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48V zapped my ribbon mic Ribbon Microphones
Old 18th December 2010
  #1
Gear Nut
 

48V zapped my ribbon mic

Ok. So I've read many times over that ribbon mics are safe from phantom power w proper cabling..... well.... I accidentally fed a pair of beyer m160's phantom power through working cables that were already plugged in and functioning... everything functioning properly before 48V was applied

48 volts later....

one of my ribbon mics just gave out... the output dropped dramatically, while the other ribbon mic seemed unharmed. I shut the preamp immediately and ran to tend to my dead mic. In a sort of grieving state, I reached out a finger to caress the grill and at that moment, it stike-'d me....

when I tried to track drums again, the output of the seemingly dead mic had risen slightly.... I repeated the process (finger stike'd again and again) until the output seemed close to normal.

any ideas?? err I'm gonna go to a dark corner and
Old 18th December 2010
  #2
You should stop doing that!

Clearly there is a short somewhere or you would not be getting shocked.

You are at risk of damaging the ribbon if you have not done so already.

.
Old 19th December 2010
  #3
Gear Nut
 

Quote:
Originally Posted by Trakworx View Post
You should stop doing that!

Clearly there is a short somewhere or you would not be getting shocked.

You are at risk of damaging the ribbon if you have not done so already.

.
..

i can't tell if it is functioning properly... it seems back to normal. it seemed to get more normal as I channeled the electricity into my finger. *shrug*
Old 19th December 2010
  #4
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drBill's Avatar
But why are you continuing to feed it 48v?!?!?!?!?!? tutt
Old 19th December 2010
  #5
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dcrigger's Avatar
 

Quote:
Originally Posted by Fluner View Post
Ok. So I've read many times over that ribbon mics are safe from phantom power w proper cabling.....
Where'd you read that?

Of course, if every thing's perfect - with balance maintained 100% of every fraction of a second - sure. But who can depend on that? I've never read of anyone suggesting that allowing 48v to get at at your ribbons is ever a good idea.


David
Old 19th December 2010
  #6
Lives for gear
Actually, DC, there was a fairly recent thread here where a few folks of large cred pretty much called the phantom thing a myth.

I don't agree, and I don't do it. But I was surprised to see at least one person I respect a lot call it legend.
Old 19th December 2010
  #7
With proper wiring and proper usage, phantom power shouldn't damage most ribbon mics.

People have used ribbon mics for decades through consoles that didn't even allow the user to switch the phantom power off. Miswired cables, cross patching mic lines, and other improper wiring can damage ribbon mics when combined with phantom power.

It sounds like something is miswired, are you using a patchbay?
Old 19th December 2010
  #8
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OhioGreg's Avatar
 

Quote:
Originally Posted by dcrigger View Post
I've never read of anyone suggesting that allowing 48v to gat at at your ribbons is ever a good idea.
Sure! It's a no no.tutt
Old 19th December 2010
  #9
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dcrigger's Avatar
 

Quote:
Originally Posted by Steffmo View Post
Actually, DC, there was a fairly recent thread here where a few folks of large cred pretty much called the phantom thing a myth.

I don't agree, and I don't do it. But I was surprised to see at least one person I respect a lot call it legend.
Oops - I'll have to do a search for it. Though like you, I doubt I'll be running to test the theory out on my Coles. :-)

David
Old 19th December 2010
  #10
Old 19th December 2010
  #11
Quote:
Originally Posted by dcrigger View Post
Oops - I'll have to do a search for it. Though like you, I doubt I'll be running to test the theory out on my Coles. :-)

David
the issue with phantom power and ribbon mics is when applied through a patchbay or used in some other way with a TRS connection. An XLR connection maintains balance because all three pins connect at the same time, but when pulling a patch cable, there is an instant where only one side is feeding the mic, creating a large voltage on one side of the ribbon, and causing the ribbon to shoot to one side...

anyway, take your microphone to someone knowledgeable who can open it up and see whats wrong...there has to be some kind of short or miswiring of some sort.
Old 19th December 2010
  #12
Lives for gear
 

If you're getting a zap from the grille then something is improperly wired. Get yourself a $10 voltmeter and measure the voltages at the female XLR connector which connects to your mic. There should be 48 volts (or so) between pin 2 and pin 1, and between pin 3 and pin 1. There should be no voltage reading between pin 2 and pin 3. If you get anything different then your mic cable isn't supplying proper phantom power and needs to be rewired. Also see if there is a voltage reading between pin 1 and the connector shell.
Old 19th December 2010
  #13
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lm66's Avatar
I use my Beyer M-160 since several years with 48V (my Revox console does'nt allow to send it on separate channels).

I never had any problem !!!...

Look somewhere else for your problem, except if your cable is not a symmetrical one.
Old 19th December 2010
  #14
Quote:
Originally Posted by Trakworx View Post
You should stop doing that!

Clearly there is a short somewhere or you would not be getting shocked.

You are at risk of damaging the ribbon if you have not done so already.

.
Right. I honestly don't think properly functioning phantom could give you a shock. I've never even been tickled.

The IEC spec is 48v at 10 mA. (1/1,000 of an amp)


Never having owned any ribbon recording mics (hangs head in shame), I've a little hazy on the particulars of the apparently small subset of older ribbon mics which are subject to being endangered by phantom, but it's my thinking if you got shocked that there's something significantly wrong.
Old 19th December 2010
  #15
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Quote:
Originally Posted by theblue1 View Post
Right. I honestly don't think properly functioning phantom could give you a shock. I've never even been tickled.

The IEC spec is 48v at 10 mA. (1/1,000 of an amp)
You've never been tickled cause it was properly functioning...

Quote:
As shown in the chart, shock is relatively more severe as the current rises. For currents above 10 milliamps, muscular contractions are so strong that the victim cannot let go of the wire that is shocking him. At values as low as 20 milliamps, breathing becomes labored, finally ceasing completely even at values below 75 milliamps.

As the current approaches 100 milliamps, ventricular fibrillation of the heart occurs - an uncoordinated twitching of the walls of the heart's ventricles which results in death.


Above 200 milliamps, the muscular contractions are so severe that the heart is forcibly clamped during the shock. This clamping protects the heart from going into ventricular fibrillation, and the victim's chances for survival are good. - Source (random google search, but it's the same as what I learned when I was in school)
Granted, the skin is a decent insulator, but it doesn't take much current to hurt.
Old 19th December 2010
  #16
Quote:
Originally Posted by scottwilson View Post
You've never been tickled cause it was properly functioning...

Granted, the skin is a decent insulator, but it doesn't take much current to hurt.
Uh oh... I guess I've been living a charmed life. heh

I'd already suspected that: I did get a blast of 220v from hand to hand [ie, straight through the heart area] one time, but that was AC. Had it been DC, I'd probably still be there, my arms stretched between the sink and the electric range in my old house, a testimony to bad kitchen remodeling and my own stupidity. As it was, I had a tiny bit of a burn on both hands -- and a very odd muscle feeling through my chest for a few moments afterward. Let's call it a wake up call. (The stove had been there when I bought the joint. And, yes, I wrote it into the sale papers that it was their responsibility to test and fix the stove. I didn't want some other dummy finding out the hard way.)

Thanks for the corrected info.


Here is a link to similar info for those, like me, who need to brush up:

http://hyperphysics.phy-astr.gsu.edu...ric/shock.html

Of particular interest is the grid on body impedance. It's really instructive to see what a very wide range of impedance the body can have, depending on circumstances. Pretty interesting. You bet.
Old 19th December 2010
  #17
Quote:
Originally Posted by trmchenry View Post
That link makes my browser crash. Here it is on youtube:

YouTube - Ribbon Microphones and Phantom Power
Old 19th December 2010
  #18
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Bryce's Avatar
Cloud Microphones makes a box called a Cloudlifter that converts phantom power into 20dB+ of gain. The phantom power never gets to the mic, so you don't have to worry about turning it off.

Even cooler - it works with any passive mic, not just ribbons.

dB
Old 19th December 2010
  #19
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Sigma's Avatar
Quote:
Originally Posted by dcrigger View Post
Where'd you read that?

Of course, if every thing's perfect - with balance maintained 100% of every fraction of a second - sure. But who can depend on that? I've never read of anyone suggesting that allowing 48v to get at at your ribbons is ever a good idea.


David
60's ..70's consoles had 48 volt phantom running all the time..we had a few dozen 77d's and dx's plus a few bk 5's and some 160's and never had an issue
Old 19th December 2010
  #20
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Quote:
Originally Posted by Bryce View Post
Cloud Microphones makes a box called a Cloudlifter that converts phantom power into 20dB+ of gain. The phantom power never gets to the mic, so you don't have to worry about turning it off.

Even cooler - it works with any passive mic, not just ribbons.
A lot of people like these:

FetHead - tritonaudio
Old 19th December 2010
  #21
Gear Guru
 
drBill's Avatar
Quote:
Originally Posted by chris319 View Post
A lot of people like these:

FetHead - tritonaudio
thumbsupthumbsup

Fixes your 48v problem AND gives you 20+dB more gain. What's not to like about that?
Old 19th December 2010
  #22
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PlugHead's Avatar
 

Quote:
Originally Posted by trmchenry View Post
nice - thx for the link.

Still, never any issues with my ribbons and p48, and I have loads of ribbon mics.

One thing I haven't had in a long time is a TT Patchbay, and tho I'm installing one this winter, I hope to avoid these issues once installed.

Is there any easy way to avoid this transient spike while inserting cables into the PB? Can we only avoid it via powering down the pre's before connection and powering back up afterward, etc?

thx!
Old 20th December 2010
  #23
Gear Nut
 

Quote:
Originally Posted by chris319 View Post
If you're getting a zap from the grille then something is improperly wired. Get yourself a $10 voltmeter and measure the voltages at the female XLR connector which connects to your mic. There should be 48 volts (or so) between pin 2 and pin 1, and between pin 3 and pin 1. There should be no voltage reading between pin 2 and pin 3. If you get anything different then your mic cable isn't supplying proper phantom power and needs to be rewired. Also see if there is a voltage reading between pin 1 and the connector shell.
good idea.. I tested the preamp I will definitely check my cable with the 48V engaged. The cable was checked on its own and there was no leakage between pin/pin pin/casing.. but I will check again w 48V

no patchbay involved.. only an 20ish ft balanced XLR (no TRS's)
the shock was a tickle and from the grille


It all happened when I received a new preamp in the mail, Jim William's High Speed pre... I saw the 48V label beneath the switch and assumed that when the switch was pointed towards "48V", phantom power would be engaged....
WRONG.... so I ignorantly pushed the switches , w/o consulting my volt-meter, away from the "48V" print.
IMO that print under the switch is very counterintuitive and misleading... however I'm still an idiot for not checking w a meter first.
*goes to check cables*
Old 27th December 2010
  #24
Here for the gear
 

what about this?

YouTube - Crowley and Tripp Roswellite (tm) Ribbon Microphone Material

hard to see that being blown by 48V
Old 27th December 2010
  #25
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Lance Lawson's Avatar
 

Ahh no ribbon mics are very prone to frying when fed phantom power. Its dynamic mics that are safe.
Old 27th December 2010
  #26
Here for the gear
 

Did you look at that video? I'm convinced. They must have zapped that ribbon a hundred times. Shows that 48V won't hurt it.
Old 27th December 2010
  #27
Registered User
 
Rick Sutton's Avatar
 

Quote:
Originally Posted by Lance Lawson View Post
Ahh no ribbon mics are very prone to frying when fed phantom power. Its dynamic mics that are safe.
They are not very prone. Unless you consider 1 in many millions of instances to constitute very.

Also ribbon mics are dynamic mics. So you may be contradicting yourself.
Old 27th December 2010
  #28
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softwareguy's Avatar
 

Quote:
Originally Posted by Fluner View Post
It all happened when I received a new preamp in the mail, Jim William's High Speed pre...
That's a very nice pre, especially for ribbons. Loads of clarity and gain, very high impedance. Should be just the ticket.

I have to say, I have several ribbon mics including some old RCA's, and I'm definitely in the camp that a little 48v between friends shouldn't hurt anything, especially for a modern mic like a beyer.

Since the shock came from the mic and you clearly have a short somewhere, I would check the mic itself very carefully for faults and/or for wires that may be touching the mic case. It is interesting that the m160 had a brother that was fine, and it really suggests that the fault is with the mic itself.

Good luck getting it sorted out. As Gilda Radner used to say, "It's always something!"
Old 27th December 2010
  #29
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Hammer Mark's Avatar
All ribbons have impedance converting transformers that isolate the ribbon from DC current. Unless I misunderstand the wiring here, P48 shouldn't be a problem.
Old 27th December 2010
  #30
Quote:
Originally Posted by Recordiosity View Post
Did you look at that video? I'm convinced. They must have zapped that ribbon a hundred times. Shows that 48V won't hurt it.
Careful... that video was demonstrating a special type of ribbon (Roswellite). Most ribbons can be damaged or broken IF there is a short or you hot-patch it in a TT or TRS patchbay. This is the video to watch:

YouTube - Ribbon Microphones and Phantom Power

.
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