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A Way To Diffuse Phantom Power?
Old 29th December 2007
  #31
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rackdude's Avatar
 

Alright, with no patchbay, just running the xlr cable from the ribbon to the mixer, just a cheap alesis I'm using for a location-esque recording, will not blow the ribbon?

I'll be using a normal magonomi *spelled wrong...* cable. No modifications at all. The ribbon is the RSM4 from nady, its a pretty new age mic.

I think thats the consensus but I want a yes before I try it.
Old 30th December 2007
  #32
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De chromium cob's Avatar
 

Quote:
Originally Posted by rackdude View Post
Alright, with no patchbay, just running the xlr cable from the ribbon to the mixer, just a cheap alesis I'm using for a location-esque recording, will not blow the ribbon?

I'll be using a normal magonomi *spelled wrong...* cable. No modifications at all. The ribbon is the RSM4 from nady, its a pretty new age mic.

I think thats the consensus but I want a yes before I try it.
Old 30th December 2007
  #33
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rackdude's Avatar
 

You stated that the cable has to be wired correctly, so I really just wanted a yes or no. I think the magonomi is wired correctly, I haven't messed with it. The pins would be to wherever they go when you buy the cable. so its alright to do? Or are the cables all made differently so I would have to personally check *which doesn't seem reasonable if it's factory made...*
Old 30th December 2007
  #34
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This is quite the thread. Of course phantom power cannot cause damage to a ribbon/dynamic mic if using proper XLR mic cables. Just one minor point to your good post Duardo -- female XLR Pin 1 (ground) is actually set forward from 2 & 3 and makes contact first, eliminating the problems that TS/TRS/RCA can cause.

Steve
Old 30th December 2007
  #35
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I have said this OVER and OVER just like Sigma...

YOU WILL NOT BLOW UP A RIBBON MIC IF YOU USE IT WITH A PHANTOM POWER SYSTEM AND EVERYTHING IS WIRED CORRECTLY.

How long have guys like me and SIGMA been around recording equipment?
I know that I have been around pro gear WITH PERMANENT PHANTOM since 1975.
I bet that SAIGMA was at his dad's studio even before that!

I will repeat... I have never seen a ribbon mic damaged due to phantom power.
I have seen them ruined because they were dropped a few times.
I have nice looking M160 that was dropped on the parquet floor of a studio rendering it useless.

You could damage the ribbon if you had say PIN #1 switched with either PIN #2 or PIN#3. In this case the 48V would make a circuit through PINS #2 and #3.
this probebly would damge the ribbon.

STILL, you would have had to just made the cable wrong and then used it for the first time with the ribbon/phantom system.
The reason why is because if you had a cable mis-wired wrong enough to cause this situation it would hum like a bitch and you would have found it when using it on an dynamic mic and it wouldn't have powered any condenser mics either.

Also, you guys were taling about using the TRS "LINE IN" for gain.
If your "digital" console happens to be a Yamaha like an 01v, 02r, etc...
The 1/4" TRS jack is the same circuit as the XLR jack. they are not seperate amplifier circuits.
There is phantom on the TRS as well as the XLR when phantom is switched on.

Also, line level amplificxation IS TOO LOW to amplify a ribbon mic.

This post is as rediculous as the question about using an 1176 as a mic pre.

Just do stuff right and you won't have probelmes.
DON'T MAKE THE SIMPLE STUFF HARD BY DOING REDICULOUS STUFF!
Old 30th December 2007
  #36
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Also, let me add this...

In order for a mic to be "shorted" in a manner that would damage a ribbon mic the wire connected to either PIN #2 or PIN #3 would have to be loose AND the SHEILD would have to be loose as well.
If the SHEILD touched either PIN #2 or PIN#3 with those two pin's proper wire NOT connected the 48V could flow through the ribbon.

The mi-connection would have to remain in this condition ling enough to heat up and ruin the ribbon.
I don't believe that an instantaneous condition from an intermittant cable would cause anything more than A LOT of noise.

If you have mic cables in this condition you probebly have other problems.
Old 30th December 2007
  #37
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oldgreensock's Avatar
 

Just cut pin 1

No one really seems to want to break it down for you so here it goes. Phantom power uses pin one of the xlr connector, which has a dual chore of sending the shield to ground to prevent hums. If you cut the connection to pin one on the microphone side of the cable, the cable will not be able to pass Phantom to your ribbon mic. The cable will still reject hums and interference because shield will still go to ground on the mixer side. This cropped cable will work with dynamic and ribbon mics only, and will no longer work with condensers unless you solder pin 1 back together. The only reason that pin one of an xlr connector is connected at both ends these days is to allow the passage of phantom power.

PS: read Rane note 110 Sound System Interconnection
Old 30th December 2007
  #38
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Your description of dropping the sheild at one end of a cable is common stuff.
The only thing is that it really applies to cables carryiing LINE LEVEL signals.

In the case with with LINE LEVEL cables both audio devices that are interconnected with the cable in question have a ground system in place.
Generally, the device will have a steel chassis, a ground plane and other parts of the circuits that are tied to GND via the AC mains GND.
The system you describe is really implemented to eliminate a ground loop caused by two seperate GND paths.

A microphone on the other hand derives it's internal GNd via the sheild wire.
If you drop the sheild (PIN#1) the body of the mic is not grounded and has it's sheilding greatly compromised.

I'LL SAY IT AGAIN JUST LIKE SIGMA HAS OVER AND OVER...
Properly wired phantom power WILL NOT harm your ribbon mics.

OLDGREENSOCK's idea is good on paper and perhaps someone has used this and it worked.
I've never seen it done and who'd want a mic cable floating around without the sheild tied?

I'll also be really honest about the dropping GND on one end of a cable thing.
I wire ALL of my studio stuff this way and I have done o for years.

LIVE AUDIO?
I never do it and our rigs are dead silent.
50kW P.A.s have to be when used in corporate audio.
I have never seen a live sound cable wired this way.. on purpose.
Old 30th December 2007
  #39
Mastering
 

Quote:
Originally Posted by rackdude View Post
Ok, I'm micing a drum set a pretty minimalist way. But, the problem is, I have some condensors going, but also a ribbon on the kick (Nady RSM4). My mixer only has 1 phontom power switch for all channels. Is there a way to diffuse the phantom power by converting it to TRS and back or something? I also got a digitech gnx2, I was thinking... because for some reason it has a mic in and out, maybe if I run it through there, the phantom power will die out or not transmit through... maybe?
NO NO NO! There is no simple mod to a cable that will remove phantom power! Changing to TRS will accomplish nothing.

First of all, the potential of damage to ribbon microphones with phantom power on is very small, would only occur if the ribbon mike does not have an output transformer (highly unlikely). And if you follow the important practice of turning the phantom OFF before plugging or unplugging mikes, then you can use a ribbon with phantom on with no troubles, because the major troubles are the transients that can (highly unlikely, but possible) blow the ribbon when plugging it into a phantom circuit.

That said, you can have your console modified to disconnect the phantom power on certain modules. It is not a difficult modification, and a lot easier than the next choice.

The ONLY safe way to remove phantom power going to a mike if the phantom is on in the console is to add an isolation transformer in between. Conceivably a couple of large coupling caps, but I wouldn't recommend either solution. The best one is to ignore it, it's really not a problem, as I mentioned above, or modify your console.

BK
Old 30th December 2007
  #40
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nosebleedaudio's Avatar
The bays I have wired for mic level are one; 1/4", two; grounds are NOT connected until the connector is plug in because I DO NOT buss the grounds or are they connected to anything until the conection is made, they are not normaled...
This way you CAN NOT have a miswired situation.
Old 30th December 2007
  #41
So much gear... and PLENTY of time!
Old 30th December 2007
  #42
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No joke Joel!

Here's the scoop guys...

The PHANTOM POWER system that is commonly used in studio and stage audio is the method of pantom power developed by Nuemann to power their line of FET condensers (U87, KM 84, etc..)
If wired correctly it WILL NOT damage a ribbon mic.
If wired incorrectly it will not power a condenser.

There is another type of "phantom power" called "T-Power" and is mostly only used in film audio. It is a 12V system.
IT WILL RUIN A RIBBON MIC!
In thirty one years of pro audio I have never seen a "T-Power" system in use.

If you want to see another explanation with schematics go here:
http://www.new-line.nl/default.asp?i=61

Let's see consoles I have owned that had phantom permanently wired to the mics:

TASCAM model 10 (had a global phantom board between console and mic panel)
UA 16 x 3 (global phantom)
Sphere Eclipse C (global phantom)
Soundtracs CM4400 (global phantom)
MCI JH-538D (global phantom) (the D seies 500s do have a on off on each channel)


Let's see consoles I have used that had phantom permanently wired to the mics:

Neve 8128 (global phantom)
Neve 8058 (global phantom)
Neve 8068mkII (global phantom)
SSL 4048 (global phantom)
Harrison MR4 (global phantom)

Number of ribbon mics that were damged by phantom since 1975: ZERO

I also belive that it is a myth that permanent phantom power damages mic transformers over time. Leaving a mic transformer permanently energized with 48V DC suppossedly magnetizes them or causes them to "go bad."
I deal with some older consoles all the time and the transformers seem OK to me!

Carry on...
Old 30th December 2007
  #43
Gear Nut
 
ARude's Avatar
 

Quote:
Originally Posted by rackdude View Post
Ok, I'm micing a drum set a pretty minimalist way. But, the problem is, I have some condensors going, but also a ribbon on the kick (Nady RSM4).
Does anybody else see a problem with this setup? I'd be more worried about the possible damage to the ribbon being placed in close proximity to the kick drum head or beater.

From the RSM 4 manual:

1. Always protect your RSM-4 from any hard knocks, such as from dropping the mic, or not properly padding in shipment, as such jolts can destroy the ribbon assembly. Always handled with complete care.
2. Prevent any sudden or strong blasts of air movement from ever reaching your microphone, as they can tear and destroy the fragile ribbon. Never blow into your RSM-4! When using, always utilize a pop filter, such as the optional Nady MPF-6, to prevent any percussive sounds from damaging the ribbon. Such filters also prevent damage from moisture from mouth spray.
3. Never intentionally or accidentally apply any phantom power from your mixer or a phantom power supply to your RSM-4 as it can burn up the ribbon. Please always check carefully before connecting your ribbon mic that there is no phantom power being provided to the RSM-4.


The Motown guys would use a RCA 44 inside a kick drum but would turn it so that the minima faced the beater head. That's where the legendary "hartbeat" kick sound came from. Why they did it at all is because they were always short of mics so they resorted to that application by necessity.

The problem with phantom power and ribbon mics is not when the power is applied properly but when it is applied unevenly, say an open pin 2 or 3. There is another possibility that might be more of a problem with the less expensive ribbons that of current leakage through the windings of the microphone's transformer causing damage. It's like playing Russian roulette, why take the chance? Use a seperate mic pre WITHOUT phantom power applied.
Old 30th December 2007
  #44
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rackdude's Avatar
 

Alright, I had it plugged in with a normal factory maganomi and it seemed fine when I turned the phantom on. The kick mic wasn't too close because I was recording a jazz drummer, didn't want too much bite. The drum didn't have a whole on it anyways. In the Nady's specs it states that it has high spl handling *165*

Why do they want to mess with their customers so much by putting contradicting data in their manual!!!

I think I just got cables 101. Thanks. This knowledge will come in handy some time in the future.
Old 30th December 2007
  #45
Gear Addict
 

Quote:
Originally Posted by bob katz View Post
NO NO NO! There is no simple mod to a cable that will remove phantom power! Changing to TRS will accomplish nothing.

First of all, the potential of damage to ribbon microphones with phantom power on is very small, would only occur if the ribbon mike does not have an output transformer (highly unlikely). And if you follow the important practice of turning the phantom OFF before plugging or unplugging mikes, then you can use a ribbon with phantom on with no troubles, because the major troubles are the transients that can (highly unlikely, but possible) blow the ribbon when plugging it into a phantom circuit.

That said, you can have your console modified to disconnect the phantom power on certain modules. It is not a difficult modification, and a lot easier than the next choice.

The ONLY safe way to remove phantom power going to a mike if the phantom is on in the console is to add an isolation transformer in between. Conceivably a couple of large coupling caps, but I wouldn't recommend either solution. The best one is to ignore it, it's really not a problem, as I mentioned above, or modify your console.

BK

Thank god someone stepped in with reality.

I'm not trying to be mean, but why in the hell would using an XLR to TRS somehow remove phantom power? I mean, both have three connections/pins and you still haven't done anything to stop phantom from being sent through the cable? My understanding of the ribbon/48v situation is this: The ribbon never actually sees phantom power, assuming the cable is wired correctly and nothing else funny is going on. What would/could damage the ribbon is the phantom power being applied unevenly - the most notable example would be the aforementioned hot-plugging using a patchbay while phantom is on. The rule I was always thought was is that you plug in the mic, then turn on phantom, then turn up the gain. This minimizes the chances of funny things happening.
Old 30th December 2007
  #46
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poncival's Avatar
I Don't want to miss out on the Phantom/Ribbon Diatribe Fest

OK I can't resist chiming in here with a couple things that came to mind, this topic has definitely been done to death but it keeps coming up because the bottom line always seems to be "don't worry about it at all, but be careful, and make sure you don't have a miswired mic cable and make sure you don't hot-patch with a TRS patchbay with Phantom Power on" by which time the "don't worry about it" part has pretty much disappeared, which brings us back to "is it safe, should I worry?"

The standard Switchcraft style TRS jacks plugged into a standard "modern" TRS patch bay can be plugged in half way, a la the Mackie 1604 "insert plugged in halfway direct out trick." IF that happens with a ribbon mic and phantom power is applied to that patch point, pin 3 and pin 1 of the patchbay will be going to pin 2 and pin 3 of the mic output. This can burn up a ribbon, especially if it's left on for a few minutes.

I am not so sure that the nearly instantaneous pop of phantom power across the ribbon while properly plugging the TRS into the patchbay ALL THE WAY quickly like normal, but this is where you want to be safe and make sure the phantom is turned off while plugging your mics in and THEN turning your phantom power on. This way you won't have any problem (as long as your TRS cables are plugged in all the way and you don't have any miswired patchbays etc......)

I understand this is part of the reason Neve used the "mil spec" 1/4" connectors (such as the Neutrik NP3TB) on their classic patchbays, not only to reduce wear and tear on the contact points but also so that while you are plugging it in, pin 2 does not connect to anything until it is properly seated at its position at "pin 2" of the socket. Of course by "pin 2" of the TRS I am talking about the "tip" which is hot. Also note that these connectors most likely will NOT work in a standard patchbay such as the one you just bought at your local guitar shop.

If you look carefully, you will notice that TT plugs and jacks also work this way..... Which means that if you have a TRS NP3TB type patchbay or a TT patchbay you will also not have any problems plugging in your ribbon mic while phantom power is applied. But still, be careful anyway and turn it off first. Because despite the "failsafe" aspect of these types of connectors, there is always the chance that some stray piece of metal may have fallen into your patchbay or something unlikely like that which could possibly cause a short.


OK another thing that came to mind when I read about how XLR's are set up so on the male, pin 1 sticks out a little further than pins 2 and 3 so the ground is connected first... although it might not make much of a difference in the long run, when you are soldering your mic cables together be sure not to heat up the pins of the male so much that they move around in the plastic, it takes a little effort to screw them up this bad but I have seen some homemade cables that were otherwise OK and worked fine for a while but eventually the pins would push back into the metal body of the connector and cause a short inside as they flopped around.

"Slightly" OT I guess but that's one of those things that you don't think about until it causes a disaster at the wrong moment and eventually you are able to chase it down to the fact that one of the pins on the mic cabnle wasn't making contact because only a tiny bit or NONE of it was actually sticking into the female like it should because of an overheated soldering iron or because of keeping an iron of proper temperature on the pin for WAY too long while making the cable.

Usually it's obvious when you are roasting the plastic and sometimes the pins will get all googley-eyed and you can't even plug the XLR in at all but other times it seems to work great for the first 100 plug-ins and then one time (usually when you're on the first day with a hugely important client) the pin decides to just jump out of the hole and short something out, and it's always the last place you look because "that cable has been working great for a year now" etc...

HOPEFULLY you will never have to worry about this with factory cables, but it can happen with Neutrik or Switchcrafts and I would assume any xlr male if they have been overheated.

Happy patching! stikestikestikestikestike
fuuck
Old 30th December 2007
  #47
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De chromium cob's Avatar
 

Quote:
Originally Posted by Mosby View Post
Thank god someone stepped in with reality.
You mean reality like suggesting to mod a Alesis mixer? A mod that would cost someone more than the cost of the actual mixer BTW....

Is reality restating what has been said and explained over and over numerous times in the thread?

Or is it that its only reality when Bob Katz says it?

Please explain to me how my posts were NOT reality...
Old 31st December 2007
  #48
Gear Nut
 
ARude's Avatar
 

I wasn't going to add to the discussion but I'm having WAY too much fun to stop now...

Here what Cascade recommends for ribbon mics being used on phantom power systems.

RODE D-PowerPlug Add +20 db of Gain to your Ribbon Microphone

It's a good idea on a couple of levels but with RSM 4's selling for $80 on MF [as I write this] the solution costs more than the mic. I'm thinking about picking up a couple for live work. I have a preamp that can selectively phantom power each channel and I have a very specific application [horns]...

It’s obvious that some here don't understand why ribbons are so much more fragile than dynamics or condensers. The motor consists of a very thin, easily damaged ribbon of aluminum suspended in a magnetic field. The rule of thumb is if you can feel the blast of air on the back of your hand, don't put a ribbon mic there. Plosives can stretch or rip the ribbon. An uninformed vocalist blowing on the mic to test it can damage the ribbon. This is what gives them their remarkable detail but also makes them easier to damage. While they will take a lot of SPL I don't recommend ribbon mic's for recording gun shots.

BTW: A damaged ribbon will sound darker or not sound at all.
Old 31st December 2007
  #49
Of course not, for recording gun shots you use a "shotgun" mic, obviously.
Old 31st December 2007
  #50
XJR
Gear Maniac
 

Well I might be wrong but the ribbon mic is transformer coupled right ? and DC doesn't pass through a transformer. Therefore if you stick to proper wired balanced XRL cables and don't turn on the phantom power until all connections are made then everything should be fine.
Old 31st December 2007
  #51
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Quote:
Originally Posted by De chromium cob View Post
You mean reality like suggesting to mod a Alesis mixer? A mod that would cost someone more than the cost of the actual mixer BTW....

Is reality restating what has been said and explained over and over numerous times in the thread?

Or is it that its only reality when Bob Katz says it?

Please explain to me how my posts were NOT reality...
I had the same question!
Bob Katz only spoke of how cutting the sheild at the mic end was not a great idea (ya' think not?)
He spoke of how you could use a transformer or caps.
Well, YEAH! There are usually transformers in ribbon mics.
Most mics are high impedence designs so they need a transformer to interface the mic to the console.

GaDAMN, how much further could I have explained it?

Lessee, I have BUILT several phantom power units from scratch over the years and I have never blown up a ribbon in thirty plus years of audio work.

You know the real deal with this?
DON'T USE F*CKING TRS CABLES ON MICS!

..and what does it mean to " DIFUSSE" phantom power?
That title was the reason I read the post in the first place.
"What is this about? Oughta' be funny!"
I knew that it would be chock full-O-mis-information from the post's title!

You know the sad part of this whole post?
Phantom power is probebly one of the SIMPLEST circuits in audio!

The fact that this post has gone on as long as it has and the fact that everyone had to explain phantom power and why it wouldn't hurt a ribbon OVER AND OVER shows that Gearslutz IS NOT viewed as a great place to get useful technical info. Well, until Bob Katz speaks about one detail of the posts. Yes, Bob, you are correct in what you said. No, No, NO!! Don't undo the sheild at the mic like on a line level cable... except it would be BACKWARDS from how you wire line level cables. You tie the sheild at the source and the mic is the source here. BUT DON'T DO IT!

Maybe my explanation and few others went over some people's heads?
I just don't get it.

Oh well, we tried!
Old 31st December 2007
  #52
It's all those twenty-five cent words, like "transformers" and "coupled,"
Old 31st December 2007
  #53
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Shaking my head in disbelief saying,
must be... must be...

Like I said, "It ain't rocket surgery!"
Old 31st December 2007
  #54
Gear Nut
 
ARude's Avatar
 

Quote:
Originally Posted by joelpatterson View Post
Of course not, for recording gun shots you use a "shotgun" mic, obviously.
LOL...

Too many of you are taking this WAY to seriously. Sometimes the best way to learn is to "tune for maximum smoke."
Old 31st December 2007
  #55
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Oh, I "learned" something allright.
Old 31st December 2007
  #56
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nosebleedaudio's Avatar
One thing to know is this: if you have a cable that is shorted, pin 1 to pin 2 for ex. and its a dynamic mic IT WILL hum, had this problem a few weeks ago.
Was a SM57 and was was not hurt, not saying it could not be hurt just that I caught it in a few minutes.
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