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Trying to understand phantom power

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Anonymous
March 17, 2005 6:27:41 PM

Archived from groups: rec.audio.pro (More info?)

OK...I need someoene to explain to me something regarding phantom power
and mics.

For purposes of this discussion, let's use the Rode NT4 mic which is an
XLR mic that can be powered from its own batter or phantom power (I
guess meaning a preamp).

What is the difference, all else being equal, between using this mic
(self-powered by its own battery) direct into a recorder and running
this mic through a preamp and then into a recorder.

In other words, if this mic can run on it's own power into a recorder,
what is the benefit of a preamp, if there is one?

Thanks!
Anonymous
March 17, 2005 7:02:21 PM

Archived from groups: rec.audio.pro (More info?)

<<OK...I need someoene to explain to me something regarding phantom
power
and mics. >>

In the simplest terms, microphones requiring phantom power are called
condenser mics. Phantom power comes from the mic pre on your mixer or
an external power supply. The power supplies sole function is to
provide voltage to operate the mic. Regardless of the source phantom
power applies voltage to a plate in the microphone. Sound hits the
mic's diaphram and the diaphram moves toward the plate effectively
pushing voltage out of the plate, the output is directly proportional
to the amount the diaphram moves.
As the other posters have said chances are the output of the microphone
would not be sufficient to get adequate level into a recorder. That is
the preamps job to raise the gain of the incoming signal from the
microphone.
Anonymous
March 17, 2005 8:31:58 PM

Archived from groups: rec.audio.pro (More info?)

PhiloMertz wrote:

>OK...I need someoene to explain to me something regarding phantom power
>and mics.
>
>For purposes of this discussion, let's use the Rode NT4 mic which is an
>XLR mic that can be powered from its own batter or phantom power (I
>guess meaning a preamp).

A preamp is only one way to provide phantom power to a mic that needs it.
Others include mixers with suitably equipped mic inputs and devices that
do nothing but provide phantom power.

>What is the difference, all else being equal, between using this mic
>(self-powered by its own battery) direct into a recorder and running
>this mic through a preamp and then into a recorder.
>
>In other words, if this mic can run on it's own power into a recorder,
>what is the benefit of a preamp, if there is one?

The primary benefit is that you don't have to use a battery in the mic.

Another benefit may be that the preamp, or whatever, may result in better
sound than the one in the recorder. Or it might not. Or it might with
some mics and not others. Or...

--
========================================================================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mkesti@gv.net | - The Who, Bargain
Related resources
Anonymous
March 17, 2005 9:07:46 PM

Archived from groups: rec.audio.pro (More info?)

"PhiloMertz" wrote ...
> OK...I need someoene to explain to me something regarding
> phantom power and mics.
>
> For purposes of this discussion, let's use the Rode NT4 mic
> which is an XLR mic that can be powered from its own batter
> or phantom power (I guess meaning a preamp).

No phantom power does not mean a preamp. Phantom power is
a method of powering microphones so that you don't have to use
batteries, etc.

Many preamps provide phantom power, but it is not a requirement
that a preamp provide phantom power. Likewise you can provide
phantom power without using a preamp. They are independent.

> What is the difference, all else being equal, between using this
> mic (self-powered by its own battery) direct into a recorder
> and running this mic through a preamp and then into a recorder.

> In other words, if this mic can run on it's own power into a
> recorder, what is the benefit of a preamp, if there is one?

Perhaps you wish to restate your questions now that you know
that phantom power and preamps are not associated in the way
you assumed.

You didn't state whether your recorder has a mic input or only
a line-level input? Generic answers to your questions quickly
loose their meaning in the absense of this kind of detail.

I have an NT4 and I use it with phantom power when recording
with my bigger rigs (mixers, multi-track hard drive recorder, etc.)
But I am considering taking it with me to Spain this summer when
our choir (at work) travels to an international choral festival. I am
trying to figure out what to record on (DAT, Hi-MD, etc.) In that
case I will be using the internal battery as none of the recorder
options provide phantom power, but do have mic-level inputs.
Anonymous
March 17, 2005 9:36:19 PM

Archived from groups: rec.audio.pro (More info?)

PhiloMertz <PhiloMertz@gmail.com> wrote:
>OK...I need someoene to explain to me something regarding phantom power
>and mics.
>
>For purposes of this discussion, let's use the Rode NT4 mic which is an
>XLR mic that can be powered from its own batter or phantom power (I
>guess meaning a preamp).
>
>What is the difference, all else being equal, between using this mic
>(self-powered by its own battery) direct into a recorder and running
>this mic through a preamp and then into a recorder.

If the recorder has an internal preamp with a mike input, there is none.

>In other words, if this mic can run on it's own power into a recorder,
>what is the benefit of a preamp, if there is one?

About 40 dB of amplification.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
March 17, 2005 9:48:51 PM

Archived from groups: rec.audio.pro (More info?)

phantom power mic pre

time to check books out of your public library and go to the local
music store and look and ask questions with product next to you. look
at their mics and mixers and recording devices
ask these questions then. take guitar and demo the mics in store to
start.
did you research the fmr rnp mic pre amp???? <
http://www.fmraudio.com/RNP8380.htm >

dale
Anonymous
March 17, 2005 10:29:48 PM

Archived from groups: rec.audio.pro (More info?)

Mike,

You wrote:
"A preamp does more than power a microphone. It amplifies the signal up

to "line" level, which is necessary for a recorder that doesn't have a
microphone input."

Yes, this is where I was confused! So, even a self powered mic still
needs to have the signal amplified...OK I think I got it.

Thanks to all for the help! You are all gracious with your time and
knowledge.
Anonymous
March 17, 2005 10:37:01 PM

Archived from groups: rec.audio.pro (More info?)

If you really want an in-depth understanding you should read up on the
differences between ribbon, dynamic and condenser mics ....also the
difference between mic level and line level ....basically, phantom power has
nothing to do w/ amplifying a mic's signal to line level, it just provides a
medium (electricity) for capacitance between the diaphragm and the back
plate of condenser mics....some, usually more expensive condensers might
have their own power supply to ensure that your mic is getting clean,
well-regulated electricity at the exact voltage, amperage, resistance, etc.

--

Jonny Durango

"Patrick was a saint. I ain't."

http://www.jdurango.com



"PhiloMertz" <PhiloMertz@gmail.com> wrote in message
news:1111102061.328888.180970@f14g2000cwb.googlegroups.com...
> OK...I need someoene to explain to me something regarding phantom power
> and mics.
>
> For purposes of this discussion, let's use the Rode NT4 mic which is an
> XLR mic that can be powered from its own batter or phantom power (I
> guess meaning a preamp).
>
> What is the difference, all else being equal, between using this mic
> (self-powered by its own battery) direct into a recorder and running
> this mic through a preamp and then into a recorder.
>
> In other words, if this mic can run on it's own power into a recorder,
> what is the benefit of a preamp, if there is one?
>
> Thanks!
>
Anonymous
March 17, 2005 10:37:24 PM

Archived from groups: rec.audio.pro (More info?)

Thanks Richard. Well, I don't have any equipment yet, but I was
thinking of a scenario where you could use a professional level
condensor mic with something like the Edirol R-1.

The R-1 does have a mic input but the manual says only to use mics with
plu-in power, which I understand would exclude mics like the NT4. So
then I thought you could use the NT4 with its battery power (before I
understood what Mike explained above) into the R-1's line level input.

So, I think the answer is you cannot use the NT4 directly into the
mic-in, but you could use it in the line-in if you also have an
external power source (preamp) to amplify the signal.

Did I get that right?
Anonymous
March 17, 2005 11:44:24 PM

Archived from groups: rec.audio.pro (More info?)

psalter wrote:


> In the simplest terms, microphones requiring phantom power are called
> condenser mics.


Except that isn't what the terms mean and for the OP to think so would
be confusing to him down the road.

Condensors generally require power, and that's what the phantom power or
battery do, but other devices or types of mics can require power too.
Anonymous
March 17, 2005 11:46:02 PM

Archived from groups: rec.audio.pro (More info?)

In article <1111102061.328888.180970@f14g2000cwb.googlegroups.com> PhiloMertz@gmail.com writes:

> For purposes of this discussion, let's use the Rode NT4

> What is the difference, all else being equal, between using this mic
> (self-powered by its own battery) direct into a recorder and running
> this mic through a preamp and then into a recorder.

No batteries. That's all.

> In other words, if this mic can run on it's own power into a recorder,
> what is the benefit of a preamp, if there is one?

A preamp does more than power a microphone. It amplifies the signal up
to "line" level, which is necessary for a recorder that doesn't have a
microphone input.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
March 18, 2005 1:41:43 AM

Archived from groups: rec.audio.pro (More info?)

On 17 Mar 2005 19:29:48 -0800, "PhiloMertz" <PhiloMertz@gmail.com>
wrote:

>You are all gracious with your time and
>knowledge.

Hey you got lucky...

Al
Anonymous
March 18, 2005 2:35:49 AM

Archived from groups: rec.audio.pro (More info?)

On 17 Mar 2005 15:27:41 -0800, "PhiloMertz" <PhiloMertz@gmail.com>
wrote:

>OK...I need someoene to explain to me something regarding phantom power
>and mics.
>
>For purposes of this discussion, let's use the Rode NT4 mic which is an
>XLR mic that can be powered from its own batter or phantom power (I
>guess meaning a preamp).
>
>What is the difference, all else being equal, between using this mic
>(self-powered by its own battery) direct into a recorder and running
>this mic through a preamp and then into a recorder.
>
>In other words, if this mic can run on it's own power into a recorder,
>what is the benefit of a preamp, if there is one?
>
>Thanks!

You need the pre amp to amplify the signal from the mic up to line
level so your mixer can handle it. Whether the pre amp supplies the
power or the internal battery supplies it is largely a matter of
convenience. Many small or battery powered pre-amps will not have the
facility to supply phantom power to the mic.

If your recorder has microphone level inputs, then very likely it can
not supply phantom power, and you will need to use the Rodes' internal
batteries.

d
Pearce Consulting
http://www.pearce.uk.com
Anonymous
March 18, 2005 6:17:54 AM

Archived from groups: rec.audio.pro (More info?)

and what happens when you do not like how the NT4 sounds??

dale
Anonymous
March 18, 2005 8:19:36 AM

Archived from groups: rec.audio.pro (More info?)

On 17 Mar 2005 19:37:24 -0800, "PhiloMertz" <PhiloMertz@gmail.com>
wrote:

>Thanks Richard. Well, I don't have any equipment yet, but I was
>thinking of a scenario where you could use a professional level
>condensor mic with something like the Edirol R-1.
>
>The R-1 does have a mic input but the manual says only to use mics with
>plu-in power, which I understand would exclude mics like the NT4. So

Looking at these specs:
http://www.edirol.com/products/info/r1.html
"Plug-in power" is often called bias power, which is about 5 volts
with a series resistor, used to power small electret condenser mics
that plug into and come with computer soundcards, minidisc players and
such.

>then I thought you could use the NT4 with its battery power (before I
>understood what Mike explained above) into the R-1's line level input.

No, you would need a preamp between the mic and the line level
input.

>So, I think the answer is you cannot use the NT4 directly into the
>mic-in, but you could use it in the line-in if you also have an
>external power source (preamp) to amplify the signal.

An "external power source" (usually called Phantom Power) and a
preamp are two different things, though many (most?) preamps have
Phantom Power built in. Phantom Power is a 48V power source through
series resistors through the signal lines of a balanced microphone
that powers it. A preamp is an electronic circuit (either in its own
box or as part of a mixer) that amplifies a mic signal enough to drive
a "line-level" input.

I found this on the Edirol site under
Product Support/Search our Knowledge Base and putting xlr mic into the
Search by Keyword box:

"How can I connect a good quality XLR mic to this device? Are they
good quality mics with 1/8 in connectors? (submitted 12/19/2004)
It's recommended that you use a stereo mic in order to record left and
right sound. If you use a mono mic, you need to set the R-1 to record
mono (see pg 13 of your manual). If you have an XLR mic, you'll need a
mic pre-amp. These devices are available in a wide array of styles,
functions (and costs) from your local music retailer. "

The "you'll need a mic pre-amp" doesn't seem right to me (not that
you can't do that, but the mic input itself should be usable). I'm
thinking you should be able to hook up the NT4 to the input with an
adapter cable with capacitors in the signal lines, but I just found
this:

http://www.rodemicrophones.com/specsnt4/nt4specs.htm
which says (among other things):
Custom stereo cables (included) dual XLR and mini stereo jack
^^^^ ^^^^^^ ^^^^

So it seems to me they designed the NT4 (while running on its own
internal battery) to plug directly into "bias-power" mic-input devices
such as minidisc recorders and the R-1. It would be good if the NT4
page actually said it has capacitively coupled outputs, but I think it
should work anyway.

Another site you might read is the FAQ, it explains phantom power for
mics, though it doesn't cover 1/8" jacks and plugs or bias power:

http://www.recaudiopro.net

>Did I get that right?

-----
http://mindspring.com/~benbradley
Anonymous
March 18, 2005 11:10:03 AM

Archived from groups: rec.audio.pro (More info?)

PhiloMertz wrote:

> Mike,

> You wrote:
> "A preamp does more than power a microphone. It amplifies the signal up

> to "line" level, which is necessary for a recorder that doesn't have a
> microphone input."

> Yes, this is where I was confused! So, even a self powered mic still
> needs to have the signal amplified...OK I think I got it.

You might enjoy reading the RAP FAQ, findable at:

www.recaudio.pro.net


--
ha
Anonymous
March 18, 2005 1:01:17 PM

Archived from groups: rec.audio.pro (More info?)

In article <1111117044.964375.20590@o13g2000cwo.googlegroups.com> PhiloMertz@gmail.com writes:

> The R-1 does have a mic input but the manual says only to use mics with
> plu-in power, which I understand would exclude mics like the NT4. So
> then I thought you could use the NT4 with its battery power (before I
> understood what Mike explained above) into the R-1's line level input.

Plug-in power is a different cirucit configuration than phantom power.
It's an unbalanced input (all mic preamps that are designed to be used
with "studio" mics have balanced inputs) and a DC voltage rides on the
hot signal lead going to the microphone. There's a capacitor inside
the recorder that blocks the DC from the recorder's input circuit. The
capsules used in these "plug-in power" mics are designed to take DC
voltage across their signal leads, separating the DC and the mic audio
signal internally.

This would be a good question to aske Rode directly. I know that I've
seen people using the NT4 with battery power plugged into Minidisk
recorders, which typically provide plug-in power. It's possible that
the NT4 is designed to block or ignore DC when it's not running on
phantom power. If that's the case, it would work fine with the Edirol
R-1.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
March 18, 2005 1:01:18 PM

Archived from groups: rec.audio.pro (More info?)

In article <1111144674.175643.260550@f14g2000cwb.googlegroups.com> dallen@frognet.net writes:

> and what happens when you do not like how the NT4 sounds??

EVERYBODY likes how the NT4 sounds (at least when comparing it to
built-in mics)

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
March 18, 2005 2:54:45 PM

Archived from groups: rec.audio.pro (More info?)

"PhiloMertz" wrote ...
> Thanks Richard. Well, I don't have any equipment yet, but I was
> thinking of a scenario where you could use a professional level
> condensor mic with something like the Edirol R-1.
>
> The R-1 does have a mic input but the manual says only to use mics with
> plu-in power, which I understand would exclude mics like the NT4.

No it does not exclude mics like NT4. "Plug-in power" means that
the device (the R1 in this case) provides a low-voltage DC bias
voltage on the microphone input connector. This is the kind of power
required by small electret condenser mics (like the kind supplied for
computer sound cards, the kind that "tapers" and video camcorders
use, etc.)

The presense of this bias voltage does NOT preclude using conventional
microphones with the input. By conventional I mean dynamic mics (which
require no power, phantom or "bias") or condenser mics like the NT4
which have an internal power supply (the battery).

> So then I thought you could use the NT4 with its battery power (before I
> understood what Mike explained above) into the R-1's line level input.

You can. You may have to rig a cable with DC-blocking capacitors
to keep the "bias voltage" out of the NT4. Or it may not even care
about the "plug-in power" bias voltage since it can take the 48v phantom
power. My NT4 even came with a cable with a 1./8" stereo mini-phone
connector which I expect would plug directly into the R1.

> So, I think the answer is you cannot use the NT4 directly into the
> mic-in,

No. I have an 85% confidence factor that you can plug the NT4
(powered by the internal battery) directly into the R1 and never
give it a second thought.

The other 15% of uncertainty is whether you have to block the
"plug-in power" bias voltage but that is trivial: a couple of capacitors
as shown on my web page
http://www.rcrowley.com/CamAdapt.htm This was written for
use with camcorders but the "plug-in power" appears to be
exactly the same for the Edirol R1 as for most video camcorders.

> but you could use it in the line-in if you also have an
> external power source (preamp) to amplify the signal

> Did I get that right?.

No. The NT4 does not require an external power source
when you use the internal battery.

Furthermore, you still seem to be associating "external power
source" with "preamp" and I must repeat that they are NOT
the same thing. You can have a preamp without phantom
power and you can have a phantom power supply without
a preamp.

And lastly, you cannot plug a microphone of ANY description
into a line-level input and expect it to work. You need 40-60dB
of gain between any microphone and any line-level input. This
is what a mic preamp does and has absolutely NOTHING to
do with the power ("plug-in", "phantom", "battery" or otherwise)
Anonymous
March 18, 2005 9:27:38 PM

Archived from groups: rec.audio.pro (More info?)

On Thu, 17 Mar 2005 20:44:24 -0800, S O'Neill <nopsam@nospam.net>
wrote:

>psalter wrote:
>
>
>> In the simplest terms, microphones requiring phantom power are called
>> condenser mics.
>
>
>Except that isn't what the terms mean and for the OP to think so would
>be confusing to him down the road.
>
>Condensors generally require power, and that's what the phantom power or
> battery do, but other devices or types of mics can require power too.
What no one has mentioned as the main definition.
Phantom power: Power Over The Signal Wires.
In the US Navy, we had remote Carbon Mics that used phantom power to
excite the Mic and control th PTT circuit over 4 telephone wires (2
pr).


, _
, | \ MKA: Steve Urbach
, | )erek No JUNK in my email please
, ____|_/ragonsclaw dragonsclawJUNK@JUNKmindspring.com
, / / / Running United Devices "Cure For Cancer" Project 24/7 Have you helped? http://www.grid.org
Anonymous
March 18, 2005 10:29:28 PM

Archived from groups: rec.audio.pro (More info?)

Read the FAQ at http://www.recaudiopro.net/. That should get you started in
understanding why your question isn't really a question at all. It's kinda
like asking why, if apple is a fruit and it's red, why aren't all fruits
red.

--


Roger W. Norman
SirMusic Studio
http://blogs.salon.com/0004478/

"PhiloMertz" <PhiloMertz@gmail.com> wrote in message
news:1111102061.328888.180970@f14g2000cwb.googlegroups.com...
> OK...I need someoene to explain to me something regarding phantom power
> and mics.
>
> For purposes of this discussion, let's use the Rode NT4 mic which is an
> XLR mic that can be powered from its own batter or phantom power (I
> guess meaning a preamp).
>
> What is the difference, all else being equal, between using this mic
> (self-powered by its own battery) direct into a recorder and running
> this mic through a preamp and then into a recorder.
>
> In other words, if this mic can run on it's own power into a recorder,
> what is the benefit of a preamp, if there is one?
>
> Thanks!
>
Anonymous
March 19, 2005 3:40:23 AM

Archived from groups: rec.audio.pro (More info?)

On Fri, 18 Mar 2005 19:29:28 -0500, "Roger W. Norman"
<rnorman@starpower.net> wrote:

>Read the FAQ at http://www.recaudiopro.net/. That should get you started in
>understanding why your question isn't really a question at all. It's kinda
>like asking why, if apple is a fruit and it's red, why aren't all fruits
>red.

Or if fruit flies like an apple, why time flies like an arrow.
-----
http://mindspring.com/~benbradley
Anonymous
March 19, 2005 4:57:22 AM

Archived from groups: rec.audio.pro (More info?)

Mike Rivers wrote:

>> The R-1 does have a mic input but the manual says only to use mics with
>> plu-in power, ...
> This would be a good question to aske Rode directly. I know that I've
> seen people using the NT4 with battery power plugged into Minidisk
>
> ... It's possible that the NT4 is designed to block or ignore DC when
> it's not running on phantom power. If that's the case, it would work fine
> with the Edirol R-1.

The R-1 has a switch (not a menu item, thank the fw gods) to turn off
the plug-in power. It's labeled:

MIC TYPE
DYN..CND
Anonymous
March 19, 2005 11:17:55 AM

Archived from groups: rec.audio.pro (More info?)

In article <6GL_d.11406$DW.2804@newssvr17.news.prodigy.com> gidney_n_cloyd@yahoo.com writes:

> The R-1 has a switch (not a menu item, thank the fw gods) to turn off
> the plug-in power.

Good thing somebody around here reads the instructions.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
!