Hey all.

Kind of a stupid question, but here goes (have mercy):

I have a mixer that has a "global" phantom power switch - i.e. when you turn
it on, ALL the XLR balanced inputs on the board get 48v phantom power. I
have 2 condenser mics which need phantom power; but I also want to run a few
additional non-condenser balanced mics (i.e. sm58's or similar) into this
board.

So, my question is...do I risk any damage to either the mics or the board if
I run those non-condensor mics into a balanced XLR input that has phantom
power turned on? I'd like to avoid having to buy 2 separate phantom power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

TIA,

ray

No problem for dynamics ,
but be careful with ribbon mikes ,they don't love it
Oleg Kaizerman (gebe) Hollyland

"Ray B." wrote in message
news:_j5xb.230400$mZ5.1738472@attbi_s54...
Hey all.

Kind of a stupid question, but here goes (have mercy):

I have a mixer that has a "global" phantom power switch - i.e. when you
turn
it on, ALL the XLR balanced inputs on the board get 48v phantom power. I
have 2 condenser mics which need phantom power; but I also want to run a
few
additional non-condenser balanced mics (i.e. sm58's or similar) into this
board.

So, my question is...do I risk any damage to either the mics or the board
if
I run those non-condensor mics into a balanced XLR input that has phantom
power turned on? I'd like to avoid having to buy 2 separate phantom power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

TIA,

ray

Thanks guys for the quick and informative responses....sounds like I should
be fine as long as I use balanced cables to connect to the non-condenser
balanced mics. And I'll definitely make sure everything is connected BEFORE
I turn on the phantom power.

Thanks again,

ray

"Oleg Kaizerman" kaizero wrote in message
...
No problem for dynamics ,
but be careful with ribbon mikes ,they don't love it
Oleg Kaizerman (gebe) Hollyland

"Ray B." wrote in message
news:_j5xb.230400$mZ5.1738472@attbi_s54...
Hey all.

Kind of a stupid question, but here goes (have mercy):

I have a mixer that has a "global" phantom power switch - i.e. when you
turn
it on, ALL the XLR balanced inputs on the board get 48v phantom power. I
have 2 condenser mics which need phantom power; but I also want to run a
few
additional non-condenser balanced mics (i.e. sm58's or similar) into
this
board.

So, my question is...do I risk any damage to either the mics or the
board
if
I run those non-condensor mics into a balanced XLR input that has
phantom
power turned on? I'd like to avoid having to buy 2 separate phantom
power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

TIA,

ray

Oleg Kaizerman kaizero wrote:
No problem for dynamics ,
but be careful with ribbon mikes ,they don't love it

This is correct for dynamics with balanced outputs that use a
transformer (for those, the phantom power will cancel between the two
legs) but might not be correct for single ended dynamics. For those,
the 48 VDC will result in a displacement of the diaphragm, and at the
least have an effect on dynamic range.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

On Wed, 26 Nov 2003 17:23:06 GMT, "Ray B."
wrote:

So, my question is...do I risk any damage to either the mics or the board if
I run those non-condensor mics into a balanced XLR input that has phantom
power turned on? I'd like to avoid having to buy 2 separate phantom power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

A faulty cable or XLR plug might expose the SM58 to some risk. If
connected correctly, it will be OK. They are routinely run on
phantom powered channels.

CubaseFAQ page www.laurencepayne.co.uk/CubaseFAQ.htm

I also have a board with a power switch the problem I have is getting noise
out of my speakers when I have the phantom power on. The noise is worse
when I have one or more of my Samson wireless mic's plugged in.

--
George H. Sherlock
"Ray B." wrote in message
news:_j5xb.230400$mZ5.1738472@attbi_s54...
Hey all.

Kind of a stupid question, but here goes (have mercy):

I have a mixer that has a "global" phantom power switch - i.e. when you
turn
it on, ALL the XLR balanced inputs on the board get 48v phantom power. I
have 2 condenser mics which need phantom power; but I also want to run a
few
additional non-condenser balanced mics (i.e. sm58's or similar) into this
board.

So, my question is...do I risk any damage to either the mics or the board
if
I run those non-condensor mics into a balanced XLR input that has phantom
power turned on? I'd like to avoid having to buy 2 separate phantom power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

TIA,

ray

Well, I went ahead and ran the phantom power to my condenser and
non-condenser mic's, and everything seems fine.

I initially had some noise on one of the non-condenser mics, but after
changing cables, the problem went away. Everything sounds great...nice and
quiet.

George, try changing cables....you might have a bad one.

-ray

"George H. Sherlock" wrote in message
news:Jw8xb.230866$mZ5.1742827@attbi_s54...
I also have a board with a power switch the problem I have is getting
noise
out of my speakers when I have the phantom power on. The noise is worse
when I have one or more of my Samson wireless mic's plugged in.

--
George H. Sherlock
"Ray B." wrote in message
news:_j5xb.230400$mZ5.1738472@attbi_s54...
Hey all.

Kind of a stupid question, but here goes (have mercy):

I have a mixer that has a "global" phantom power switch - i.e. when you
turn
it on, ALL the XLR balanced inputs on the board get 48v phantom power. I
have 2 condenser mics which need phantom power; but I also want to run a
few
additional non-condenser balanced mics (i.e. sm58's or similar) into
this
board.

So, my question is...do I risk any damage to either the mics or the
board
if
I run those non-condensor mics into a balanced XLR input that has
phantom
power turned on? I'd like to avoid having to buy 2 separate phantom
power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

TIA,

ray

Also if you have any mics that have there own power supply (i.e.tube
mics)
those should not have phantom power applied.

This has not been my experience. I think tube mics with their own
power supply would be completely unaffected by phantom power, and my
personal experience has born this out.

Being about the most forgetful person in the world, I am constantly
connecting tube mics and ribbon mics to preamps where the phantom
switch had been left on from previous usage. Sometimes i notice and
turn the phantom off, sometimes I don't. I've never had any problems
with either sound deterioration or microphone damage.

The real risk is if you should accidently use a miswired cable.
Sending phantom via a cable with the pins miswired is a recipe for
disaster.

littledog wrote:

Also if you have any mics that have there own power supply (i.e.tube
mics)
those should not have phantom power applied.

This has not been my experience. I think tube mics with their own
power supply would be completely unaffected by phantom power, and my
personal experience has born this out.

This is true in most cases... there have been some tube mics built with a
transformerless output where phantom will indeed trash the output
amplifier. The first ones that come to mind like that are some custom
Manley 'Gold Reference' mics... but that means they do exist, and you
kind of have to watch out for stuff like that.
--
Fletcher
Mercenary Audio
TEL: 508-543-0069
FAX: 508-543-9670
http://www.mercenary.com
"this is not a problem"

Good questions Ray.....

Dynamic mics should ignore phantom power...

Phantom power works by supplying +48 volts equally on pins 2 and 3....pin 1
is the ground

In a dynamic or ribbon mic the +48 volts is present on both pins so they are
nulled out. This is called "common mode rejection"

As long as the connections and cable are not defective all works well.

Some boards have switches on each channel to disable the power. It is easy
to add your own.

Inside to board there are two 6.81K resistors that feed the 48 volts to pins
2 & 3. you can place a switch just upstream from them to switch off the
power. You can do this for each channel or in sections.

I have heard several manufactures call this mod "unnecessary", "unneeded",
"only for the uninformed" etc.

I say "take a look at the Tascam da88 that gets plugged into a board with
the phantom turned on. It isn't pretty."

I hope this helps.

Greg Dwinell




"Ray B." wrote in message
news:_j5xb.230400$mZ5.1738472@attbi_s54...
Hey all.

Kind of a stupid question, but here goes (have mercy):

I have a mixer that has a "global" phantom power switch - i.e. when you
turn
it on, ALL the XLR balanced inputs on the board get 48v phantom power. I
have 2 condenser mics which need phantom power; but I also want to run a
few
additional non-condenser balanced mics (i.e. sm58's or similar) into this
board.

So, my question is...do I risk any damage to either the mics or the board
if
I run those non-condensor mics into a balanced XLR input that has phantom
power turned on? I'd like to avoid having to buy 2 separate phantom power
supplies just for those 2 condenser mics, given the fact that my current
board does have phantom power.

TIA,

ray

Some boards have switches on each channel to disable the power. It is easy
to add your own.
I have heard several manufactures call this mod "unnecessary", "unneeded",
"only for the uninformed" etc.

Any manufacturer making such a claim is a clueless idiot whose gear should be
avoided. Line level sources get plugged into mic preamps all the time. As long
as a 20 or 30 db pad is available it oftentimes is the best way to make a rig
work in the field. Anybody who has plugged a transformerless output device into
a channel with phantom applied quickly learns why we have switches, & also
learns why you never hand a cable to a video camera operator without personally
checking that he is switched to line in.


Scott Fraser

"Ray B." wrote:
I have a mixer that has a "global" phantom power switch

Another thing to watch out for is plugging things into the 1/4" input
jacks with phantom on. These will almost assuredly be capacitor
isolated, so no current can flow long term in the 1/4" circuit.

But I found that one mixer had no bleed resistors so the capacitors
didn't charge up until you plugged something into the jack. Then the
thing you just plugged in had to pass the current needed to charge the
capacitor to 48 volts. This caused a CD player to stop working.
Fortunately, it recovered after all power was removed and then
restored. Must have tripped some IC into SCR mode.

BH

In article , Fletcher
wrote:

This is true in most cases...

My understanding is that the problems arise with mikes having a
grounded center tap on their output transformer. Other problems are
hot-plugging mikes with the power on or using a microphone patch bay
that has phantom power running through it.

--
Bob Olhsson Audio Mastery, Nashville TN 615.385.8051
Mastering, Audio for Picture, Mix Evaluation and Quality Control
http://www.hyperback.com/olhsson.html
Over 40 years making people sound better than they ever imagined!

In rec.audio.pro wrote:
Good questions Ray.....

Dynamic mics should ignore phantom power...

"Should" is the operative word here. Most do work, BUT be aware
that every now and then you find one that has the output transformer
center tap connected to ground. That shorts out Phantom power.
If the 6.8k resistors are large enough and the phantom power supply
has enough "oomph" it won't do much, but DC throught the mic
transformer windings is not a good thing.

Phantom power works by supplying +48 volts equally on pins 2 and 3....pin 1
is the ground

In a dynamic or ribbon mic the +48 volts is present on both pins so they are
nulled out. This is called "common mode rejection"

Not exaclty. What you need is for pins 2 and 3 to "float" with respect to
ground. You can use an ohm meter to check pins 2 and 3 to pin 1 and
to the mic case. It should read an open circuit for BOTH polarities
of the test leads.

Some boards have switches on each channel to disable the power. It is easy
to add your own.

Inside to board there are two 6.81K resistors that feed the 48 volts to pins
2 & 3. you can place a switch just upstream from them to switch off the
power. You can do this for each channel or in sections.

I have heard several manufactures call this mod "unnecessary", "unneeded",
"only for the uninformed" etc.

"Uninformed", my butt! I strongly urge installing these switches on
at least a couple channels so if worse comes to worse and you find you
have a couple mics that do not "float", you can put them in those
channels and turn off Phantom power.

Benj

Ray B. wrote:

Thanks guys for the quick and informative responses....sounds like I should
be fine as long as I use balanced cables to connect to the non-condenser
balanced mics. And I'll definitely make sure everything is connected BEFORE
I turn on the phantom power.


Yes, you have a complete and thorough handle on everything you need to
be concerned with. Barring defective equipment, you have nothing to
worry about regarding phantom power and microphones.

ulysses

Oleg Kaizerman wrote:

No problem for dynamics, but be careful with ribbon mikes ,they don't love it

This is a myth. Or at the worst, an exaggerated hypothetical
possibility.

ulysses

In Article , Justin Ulysses
Morse wrote:
Oleg Kaizerman wrote:

No problem for dynamics, but be careful with ribbon mikes ,they don't love
it

This is a myth. Or at the worst, an exaggerated hypothetical
possibility.

ulysses


The ribbon issue has more to do with connecting the ribbon mic to the preamp
while the phantom power is ON. IF, while plugging the mic in, the pins touch
in an unfriendly manner, you can zap the ribbon.

Turn phantom power off, plug in ribbon mic, turn phantom on, and you should
be OK.

The Royer 122 ribbon, to the contrary, actually uses phantom power to power
a small amp in the mic.

There are also some unbalanced mics that will fry if you connect them to a
balanced mic input with phantom ON.

Now you know the rest of the story.

Regards,

Ty Ford

**Until the worm goes away, I have put "not" in front of my email address.
Please remove it if you want to email me directly.
For Ty Ford V/O demos, audio services and equipment reviews,
click on http://www.jagunet.com/~tford

Ty Ford wrote:

The ribbon issue has more to do with connecting the ribbon mic to the preamp
while the phantom power is ON. IF, while plugging the mic in, the pins touch
in an unfriendly manner, you can zap the ribbon.

There's your hypothetical, but I've never actually seen it happen.
Have you? I've plugged ribbon mikes into phantom powered preamps many
times, and I know a great many other people have too, in studios where
the phantom is on 24/7 and they never give it a passing thought. Do
those people find themselves reribboning their mikes on a weekly basis?
Or yearly even? There are much easier ways to blow a ribbon, and I
would bet that most of the time the user doesn't necessarily know
exactly what the cause was. I've heard some tall tales about airflow
from drums, amps, the lid to the microphone's carrying case, etc.
Obviously ribbons do get wrecked occasionally, so at least one of these
is a reasonably common occurrence. But the way you hear people warn
each other on these forums about the fragility of ribbons, you'd think
they're made out of cobwebs and butterflies. They're not. All of my
ribbon mikes have been very robust and reliable. The risk of blowing a
ribbon is hugely overstated. I'm not saying it never happens.

ulysses

Bob Olhsson wrote:

In article , Fletcher
wrote:

This is true in most cases...

My understanding is that the problems arise with mikes having a
grounded center tap on their output transformer. Other problems are
hot-plugging mikes with the power on or using a microphone patch bay
that has phantom power running through it.

Yup, it's the centre tap that screws it up for sure.

Hot-plugging prolly explained a few mic I/P failures on Studiomaster
desks prior to me - lol. A few diodes to the supply rails fix that.


Graham

wrote:

In rec.audio.pro wrote:
Good questions Ray.....

Dynamic mics should ignore phantom power...

"Should" is the operative word here. Most do work, BUT be aware
that every now and then you find one that has the output transformer
center tap connected to ground. That shorts out Phantom power.
If the 6.8k resistors are large enough and the phantom power supply
has enough "oomph" it won't do much, but DC throught the mic
transformer windings is not a good thing.

Ah - but the currents are in opposite polarity, so they cancel out.


Phantom power works by supplying +48 volts equally on pins 2 and 3....pin 1
is the ground

In a dynamic or ribbon mic the +48 volts is present on both pins so they are
nulled out. This is called "common mode rejection"

Not exaclty. What you need is for pins 2 and 3 to "float" with respect to
ground. You can use an ohm meter to check pins 2 and 3 to pin 1 and
to the mic case. It should read an open circuit for BOTH polarities
of the test leads.

Some boards have switches on each channel to disable the power. It is easy
to add your own.

Inside to board there are two 6.81K resistors that feed the 48 volts to pins
2 & 3. you can place a switch just upstream from them to switch off the
power. You can do this for each channel or in sections.

I have heard several manufactures call this mod "unnecessary", "unneeded",
"only for the uninformed" etc.

"Uninformed", my butt! I strongly urge installing these switches on
at least a couple channels so if worse comes to worse and you find you
have a couple mics that do not "float", you can put them in those
channels and turn off Phantom power.

If you have CT transformer mics, the main problem is that Pin 2 and Pin3 don't
make contact at the same point in time when plugging/unplugging. When you
disconnect the mic this results in a flyback pulse from the stored energy in the
tranformer inductance to the still-connected pin.

This can be enough to 'fry' an input stage transistor for example.

No 'hot-plugging' = NO PROBLEM !


Graham

There's your hypothetical, but I've never actually seen it happen.
Have you? I've plugged ribbon mikes into phantom powered preamps many
times, and I know a great many other people have too, in studios where
the phantom is on 24/7 and they never give it a passing thought. Do
those people find themselves reribboning their mikes on a weekly basis?

Or yearly even? There are much easier ways to blow a ribbon, and I
would bet that most of the time the user doesn't necessarily know
exactly what the cause was. I've heard some tall tales about airflow
from drums, amps, the lid to the microphone's carrying case, etc.
Obviously ribbons do get wrecked occasionally, so at least one of these
is a reasonably common occurrence. But the way you hear people warn
each other on these forums about the fragility of ribbons, you'd think
they're made out of cobwebs and butterflies. They're not. All of my
ribbon mikes have been very robust and reliable. The risk of blowing a
ribbon is hugely overstated. I'm not saying it never happens.

ulysses



Don't do lit with an RCA 77DX that hasn't been modified to fix the grounded
center tap thing.

Been there, done that, paid for a new ribbon.


Richard H. Kuschel
"I canna change the law of physics."-----Scotty

In article , Justin
Ulysses Morse wrote:

There's your hypothetical, but I've never actually seen it happen.
Have you?

I heard a pop come out of my brand new RCA 77DX the first time I
plugged it into phantom power.

--
Bob Olhsson Audio Mastery, Nashville TN 615.385.8051
Mastering, Audio for Picture, Mix Evaluation and Quality Control
http://www.hyperback.com/olhsson.html
Over 40 years making people sound better than they ever imagined!

"Pooh Bear" wrote in message
...
Bob Olhsson wrote:

In article , Fletcher
wrote:

This is true in most cases...

My understanding is that the problems arise with mikes having a
grounded center tap on their output transformer. Other problems are
hot-plugging mikes with the power on or using a microphone patch bay
that has phantom power running through it.

Yup, it's the centre tap that screws it up for sure.

Hot-plugging prolly explained a few mic I/P failures on Studiomaster
desks prior to me - lol. A few diodes to the supply rails fix that.

Yep seen plenty of blown diodes to the Supply rails from SC mic cables to

Richard Freeman wrote:

"Pooh Bear" wrote in message
...
Bob Olhsson wrote:

In article , Fletcher
wrote:

This is true in most cases...

My understanding is that the problems arise with mikes having a
grounded center tap on their output transformer. Other problems are
hot-plugging mikes with the power on or using a microphone patch bay
that has phantom power running through it.

Yup, it's the centre tap that screws it up for sure.

Hot-plugging prolly explained a few mic I/P failures on Studiomaster
desks prior to me - lol. A few diodes to the supply rails fix that.

Yep seen plenty of blown diodes to the Supply rails from SC mic cables to

Ouch !

We fit a current limiting resistor now too. Should stop that.


Graham

Pooh Bear wrote:

Richard Freeman wrote:

"Pooh Bear" wrote in message
...
Bob Olhsson wrote:

In article , Fletcher
wrote:

This is true in most cases...

My understanding is that the problems arise with mikes having a
grounded center tap on their output transformer. Other problems are
hot-plugging mikes with the power on or using a microphone patch bay
that has phantom power running through it.

Yup, it's the centre tap that screws it up for sure.

Hot-plugging prolly explained a few mic I/P failures on Studiomaster
desks prior to me - lol. A few diodes to the supply rails fix that.

Yep seen plenty of blown diodes to the Supply rails from SC mic cables to

Ouch !

We fit a current limiting resistor now too. Should stop that.


Graham

I am a bit confused here. First I haven't heard of a mic with a centre
tapped transformer for many many years and second, all phantom power
supplies feed thru series resistors anyway and adding any extra ones may
reduce the voltage seen by phantom powered mics.

Ian