mte Posted June 5, 2001 Share Posted June 5, 2001 Hey guys I like this forum very much... Well I was just wondering what the Phantom Power +48V (or sth similar) on some mixers means and what it is used for?? thanks, Matej Link to comment Share on other sites More sharing options...
Ethan Winer Posted June 5, 2001 Share Posted June 5, 2001 Matej, Hey guys I like this forum very much ... Well I was just wondering what the Phantom Power +48V (or sth similar) on some mixers means and what it is used for?? All condenser microphones have a preamp circuit inside them, so the phantom power is a way to send the power needed down the same two wires that return the audio. Some condensers have a battery and don't need external power, but most "pro" condenser mikes require this. --Ethan The acoustic treatment experts Ethan's Audio Expert Book Link to comment Share on other sites More sharing options...
Nawor Posted June 5, 2001 Share Posted June 5, 2001 Originally posted by mte: Hey guys I like this forum very much... Well I was just wondering what the Phantom Power +48V (or sth similar) on some mixers means and what it is used for?? thanks, Matej Okay MateJ are you ready for this??!!.... and don't flame me too much guys!! Phantom power is, like the name implies, a bit 'ghostly' in it's concept. Dynamic or moving coil microphones eg. (Shure SM58's etc) generate their output signal using electro magnetic force EMF (a tiny coil of wire moving inside a magnetic field) so don't require any kind of seperate voltage supply (ie. phantom power) to work except for a preamplifier to make the signal strong enough to drive the next stage of the chain. Condensor microphones need a voltage supply in order to work. They have a bunch of electronics inside them, transistors, resistors capacitors etc. This internal circuit both powers or 'energises' the mic capsule or diaphragm with a charge (voltage) and also helps to interface the electrical output (signal) with the outside world. Without this internal circuit and the power supply to feed it the mic would be as quiet as a church mouse. Now here comes the tricky part. You should no doubt be familiar with 'cannon' or XLR type connectors. These connectors have three conductive pins that carry signals to and from most pro or semi-pro audio equipment. Normally we only need two wires to carry a signal, so why in this case do we need three? This is to help cancel out any outside electrical noise that might find its way into the cable and wind up on our recording. ie buzzes and hums etc. lighting dimmers fridges switching on and off etc. This arrangement will also help us with the implemention of phantom power. (more about this a bit later in this epic!) These 3 wire cables with their 3 pin connectors are known as 'balanced differential lines'. The microphone preamplifier is looking only at the voltage DIFFERENCE that it sees between pins 2 & 3 (pin 1 is ground) and this is what it amplifys. The DIFFERENCE SIGNAL! The music signal (the signal we want) is always alternating (AC voltage) backwards and forwards in opposing phase between pins 2 & 3. So there is aways a difference present at the output of pins 2 & 3. Without this difference in voltage we would have nothing (no signal) to amplify and therefore NO SOUND. A microphone cable can act a bit like an antenna and pick up all kinds of electrical junk that floats around the airwaves. This can be induced into our mic cable and this is where the advantage of balanced differential lines comes to our aid. Any noise that gets into the cable will appear EQUALLY and IN PHASE (either both + or both - volts) at the same time on conductors 2 & 3. As this signal, or noise (which we don't want) is of equal strength and frequency and phase, it presents NO DIFFERENCE between the output of pins 2 & 3. Therefore no 'noise' signal is left to amplify because it has essentially been cancelled out of the picture. That's why balanced lines are essential for long cable runs in electrically noisy environments. As it happens, fortunately this system also allows us to send a 'phantom' supply voltage to our condensor mics to power them WITHOUT having to resort to any additional conductors. The Phantom power (usually +48 volts DC) can be sent up the cable to the microphone equally through pins 2 & 3. It is then 'tapped' off via some closely matched resistors to feed the microphone's on board circuit to power all the electronics I mentioned at the beginning. As this supply voltage appears equally on both pins 2 & 3, once again there is no difference signal to amplify between the output of 2 & 3 so it appears invisible to the mic preamplifier, just as any induced noise would be. Additional DC blocking capacitors, on lines 2 & 3, at the input of the mic pre-amplifier also act as DC voltage filters while still allowing the music signal (AC voltage) to pass unaffected. The term 'Phantom' power then refers to the fact that the DC supply voltage is 'superimposed' onto the same two conductors (pins 2 & 3) that the music signal uses... without any side effects. (Yeah I know... say cheese Hiraga!) So as far as the music is concerned it's a ghostlike or 'Phantom' power supply that it can't see! In most cases standard balanced dynamic microphones (SM58's etc.) can be connected to inputs where phantom power is present without causing a problem. The balancing transformer at the output of the mic also interfaces with the XLR cable 'differentially'. So even though the 48 volts may be present, it won't cause any harm. BUT do NOT connect unbalanced and ribbon mics to an active phantom circuit or you may do some damage. Er... sorry for the epic and I hope all this makes some kind of sense... if it don't... just use a 57 and don't worry about it! Cheers Rowan This message has been edited by Rowan on 06-05-2001 at 11:06 AM "WARNING!" - this artificial fruit juice may contain traces of REAL FRUIT!! Link to comment Share on other sites More sharing options...
seclusion Posted June 5, 2001 Share Posted June 5, 2001 Please don't take offence but this reminds me of the high school days when I was just a bit"Smoke Enhanced".. We were setting up the mics and buddy was saying that things sounded better with the 48V on... "Well of course it'd sound better why else would it be there"... We were using 58's mostly on eveything.. 1 kik, 2 vox the rest was live off the floor.. God did we suck sound wise.. Dynamic mics need no phantom power.. But we were so cool.. Brian Smile if you're not wearin panties. Link to comment Share on other sites More sharing options...
hiraga Posted June 5, 2001 Share Posted June 5, 2001 CHEEEEEEEEEEEEEEEEEEEEEEEZE!!!!! Phantompower is just another stoopit convinient cheapass thang... I dunno why puttin' +48V on a dynamic will sound any better?? It'll just bring more noize into the recording. And if the 48V isn't EXACTLY the same on pin 2&3 the mic can act funny if it hasn't got a trannie. Not all dynamics has that. If the cable breaks, then shit will hit the fan!! Rowan said it with a thousand words. But he's spot on. The 48 volts is used to power condensers and DIs/Linedrivers too. Link to comment Share on other sites More sharing options...
seclusion Posted June 5, 2001 Share Posted June 5, 2001 I know that but back in high school we were just a little misinformed... When you pushed the 48v in or out there was no diff... But man.. "We could hear the diff".. We were so stoned that the mic could of been unplugged and it would of sounded good.. What a dick I was... am.. Brian Smile if you're not wearin panties. Link to comment Share on other sites More sharing options...
hiraga Posted June 5, 2001 Share Posted June 5, 2001 Yeah, well I've chased enough ghosts when being fucked into oblivion on all kinds of naughty stuff.. LSD mixing is an art in itself. One day it'll make sense to me.. The few dayz I bothered showing up in high school (uhh it's only like.. ten years ago?), we certainly didn't learn anything about phantompower.. if we did I'd probably would show up more! Hahaha.. the only *phantompower* I saw there was the principal sending me a note that I should get my ass in gear from time to time.. what a waste of time. Hey, there's nothing wrong with being a dick.. the chicks luv it! Link to comment Share on other sites More sharing options...
fantasticsound Posted June 5, 2001 Share Posted June 5, 2001 Craig, HELP!!!! (putting on flame suit.) Isn't Rowan out of phase, with his answer? The program signal is sent out of phase on Pins 2 & 3, and induced noise would be IN PHASE on 2 & 3. Phantom power is sent as two out of phase voltages that add up to the actual power rating. (+24v on one lead, -24v on the other. This cancels the phantom power at the mic end if no phantom powered electronics are present to rectify the two voltages to +48v and siphon it off.) I thought the inverted signal was flipped BACK into phase at an input, which yields in phase program and out of phase noise. (Hence, theoretically, no added noise.) To demonstrate out of phase, equivalent signals, here's something you can do with no equipment. Place your hands together. Put pressure on both hands, against one another. If your hands move, that represents a signal. An AC signal is represented by your hands shaking back and forth. A DC signal would be represented by one hand pushing the other consistantly over to one side. Fluctuating DC would be on one side, but not consistant in postion. Clipping a signal is represented by pushing one arm or the other as far as it can go. (Don't clip too hard with the demonstration or you'll break your arm!) Now for reverse phase signals. Increase the pressure on both hands. Ignoring the tension shake, (This is your body, not electronics, and THEY can have this problem too!) notice you can exert incredible force while your hands essentially stay motionless. When two equivalent, out of phase signals are added to one another, they exert pressure, but the sum equals 0! As in no voltage, no speaker cone movement, NO SOUND. Since the induced noise hits pins 2 & 3 equally, and then one's phase is flipped, the noise cancels itself out, just as your opposing hand pressure yields no movement. There is also a way to represent this relationship with a mirror, but I'll save that one. Separating the visual reference from the numbers involved is essential, and may be more difficult to explain properly. Neil This message has been edited by fantasticsound on 06-05-2001 at 02:51 PM It's easiest to find me on Facebook. Neil Bergman Soundclick fntstcsnd Link to comment Share on other sites More sharing options...
hiraga Posted June 6, 2001 Share Posted June 6, 2001 No, it's +48VDC reference to ground awrite.. Link to comment Share on other sites More sharing options...
Gus Lozada Posted June 6, 2001 Share Posted June 6, 2001 Originally posted by seclusion: But man.. "We could hear the diff".. Brian http://www.musicplayer.com/ubb/biggrin.gifhttp://www.musicplayer.com/ubb/biggrin.gifhttp://www.musicplayer.com/ubb/biggrin.gifhttp://www.musicplayer.com/ubb/biggrin.gif AHAHAHAHAHAHAHAHHAHAHAHA!!! http://www.musicplayer.com/ubb/biggrin.gifhttp://www.musicplayer.com/ubb/biggrin.gifhttp://www.musicplayer.com/ubb/biggrin.gifhttp://www.musicplayer.com/ubb/biggrin.gif Those ol'good days... Músico, Productor, Ingeniero, Tecnólogo Senior Product Manager, América Latina y Caribe - PreSonus at Fender Musical Instruments Company Instagram: guslozada Facebook: Lozada - Música y Tecnología www.guslozada.com Link to comment Share on other sites More sharing options...
Nawor Posted June 6, 2001 Share Posted June 6, 2001 Fantasticsound wrote Isn't Rowan out of phase, with his answer? Sorry but I might not have been quite clear here. The +48 volts is applied EQUALLY to pins 2 & 3 with it's GROUND REFERENCE on PIN 1 as Hiraga pointed out. In fact there is only ONE +48 source which is split into two and is fed via two matched 6.8k resistors to the mic up pins 2 & 3. As I said the mic amplifier is looking for a voltage DIFFERENCE between 2 & 3. As long as the resistors are accurately matched, in the order of tenths of an ohm, then putting a DC volt meter between pins 2 & 3 will register NO voltage. What the micpre can't see, it CAN'T amplify! Look at it this way.... Q. What is the difference between +48volts and +48volts? A. ZERO volts! Get my drift? If however we measure the difference between pin 1 (ground) and either pin 2 OR 3 OR both of them together, THEN we will see 48 volts! In a balanced differential setup we don't actually need pin 1 (ground) to transmit our audio signal because the micpre (active or transformer) is ONLY interested in the voltage difference that it sees on pins 2 & 3. And this is our alternating audio signal which does NOT appear equally on pins 2 & 3. In this case connecting an AC voltmeter across pins 2 & 3 (with the music 'a pumpin') will register a signal and then our good 'ol micpre has something to work on. In a balanced system ( 3 conductors) pin 1 is connected to the cable screen for additional noise screening and also acts as the negative ground reference for the +48volt phantom power. It carries NO audio signal. However in an unbalanced system (2 conductors) the screen is required to carry the audio signal (- phase) so phantom power cannot be used here. The center conductor of course handles the + phase. I know this balanced line and phantom power stuff can seem a bit cryptic at first but once you understand the terminology ie. DIFFERENTIAL then it will begin to make sense. Remember we need a DIFFERENCE to make a difference!! See Ya! This message has been edited by Rowan on 06-05-2001 at 08:27 PM "WARNING!" - this artificial fruit juice may contain traces of REAL FRUIT!! Link to comment Share on other sites More sharing options...
Duhduh Posted June 6, 2001 Share Posted June 6, 2001 Originally posted by Rowan: In most cases standard balanced dynamic microphones (SM58's etc.) can be connected to inputs where phantom power is present without causing a problem. If thats the case, then how did I blow up my first D-112 by leaving the phantom power on on its input? "Meat is the only thing you need beside beer! Big hunks of meat and BEER!!...Lots of freakin' BEER." "Hey, I'm not Jesus Christ, I can't turn water into wine. The best I can do is turn beer into urine." Zakk Wylde http://www.hepcnet.net/bbssmilies/super.gif http://smileys.smileycentral.com/cat/15_1_109.gif Link to comment Share on other sites More sharing options...
fantasticsound Posted June 6, 2001 Share Posted June 6, 2001 That's easy. Faulty phantom power system or something unrelated. Phantom power that is properly working will damage ribbon transducers, but not dynamics. I'm ignorant about why it damages ribbons, but it can. Neil It's easiest to find me on Facebook. Neil Bergman Soundclick fntstcsnd Link to comment Share on other sites More sharing options...
S_Gould Posted June 6, 2001 Share Posted June 6, 2001 More likely a bad mic cable than a bad phantom power supply. If the cable is cheap or old, it is unlikely to exhibit equal resistance on both legs of the signal. Scott Link to comment Share on other sites More sharing options...
hiraga Posted June 6, 2001 Share Posted June 6, 2001 I'm compiling all this shit.. look out for the "Phantom Power Vol. 1,2,3,4,5,6,7,8 & 9"... the never ending story. Phantompower kills dynamics when the +48V dissapear from either pin 2 OR 3. Then you'll have 48 volts on the diaphragm and it'll move outwards an inch ONE time.. then it's like ..dead! Ribbons have a transformer inside, but they can't can't handle the high DC voltage. The trannie COULD be made to deal with it, but most ribbon (except the Royers) were made before that stoopit phantompower was invented, so they didn't think of that. Link to comment Share on other sites More sharing options...
fantasticsound Posted June 8, 2001 Share Posted June 8, 2001 Originally posted by hiraga: ...Ribbons have a transformer inside, but they can't can't handle the high DC voltage. The trannie COULD be made to deal with it, but most ribbon (except the Royers) were made before that stoopit phantompower was invented, so they didn't think of that. Will the Royer's stand up to a phantom power send, Hiraga? Thanks for the info, too. Neil It's easiest to find me on Facebook. Neil Bergman Soundclick fntstcsnd Link to comment Share on other sites More sharing options...
hiraga Posted June 8, 2001 Share Posted June 8, 2001 Yarz, they'll take the heat. I think it also says so on their website. The B&O BM series of ribbon mics, which I'm very very fond of, doesn't. Unfortunally I speak from experience... arggghhh!!!! So, no more phanttompower questionz..?? No? Not even single tiny one..? No? Please..?? Link to comment Share on other sites More sharing options...
Nawor Posted June 8, 2001 Share Posted June 8, 2001 Hiraga wrote So, no more phanttompower questionz..?? No? Not even single tiny one..? No? Please..?? What... not even a teensy weensy one? This message has been edited by Rowan on 06-08-2001 at 11:43 AM "WARNING!" - this artificial fruit juice may contain traces of REAL FRUIT!! Link to comment Share on other sites More sharing options...
hiraga Posted June 8, 2001 Share Posted June 8, 2001 Ahhh.. come on! Have anyone ever thought about why it's 48V and not 15-18V, that's allready present inside the console, thus cheaper to implement? Or why not use both the +/- 15-18V?... Or why a crappy phantompower will screw up a great mic's dynamic performance and noise floor... Or what stupid company that invented the phantompower?... Or do I really have a life?? Link to comment Share on other sites More sharing options...
miroslav Posted June 8, 2001 Share Posted June 8, 2001 Hey guys...a slight tangent, but relative. I have a few 20 year old EV condenser mics that worked off these AA size 4.5 volt batteries. The batteries were always a bitch to find, didn't last long and weren't cheap. Haven't used the mics in a while, but they were great vocal mics on stage. Would like to put them back into service but have them run off 48V phantom instead of those batteries. I think way back, EV had a kit to do just that, and if I remember, once modified, they said it was permanent...you couldn't go back to battries. But if I recall, they wanted about $40 bucks per microphone, and in those days I didn't want (couldn't afford) to pay that. So...any possibility to easily/cheaply modify them? Seems to me, all it would take is to bump the 48V down to the battery strength of 4.5V. ...yes...no? What would be needed? The 48V is DC not AC...yes...no? Uh..DUH???!!!! This message has been edited by miroslav on 06-08-2001 at 12:12 PM miroslav - miroslavmusic.com "Just because it happened to you, it doesn't mean it's important." Link to comment Share on other sites More sharing options...
hiraga Posted June 8, 2001 Share Posted June 8, 2001 Ohh, if phantompower was AC it wouldn't work at all.. First is the mic balanced (does it have an XLR connector?)? Must be/have. If not you'll need a GOOD transformer (must be small to fit inside the mic. Next you'll have to make a Vreg. You could use a TO92 version of the LM317T (100mA) plus a few caps. I'll draw you a schematic, if you can email/fax the mic schematic too me. I can also build it for you. Or mod the whole mic. But you're gonna have to wait until I get my lab up. Dunno when. You'd be better off using batteries anyway. It'll sound better too. I'd look for some rechargeble ones.. Link to comment Share on other sites More sharing options...
hiraga Posted June 8, 2001 Share Posted June 8, 2001 At +4,5VDC they're probably not condersers but electrets. Nothing wrong with that though (I think some, or one, of the AKG C1/2/3/4000 is too..) Link to comment Share on other sites More sharing options...
miroslav Posted June 8, 2001 Share Posted June 8, 2001 hiraga, Yes, it uses XLR. I might still have some spec sheets on it...somewhere...let me dig around over the weekend. I have four of these mics...was wondering...would this "converter" HAVE to be inside of the mic (where the bats use to go)...or could there be an external "box" that could possibly handle all four mics??? Then internally, I can just hard-wire a bypass for the battery connections...? I don't think I have any actual schematics...but I will open the mic up and just draw the wiring layout/capsule config myself. No need to burn too many brain cells and time over this, but it would be nice to put these mics to use... Will get back to you on this. Thanks, Miroslav miroslav - miroslavmusic.com "Just because it happened to you, it doesn't mean it's important." Link to comment Share on other sites More sharing options...
hiraga Posted June 8, 2001 Share Posted June 8, 2001 Well, you could have an external box, but what a hassle! Like I said, I'd stick with the batteries. Superior sound.. Burnin' brain cells is a favourite hobby of mine, anyhoo.. Link to comment Share on other sites More sharing options...
miroslav Posted June 8, 2001 Share Posted June 8, 2001 hiraga, Well blow me away! Just called EV and they STILL have the phantom power kits for these mics!!! These things are about 24 years old. But they still want $36.00 a pop for them...oh well. Yes, I agree on using bats, but the ones for these mice are HARD to come by...even by EVs admission...and they are not cheap! So, in the long run, the pahntom power conversion might be the best way to go if I plan on using these babies. Unless you think there is a much more cost effective solution...I will probably buy the conversion kits on Monday...let me know your thoughts. Later! miroslav - miroslavmusic.com "Just because it happened to you, it doesn't mean it's important." Link to comment Share on other sites More sharing options...
hiraga Posted June 8, 2001 Share Posted June 8, 2001 4x36US$??? Whooha! Well, I can do it for roughly... 4x34,95US$.. harharhar.. That's awfully lotta money. how much did you pay for those suckers anyway?? No, I can do it for free, 'cept the parts. Which I DON'T know how much will set you back. If there's no need for a transformer, I reckon a buck or two pr. mic. But I need the schematic of the mics. And, as I said, my lab isn't up. I dunno when. Is it urgent? I'm sure it's possible to dig up some rechargeble batteries, though.. Link to comment Share on other sites More sharing options...
miroslav Posted June 12, 2001 Share Posted June 12, 2001 hiraga, They cost about $100 each back in 1978...Electro Voice PL76 electret condenser. I got the schematics for the mics. Along with the schematics, I also found out that besides the "weird" 4.5 volt batteries...I CAN also use standard AA 1.5 volt batteries with only a slight decrease in output and dynamic range. Plus, the AAs will last about a 1000 hours while the 4.5 batteries anywhere from 150-300 hours depending on which brand I get. After digging a bit through my "studio stuff", I actually found one of the 4.5 volt batteries...tested it, and it was still showing about 4.4 volts. So before I go any further with anything, in the next few(?) days, I will compare the output/dynamic range between the AA and 4.5 bats. I am sure I can easily make up any output difference with a decent mic pre. The dynamic range...well, I think the difference will only be at the very extremes. I really wasn't planning to use these mics for critical vocals/acoustics/pianos... but possibly for Bvox, crunch git, and LF stuff, since the mics have some good, ass kicking bass proximity effect at =>3 inches. Barry White...look out..."...oooh baby sweet baby, what am I gonna' do..." If you want me to send/fax you the schematics...tell me where? My email is in my profile above. MUCH THANKS for you offer to mod them for only parts cost...if you give me a required parts list based on the schematics, I can probably do it myself and save you the hassle. Thanks again...let me know. miroslav - miroslavmusic.com "Just because it happened to you, it doesn't mean it's important." Link to comment Share on other sites More sharing options...
hiraga Posted June 12, 2001 Share Posted June 12, 2001 Well, 1,5V is not so good. The internal transistor *wastes* 0,6-0,7V so to speak,, which gives leaves very very little headroom. I think you can make it clip with any instrument at just about any range.. My faxnumber: 0045 6613 2534 (Including area code to Denmark) Link to comment Share on other sites More sharing options...
miroslav Posted June 13, 2001 Share Posted June 13, 2001 hiraga, Do to circumstances beyond my control...I can't fax outside of the US from my present location. If you are still game...I can e-mail you a .ZIP file with the 5 pages (669KB) containing the schematics/specs, or I can snail-mail them to you in Denmark...could take a week or more(?). Either way...I would need either (E or postal) address from you. Againafter you see the diagramsif you think something can be made for just a few $$$, then give me a parts list and a rough design diagram, and I'll give it a shot. Otherwise...not a big deal if you don't want to bother further... After spending some time on the Internet and on the phone trying to locate the recommended 4.5 volt batteriesI realize that I'm going to have to go with a phantom power rigeither "home made" w/your design, or just buy the fuckers from Electro Voice! (I could have them in my hands within a few days.) But the 4.5 volt batslooks like everyone that made them, has discontinued them So I'm looking at: (1.)spending $150 to keep these four microphones still usableor (2.)what ever you can come up with. Either way...not the end of the world...hahaha! Let me know.thanks again, Miroslav miroslavl@yahoo.com miroslav - miroslavmusic.com "Just because it happened to you, it doesn't mean it's important." Link to comment Share on other sites More sharing options...
hiraga Posted June 13, 2001 Share Posted June 13, 2001 Look, frying brain cells is where I get my kicks, so I'm not gonna let you off the hook that easily, mmm'kay?!! And I'm not gonna let those corporate slimes eat all you hardearned money, so I'll drop you a note. I got no probs in a huge zip file, or whatever.. Stay tuned! Link to comment Share on other sites More sharing options...
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