<s>
A	O
phone	B-Device
connector	I-Device
,	O
also	O
known	O
as	O
phone	O
jack	O
,	O
audio	B-Device
jack	I-Device
,	O
headphone	B-Device
jack	I-Device
or	O
jack	B-Device
plug	I-Device
,	O
is	O
a	O
family	O
of	O
electrical	B-Protocol
connectors	I-Protocol
typically	O
used	O
for	O
analog	O
audio	O
signals	O
.	O
</s>
<s>
The	O
phone	B-Device
connector	I-Device
was	O
invented	O
for	O
use	O
in	O
telephone	B-Device
switchboards	I-Device
in	O
the	O
19th	O
century	O
and	O
is	O
still	O
widely	O
used	O
.	O
</s>
<s>
The	O
phone	B-Device
connector	I-Device
is	O
cylindrical	O
in	O
shape	O
,	O
with	O
a	O
grooved	O
tip	O
to	O
retain	O
it	O
.	O
</s>
<s>
Three-contact	O
versions	O
are	O
known	O
as	O
TRS	B-Device
connectors	I-Device
(	O
tip	O
,	O
ring	O
,	O
sleeve	O
)	O
.	O
</s>
<s>
stereo	B-Device
plug	I-Device
,	O
headphone	B-Device
jack	I-Device
,	O
microphone	B-Device
jack	I-Device
,	O
aux	O
input	O
,	O
etc	O
.	O
</s>
<s>
The	O
3.5mm	O
versions	O
are	O
mini-phone	O
,	O
mini-stereo	B-Device
,	O
mini	B-Device
jack	I-Device
,	O
etc	O
.	O
</s>
<s>
In	O
the	O
UK	O
,	O
jack	B-Device
plug	I-Device
and	O
jack	O
socket	O
are	O
the	O
male	O
and	O
female	O
phone	B-Device
connectors	I-Device
.	O
</s>
<s>
In	O
the	O
US	O
,	O
a	O
stationary	O
(	O
more	O
fixed	O
)	O
electrical	B-Protocol
connector	I-Protocol
is	O
the	O
jack	O
.	O
</s>
<s>
The	O
terms	O
phone	O
plug	O
and	O
phone	O
jack	O
sometimes	O
refer	O
to	O
different	O
genders	O
of	O
phone	B-Device
connectors	I-Device
,	O
but	O
also	O
sometimes	O
refer	O
to	O
the	O
RJ11	O
and	O
older	O
telephone	B-Protocol
plugs	I-Protocol
and	O
corresponding	O
jacks	O
that	O
connect	O
wired	O
telephones	O
to	O
wall	O
outlets	O
.	O
</s>
<s>
Phone	O
plugs	B-Protocol
and	O
jacks	O
are	O
different	O
from	O
phono	B-Protocol
plugs	I-Protocol
and	O
phono	B-Device
jacks	I-Device
(	O
or	O
in	O
the	O
UK	O
,	O
phono	O
socket	O
)	O
which	O
are	O
RCA	B-Protocol
connectors	I-Protocol
common	O
in	O
consumer	O
hi-fi	O
and	O
audiovisual	O
equipment	O
.	O
</s>
<s>
Modern	O
phone	B-Device
connectors	I-Device
are	O
available	O
in	O
three	O
standard	O
sizes	O
.	O
</s>
<s>
The	O
original	O
version	O
descends	O
from	O
as	O
early	O
as	O
1877	O
,	O
when	O
the	O
first-ever	O
telephone	B-Device
switchboard	I-Device
was	O
installed	O
at	O
109	O
Court	O
Street	O
in	O
Boston	O
in	O
a	O
building	O
owned	O
by	O
Charles	O
Williams	O
,	O
Jr.	O
;	O
or	O
1878	O
,	O
when	O
an	O
early	O
switchboard	O
was	O
used	O
for	O
the	O
first	O
commercial	O
manual	B-Device
telephone	I-Device
exchange	I-Device
in	O
New	O
Haven	O
,	O
Connecticut	O
created	O
by	O
George	O
W	O
.	O
Coy	O
.	O
</s>
<s>
Western	O
Electric	O
was	O
the	O
manufacturing	O
arm	O
of	O
the	O
Bell	O
System	O
,	O
and	O
thus	O
originated	O
or	O
refined	O
most	O
of	O
the	O
engineering	O
designs	O
,	O
including	O
the	O
telephone	B-Protocol
jacks	I-Protocol
and	O
plugs	B-Protocol
which	O
were	O
later	O
adopted	O
by	O
other	O
industries	O
,	O
including	O
the	O
U.S.	O
military	O
.	O
</s>
<s>
EIA	O
RS-453	O
:	O
Dimensional	O
,	O
Mechanical	O
and	O
Electrical	O
Characteristics	O
Defining	O
Phone	O
Plugs	B-Protocol
&	O
Jacks	O
standard	O
of	O
diameter	O
,	O
also	O
found	O
in	O
IEC	O
60603-11:1992	O
Connectors	O
for	O
frequencies	O
below	O
3	O
MHz	O
for	O
use	O
with	O
printed	O
boards	O
–	O
Part	O
11	O
:	O
Detail	O
specification	O
for	O
concentric	O
connectors	O
(	O
dimensions	O
for	O
free	O
connectors	O
and	O
fixed	O
connectors	O
)	O
.	O
</s>
<s>
U.S.	O
military	O
versions	O
of	O
the	O
Western	O
Electric	O
plugs	B-Protocol
were	O
initially	O
specified	O
in	O
Amendment	O
No.1	O
,	O
MIL-P-642	O
,	O
and	O
included	O
:	O
</s>
<s>
MIL-P-642/5A	O
:	O
Plug	O
,	O
Telephone	O
(	O
TYPE	O
PJ-068	O
)	O
and	O
Accessory	O
Screws	O
(	O
1973	O
)	O
,	O
and	O
MIL-DTL-642F	O
:	O
Plugs	B-Protocol
,	O
Telephone	O
,	O
and	O
Accessory	O
Screws	O
(	O
2015	O
)	O
,	O
with	O
diameter	O
,	O
also	O
known	O
by	O
the	O
earlier	O
Signal	O
Corps	O
PL-68	O
designation	O
.	O
</s>
<s>
These	O
are	O
commonly	O
used	O
as	O
the	O
microphone	B-Device
jack	I-Device
for	O
aviation	O
radios	O
,	O
and	O
on	O
Collins	O
S-line	O
and	O
many	O
Drake	O
amateur	O
radios	O
.	O
</s>
<s>
MIL-DTL-642F	O
states	O
,	O
"	O
This	O
specification	O
covers	O
telephone	B-Protocol
plugs	I-Protocol
used	O
in	O
telephone	O
(	O
including	O
telephone	B-Device
switchboard	I-Device
consoles	O
)	O
,	O
telegraph	O
,	O
and	O
teletype	O
circuits	O
,	O
and	O
for	O
connecting	O
headsets	B-Device
,	O
handsets	O
,	O
and	O
microphones	B-Application
into	O
communications	O
circuits.	O
"	O
</s>
<s>
The	O
three-conductor	O
version	O
became	O
very	O
popular	O
with	O
its	O
application	O
on	O
the	O
Walkman	O
in	O
1979	O
,	O
as	O
unlike	O
earlier	O
transistor	O
radios	O
,	O
these	O
devices	O
had	O
no	O
speaker	O
of	O
their	O
own	O
;	O
the	O
usual	O
way	O
to	O
listen	O
to	O
them	O
was	O
to	O
plug	O
in	O
headphones	B-Device
.	O
</s>
<s>
They	O
often	O
appeared	O
next	O
to	O
a	O
3.5mm	O
microphone	B-Device
jack	I-Device
for	O
a	O
remote	O
control	O
on-off	O
switch	O
on	O
early	O
portable	O
tape	O
recorders	O
;	O
the	O
microphone	B-Application
provided	O
with	O
such	O
machines	O
had	O
the	O
on-off	O
switch	O
and	O
used	O
a	O
two-pronged	O
connector	O
with	O
both	O
the	O
3.5	O
and	O
2.5mm	O
plugs	B-Protocol
.	O
</s>
<s>
2.5mm	O
phone	O
jacks	O
have	O
also	O
been	O
used	O
as	O
the	O
headset	B-Device
jacks	I-Device
on	O
mobile	O
telephones	O
(	O
see	O
)	O
.	O
</s>
<s>
All	O
sizes	O
are	O
now	O
readily	O
available	O
in	O
two-conductor	O
(	O
unbalanced	O
mono	O
)	O
and	O
three-conductor	O
(	O
balanced	B-Protocol
mono	O
or	O
unbalanced	O
stereo	O
)	O
versions	O
.	O
</s>
<s>
It	O
is	O
also	O
used	O
for	O
a	O
combination	O
of	O
stereo	O
audio	O
,	O
a	O
microphone	B-Application
,	O
and	O
controlling	O
media	O
playback	O
,	O
calls	O
,	O
volume	O
and/or	O
a	O
virtual	B-Protocol
assistant	I-Protocol
on	O
some	O
laptop	O
computers	O
and	O
most	O
mobile	O
phones	O
,	O
and	O
some	O
handheld	O
amateur	O
radio	O
transceivers	O
from	O
Yaesu	O
.	O
</s>
<s>
Some	O
headphone	B-Device
amplifiers	O
have	O
used	O
it	O
to	O
connect	O
"	O
balanced	B-Protocol
"	O
stereo	B-Device
headphones	I-Device
,	O
which	O
require	O
two	O
conductors	O
per	O
audio	O
channel	O
as	O
the	O
channels	O
do	O
not	O
share	O
a	O
common	O
ground	O
.	O
</s>
<s>
103	O
plugs	B-Protocol
and	O
matching	O
jacks	O
for	O
patching	O
audio	O
throughout	O
studios	O
.	O
</s>
<s>
Because	O
of	O
the	O
large	O
amount	O
of	O
space	O
these	O
patch	B-Protocol
panels	I-Protocol
required	O
,	O
the	O
industry	O
began	O
switching	O
to	O
3-conductor	O
plugs	B-Protocol
and	O
jacks	O
in	O
the	O
late	O
1940s	O
,	O
using	O
the	O
WE	O
Type	O
291	O
plug	O
with	O
WE	O
type	O
239	O
jacks	O
.	O
</s>
<s>
The	O
three-conductor	O
TRS	O
versions	O
are	O
capable	O
of	O
handling	O
balanced	B-Protocol
line	O
signals	O
and	O
are	O
used	O
in	O
professional	O
audio	O
installations	O
.	O
</s>
<s>
Though	O
unable	O
to	O
handle	O
as	O
much	O
power	O
,	O
and	O
less	O
reliable	O
than	O
a	O
jack	O
,	O
Bantam	O
connectors	O
are	O
used	O
for	O
mixing	O
console	O
and	O
outboard	O
patchbays	B-Protocol
in	O
recording	O
studio	O
and	O
live	O
sound	O
applications	O
,	O
where	O
large	O
numbers	O
of	O
patch	O
points	O
are	O
needed	O
in	O
a	O
limited	O
space	O
.	O
</s>
<s>
The	O
slightly	O
different	O
shape	O
of	O
Bantam	O
plugs	B-Protocol
is	O
also	O
less	O
likely	O
to	O
cause	O
shorting	O
as	O
they	O
are	O
plugged	O
in	O
.	O
</s>
<s>
A	O
two-pin	O
version	O
,	O
known	O
to	O
the	O
telecom	O
industry	O
as	O
a	O
"	O
310	O
connector	O
"	O
,	O
consists	O
of	O
two	O
-inch	O
phone	O
plugs	B-Protocol
at	O
a	O
centre	O
spacing	O
of	O
.	O
</s>
<s>
The	O
socket	O
versions	O
of	O
these	O
can	O
be	O
used	O
with	O
normal	O
phone	O
plugs	B-Protocol
provided	O
the	O
plug	O
bodies	O
are	O
not	O
too	O
large	O
,	O
but	O
the	O
plug	O
version	O
will	O
only	O
mate	O
with	O
two	O
sockets	O
at	O
inches	O
centre	O
spacing	O
,	O
or	O
with	O
line	O
sockets	O
,	O
again	O
with	O
sufficiently	O
small	O
bodies	O
.	O
</s>
<s>
These	O
connectors	O
are	O
still	O
used	O
today	O
in	O
telephone	O
company	O
central	O
offices	O
on	O
"	O
DSX	O
"	O
patch	B-Protocol
panels	I-Protocol
for	O
DS1	B-Protocol
circuits	I-Protocol
.	O
</s>
<s>
Plugging	O
a	O
stereo	B-Device
plug	I-Device
into	O
one	O
of	O
the	O
two	O
mono	O
jacks	O
typically	O
results	O
in	O
the	O
audio	O
coming	O
into	O
only	O
one	O
ear	O
.	O
</s>
<s>
A	O
short-barrelled	O
version	O
of	O
the	O
phone	O
plug	O
was	O
used	O
for	O
20th	O
century	O
high-impedance	O
mono	O
headphones	B-Device
,	O
and	O
in	O
particular	O
those	O
used	O
in	O
World	O
War	O
II	O
aircraft	O
.	O
</s>
<s>
The	O
US	O
military	O
uses	O
a	O
variety	O
of	O
phone	B-Device
connectors	I-Device
including	O
-inch	O
(	O
0.281	O
inch	O
,	O
7.14mm	O
)	O
and	O
-inch	O
(	O
0.25inch	O
,	O
6.35mm	O
)	O
diameter	O
plugs	B-Protocol
.	O
</s>
<s>
Commercial	O
and	O
general	O
aviation	O
(	O
GA	O
)	O
civil	O
aircraft	O
headsets	B-Device
often	O
use	O
a	O
pair	O
of	O
phone	B-Device
connectors	I-Device
.	O
</s>
<s>
A	O
standard	O
-inch	O
(	O
6.3	O
mm	O
)	O
2	O
or	O
3-conductor	O
plug	O
,	O
type	O
PJ-055	O
,	O
is	O
used	O
for	O
headphones	B-Device
.	O
</s>
<s>
For	O
the	O
microphone	B-Application
,	O
a	O
smaller	O
-inch	O
(	O
0.206inch	O
/	O
5.23	O
mm	O
)	O
diameter	O
3-conductor	O
plug	O
,	O
type	O
PJ-068	O
,	O
is	O
used	O
.	O
</s>
<s>
These	O
are	O
also	O
known	O
as	O
US	O
NATO	O
plugs	B-Protocol
.	O
</s>
<s>
These	O
have	O
a	O
diameter	O
shaft	O
with	O
four	O
conductors	O
,	O
allowing	O
two	O
for	O
the	O
headphones	B-Device
,	O
and	O
two	O
for	O
the	O
microphone	B-Application
.	O
</s>
<s>
There	O
is	O
a	O
confusingly	O
similar	O
four-conductor	O
British	O
connector	O
,	O
Type	O
671	O
(	O
10H/18575	O
)	O
,	O
with	O
a	O
slightly	O
larger	O
diameter	O
of	O
used	O
for	O
headsets	B-Device
in	O
many	O
UK	O
military	O
aircraft	O
and	O
often	O
referred	O
to	O
as	O
a	O
UK	O
NATO	O
or	O
European	O
NATO	O
connector	O
.	O
</s>
<s>
Many	O
different	O
configurations	O
of	O
these	O
phone	O
plugs	B-Protocol
were	O
used	O
,	O
some	O
accommodating	O
five	O
or	O
more	O
conductors	O
,	O
with	O
several	O
tip	O
profiles	O
.	O
</s>
<s>
Of	O
these	O
many	O
varieties	O
,	O
only	O
the	O
two-conductor	O
version	O
with	O
a	O
rounded	O
tip	O
profile	O
was	O
compatible	O
between	O
different	O
manufacturers	O
,	O
and	O
this	O
was	O
the	O
design	O
that	O
was	O
at	O
first	O
adopted	O
for	O
use	O
with	O
microphones	B-Application
,	O
electric	O
guitars	O
,	O
headphones	B-Device
,	O
loudspeakers	O
,	O
and	O
other	O
audio	O
equipment	O
.	O
</s>
<s>
When	O
a	O
three-conductor	O
version	O
of	O
the	O
6.35mm	O
plug	O
was	O
introduced	O
for	O
use	O
with	O
stereo	B-Device
headphones	I-Device
,	O
it	O
was	O
given	O
a	O
sharper	O
tip	O
profile	O
in	O
order	O
to	O
make	O
it	O
possible	O
to	O
manufacture	O
jacks	O
that	O
would	O
accept	O
only	O
stereo	B-Device
plugs	I-Device
,	O
to	O
avoid	O
short-circuiting	O
the	O
right	O
channel	O
of	O
the	O
amplifier	O
.	O
</s>
<s>
This	O
attempt	O
has	O
long	O
been	O
abandoned	O
,	O
and	O
now	O
the	O
convention	O
is	O
that	O
all	O
plugs	B-Protocol
fit	O
all	O
sockets	O
of	O
the	O
same	O
size	O
,	O
regardless	O
of	O
whether	O
they	O
are	O
balanced	B-Protocol
or	O
unbalanced	O
,	O
mono	O
or	O
stereo	O
.	O
</s>
<s>
Most	O
6.35mm	O
plugs	B-Protocol
,	O
mono	O
or	O
stereo	O
,	O
now	O
have	O
the	O
profile	O
of	O
the	O
original	O
stereo	B-Device
plug	I-Device
,	O
although	O
a	O
few	O
rounded	O
mono	O
plugs	B-Protocol
are	O
still	O
produced	O
.	O
</s>
<s>
The	O
profiles	O
of	O
stereo	O
miniature	O
and	O
sub-miniature	O
plugs	B-Protocol
have	O
always	O
been	O
identical	O
to	O
the	O
mono	O
plugs	B-Protocol
of	O
the	O
same	O
size	O
.	O
</s>
<s>
However	O
,	O
if	O
equipment	O
is	O
not	O
designed	O
for	O
such	O
a	O
use	O
,	O
grounding	O
the	O
right	O
channel	O
causes	O
a	O
short	B-Application
circuit	I-Application
which	O
has	O
the	O
potential	O
to	O
damage	O
an	O
audio	O
amplifier	O
channel	O
.	O
</s>
<s>
Because	O
of	O
a	O
lack	O
of	O
standardization	O
in	O
the	O
past	O
regarding	O
the	O
dimensions	O
(	O
length	O
)	O
given	O
to	O
the	O
ring	O
conductor	O
and	O
the	O
insulating	O
portions	O
on	O
either	O
side	O
of	O
it	O
in	O
6.35mm	O
(	O
in	O
)	O
phone	B-Device
connectors	I-Device
and	O
the	O
width	O
of	O
the	O
conductors	O
in	O
different	O
brands	O
and	O
generations	O
of	O
sockets	O
,	O
there	O
are	O
occasional	O
issues	O
with	O
compatibility	O
between	O
differing	O
brands	O
of	O
plug	O
and	O
socket	O
.	O
</s>
<s>
This	O
can	O
result	O
in	O
a	O
contact	O
in	O
the	O
socket	O
bridging	O
(	O
shorting	O
)	O
the	O
ring	O
and	O
sleeve	O
contacts	O
on	O
a	O
phone	B-Device
connector	I-Device
.	O
</s>
<s>
A	O
considerable	O
variety	O
of	O
line	O
plugs	B-Protocol
and	O
panel	O
sockets	O
is	O
available	O
,	O
including	O
plugs	B-Protocol
suiting	O
various	O
cable	O
sizes	O
,	O
right-angle	O
plugs	B-Protocol
,	O
and	O
both	O
plugs	B-Protocol
and	O
sockets	O
in	O
a	O
variety	O
of	O
price	O
ranges	O
and	O
with	O
current	O
capacities	O
up	O
to	O
15	O
amperes	B-General_Concept
for	O
certain	O
heavy-duty	O
in	O
versions	O
intended	O
for	O
loudspeaker	O
connections	O
.	O
</s>
<s>
Common	O
uses	O
of	O
phone	O
plugs	B-Protocol
and	O
their	O
matching	O
sockets	O
include	O
:	O
</s>
<s>
Headphone	B-Device
and	O
earphone	O
jacks	O
on	O
a	O
wide	O
range	O
of	O
equipment	O
.	O
</s>
<s>
6.35mm	O
(	O
in	O
)	O
plugs	B-Protocol
are	O
common	O
on	O
home	O
and	O
professional	O
component	O
equipment	O
,	O
while	O
3.5mm	O
plugs	B-Protocol
are	O
nearly	O
universal	O
for	O
portable	O
audio	O
equipment	O
and	O
headphones	B-Device
.	O
</s>
<s>
2.5mm	O
plugs	B-Protocol
are	O
not	O
as	O
common	O
,	O
but	O
are	O
used	O
on	O
communication	O
equipment	O
such	O
as	O
cordless	O
phones	O
,	O
mobile	O
phones	O
,	O
and	O
two-way	O
radios	O
,	O
especially	O
in	O
the	O
earliest	O
years	O
of	O
the	O
21st	O
century	O
before	O
the	O
3.5mm	O
became	O
standard	O
on	O
mobile	O
phones	O
.	O
</s>
<s>
The	O
use	O
of	O
headphone	B-Device
jacks	I-Device
in	O
smartphones	B-Application
is	O
declining	O
in	O
favor	O
of	O
USB-C	O
connectors	O
and	O
wireless	O
Bluetooth	B-Protocol
solutions	O
.	O
</s>
<s>
Consumer	O
electronics	O
devices	O
such	O
as	O
digital	B-Device
cameras	I-Device
,	O
camcorders	O
,	O
and	O
portable	O
DVD	O
players	O
use	O
3.5mm	O
connectors	O
for	O
composite	O
video	O
and	O
audio	O
output	O
.	O
</s>
<s>
Cables	O
designed	O
for	O
this	O
use	O
are	O
often	O
terminated	O
with	O
RCA	B-Protocol
connectors	I-Protocol
on	O
the	O
other	O
end	O
.	O
</s>
<s>
Hands-free	O
sets	O
and	O
headsets	B-Device
often	O
use	O
3.5mm	O
or	O
2.5mm	O
connectors	O
.	O
</s>
<s>
TRS	B-Device
connectors	I-Device
are	O
used	O
for	O
mono	O
audio	O
out	O
and	O
an	O
unbalanced	O
microphone	B-Application
(	O
with	O
a	O
shared	O
ground	O
)	O
.	O
</s>
<s>
Four-conductor	O
TRRS	O
phone	B-Device
connectors	I-Device
add	O
an	O
additional	O
audio	O
channel	O
for	O
stereo	O
output	O
.	O
</s>
<s>
TRRS	O
connectors	O
used	O
for	O
this	O
purpose	O
are	O
sometimes	O
interoperable	O
with	O
TRS	B-Device
connectors	I-Device
,	O
depending	O
on	O
how	O
the	O
contacts	O
are	O
used	O
.	O
</s>
<s>
Microphone	B-Application
inputs	O
on	O
tape	O
and	O
cassette	O
recorders	O
,	O
sometimes	O
with	O
remote	O
control	O
switching	O
on	O
the	O
ring	O
,	O
on	O
early	O
,	O
monaural	O
cassette	O
recorders	O
mostly	O
a	O
dual-pin	O
version	O
consisting	O
of	O
a	O
3.5mm	O
TS	O
for	O
the	O
microphone	B-Application
and	O
a	O
2.5mm	O
TS	O
for	O
remote	O
control	O
which	O
switches	O
the	O
recorder	O
's	O
power	O
supply	O
.	O
</s>
<s>
Patching	O
points	O
(	O
insert	B-Protocol
points	I-Protocol
)	O
on	O
a	O
wide	O
range	O
of	O
equipment	O
.	O
</s>
<s>
Personal	B-Device
computer	I-Device
sound	I-Device
cards	I-Device
,	O
such	O
as	O
Creative	O
Labs	O
 '	O
Sound	B-Application
Blaster	I-Application
line	O
,	O
use	O
a	O
3.5mm	O
phone	B-Device
connector	I-Device
as	O
a	O
mono	O
microphone	B-Application
input	O
,	O
and	O
deliver	O
a	O
5V	O
bias	O
voltage	O
on	O
the	O
ring	O
to	O
power	O
the	O
FET	B-Application
preamplifier	O
built	O
into	O
electret	B-Algorithm
microphones	I-Algorithm
.	O
</s>
<s>
The	O
Apple	B-Operating_System
PlainTalk	I-Operating_System
microphone	B-Device
jack	I-Device
used	O
on	O
some	O
older	O
Macintosh	O
systems	O
is	O
designed	O
to	O
accept	O
an	O
extended	O
3.5mm	O
three-conductor	O
phone	B-Device
connector	I-Device
;	O
in	O
this	O
case	O
,	O
the	O
tip	O
carries	O
power	O
for	O
a	O
preamplifier	O
inside	O
the	O
microphone	B-Application
.	O
</s>
<s>
It	O
cannot	O
accept	O
a	O
standard	O
microphone	B-Application
without	O
a	O
preamp	O
.	O
</s>
<s>
If	O
a	O
PlainTalk-compatible	O
microphone	B-Application
is	O
not	O
available	O
,	O
the	O
jack	O
can	O
accept	O
a	O
line-level	O
sound	O
input	O
.	O
</s>
<s>
Normally	O
,	O
3.5mm	O
three-conductor	O
sockets	O
are	O
used	O
in	O
computer	B-Device
sound	I-Device
cards	I-Device
for	O
stereo	O
output	O
.	O
</s>
<s>
Thus	O
,	O
for	O
a	O
sound	B-Device
card	I-Device
with	O
5.1	O
output	O
,	O
there	O
will	O
be	O
three	O
sockets	O
to	O
accommodate	O
six	O
channels	O
:	O
front	O
left	O
and	O
right	O
;	O
surround	O
left	O
and	O
right	O
;	O
and	O
center	O
and	O
subwoofer	O
.	O
</s>
<s>
6.1	O
and	O
7.1	O
channel	O
sound	B-Device
cards	I-Device
from	O
Creative	O
Labs	O
,	O
however	O
,	O
use	O
a	O
single	O
three-conductor	O
socket	O
(	O
for	O
the	O
front	O
speakers	O
)	O
and	O
two	O
four-conductor	O
sockets	O
.	O
</s>
<s>
This	O
is	O
to	O
accommodate	O
rear-center	O
(	O
6.1	O
)	O
or	O
rear	O
left	O
and	O
right	O
(	O
7.1	O
)	O
channels	O
without	O
the	O
need	O
for	O
additional	O
sockets	O
on	O
the	O
sound	B-Device
card	I-Device
.	O
</s>
<s>
Some	O
portable	O
computers	O
have	O
a	O
combined	O
3.5mm	O
TRS-TOSLINK	B-Protocol
jack	O
,	O
supporting	O
stereo	O
audio	O
output	O
using	O
a	O
TRS	B-Device
connector	I-Device
,	O
or	O
TOSLINK	B-Protocol
(	O
stereo	O
or	O
5.1	O
Dolby	O
Digital/DTS	O
)	O
digital	O
output	O
using	O
a	O
suitable	O
optical	O
adapter	O
.	O
</s>
<s>
Some	O
newer	O
computers	O
,	O
such	O
as	O
Lenovo	O
laptops	O
,	O
have	O
3.5mm	O
TRRS	O
headset	B-Device
sockets	O
,	O
which	O
are	O
compatible	O
with	O
phone	O
headsets	B-Device
and	O
may	O
be	O
distinguished	O
by	O
a	O
headset	B-Device
icon	O
instead	O
of	O
the	O
usual	O
headphones	B-Device
or	O
microphone	B-Application
icons	O
.	O
</s>
<s>
These	O
are	O
particularly	O
used	O
for	O
voice	B-Application
over	I-Application
IP	I-Application
.	O
</s>
<s>
Attempting	O
to	O
fully	O
insert	B-Protocol
the	O
longer	O
(	O
17mm	O
)	O
plug	O
into	O
a	O
receptacle	O
designed	O
for	O
the	O
shorter	O
(	O
15mm	O
)	O
plug	O
may	O
damage	O
the	O
receptacle	O
,	O
and	O
may	O
damage	O
any	O
electronics	O
located	O
immediately	O
behind	O
the	O
receptacle	O
.	O
</s>
<s>
A	O
shorter	O
plug	O
in	O
a	O
socket	O
designed	O
for	O
the	O
longer	O
connector	O
may	O
not	O
be	O
retained	O
firmly	O
and	O
may	O
result	O
in	O
wrong	O
signal	O
routing	O
or	O
a	O
short	B-Application
circuit	I-Application
inside	O
the	O
equipment	O
(	O
e.g.	O
</s>
<s>
The	O
shorter	O
15mm	O
TRRS	O
variant	O
is	O
more	O
common	O
and	O
physically	O
compatible	O
with	O
standard	O
3.5mm	O
TRS	O
and	O
TS	B-Device
connectors	I-Device
.	O
</s>
<s>
Many	O
small	O
video	O
cameras	O
,	O
laptops	O
,	O
recorders	O
and	O
other	O
consumer	O
devices	O
use	O
a	O
3.5mm	O
microphone	B-Application
connector	O
for	O
attaching	O
a	O
microphone	B-Application
to	O
the	O
system	O
.	O
</s>
<s>
Devices	O
that	O
use	O
an	O
unpowered	O
microphone	B-Application
:	O
usually	O
a	O
cheap	O
dynamic	O
or	O
piezoelectric	O
microphone	B-Application
.	O
</s>
<s>
The	O
microphone	B-Application
generates	O
its	O
own	O
voltage	O
and	O
needs	O
no	O
power	O
.	O
</s>
<s>
Devices	O
that	O
use	O
a	O
self-powered	O
microphone	B-Application
:	O
usually	O
a	O
condenser	O
microphone	B-Application
with	O
an	O
internal	O
battery-powered	O
amplifier	O
.	O
</s>
<s>
Devices	O
that	O
use	O
a	O
plug-in	O
powered	O
microphone	B-Application
:	O
an	O
electret	B-Algorithm
microphone	I-Algorithm
containing	O
an	O
internal	O
FET	B-Application
amplifier	O
.	O
</s>
<s>
These	O
provide	O
a	O
good	O
quality	O
signal	O
,	O
in	O
a	O
very	O
small	O
microphone	B-Application
.	O
</s>
<s>
However	O
,	O
the	O
internal	O
FET	B-Application
needs	O
a	O
DC	O
power	O
supply	O
,	O
which	O
is	O
provided	O
as	O
a	O
bias	O
voltage	O
for	O
an	O
internal	O
preamp	O
transistor	O
.	O
</s>
<s>
Plug-in	O
power	O
is	O
supplied	O
on	O
the	O
same	O
line	O
as	O
the	O
audio	O
signal	O
,	O
using	O
an	O
RC	B-Algorithm
filter	I-Algorithm
.	O
</s>
<s>
The	O
DC	O
bias	O
voltage	O
supplies	O
the	O
FET	B-Application
amplifier	O
(	O
at	O
a	O
low	O
current	O
)	O
,	O
while	O
the	O
capacitor	O
decouples	O
the	O
DC	O
supply	O
from	O
the	O
AC	O
input	O
to	O
the	O
recorder	O
.	O
</s>
<s>
If	O
a	O
recorder	O
provides	O
plug-in	O
power	O
,	O
and	O
the	O
microphone	B-Application
does	O
not	O
need	O
it	O
,	O
everything	O
will	O
usually	O
work	O
well	O
.	O
</s>
<s>
In	O
the	O
converse	O
case	O
(	O
recorder	O
provides	O
no	O
power	O
;	O
microphone	B-Application
needs	O
power	O
)	O
,	O
no	O
sound	O
will	O
be	O
recorded	O
.	O
</s>
<s>
Three	O
-	O
or	O
four-conductor	O
(	O
TRS	O
or	O
TRRS	O
)	O
2.5mm	O
and	O
3.5mm	O
sockets	O
are	O
common	O
on	O
older	O
cell	O
phones	O
and	O
newer	O
smartphones	B-Application
respectively	O
,	O
providing	O
mono	O
(	O
three	O
conductor	O
)	O
or	O
stereo	O
(	O
four	O
conductor	O
)	O
sound	O
and	O
a	O
microphone	B-Application
input	O
,	O
together	O
with	O
signaling	O
(	O
e.g.	O
,	O
push	O
a	O
button	O
to	O
answer	O
a	O
call	O
)	O
.	O
</s>
<s>
These	O
are	O
used	O
both	O
for	O
handsfree	O
headsets	B-Device
and	O
for	O
stereo	B-Device
headphones	I-Device
.	O
</s>
<s>
3.5mm	O
TRRS	O
(	O
stereo-plus-mic	O
)	O
sockets	O
became	O
particularly	O
common	O
on	O
smartphones	B-Application
,	O
and	O
have	O
been	O
used	O
e.g.	O
</s>
<s>
by	O
Nokia	O
since	O
2006	O
;	O
they	O
are	O
often	O
compatible	O
with	O
standard	O
3.5mm	O
stereo	B-Device
headphones	I-Device
.	O
</s>
<s>
Some	O
computers	O
now	O
also	O
include	O
a	O
TRRS	O
headset	B-Device
socket	O
,	O
compatible	O
with	O
the	O
headsets	B-Device
intended	O
for	O
smartphones	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
plugging	O
TRRS	O
headphones	B-Device
into	O
a	O
TRS	O
headset	B-Device
socket	O
,	O
TRS	O
headset	B-Device
into	O
a	O
TRRS	O
socket	O
,	O
or	O
plugging	O
TRRS	O
headphones	B-Device
from	O
one	O
manufacturer	O
into	O
a	O
TRRS	O
socket	O
from	O
another	O
may	O
not	O
function	O
correctly	O
,	O
or	O
at	O
all	O
.	O
</s>
<s>
Mono	O
audio	O
will	O
usually	O
work	O
,	O
but	O
stereo	O
audio	O
or	O
the	O
microphone	B-Application
may	O
not	O
work	O
.	O
</s>
<s>
Where	O
they	O
differ	O
is	O
in	O
the	O
placement	O
of	O
the	O
microphone	B-Application
and	O
return	O
contacts	O
.	O
</s>
<s>
The	O
first	O
,	O
which	O
places	O
the	O
ground	O
return	O
on	O
the	O
sleeve	O
and	O
the	O
microphone	B-Application
on	O
the	O
second	O
ring	O
,	O
is	O
standardized	O
in	O
OMTP	O
and	O
has	O
been	O
accepted	O
as	O
a	O
national	O
Chinese	O
standard	O
YDT	O
1885	O
–	O
2009	O
.	O
</s>
<s>
It	O
is	O
mostly	O
used	O
on	O
older	O
devices	O
,	O
such	O
as	O
older	O
Nokia	O
mobiles	O
,	O
older	O
Samsung	B-Application
smartphones	B-Application
,	O
and	O
some	O
Sony	O
Ericsson	O
phones	O
,	O
and	O
products	O
meant	O
for	O
the	O
Chinese	O
market	O
.	O
</s>
<s>
Headsets	B-Device
using	O
this	O
wiring	O
may	O
be	O
indicated	O
by	O
black	O
plastic	O
separators	O
between	O
the	O
rings	O
.	O
</s>
<s>
The	O
second	O
,	O
which	O
reverses	O
these	O
contacts	O
,	O
with	O
the	O
microphone	B-Application
on	O
the	O
sleeve	O
,	O
is	O
used	O
by	O
Apple	O
's	O
iPhone	B-Device
line	O
until	O
the	O
6S	B-Operating_System
and	O
SE	O
(	O
1st	O
)	O
,	O
and	O
has	O
become	O
the	O
de	O
facto	O
TRRS	O
standard	O
,	O
to	O
maintain	O
compatibility	O
with	O
these	O
products	O
.	O
</s>
<s>
It	O
is	O
now	O
used	O
by	O
HTC	B-Application
devices	O
,	O
recent	O
Samsung	B-Application
,	O
Nokia	O
,	O
and	O
Sony	O
phones	O
,	O
among	O
others	O
.	O
</s>
<s>
Headsets	B-Device
using	O
this	O
wiring	O
may	O
be	O
indicated	O
by	O
white	O
plastic	O
separators	O
between	O
the	O
rings	O
.	O
</s>
<s>
If	O
a	O
CTIA	O
headset	B-Device
is	O
connected	O
to	O
a	O
mobile	O
phone	O
with	O
OMTP	O
interface	O
,	O
the	O
missing	O
ground	O
will	O
effectively	O
connect	O
speakers	O
in	O
out-of-phase	O
series	O
,	O
resulting	O
in	O
no	O
voice	O
on	O
typical	O
popular	O
music	O
recordings	O
where	O
the	O
singers	O
are	O
in	O
the	O
center	O
;	O
in	O
this	O
case	O
,	O
if	O
the	O
main	O
microphone	B-Application
button	O
is	O
held	O
down	O
,	O
shorting	O
across	O
the	O
microphone	B-Application
and	O
restoring	O
ground	O
,	O
the	O
correct	O
sound	O
may	O
be	O
audible	O
.	O
</s>
<s>
Standard	O
Tip	O
Ring	O
1	O
Ring	O
2	O
Sleeve	O
Devices	O
using	O
this	O
standard	O
CTIA	O
,	O
AHJ	O
Left	O
audio	O
Right	O
audio	O
Ground	O
Microphone	B-Application
Most	O
Android	B-Application
devices	O
.	O
</s>
<s>
Apple	O
,	O
HTC	B-Application
,	O
LG	O
,	O
BlackBerry	B-Operating_System
,	O
latest	O
Nokia	O
(	O
)	O
,	O
latest	O
Samsung	B-Application
,	O
Jolla	B-Operating_System
,	O
Microsoft	O
(	O
including	O
Surface	B-Device
,	O
and	O
Xbox	O
One	O
controller	O
)	O
,	O
Sony	O
Playstation	O
4	O
(	O
DualShock	O
4	O
)	O
,	O
Google	O
Pixel	O
4a	O
,	O
Librem	B-Application
5	I-Application
CTIA-style	O
AV	O
Left	O
audio	O
Right	O
audio	O
Ground	O
CVBS	O
video	O
Apple	B-Device
iPod	I-Device
(	O
up	O
to	O
6th	O
generation	O
)	O
,	O
Raspberry	B-Operating_System
Pi	I-Operating_System
(	O
2014	O
onwards	O
)	O
,	O
Xbox	O
360	O
E	O
,	O
Zune	B-Library
(	O
defunct	O
)	O
,	O
some	O
older	O
mobile	O
phones	O
(	O
including	O
Nokia	B-Application
N93	I-Application
,	O
Nokia	B-Language
N95	I-Language
,	O
Samsung	B-Application
Galaxy	I-Application
S	I-Application
GT-I9000	B-Application
,	O
T-Mobile	O
Sidekick	O
4G	O
)	O
OMTP	O
Left	O
audio	O
Right	O
audio	O
Microphone	B-Application
Ground	O
Old	O
Nokia	O
and	O
also	O
Lumia	B-Device
starting	O
from	O
the	O
2nd	O
generation	O
)	O
,	O
old	O
Samsung	B-Application
(	O
2012	O
Chromebooks	B-Operating_System
)	O
,	O
some	O
old	O
Sony	O
Ericsson	O
smartphones	B-Application
(	O
2010	O
and	O
2011	O
Xperias	O
)	O
,	O
Sony	O
(	O
PlayStation	B-Device
Vita	I-Device
)	O
,	O
OnePlus	B-Application
One	I-Application
.	O
</s>
<s>
OMTP-style	O
radios	O
Speaker	O
Clone	O
Microphone	B-Application
/	O
PTT	O
Ground	O
Yaesu	O
FT-60R	O
amateur	O
radio	O
hand-held	O
.	O
</s>
<s>
On	O
some	O
early	O
Sony	O
camcorders	O
,	O
this	O
socket	O
doubled	O
up	O
as	O
a	O
headphone	B-Device
socket	O
.	O
</s>
<s>
When	O
a	O
headphone	B-Device
plug	O
was	O
inserted	O
,	O
ring	O
2	O
was	O
shorted	O
to	O
the	O
sleeve	O
contact	O
and	O
the	O
camcorder	O
output	O
the	O
right	O
audio	O
on	O
ring	O
1.Sony	O
and	O
Panasonic	O
camcorder	O
service	O
manuals	O
Video/audio	O
2	O
CVBS	O
video	O
Left	O
audio	O
Right	O
audio	O
Ground	O
Unknown	O
camcorders	O
,	O
portable	O
VCD	O
and	O
DVD	O
players	O
,	O
Western	O
Digital	O
TV	O
live	O
!,	O
some	O
newer	O
LG	O
TVs	O
.	O
</s>
<s>
The	O
4-pole	O
3.5mm	O
connector	O
is	O
defined	O
by	O
the	O
Japanese	O
standard	O
JEITA/EIAJ	O
RC-5325A	O
,	O
"	O
4-Pole	O
miniature	O
concentric	O
plugs	B-Protocol
and	O
jacks	O
"	O
,	O
originally	O
published	O
in	O
1993	O
.	O
</s>
<s>
3-pole	O
3.5mm	O
TRS	B-Device
connectors	I-Device
are	O
defined	O
in	O
JIS	O
C	O
6560	O
.	O
</s>
<s>
The	O
USB	O
Type-C	O
Cable	O
and	O
Connector	O
Specification	O
specifies	O
a	O
mapping	O
from	O
a	O
USB-C	O
jack	O
to	O
a	O
4-pole	O
TRRS	O
jack	O
,	O
for	O
the	O
use	O
of	O
headsets	B-Device
,	O
and	O
supports	O
both	O
CTIA	O
and	O
OMTP	O
(	O
YD/T	O
1885	O
–	O
2009	O
)	O
modes	O
.	O
</s>
<s>
The	O
last	O
two	O
conductors	O
may	O
then	O
be	O
switches	O
to	O
allow	O
a	O
device	O
made	O
to	O
one	O
standard	O
to	O
be	O
used	O
with	O
a	O
headset	B-Device
made	O
to	O
the	O
other	O
.	O
</s>
<s>
Compared	O
to	O
the	O
TRRS	O
standard	O
,	O
TRRRS	O
provides	O
one	O
extra	O
conductor	O
that	O
can	O
be	O
used	O
for	O
connecting	O
a	O
second	O
microphone	B-Application
or	O
providing	O
power	O
to	O
or	O
from	O
the	O
audio	O
accessory	O
.	O
</s>
<s>
P.382	O
requires	O
compliant	O
sockets	O
and	O
plugs	B-Protocol
to	O
be	O
backward	O
compatible	O
with	O
legacy	O
TRRS	O
and	O
TRS	B-Device
connectors	I-Device
.	O
</s>
<s>
TRRRS	O
connectors	O
enable	O
the	O
following	O
audio	O
applications	O
:	O
active	O
noise	O
canceling	O
,	O
binaural	O
recording	O
and	O
others	O
,	O
where	O
dual	O
analog	O
microphone	B-Application
lines	O
can	O
be	O
directly	O
connected	O
to	O
a	O
host	O
device	O
.	O
</s>
<s>
It	O
was	O
commonly	O
found	O
on	O
Sony	O
phones	O
starting	O
with	O
the	O
Xperia	O
Z1-XZ1	O
and	O
Xperia	B-Application
1	I-Application
II	I-Application
.	O
</s>
<s>
Another	O
TRRRS	O
standard	O
for	O
4.4mm	O
connectors	O
following	O
JEITA	O
RC-8141C	O
was	O
introduced	O
in	O
2015	O
and	O
is	O
used	O
for	O
balanced	B-Protocol
audio	I-Protocol
connections	O
,	O
in	O
particular	O
for	O
headphone	B-Device
cables	O
.	O
</s>
<s>
It	O
is	O
used	O
by	O
some	O
Sony	O
products	O
like	O
the	O
M1Z	O
Walkman	O
of	O
their	O
Signature	O
series	O
and	O
by	O
some	O
Sennheiser	O
products	O
like	O
the	O
HD	O
820	O
headphone	B-Device
or	O
the	O
HDC	O
820	O
DAC	O
headphone	B-Device
amplifier	O
.	O
</s>
<s>
The	O
more	O
recent	O
pattern	O
of	O
one	O
NC	O
contact	O
for	O
each	O
signal	O
path	O
,	O
internally	O
attached	O
to	O
the	O
connector	O
contact	O
,	O
stems	O
from	O
their	O
use	O
as	O
headphone	B-Device
jacks	I-Device
.	O
</s>
<s>
In	O
many	O
amplifiers	O
and	O
equipment	O
containing	O
them	O
,	O
such	O
as	O
electronic	O
organs	O
,	O
a	O
headphone	B-Device
jack	I-Device
is	O
provided	O
that	O
disconnects	O
the	O
loudspeakers	O
when	O
in	O
use	O
.	O
</s>
<s>
In	O
other	O
equipment	O
,	O
a	O
dummy	O
load	O
is	O
provided	O
when	O
the	O
headphones	B-Device
are	O
not	O
connected	O
.	O
</s>
<s>
One	O
is	O
to	O
interrupt	O
a	O
signal	O
path	O
in	O
a	O
mixing	O
console	O
to	O
insert	B-Protocol
an	O
effects	O
processor	O
.	O
</s>
<s>
This	O
is	O
accomplished	O
by	O
using	O
one	O
NC	O
contact	O
of	O
a	O
stereo	B-Device
jack	I-Device
to	O
connect	O
the	O
tip	O
and	O
ring	O
together	O
to	O
affect	O
a	O
bypass	O
when	O
no	O
plug	O
is	O
inserted	O
.	O
</s>
<s>
A	O
similar	O
arrangement	O
is	O
used	O
in	O
patch	B-Protocol
panels	I-Protocol
for	O
normalization	O
(	O
see	O
)	O
.	O
</s>
<s>
A	O
standard	O
stereo	B-Device
jack	I-Device
is	O
used	O
on	O
most	O
battery-powered	O
guitar	O
effects	O
pedals	O
to	O
eliminate	O
the	O
need	O
for	O
a	O
separate	O
power	O
switch	O
.	O
</s>
<s>
When	O
the	O
user	O
plugs	B-Protocol
in	O
a	O
two-conductor	O
(	O
mono	O
)	O
guitar	O
or	O
microphone	B-Application
lead	O
,	O
the	O
resulting	O
short	B-Application
circuit	I-Application
between	O
sleeve	O
and	O
ring	O
connects	O
an	O
internal	O
battery	O
to	O
the	O
unit	O
's	O
circuitry	O
,	O
ensuring	O
that	O
it	O
powers	O
up	O
or	O
down	O
automatically	O
whenever	O
a	O
signal	O
lead	O
is	O
inserted	O
or	O
removed	O
.	O
</s>
<s>
POM	O
)	O
into	O
a	O
single	O
piece	O
in	O
such	O
a	O
way	O
that	O
pins	O
do	O
n't	O
short	B-Application
circuit	I-Application
.	O
</s>
<s>
When	O
a	O
phone	B-Device
connector	I-Device
is	O
used	O
to	O
make	O
a	O
balanced	B-Protocol
connection	O
,	O
the	O
two	O
active	O
conductors	O
are	O
both	O
used	O
for	O
a	O
monaural	O
signal	O
.	O
</s>
<s>
Another	O
advantage	O
offered	O
by	O
TRS	B-Device
phone	I-Device
connectors	I-Device
used	O
for	O
balanced	B-Protocol
microphone	B-Application
inputs	O
is	O
that	O
a	O
standard	O
unbalanced	O
signal	O
lead	O
using	O
a	O
TS	O
phone	O
jack	O
can	O
simply	O
be	O
plugged	O
into	O
such	O
an	O
input	O
.	O
</s>
<s>
A	O
disadvantage	O
of	O
using	O
phone	B-Device
connectors	I-Device
for	O
balanced	B-Protocol
audio	I-Protocol
connections	O
is	O
that	O
the	O
ground	O
mates	O
last	O
and	O
the	O
socket	O
grounds	O
the	O
plug	O
tip	O
and	O
ring	O
when	O
inserting	O
or	O
disconnecting	O
the	O
plug	O
.	O
</s>
<s>
This	O
problem	O
does	O
not	O
occur	O
when	O
using	O
the	O
'	O
gauge	O
B	O
 '	O
(	O
BPO	O
)	O
phone	B-Device
connector	I-Device
(	O
PO	O
316	O
)	O
which	O
although	O
it	O
is	O
of	O
0.25in	O
(	O
6.35mm	O
)	O
diameter	O
has	O
a	O
smaller	O
tip	O
and	O
a	O
recessed	O
ring	O
so	O
that	O
the	O
ground	O
contact	O
of	O
the	O
socket	O
never	O
touches	O
the	O
tip	O
or	O
ring	O
of	O
the	O
plug	O
.	O
</s>
<s>
This	O
type	O
was	O
designed	O
for	O
balanced	B-Protocol
audio	I-Protocol
use	O
,	O
being	O
the	O
original	O
telephone	O
'	O
switchboard	O
 '	O
connector	O
and	O
is	O
still	O
common	O
in	O
broadcast	O
,	O
telecommunications	O
and	O
many	O
professional	O
audio	O
applications	O
where	O
it	O
is	O
vital	O
that	O
permanent	O
circuits	O
being	O
monitored	O
(	O
bridged	O
)	O
are	O
not	O
interrupted	O
by	O
the	O
insertion	O
or	O
removal	O
of	O
connectors	O
.	O
</s>
<s>
This	O
same	O
tapered	O
shape	O
used	O
in	O
the	O
'	O
gauge	O
B	O
 '	O
(	O
BPO	O
)	O
plug	O
can	O
be	O
seen	O
also	O
in	O
aviation	O
and	O
military	O
applications	O
on	O
various	O
diameters	O
of	O
jack	B-Protocol
connector	I-Protocol
including	O
the	O
PJ-068	O
and	O
'	O
bantam	O
 '	O
plugs	B-Protocol
.	O
</s>
<s>
Phone	B-Device
connectors	I-Device
with	O
three	O
conductors	O
are	O
also	O
commonly	O
used	O
as	O
unbalanced	O
audio	O
patch	O
points	O
(	O
or	O
insert	B-Protocol
points	I-Protocol
,	O
or	O
simply	O
inserts	B-Protocol
)	O
,	O
with	O
the	O
output	O
on	O
many	O
mixers	O
found	O
on	O
the	O
tip	O
(	O
left	O
channel	O
)	O
and	O
the	O
input	O
on	O
the	O
ring	O
(	O
right	O
channel	O
)	O
.	O
</s>
<s>
Other	O
mixers	O
have	O
unbalanced	O
insert	B-Protocol
points	I-Protocol
with	O
"	O
ring	O
send	O
,	O
tip	O
return	O
"	O
.	O
</s>
<s>
In	O
the	O
same	O
fashion	O
,	O
use	O
of	O
a	O
"	O
tip	O
return	O
"	O
insert	B-Protocol
style	O
allows	O
a	O
mono	O
phone	O
plug	O
to	O
bring	O
an	O
unbalanced	O
signal	O
directly	O
into	O
the	O
circuit	O
,	O
though	O
in	O
this	O
case	O
the	O
output	O
must	O
be	O
robust	O
enough	O
to	O
withstand	O
being	O
grounded	O
.	O
</s>
<s>
Combining	O
send	O
and	O
return	O
functions	O
via	O
single	O
in	O
TRS	B-Device
connectors	I-Device
in	O
this	O
way	O
is	O
seen	O
in	O
very	O
many	O
professional	O
and	O
semi-professional	O
audio	O
mixing	O
desks	O
,	O
because	O
it	O
halves	O
the	O
space	O
needed	O
for	O
insert	B-Protocol
jack	B-Protocol
fields	I-Protocol
which	O
would	O
otherwise	O
need	O
two	O
jacks	O
,	O
one	O
for	O
send	O
and	O
one	O
for	O
return	O
.	O
</s>
<s>
In	O
some	O
three-conductor	O
TRS	O
phone	O
inserts	B-Protocol
,	O
the	O
concept	O
is	O
extended	O
by	O
using	O
specially	O
designed	O
phone	O
jacks	O
that	O
will	O
accept	O
a	O
mono	O
phone	O
plug	O
partly	O
inserted	O
to	O
the	O
first	O
click	O
and	O
will	O
then	O
connect	O
the	O
tip	O
to	O
the	O
signal	O
path	O
without	O
breaking	O
it	O
.	O
</s>
<s>
Most	O
standard	O
phone	B-Device
connectors	I-Device
can	O
also	O
be	O
used	O
in	O
this	O
way	O
with	O
varying	O
success	O
,	O
but	O
neither	O
the	O
switch	O
contact	O
nor	O
the	O
tip	O
contact	O
can	O
be	O
relied	O
upon	O
unless	O
the	O
internal	O
contacts	O
have	O
been	O
designed	O
with	O
extra	O
strength	O
for	O
holding	O
the	O
plug	O
tip	O
in	O
place	O
.	O
</s>
<s>
For	O
maximum	O
reliability	O
,	O
any	O
usage	O
involving	O
first	O
click	O
or	O
half-click	O
positions	O
will	O
instead	O
rewire	O
the	O
plug	O
to	O
short	O
tip	O
and	O
ring	O
together	O
and	O
then	O
insert	B-Protocol
this	O
modified	O
plug	O
all	O
the	O
way	O
into	O
the	O
jack	O
.	O
</s>
<s>
The	O
TRS	O
tip	O
return	O
,	O
ring	O
send	O
unbalanced	O
insert	B-Protocol
configuration	O
is	O
mostly	O
found	O
on	O
older	O
mixers	O
.	O
</s>
<s>
This	O
allowed	O
for	O
the	O
insert	B-Protocol
jack	O
to	O
serve	O
as	O
a	O
standard-wired	O
mono	O
line	O
input	O
that	O
would	O
bypass	O
the	O
mic	O
preamp	O
.	O
</s>
<s>
However	O
tip	O
send	O
has	O
become	O
the	O
generally	O
accepted	O
standard	O
for	O
mixer	O
inserts	B-Protocol
since	O
the	O
early-to-mid	O
1990s	O
.	O
</s>
<s>
In	O
some	O
very	O
compact	O
equipment	O
,	O
3.5mm	O
TRS	B-Device
phone	I-Device
connectors	I-Device
are	O
used	O
as	O
patch	O
points	O
.	O
</s>
<s>
Some	O
sound	O
recording	O
devices	O
use	O
a	O
three-conductor	O
phone	B-Device
connector	I-Device
as	O
a	O
mono	O
microphone	B-Application
input	O
,	O
using	O
the	O
tip	O
as	O
the	O
signal	O
path	O
and	O
the	O
ring	O
to	O
connect	O
a	O
standby	O
switch	O
on	O
the	O
microphone	B-Application
.	O
</s>
<s>
Depending	O
upon	O
the	O
surface	B-Device
material	O
of	O
the	O
connectors	O
,	O
tarnished	O
ones	O
can	O
be	O
cleaned	O
with	O
a	O
burnishing	O
agent	O
(	O
for	O
solid	O
brass	O
contacts	O
typical	O
)	O
or	O
contact	O
cleaner	O
(	O
for	O
plated	O
contacts	O
)	O
.	O
</s>
