to the interface outputs. I doubt the interface outputs are transformer isolated, so because there’s no power on the tip or ring, I should be ok? I’d only have a problem if I was running 1/4” to XLR unbalanced cables, correct? I was thinking about buying or making a two channel transformer isolation box to safeguard against this, but if I run balanced cables I’m ok, unless there’s a problem with the snake?
Avoid running phantom to electronic inputs. Capacitor iso will solve but often electronic inputs don't like the 48 v DC offset that phantom sends and will act strangely
Dave Rat - yeah I would never intentionally run phantom power to them, I’m just concerned if it happens accidentally. Thanks Dave.
You can test for isolation by checking continuity of the grounds for both the input and the output --- if there is no continuity then they are isolated.
@@HazeAnderson 👍
Fantastic vid as usual Dave! Would love to hear your recommendations for study material regarding Power in the live environment. I know i'm not up to scratch on power, and with Universities putting out more engineers, I feel like power is the least understood part of this job. Hope you're in good health! ALSO WHO PUTS SUB ON THE OUTRO OF THE VIDEO?
I don't have good reference for live event power, definitely would be a good thing to find. Lots of stuff to know as well as conflicting regulations depending on country and portable versus fixed wiring.
very helpful video👍
Thank you Mika!
In a large venue where FOH and Monitor World might be on a different Phase/Leg as far as their power source will this cause an issue?
Typically a differing phase is not an issue. Its when the ground for mons and FOH are different and not tied back to the same place that issues arise. Since neutral is tied to ground somewhere in most, if not all, power systems, loads on the neutral can drag it off of zero volts and possibly drag the ground off of zero volts. Or if there is gear that somehow causes the ground to not be zero volts, that can cause issues if the ground at FOH is differing in voltage to the ground at mons. With digital snakes, this is less of an issue and usually a non issue as long as the ground offset voltages are small. With analog snakes and interconnects, even very small offsets in voltage between the ground at FOH and mons can cause hum and buzz issues. Large ground voltage offsets can be dangerous or deadly.
Great Video. 😃👍♥️
Thank you Kevin!
Super interesting. Thankyou!
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If we wanted to make a mute on/off switch with a short XLR patch cable to be able to mute any mic of our choice, with regards to phantom power, how will that work? Do we have to disconnect both pin 2 and 3 to prevent phantom power from damaging a dynamic mic?
Short pin 2 and 3 and it will mute and not pop anymore than non phantom
Dave Rat thanks man. Keep up the great videos.
Excellent vid! Does splitting a microphone signal with one of those Y-cables, if connected to both mixers, cause any degradation of sound quality?
It should not and is easy to test, just listen or measure the output of one console while plugging and unplugging the other console. Typically a console input will be like 10,000 ohms or so and a mic output will be 200 ohms or so. So, you can drive several consoles with very minimal impact on the mic output level and loading of the mic.
Hey Dave, long-time fan and love the videos! Just to calm the nerves of those in our shop - with what you stated about the current being low, can I assume that if I have wireless mic receivers receiving phantom power that there's not much cause for concern? Thanks!
It won't hurt them, that said, some electronic outputs act strangely when they see phantom and don't sound correct
Awesome!
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