<s>
Phantom	B-Algorithm
power	I-Algorithm
,	O
in	O
the	O
context	O
of	O
professional	O
audio	O
equipment	O
,	O
is	O
DC	O
electric	O
power	O
transmitted	O
through	O
microphone	B-Application
cables	O
to	O
operate	O
microphones	B-Application
that	O
contain	O
active	O
electronic	O
circuitry	O
.	O
</s>
<s>
It	O
is	O
best	O
known	O
as	O
a	O
convenient	O
power	O
source	O
for	O
condenser	O
microphones	B-Application
,	O
though	O
many	O
active	O
direct	O
boxes	O
also	O
use	O
it	O
.	O
</s>
<s>
Phantom	B-Algorithm
power	I-Algorithm
supplies	O
are	O
often	O
built	O
into	O
mixing	O
consoles	O
,	O
microphone	B-Algorithm
preamplifiers	I-Algorithm
and	O
similar	O
equipment	O
.	O
</s>
<s>
In	O
addition	O
to	O
powering	O
the	O
circuitry	O
of	O
a	O
microphone	B-Application
,	O
traditional	O
condenser	O
microphones	B-Application
also	O
use	O
phantom	B-Algorithm
power	I-Algorithm
for	O
polarizing	O
the	O
microphone	B-Application
's	O
transducer	O
element	O
.	O
</s>
<s>
Phantom	B-Algorithm
powering	I-Algorithm
was	O
first	O
used	O
(	O
and	O
still	O
is	O
used	O
)	O
in	O
copper	O
wire	O
based	O
landline	O
telephone	O
systems	O
since	O
the	O
introduction	O
of	O
the	O
rotary-dial	O
telephone	O
in	O
1919	O
.	O
</s>
<s>
The	O
first	O
known	O
commercially	O
available	O
phantom-powered	O
microphone	B-Application
was	O
the	O
Schoeps	O
model	O
CMT	O
20	O
,	O
which	O
came	O
out	O
in	O
1964	O
,	O
built	O
to	O
the	O
specifications	O
of	O
French	O
radio	O
with	O
9	O
–	O
12	O
volt	O
DC	O
phantom	B-Algorithm
power	I-Algorithm
;	O
the	O
positive	O
pole	O
of	O
this	O
powering	O
was	O
grounded	O
.	O
</s>
<s>
Microphone	B-Algorithm
preamplifiers	I-Algorithm
of	O
the	O
Nagra	O
IV-series	O
tape	O
recorders	O
offered	O
this	O
type	O
of	O
powering	O
as	O
an	O
option	O
for	O
many	O
years	O
and	O
Schoeps	O
continued	O
to	O
support	O
"	O
negative	O
phantom	O
"	O
until	O
the	O
CMT	O
series	O
was	O
discontinued	O
in	O
the	O
mid-1970s	O
,	O
but	O
it	O
is	O
obsolete	O
now	O
.	O
</s>
<s>
In	O
1966	O
,	O
Neumann	O
GmbH	O
presented	O
a	O
new	O
type	O
of	O
transistorized	O
microphone	B-Application
to	O
the	O
Norwegian	O
Broadcasting	O
Corporation	O
,	O
NRK	O
.	O
</s>
<s>
Since	O
NRK	O
already	O
had	O
48-volt	O
power	O
available	O
in	O
their	O
studios	O
for	O
their	O
emergency	O
lighting	O
systems	O
,	O
this	O
voltage	O
was	O
used	O
for	O
powering	O
the	O
new	O
microphones	B-Application
(	O
model	O
KM	O
84	O
)	O
,	O
and	O
is	O
the	O
origin	O
of	O
48-volt	O
phantom	B-Algorithm
power	I-Algorithm
.	O
</s>
<s>
The	O
International	O
Electrotechnical	O
Commission	O
Standards	O
Committee	O
's	O
"	O
Multimedia	O
systems	O
–	O
Guide	O
to	O
the	O
recommended	O
characteristics	O
of	O
analogue	O
interfaces	O
to	O
achieve	O
interoperability	O
"	O
(	O
IEC	O
61938:2018	O
)	O
specifies	O
parameters	O
for	O
microphone	B-Application
phantom	B-Algorithm
power	I-Algorithm
delivery	O
.	O
</s>
<s>
Most	O
microphones	B-Application
now	O
use	O
the	O
P48	O
standard	O
(	O
maximum	O
available	O
power	O
is	O
240mW	O
)	O
.	O
</s>
<s>
Phantom	B-Algorithm
powering	I-Algorithm
consists	O
of	O
a	O
phantom	O
circuit	O
where	O
direct	O
current	O
is	O
applied	O
equally	O
through	O
the	O
two	O
signal	O
lines	O
of	O
a	O
balanced	B-Protocol
audio	I-Protocol
connector	I-Protocol
(	O
in	O
modern	O
equipment	O
,	O
both	O
pins	O
2	O
and	O
3	O
of	O
an	O
XLR	B-Device
connector	I-Device
)	O
.	O
</s>
<s>
When	O
phantom	B-Algorithm
powering	I-Algorithm
was	O
introduced	O
,	O
one	O
of	O
its	O
advantages	O
was	O
that	O
the	O
same	O
type	O
of	O
balanced	O
,	O
shielded	O
microphone	B-Application
cable	O
that	O
studios	O
were	O
already	O
using	O
for	O
dynamic	O
microphones	B-Application
could	O
be	O
used	O
for	O
condenser	O
microphones	B-Application
.	O
</s>
<s>
This	O
is	O
in	O
contrast	O
to	O
microphones	B-Application
with	O
vacuum-tube	O
circuitry	O
,	O
most	O
of	O
which	O
require	O
special	O
,	O
multi-conductor	O
cables	O
.	O
</s>
<s>
With	O
phantom	B-Algorithm
power	I-Algorithm
,	O
the	O
supply	O
voltage	O
is	O
effectively	O
invisible	O
to	O
balanced	O
microphones	B-Application
that	O
do	O
not	O
use	O
it	O
,	O
which	O
includes	O
most	O
dynamic	O
microphones	B-Application
.	O
</s>
<s>
A	O
balanced	O
signal	O
consists	O
only	O
of	O
the	O
differences	O
in	O
voltage	O
between	O
two	O
signal	O
lines	O
;	O
phantom	B-Algorithm
powering	I-Algorithm
places	O
the	O
same	O
DC	O
voltage	O
on	O
both	O
signal	O
lines	O
of	O
a	O
balanced	O
connection	O
.	O
</s>
<s>
Connecting	O
a	O
conventional	O
microphone	B-Application
to	O
an	O
input	O
that	O
had	O
parallel	O
powering	O
enabled	O
could	O
very	O
well	O
damage	O
the	O
microphone	B-Application
.	O
</s>
<s>
The	O
IEC	O
61938	O
Standard	O
defines	O
48-volt	O
,	O
24-volt	O
,	O
and	O
12-volt	O
phantom	B-Algorithm
powering	I-Algorithm
.	O
</s>
<s>
The	O
24-volt	O
version	O
of	O
phantom	B-Algorithm
powering	I-Algorithm
,	O
proposed	O
quite	O
a	O
few	O
years	O
after	O
the	O
12	O
and	O
48	O
V	O
versions	O
,	O
was	O
also	O
included	O
in	O
the	O
DIN	O
standard	O
and	O
is	O
in	O
the	O
IEC	O
standard	O
,	O
but	O
it	O
was	O
never	O
widely	O
adopted	O
by	O
equipment	O
manufacturers	O
.	O
</s>
<s>
Nearly	O
all	O
modern	O
mixing	O
consoles	O
have	O
a	O
switch	O
for	O
turning	O
phantom	B-Algorithm
power	I-Algorithm
on	O
or	O
off	O
;	O
in	O
most	O
high-end	O
equipment	O
this	O
can	O
be	O
done	O
individually	O
by	O
channel	O
,	O
while	O
on	O
smaller	O
mixers	O
a	O
single	O
master	O
switch	O
may	O
control	O
power	O
delivery	O
to	O
all	O
channels	O
.	O
</s>
<s>
Phantom	B-Algorithm
power	I-Algorithm
can	O
be	O
blocked	O
in	O
any	O
channel	O
with	O
a	O
1:1	O
isolation	O
transformer	O
or	O
blocking	O
capacitors	O
.	O
</s>
<s>
Phantom	B-Algorithm
powering	I-Algorithm
can	O
cause	O
equipment	O
malfunction	O
or	O
even	O
damage	O
if	O
used	O
with	O
cables	O
or	O
adapters	O
that	O
connect	O
one	O
side	O
of	O
the	O
input	O
to	O
ground	O
,	O
or	O
if	O
certain	O
equipment	O
other	O
than	O
microphones	B-Application
is	O
connected	O
to	O
it	O
.	O
</s>
<s>
Instrument	O
amplifiers	O
rarely	O
provide	O
phantom	B-Algorithm
power	I-Algorithm
.	O
</s>
<s>
Some	O
microphones	B-Application
offer	O
a	O
choice	O
of	O
internal	O
battery	O
powering	O
or	O
(	O
external	O
)	O
phantom	B-Algorithm
powering	I-Algorithm
.	O
</s>
<s>
In	O
some	O
such	O
microphones	B-Application
it	O
is	O
advisable	O
to	O
remove	O
the	O
internal	O
batteries	O
when	O
phantom	B-Algorithm
power	I-Algorithm
is	O
being	O
used	O
since	O
batteries	O
may	O
corrode	O
and	O
leak	O
chemicals	O
.	O
</s>
<s>
Other	O
microphones	B-Application
are	O
specifically	O
designed	O
to	O
switch	O
over	O
to	O
the	O
internal	O
batteries	O
if	O
an	O
external	O
supply	O
fails	O
.	O
</s>
<s>
Phantom	B-Algorithm
powering	I-Algorithm
is	O
not	O
always	O
implemented	O
correctly	O
or	O
adequately	O
,	O
even	O
in	O
professional-quality	O
preamps	O
,	O
mixers	O
,	O
and	O
recorders	O
.	O
</s>
<s>
In	O
part	O
this	O
is	O
because	O
first-generation	O
(	O
late-1960s	O
through	O
mid-1970s	O
)	O
48-volt	O
phantom-powered	O
condenser	O
microphones	B-Application
had	O
simple	O
circuitry	O
and	O
required	O
only	O
small	O
amounts	O
of	O
operating	O
current	O
(	O
typically	O
less	O
than	O
1mA	O
per	O
microphone	B-Application
)	O
,	O
so	O
the	O
phantom	O
supply	O
circuits	O
typically	O
built	O
into	O
recorders	O
,	O
mixers	O
,	O
and	O
preamps	O
of	O
that	O
time	O
were	O
designed	O
on	O
the	O
assumption	O
that	O
this	O
current	O
would	O
be	O
adequate	O
.	O
</s>
<s>
This	O
practice	O
has	O
carried	O
forward	O
to	O
the	O
present	O
;	O
many	O
48-volt	O
phantom	B-Algorithm
power	I-Algorithm
supply	O
circuits	O
,	O
especially	O
in	O
low-cost	O
and	O
portable	O
equipment	O
,	O
simply	O
cannot	O
supply	O
more	O
than	O
1	O
or	O
2mA	O
total	O
without	O
breaking	O
down	O
.	O
</s>
<s>
Some	O
circuits	O
also	O
have	O
significant	O
additional	O
resistance	O
in	O
series	O
with	O
the	O
standard	O
pair	O
of	O
supply	O
resistors	O
for	O
each	O
microphone	B-Application
input	O
;	O
this	O
may	O
not	O
affect	O
low-current	O
microphones	B-Application
much	O
,	O
but	O
it	O
can	O
disable	O
microphones	B-Application
that	O
need	O
more	O
current	O
.	O
</s>
<s>
Mid-1970s	O
and	O
later	O
condenser	O
microphones	B-Application
designed	O
for	O
48-volt	O
phantom	B-Algorithm
powering	I-Algorithm
often	O
require	O
much	O
more	O
current	O
(	O
e.g.	O
,	O
2	O
–	O
4mA	O
for	O
Neumann	O
transformerless	O
microphones	B-Application
,	O
4	O
–	O
5mA	O
for	O
the	O
Schoeps	O
CMC	O
(	O
"	O
Colette	O
"	O
)	O
series	O
and	O
Josephson	O
microphones	B-Application
,	O
5	O
–	O
6mA	O
for	O
most	O
Shure	O
KSM-series	O
microphones	B-Application
,	O
8mA	O
for	O
CAD	O
Equiteks	O
and	O
10mA	O
for	O
Earthworks	O
)	O
.	O
</s>
<s>
The	O
IEC	O
standard	O
gives	O
10mA	O
as	O
the	O
maximum	O
allowed	O
current	O
per	O
microphone	B-Application
.	O
</s>
<s>
If	O
its	O
required	O
current	O
is	O
not	O
available	O
,	O
a	O
microphone	B-Application
may	O
still	O
put	O
out	O
a	O
signal	O
,	O
but	O
it	O
cannot	O
deliver	O
its	O
intended	O
level	O
of	O
performance	O
.	O
</s>
<s>
The	O
specific	O
symptoms	O
vary	O
somewhat	O
,	O
but	O
the	O
most	O
common	O
result	O
will	O
be	O
reduction	O
of	O
the	O
maximum	O
sound-pressure	O
level	O
that	O
the	O
microphone	B-Application
can	O
handle	O
without	O
overload	O
(	O
distortion	O
)	O
.	O
</s>
<s>
Some	O
microphones	B-Application
will	O
also	O
show	O
lower	O
sensitivity	O
(	O
output	O
level	O
for	O
a	O
given	O
sound-pressure	O
level	O
)	O
.	O
</s>
<s>
Most	O
ground	B-Protocol
lift	I-Protocol
switches	O
have	O
the	O
unwanted	O
effect	O
of	O
disconnecting	O
phantom	B-Algorithm
power	I-Algorithm
.	O
</s>
<s>
There	O
must	O
always	O
be	O
a	O
DC	O
current	O
path	O
between	O
pin	O
1	O
of	O
the	O
microphone	B-Application
and	O
the	O
negative	O
side	O
of	O
the	O
48-volt	O
supply	O
,	O
if	O
power	O
is	O
to	O
reach	O
the	O
microphone	B-Application
's	O
electronics	O
.	O
</s>
<s>
Lifting	O
the	O
ground	O
,	O
which	O
is	O
normally	O
pin	O
1	O
,	O
breaks	O
this	O
path	O
and	O
disables	O
the	O
phantom	B-Algorithm
power	I-Algorithm
supply	O
.	O
</s>
<s>
There	O
is	O
a	O
common	O
belief	O
that	O
connecting	O
a	O
dynamic	O
or	O
ribbon	O
microphone	B-Application
to	O
a	O
phantom-powered	O
input	O
will	O
damage	O
it	O
.	O
</s>
<s>
If	O
there	O
is	O
a	O
fault	O
in	O
the	O
cable	O
,	O
phantom	B-Algorithm
power	I-Algorithm
may	O
damage	O
some	O
mics	O
by	O
applying	O
a	O
voltage	O
across	O
the	O
output	O
of	O
the	O
microphone	B-Application
.	O
</s>
<s>
Equipment	O
damage	O
is	O
also	O
possible	O
if	O
a	O
phantom-powered	O
input	O
connected	O
to	O
an	O
unbalanced	O
dynamic	O
microphone	B-Application
or	O
electronic	O
musical	O
instruments	O
.	O
</s>
<s>
The	O
transient	O
generated	O
when	O
a	O
microphone	B-Application
is	O
hot-plugged	O
into	O
an	O
input	O
with	O
active	O
phantom	B-Algorithm
power	I-Algorithm
can	O
damage	O
the	O
microphone	B-Application
and	O
possibly	O
the	O
preamp	O
circuit	O
of	O
the	O
input	O
because	O
not	O
all	O
pins	O
of	O
the	O
microphone	B-Application
connector	O
make	O
contact	O
at	O
the	O
same	O
time	O
,	O
and	O
there	O
is	O
an	O
instant	O
when	O
current	O
can	O
flow	O
to	O
charge	O
the	O
capacitance	O
of	O
the	O
cable	O
from	O
one	O
side	O
of	O
the	O
phantom-powered	O
input	O
and	O
not	O
the	O
other	O
.	O
</s>
<s>
This	O
is	O
particularly	O
a	O
problem	O
with	O
long	O
microphone	B-Application
cables	O
.	O
</s>
<s>
It	O
is	O
considered	O
good	O
practice	O
to	O
disable	O
phantom	B-Algorithm
power	I-Algorithm
to	O
devices	O
that	O
do	O
n't	O
require	O
it	O
.	O
</s>
<s>
Digital	O
microphones	B-Application
complying	O
with	O
the	O
AES	O
42	O
standard	O
may	O
be	O
provided	O
with	O
phantom	B-Algorithm
power	I-Algorithm
at	O
10	O
volts	O
,	O
impressed	O
on	O
both	O
audio	O
leads	O
and	O
ground	O
.	O
</s>
<s>
This	O
supply	O
can	O
furnish	O
up	O
to	O
250	O
mA	O
to	O
digital	O
microphones	B-Application
.	O
</s>
<s>
A	O
keyed	O
variation	O
of	O
the	O
usual	O
XLR	B-Device
connector	I-Device
,	O
the	O
XLD	O
connector	O
,	O
may	O
be	O
used	O
to	O
prevent	O
accidental	O
interchange	O
of	O
analog	O
and	O
digital	O
devices	O
.	O
</s>
<s>
T-power	O
,	O
also	O
known	O
as	O
A-B	O
powering	O
or	O
T12	O
,	O
described	O
in	O
DIN	O
45595	O
,	O
is	O
an	O
alternative	O
to	O
phantom	B-Algorithm
powering	I-Algorithm
that	O
is	O
still	O
widely	O
used	O
in	O
the	O
world	O
of	O
production	O
film	O
sound	O
.	O
</s>
<s>
Many	O
older	O
Sennheiser	O
and	O
Schoeps	O
microphones	B-Application
use	O
this	O
powering	O
method	O
,	O
although	O
newer	O
recorders	O
and	O
mixers	O
are	O
phasing	O
out	O
this	O
option	O
.	O
</s>
<s>
Adapter	O
barrels	O
,	O
and	O
dedicated	O
power	O
supplies	O
,	O
are	O
made	O
to	O
accommodate	O
T	O
powered	O
microphones	B-Application
.	O
</s>
<s>
There	O
is	O
often	O
no	O
audible	O
difference	O
between	O
microphones	B-Application
featuring	O
this	O
method	O
and	O
microphones	B-Application
with	O
P48	O
powering	O
.	O
</s>
<s>
In	O
this	O
scheme	O
,	O
12volts	O
is	O
applied	O
through	O
180ohm	O
resistors	O
between	O
the	O
microphone	B-Application
's	O
"	O
hot	O
"	O
terminal	O
(	O
XLR	O
pin	O
2	O
)	O
and	O
the	O
microphone	B-Application
's	O
"	O
cold	O
"	O
terminal	O
(	O
XLR	O
pin	O
3	O
)	O
.	O
</s>
<s>
This	O
results	O
in	O
a	O
12-volt	O
potential	O
difference	O
with	O
significant	O
current	O
capability	O
across	O
pins	O
2	O
and	O
3	O
,	O
which	O
would	O
likely	O
cause	O
permanent	O
damage	O
if	O
applied	O
to	O
a	O
dynamic	O
or	O
ribbon	O
microphone	B-Application
.	O
</s>
<s>
Plug-in-power	O
(	O
PiP	O
)	O
is	O
the	O
low-current	O
3	O
–	O
5V	O
supply	O
provided	O
at	O
the	O
microphone	B-Application
jack	O
of	O
some	O
consumer	O
equipment	O
,	O
such	O
as	O
portable	O
recorders	O
and	O
computer	B-Device
sound	I-Device
cards	I-Device
.	O
</s>
<s>
It	O
is	O
unlike	O
phantom	B-Algorithm
power	I-Algorithm
since	O
it	O
is	O
an	O
unbalanced	O
interface	O
with	O
a	O
low	O
voltage	O
(	O
around	O
+5volts	O
)	O
connected	O
to	O
the	O
signal	O
conductor	O
with	O
return	O
through	O
the	O
sleeve	O
;	O
the	O
DC	O
power	O
is	O
in	O
common	O
with	O
the	O
audio	O
signal	O
from	O
the	O
microphone	B-Application
.	O
</s>
<s>
It	O
is	O
often	O
used	O
for	O
powering	O
electret	B-Algorithm
microphones	I-Algorithm
,	O
which	O
will	O
not	O
function	O
without	O
power	O
.	O
</s>
<s>
It	O
is	O
suitable	O
only	O
for	O
powering	O
microphones	B-Application
specifically	O
designed	O
for	O
use	O
with	O
this	O
type	O
of	O
power	O
supply	O
.	O
</s>
<s>
Damage	O
may	O
result	O
if	O
these	O
microphones	B-Application
are	O
connected	O
to	O
true	O
(	O
48V	B-Algorithm
)	O
phantom	B-Algorithm
power	I-Algorithm
through	O
a	O
3.5mm	O
to	O
XLR	O
adapter	O
that	O
connects	O
the	O
XLR	O
shield	O
to	O
the	O
3.5mm	O
sleeve	O
.	O
</s>
<s>
A	O
similar	O
line-powering	O
scheme	O
is	O
found	O
in	O
computer	B-Device
sound	I-Device
cards	I-Device
.	O
</s>
<s>
Both	O
plug-in-power	O
and	O
soundcard	B-Device
power	O
are	O
defined	O
in	O
the	O
second	O
edition	O
of	O
IEC	O
61938	O
.	O
</s>
<s>
These	O
alternative	O
powering	O
schemes	O
are	O
sometimes	O
improperly	O
referred	O
to	O
as	O
"	O
phantom	B-Algorithm
power	I-Algorithm
"	O
and	O
should	O
not	O
be	O
confused	O
with	O
true	O
48-volt	O
phantom	B-Algorithm
powering	I-Algorithm
described	O
above	O
.	O
</s>
<s>
Some	O
condenser	O
microphones	B-Application
can	O
be	O
powered	O
with	O
a	O
1.5-volt	O
cell	O
contained	O
in	O
a	O
small	O
compartment	O
in	O
the	O
microphone	B-Application
or	O
in	O
an	O
external	O
housing	O
.	O
</s>
<s>
Phantom	B-Algorithm
power	I-Algorithm
is	O
sometimes	O
used	O
by	O
workers	O
in	O
avionics	O
to	O
describe	O
the	O
DC	O
bias	O
voltage	O
used	O
to	O
power	O
aviation	O
microphones	B-Application
,	O
which	O
use	O
a	O
lower	O
voltage	O
than	O
professional	O
audio	O
microphones	B-Application
.	O
</s>
<s>
Phantom	B-Algorithm
power	I-Algorithm
used	O
in	O
this	O
context	O
is	O
8	O
–	O
16volts	O
DC	O
in	O
series	O
with	O
a	O
470ohm	O
(	O
nominal	O
)	O
resistor	O
as	O
specified	O
in	O
RTCA	O
Inc	O
.	O
standard	O
DO-214	O
.	O
</s>
<s>
These	O
microphones	B-Application
evolved	O
from	O
the	O
carbon	O
microphones	B-Application
used	O
in	O
the	O
early	O
days	O
of	O
aviation	O
and	O
the	O
telephone	O
which	O
relied	O
on	O
a	O
DC	O
bias	O
voltage	O
across	O
the	O
carbon	O
microphone	B-Application
element	O
.	O
</s>
<s>
Phantom	B-Algorithm
power	I-Algorithm
is	O
also	O
used	O
in	O
applications	O
other	O
than	O
microphones	B-Application
:	O
</s>
