Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.

d
Pearce Consulting
http://www.pearce.uk.com

On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.

d
Pearce Consulting
http://www.pearce.uk.com

On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.

d
Pearce Consulting
http://www.pearce.uk.com

Neil wrote:

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

No. Microphones don't draw 48V of current. Voltage and current are
different. Microphones draw a few milliamps of current at 48V. The
more microphones you use, the more current (in milliamps) they draw.

But they all have 48V across them, whether or not they draw any current.
(Actually, when you put a current load on them, the voltage drops a bit.)

The electrical outlets in your house all have 120V across them. You plug
in more appliances, the current demand increases but the voltage stays the
same.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

You want a good introduction to DC circuits. The Schaum's Outline is a
pretty good one, as is the first chapter of The Art Of Electronics.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Neil wrote:

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

No. Microphones don't draw 48V of current. Voltage and current are
different. Microphones draw a few milliamps of current at 48V. The
more microphones you use, the more current (in milliamps) they draw.

But they all have 48V across them, whether or not they draw any current.
(Actually, when you put a current load on them, the voltage drops a bit.)

The electrical outlets in your house all have 120V across them. You plug
in more appliances, the current demand increases but the voltage stays the
same.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

You want a good introduction to DC circuits. The Schaum's Outline is a
pretty good one, as is the first chapter of The Art Of Electronics.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Neil wrote:

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

No. Microphones don't draw 48V of current. Voltage and current are
different. Microphones draw a few milliamps of current at 48V. The
more microphones you use, the more current (in milliamps) they draw.

But they all have 48V across them, whether or not they draw any current.
(Actually, when you put a current load on them, the voltage drops a bit.)

The electrical outlets in your house all have 120V across them. You plug
in more appliances, the current demand increases but the voltage stays the
same.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

You want a good introduction to DC circuits. The Schaum's Outline is a
pretty good one, as is the first chapter of The Art Of Electronics.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article ,
(Don Pearce) wrote:

On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house
does this make them 4400 volt outlets if you use them all
no
they remain 110 volt outlets you just need to have enough amperage
avaiable to drive the load each outlet is drawing
George

In article ,
(Don Pearce) wrote:

On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house
does this make them 4400 volt outlets if you use them all
no
they remain 110 volt outlets you just need to have enough amperage
avaiable to drive the load each outlet is drawing
George

In article ,
(Don Pearce) wrote:

On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house
does this make them 4400 volt outlets if you use them all
no
they remain 110 volt outlets you just need to have enough amperage
avaiable to drive the load each outlet is drawing
George

George wrote:

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house


That's not a pretty image, George.

: )

George wrote:

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house


That's not a pretty image, George.

: )

George wrote:

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house


That's not a pretty image, George.

: )

In article ,
Don Cooper wrote:

George wrote:

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house


That's not a pretty image, George.

: )

ok I won't share where I keep the re20's
george

In article ,
Don Cooper wrote:

George wrote:

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house


That's not a pretty image, George.

: )

ok I won't share where I keep the re20's
george

In article ,
Don Cooper wrote:

George wrote:

you have 40(pulling a number out of my ass) 110 volt wall outlets in
your house


That's not a pretty image, George.

: )

ok I won't share where I keep the re20's
george

Neil wrote:
I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

The problem is electricity is very counter-intuitive, and you have
a misunderstanding about what voltage is.

Voltage is not the same thing as power. Voltage is sometimes called
"potential" (which is short for "potential difference"). You'll
notice that "potential" and "power" represent very different ideas.

When electrons are moving from point A to point B, you've got an
electric current. But, the electrons aren't going to spontaenously
all move in one direction as a group, so in order for this to happen,
there must be a force that causes them to move. Voltage is connected
with how much force there is available to possibly make the electrons
move.

I say "possibly" because another thing that's necessary is for
there to be a path for electrons to take. Unless they are
in just the right mood, electrons don't like to just fly across
open space. (Normally this takes the form of metal, which works
because electrons can move around within metal pretty easily,
so one electron can move a little bit and nudge another electron,
which then nudges another, and then pretty soon you've a bunch
of electrons inching in one direction by tiny amounts.) Anyway,
the point is that the amount of current that flows depends on
how much the electrons "want" to move (related to voltage) *and*
on how much resistance they encounter when trying to move.
(Think of walking on a sidewalk vs. walking through very shallow
water at the beach vs. walking through waist-deep water at
the beach.)

Anyway, to relate this back to the mixer, 48V just means that
the electrons have 48V of "motivation" to work with IF they
find a suitable, easy path along which to move. It doesn't
mean that any of them are actually moving at all. If there
is a perfect path where electrons encounter no resistance
at all, and if the console has no limits on its ability to
maintain 48V, then you would have infinite current. If,
however, there is some resistance, then the current will be
lower the higher the resistance is. The person who designs
a microphone can make it get just the amount of current that
it needs by designing a circuit with just the right resistance.

By the way, as for why it's 48V, I think that has to do with
a compromise. Higher-voltage circuits can transmit electricity
over long distances with less energy loss and with thinner
wires. Devices require various voltages, and on a DC circuit
it's much easier to cut voltage than it is to increase it.
So, 48V is high enough for most devices and it's easy to
drop down if you need to. However, high voltages also are
a little more difficult to deal with safely, and the government
makes it easier to get things approved if they are not too
high a voltage. (This is why people use "low-voltage lighting",
i.e. "Malibu lights" for their front yard to light up trees
and stuff.) So, 48V is a compromise between those factors.

- Logan

Neil wrote:
I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

The problem is electricity is very counter-intuitive, and you have
a misunderstanding about what voltage is.

Voltage is not the same thing as power. Voltage is sometimes called
"potential" (which is short for "potential difference"). You'll
notice that "potential" and "power" represent very different ideas.

When electrons are moving from point A to point B, you've got an
electric current. But, the electrons aren't going to spontaenously
all move in one direction as a group, so in order for this to happen,
there must be a force that causes them to move. Voltage is connected
with how much force there is available to possibly make the electrons
move.

I say "possibly" because another thing that's necessary is for
there to be a path for electrons to take. Unless they are
in just the right mood, electrons don't like to just fly across
open space. (Normally this takes the form of metal, which works
because electrons can move around within metal pretty easily,
so one electron can move a little bit and nudge another electron,
which then nudges another, and then pretty soon you've a bunch
of electrons inching in one direction by tiny amounts.) Anyway,
the point is that the amount of current that flows depends on
how much the electrons "want" to move (related to voltage) *and*
on how much resistance they encounter when trying to move.
(Think of walking on a sidewalk vs. walking through very shallow
water at the beach vs. walking through waist-deep water at
the beach.)

Anyway, to relate this back to the mixer, 48V just means that
the electrons have 48V of "motivation" to work with IF they
find a suitable, easy path along which to move. It doesn't
mean that any of them are actually moving at all. If there
is a perfect path where electrons encounter no resistance
at all, and if the console has no limits on its ability to
maintain 48V, then you would have infinite current. If,
however, there is some resistance, then the current will be
lower the higher the resistance is. The person who designs
a microphone can make it get just the amount of current that
it needs by designing a circuit with just the right resistance.

By the way, as for why it's 48V, I think that has to do with
a compromise. Higher-voltage circuits can transmit electricity
over long distances with less energy loss and with thinner
wires. Devices require various voltages, and on a DC circuit
it's much easier to cut voltage than it is to increase it.
So, 48V is high enough for most devices and it's easy to
drop down if you need to. However, high voltages also are
a little more difficult to deal with safely, and the government
makes it easier to get things approved if they are not too
high a voltage. (This is why people use "low-voltage lighting",
i.e. "Malibu lights" for their front yard to light up trees
and stuff.) So, 48V is a compromise between those factors.

- Logan

Neil wrote:
I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

The problem is electricity is very counter-intuitive, and you have
a misunderstanding about what voltage is.

Voltage is not the same thing as power. Voltage is sometimes called
"potential" (which is short for "potential difference"). You'll
notice that "potential" and "power" represent very different ideas.

When electrons are moving from point A to point B, you've got an
electric current. But, the electrons aren't going to spontaenously
all move in one direction as a group, so in order for this to happen,
there must be a force that causes them to move. Voltage is connected
with how much force there is available to possibly make the electrons
move.

I say "possibly" because another thing that's necessary is for
there to be a path for electrons to take. Unless they are
in just the right mood, electrons don't like to just fly across
open space. (Normally this takes the form of metal, which works
because electrons can move around within metal pretty easily,
so one electron can move a little bit and nudge another electron,
which then nudges another, and then pretty soon you've a bunch
of electrons inching in one direction by tiny amounts.) Anyway,
the point is that the amount of current that flows depends on
how much the electrons "want" to move (related to voltage) *and*
on how much resistance they encounter when trying to move.
(Think of walking on a sidewalk vs. walking through very shallow
water at the beach vs. walking through waist-deep water at
the beach.)

Anyway, to relate this back to the mixer, 48V just means that
the electrons have 48V of "motivation" to work with IF they
find a suitable, easy path along which to move. It doesn't
mean that any of them are actually moving at all. If there
is a perfect path where electrons encounter no resistance
at all, and if the console has no limits on its ability to
maintain 48V, then you would have infinite current. If,
however, there is some resistance, then the current will be
lower the higher the resistance is. The person who designs
a microphone can make it get just the amount of current that
it needs by designing a circuit with just the right resistance.

By the way, as for why it's 48V, I think that has to do with
a compromise. Higher-voltage circuits can transmit electricity
over long distances with less energy loss and with thinner
wires. Devices require various voltages, and on a DC circuit
it's much easier to cut voltage than it is to increase it.
So, 48V is high enough for most devices and it's easy to
drop down if you need to. However, high voltages also are
a little more difficult to deal with safely, and the government
makes it easier to get things approved if they are not too
high a voltage. (This is why people use "low-voltage lighting",
i.e. "Malibu lights" for their front yard to light up trees
and stuff.) So, 48V is a compromise between those factors.

- Logan

In article in rec.audio.pro on Fri, 24
Sep 2004 17:58:26 GMT, Don Pearce says...
On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.


How do most power supplies handle that all too possible situation of
(a) an unintentional fault causing a short between the earth and signal
pins
(b) an intentional situation of connecting an unbalanced source that has
pin 2 connected to ground, as is standard practice but which results in
phantom shorted to earth?

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

In article in rec.audio.pro on Fri, 24
Sep 2004 17:58:26 GMT, Don Pearce says...
On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.


How do most power supplies handle that all too possible situation of
(a) an unintentional fault causing a short between the earth and signal
pins
(b) an intentional situation of connecting an unbalanced source that has
pin 2 connected to ground, as is standard practice but which results in
phantom shorted to earth?

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

In article in rec.audio.pro on Fri, 24
Sep 2004 17:58:26 GMT, Don Pearce says...
On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.


How do most power supplies handle that all too possible situation of
(a) an unintentional fault causing a short between the earth and signal
pins
(b) an intentional situation of connecting an unbalanced source that has
pin 2 connected to ground, as is standard practice but which results in
phantom shorted to earth?

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

In article in rec.audio.pro on Fri,
24 Sep 2004 19:46:58 GMT, Logan Shaw says...

By the way, as for why it's 48V, I think that has to do with
a compromise.

No, like the 600 ohms impedance, 48V comes to us from telephone
technology. That is the voltage that phantom power on your telephone line
uses.

In article in rec.audio.pro on Fri,
24 Sep 2004 19:46:58 GMT, Logan Shaw says...

By the way, as for why it's 48V, I think that has to do with
a compromise.

No, like the 600 ohms impedance, 48V comes to us from telephone
technology. That is the voltage that phantom power on your telephone line
uses.

In article in rec.audio.pro on Fri,
24 Sep 2004 19:46:58 GMT, Logan Shaw says...

By the way, as for why it's 48V, I think that has to do with
a compromise.

No, like the 600 ohms impedance, 48V comes to us from telephone
technology. That is the voltage that phantom power on your telephone line
uses.

In article writes:

At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??

Uh . . .what's the specialty at this college? Auto Mechanics? Art
History? Economics? Certainly not recording.

Excusing your errors in terminology for the moment, surely if this was
some sort of recording class, the instructor would know that the
answer was "no."

For extra credit, you can ask what might happen if you were to connect
a phantom powered mic to ALL of those 32 inputs. If it's a Mackie SR
series like the SR32-4 (although that one doesn't have 32 mic inputs)
the answer is that the voltage will drop because of the load and any
mics that require 48 volts (many will work on lower voltages) will not
get sufficient voltage. When they designed that console, to cut
corners, they didn't provide sufficient current capacity for all the
inputs to be delivering full spec phantom power simultanteously. To
give them a little credt, though, at the time the console was
designed, condenser mics costing under $400 were few and far between
so it was unlikely that anyone on the Mackie budget would own 28
condenser mics. I believe I heard that it was designed to accommodate
a 25% load at full current per mic. So that's 7 mics, more if they
draw less than 10 mA of current (the at least somewhat official
maximum), or if all the mics can run at a lower voltage.



--
I'm really Mike Rivers )
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 he double-m-eleven-double-zero at yahoo

In article writes:

At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??

Uh . . .what's the specialty at this college? Auto Mechanics? Art
History? Economics? Certainly not recording.

Excusing your errors in terminology for the moment, surely if this was
some sort of recording class, the instructor would know that the
answer was "no."

For extra credit, you can ask what might happen if you were to connect
a phantom powered mic to ALL of those 32 inputs. If it's a Mackie SR
series like the SR32-4 (although that one doesn't have 32 mic inputs)
the answer is that the voltage will drop because of the load and any
mics that require 48 volts (many will work on lower voltages) will not
get sufficient voltage. When they designed that console, to cut
corners, they didn't provide sufficient current capacity for all the
inputs to be delivering full spec phantom power simultanteously. To
give them a little credt, though, at the time the console was
designed, condenser mics costing under $400 were few and far between
so it was unlikely that anyone on the Mackie budget would own 28
condenser mics. I believe I heard that it was designed to accommodate
a 25% load at full current per mic. So that's 7 mics, more if they
draw less than 10 mA of current (the at least somewhat official
maximum), or if all the mics can run at a lower voltage.



--
I'm really Mike Rivers )
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 he double-m-eleven-double-zero at yahoo

In article writes:

At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??

Uh . . .what's the specialty at this college? Auto Mechanics? Art
History? Economics? Certainly not recording.

Excusing your errors in terminology for the moment, surely if this was
some sort of recording class, the instructor would know that the
answer was "no."

For extra credit, you can ask what might happen if you were to connect
a phantom powered mic to ALL of those 32 inputs. If it's a Mackie SR
series like the SR32-4 (although that one doesn't have 32 mic inputs)
the answer is that the voltage will drop because of the load and any
mics that require 48 volts (many will work on lower voltages) will not
get sufficient voltage. When they designed that console, to cut
corners, they didn't provide sufficient current capacity for all the
inputs to be delivering full spec phantom power simultanteously. To
give them a little credt, though, at the time the console was
designed, condenser mics costing under $400 were few and far between
so it was unlikely that anyone on the Mackie budget would own 28
condenser mics. I believe I heard that it was designed to accommodate
a 25% load at full current per mic. So that's 7 mics, more if they
draw less than 10 mA of current (the at least somewhat official
maximum), or if all the mics can run at a lower voltage.



--
I'm really Mike Rivers )
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 he double-m-eleven-double-zero at yahoo

On Sat, 25 Sep 2004 09:56:03 +1200, Patrick Dunford
wrote:

In article in rec.audio.pro on Fri, 24
Sep 2004 17:58:26 GMT, Don Pearce says...
On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.


How do most power supplies handle that all too possible situation of
(a) an unintentional fault causing a short between the earth and signal
pins
(b) an intentional situation of connecting an unbalanced source that has
pin 2 connected to ground, as is standard practice but which results in
phantom shorted to earth?

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

The maximum current that can flow even in a dead short is the result
of the full 48 volts appearing across the 3000 ohms built into the
system - that is 16mA and will do no harm.

The little sparks you saw were the result of the 48volts. Pretty, but
probably not a good thing to do during a session! (Hint: you can
always switch the phantom off on the connectors you are working on ;-)

Connecting one pin to ground is not a problem - as far as phantom
power is concerned, the two mic pins are entirely separate.

d
Pearce Consulting
http://www.pearce.uk.com

On Sat, 25 Sep 2004 09:56:03 +1200, Patrick Dunford
wrote:

In article in rec.audio.pro on Fri, 24
Sep 2004 17:58:26 GMT, Don Pearce says...
On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.


How do most power supplies handle that all too possible situation of
(a) an unintentional fault causing a short between the earth and signal
pins
(b) an intentional situation of connecting an unbalanced source that has
pin 2 connected to ground, as is standard practice but which results in
phantom shorted to earth?

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

The maximum current that can flow even in a dead short is the result
of the full 48 volts appearing across the 3000 ohms built into the
system - that is 16mA and will do no harm.

The little sparks you saw were the result of the 48volts. Pretty, but
probably not a good thing to do during a session! (Hint: you can
always switch the phantom off on the connectors you are working on ;-)

Connecting one pin to ground is not a problem - as far as phantom
power is concerned, the two mic pins are entirely separate.

d
Pearce Consulting
http://www.pearce.uk.com

On Sat, 25 Sep 2004 09:56:03 +1200, Patrick Dunford
wrote:

In article in rec.audio.pro on Fri, 24
Sep 2004 17:58:26 GMT, Don Pearce says...
On 24 Sep 2004 10:44:05 -0700, (Neil) wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current, but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

I've searched for an answer to this question on the web, but I've
found no answers. Hope someone can help me!.

Thanks in advance,
Neil.

This is tricky - first we need to sort out your terminology a bit. 48V
isn't a current - it is a voltage. It is available to any mic that
needs it, but it is wired in a mode called parallel - that is it
doesn't add up for every mic, it is just 48V - no more than that. On
each mic channel it is fed to the mic through a pair of resistors of
about 6000 ohms (3000 ohms equivalent) so any single mic can take up
to 48/3000 or 0.016 amps (16mA). That is plenty for even the most
demanding phantom mic - most take much less. SOme need more, and they
come with their own power supply.

But the point is that all microphones are guaranteed to work off that
voltage and resistance combination, but most don't need that much.

As for the desk, if you have, say 24 mic channels, then the 48V power
supply must be able to supply 24 x .016 amps, or roughly half an amp.
So you see it is the amps, not the volts, that build up as you add
more microphones.


How do most power supplies handle that all too possible situation of
(a) an unintentional fault causing a short between the earth and signal
pins
(b) an intentional situation of connecting an unbalanced source that has
pin 2 connected to ground, as is standard practice but which results in
phantom shorted to earth?

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

The maximum current that can flow even in a dead short is the result
of the full 48 volts appearing across the 3000 ohms built into the
system - that is 16mA and will do no harm.

The little sparks you saw were the result of the 48volts. Pretty, but
probably not a good thing to do during a session! (Hint: you can
always switch the phantom off on the connectors you are working on ;-)

Connecting one pin to ground is not a problem - as far as phantom
power is concerned, the two mic pins are entirely separate.

d
Pearce Consulting
http://www.pearce.uk.com

Neil wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current,

Volts isn't current it's *VOLTS* ! Current is *AMPS*

Do you plan a career in pro-audio or the dole queue ? If the former, I
suggest you go learn something about the fundamentals.

but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

Checks just to make sure it isn't 1 April.

What college is that ?

Was the lecturer not present and able to answer ?

I see that you're in the UK. If you had 4 x 240V power sockets in a room
would you expect the mains supply to be 960V ?

They let too many dim kids into college these days to make the numbers
look good.


Graham

Neil wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current,

Volts isn't current it's *VOLTS* ! Current is *AMPS*

Do you plan a career in pro-audio or the dole queue ? If the former, I
suggest you go learn something about the fundamentals.

but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

Checks just to make sure it isn't 1 April.

What college is that ?

Was the lecturer not present and able to answer ?

I see that you're in the UK. If you had 4 x 240V power sockets in a room
would you expect the mains supply to be 960V ?

They let too many dim kids into college these days to make the numbers
look good.


Graham

Neil wrote:

Hello everyone,

I hope someone out there can answer my question, and I hope it doesn't
come across as too naieve!.

The question is regarding Phantom Power. At college, there is a 32
track mixing console, each track has an individual 'phantom power'
switch. The question arose in class that if every single track on the
mixer had phantom power enabled and phantom power runs at +48V, would
this equate to 1536V??, or isn't it as simple as that?. I realise most
mic's wouldn't draw 48V of current,

Volts isn't current it's *VOLTS* ! Current is *AMPS*

Do you plan a career in pro-audio or the dole queue ? If the former, I
suggest you go learn something about the fundamentals.

but if that's the case, why is
phantom power set at 48V if the microphones don't need that much to
operate?.

Checks just to make sure it isn't 1 April.

What college is that ?

Was the lecturer not present and able to answer ?

I see that you're in the UK. If you had 4 x 240V power sockets in a room
would you expect the mains supply to be 960V ?

They let too many dim kids into college these days to make the numbers
look good.


Graham

On Sat, 25 Sep 2004 09:56:03 +1200, Patrick Dunford
wrote:

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

Never solder in a powered circuit. In fact, there's good reason to not
solder in an earth grounded circuit.

Chris Hornbeck

On Sat, 25 Sep 2004 09:56:03 +1200, Patrick Dunford
wrote:

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

Never solder in a powered circuit. In fact, there's good reason to not
solder in an earth grounded circuit.

Chris Hornbeck

On Sat, 25 Sep 2004 09:56:03 +1200, Patrick Dunford
wrote:

I was working on a patch panel the other day. The desk was powered up and
had phantom on. Every time I touched my earthed soldering iron to the
signal pins there was a nice little blue spark from the phantom power.

Never solder in a powered circuit. In fact, there's good reason to not
solder in an earth grounded circuit.

Chris Hornbeck

Do you plan a career in pro-audio or the dole queue ? If the former, I
suggest you go learn something about the fundamentals. BRBR

Might could be that's exactly why he's in college, which, last I heard, still
allowed questions to be asked.

Scott Fraser

Do you plan a career in pro-audio or the dole queue ? If the former, I
suggest you go learn something about the fundamentals. BRBR

Might could be that's exactly why he's in college, which, last I heard, still
allowed questions to be asked.

Scott Fraser

Do you plan a career in pro-audio or the dole queue ? If the former, I
suggest you go learn something about the fundamentals. BRBR

Might could be that's exactly why he's in college, which, last I heard, still
allowed questions to be asked.

Scott Fraser