<s>
Powered	B-Device
speakers	I-Device
,	O
also	O
known	O
as	O
self-powered	B-Device
speakers	I-Device
and	O
active	B-Device
speakers	I-Device
,	O
are	O
loudspeakers	O
that	O
have	O
built-in	O
amplifiers	O
.	O
</s>
<s>
Powered	B-Device
speakers	I-Device
are	O
used	O
in	O
a	O
range	O
of	O
settings	O
,	O
including	O
in	O
sound	O
reinforcement	O
systems	O
(	O
used	O
at	O
live	O
music	O
concerts	O
)	O
,	O
both	O
for	O
the	O
main	O
speakers	O
facing	O
the	O
audience	O
and	O
the	O
monitor	B-Device
speakers	I-Device
facing	O
the	O
performers	O
;	O
by	O
DJs	O
performing	O
at	O
dance	O
events	O
and	O
raves	O
;	O
in	O
private	O
homes	O
as	O
part	O
of	O
hi-fi	O
or	O
home	O
cinema	O
audio	O
systems	O
and	O
as	O
computer	B-Device
speakers	I-Device
.	O
</s>
<s>
Some	O
active	B-Device
speakers	I-Device
designed	O
for	O
sound	O
reinforcement	O
system	O
use	O
have	O
an	O
onboard	O
mixing	O
console	O
and	O
microphone	B-Algorithm
preamplifier	I-Algorithm
,	O
which	O
enables	O
microphones	O
to	O
be	O
connected	O
directly	O
to	O
the	O
speaker	O
.	O
</s>
<s>
Active	B-Device
speakers	I-Device
have	O
several	O
advantages	O
,	O
the	O
most	O
obvious	O
being	O
their	O
compactness	O
and	O
simplicity	O
.	O
</s>
<s>
Additionally	O
the	O
amplifier(s )	O
can	O
be	O
designed	O
to	O
closely	O
match	O
the	O
optimal	O
requirements	O
of	O
the	O
speaker	O
it	O
will	O
power	O
;	O
and	O
the	O
speaker	O
designer	O
is	O
not	O
required	O
to	O
include	O
a	O
passive	O
crossover	B-Algorithm
,	O
decreasing	O
production	O
cost	O
and	O
possibly	O
sound	O
quality	O
.	O
</s>
<s>
Disadvantages	O
include	O
heavier	O
loudspeaker	B-Device
enclosures	I-Device
;	O
reduced	O
reliability	O
due	O
to	O
active	O
electronic	O
components	O
within	O
;	O
and	O
the	O
need	O
to	O
supply	O
both	O
the	O
audio	O
signal	O
and	O
power	O
to	O
every	O
unit	O
separately	O
,	O
typically	O
requiring	O
two	O
cables	O
to	O
be	O
run	O
to	O
each	O
speaker	O
(	O
as	O
opposed	O
to	O
the	O
single	O
cable	O
required	O
with	O
passive	O
speakers	O
and	O
an	O
external	O
amplifier	O
)	O
.	O
</s>
<s>
Powered	B-Device
speakers	I-Device
are	O
available	O
with	O
passive	O
or	O
active	B-Algorithm
crossovers	I-Algorithm
built	O
into	O
them	O
.	O
</s>
<s>
Since	O
the	O
early	O
2000s	O
,	O
powered	B-Device
speakers	I-Device
with	O
active	B-Algorithm
crossovers	I-Algorithm
and	O
other	O
DSP	O
have	O
become	O
common	O
in	O
sound	O
reinforcement	O
applications	O
and	O
in	O
studio	B-Device
monitors	I-Device
.	O
</s>
<s>
Home	O
theater	O
and	O
add-on	O
domestic/automotive	O
subwoofers	B-Application
have	O
used	O
active	O
powered	B-Device
speaker	I-Device
technology	O
since	O
the	O
late	O
1980s	O
.	O
</s>
<s>
In	O
a	O
passive	O
loudspeaker	O
system	O
the	O
low-level	O
audio	O
signal	O
is	O
first	O
amplified	O
by	O
an	O
external	O
power	O
amplifier	O
before	O
being	O
sent	O
to	O
the	O
loudspeaker	O
where	O
the	O
signal	O
is	O
split	O
by	O
a	O
passive	O
crossover	B-Algorithm
into	O
the	O
appropriate	O
frequency	O
ranges	O
before	O
being	O
sent	O
to	O
the	O
individual	O
drivers	O
.	O
</s>
<s>
A	O
powered	B-Device
loudspeaker	I-Device
works	O
the	O
same	O
way	O
as	O
a	O
passive	O
speaker	O
,	O
but	O
the	O
power	O
amplifier	O
is	O
built	O
into	O
the	O
loudspeaker	B-Device
enclosure	I-Device
.	O
</s>
<s>
In	O
a	O
fully	O
active	B-Device
loudspeaker	I-Device
system	O
each	O
driver	O
has	O
its	O
own	O
dedicated	O
power	O
amplifier	O
.	O
</s>
<s>
The	O
low-level	O
audio	O
signal	O
is	O
first	O
sent	O
through	O
an	O
active	B-Algorithm
crossover	I-Algorithm
to	O
split	O
the	O
audio	O
signal	O
into	O
the	O
appropriate	O
frequency	O
ranges	O
before	O
being	O
sent	O
to	O
the	O
power	O
amplifiers	O
and	O
then	O
on	O
to	O
the	O
drivers	O
.	O
</s>
<s>
This	O
design	O
is	O
commonly	O
seen	O
in	O
studio	B-Device
monitors	I-Device
and	O
professional	O
concert	O
audio	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
an	O
active	O
two-way	B-Algorithm
crossover	I-Algorithm
splits	O
the	O
audio	O
signal	O
,	O
usually	O
into	O
low	O
frequencies	O
and	O
mid-high	O
frequencies	O
.	O
</s>
<s>
The	O
low-frequency	O
driver	O
is	O
driven	O
by	O
its	O
own	O
amplifier	O
channel	O
while	O
the	O
mid	O
-	O
and	O
high-frequency	O
drivers	O
share	O
an	O
amplifier	O
channel	O
,	O
the	O
output	O
of	O
which	O
is	O
split	O
by	O
a	O
passive	O
two-way	B-Algorithm
crossover	I-Algorithm
.	O
</s>
<s>
The	O
term	O
"	O
active	B-Device
speakers	I-Device
"	O
can	O
also	O
refer	O
to	O
an	O
integrated	O
"	O
active	O
system	O
"	O
in	O
which	O
passive	O
loudspeakers	O
are	O
mated	O
to	O
an	O
external	O
system	O
of	O
multiple	O
amplifiers	O
fed	O
by	O
an	O
active	B-Algorithm
crossover	I-Algorithm
.	O
</s>
<s>
These	O
active	B-Device
loudspeaker	I-Device
systems	O
may	O
be	O
built	O
for	O
professional	O
concert	O
touring	O
such	O
as	O
the	O
pioneering	O
JM-3	O
system	O
designed	O
in	O
1971	O
by	O
Harry	O
McCune	O
Sound	O
Service	O
,	O
or	O
they	O
may	O
be	O
built	O
for	O
high-end	O
home	O
use	O
such	O
as	O
various	O
systems	O
from	O
Naim	O
Audio	O
and	O
Linn	O
Products	O
.	O
</s>
<s>
Some	O
of	O
the	O
first	O
powered	B-Device
loudspeakers	I-Device
were	O
JBL	O
monitor	B-Device
speakers	I-Device
.	O
</s>
<s>
With	O
the	O
addition	O
of	O
the	O
SE401	O
Stereo	O
Energizer	O
,	O
introduced	O
in	O
1964	O
,	O
any	O
pair	O
of	O
monitor	B-Device
speakers	I-Device
could	O
be	O
converted	O
to	O
self-powered	O
operation	O
with	O
the	O
second	O
speaker	O
powered	O
by	O
the	O
first	O
.	O
</s>
<s>
The	O
first	O
studio	B-Device
monitor	I-Device
with	O
an	O
active	B-Algorithm
crossover	I-Algorithm
was	O
the	O
OY	O
invented	O
1967	O
by	O
Klein-Hummel	O
.	O
</s>
<s>
An	O
early	O
example	O
of	O
a	O
bi-amplified	O
powered	O
studio	B-Device
monitor	I-Device
is	O
the	O
Altec	O
9846B	O
,	O
introduced	O
in	O
1971	O
,	O
which	O
combined	O
the	O
passive	O
9846-8A	O
speaker	O
with	O
the	O
new	O
771B	O
Bi-amplifier	O
with	O
60	O
watts	O
for	O
the	O
woofer	B-Device
and	O
30	O
watts	O
for	O
the	O
high	O
frequency	O
compression	B-Device
driver	I-Device
.	O
</s>
<s>
In	O
the	O
late	O
1970s	O
,	O
Paramount	O
Pictures	O
contracted	O
with	O
AB	O
Systems	O
to	O
design	O
a	O
powered	B-Device
speaker	I-Device
system	O
.	O
</s>
<s>
It	O
used	O
active	O
electronics	O
mounted	O
outside	O
of	O
the	O
loudspeaker	B-Device
enclosure	I-Device
,	O
including	O
Meyer	O
's	O
integrated	O
active	B-Algorithm
crossover	I-Algorithm
with	O
feedback	O
comparator	O
circuits	O
determining	O
the	O
level	O
of	O
limiting	O
,	O
often	O
connected	O
to	O
third-party	O
customer-specified	O
amplifiers	O
.	O
</s>
<s>
In	O
1990	O
,	O
Meyer	O
produced	O
its	O
first	O
powered	B-Device
speaker	I-Device
:	O
the	O
HD-1	O
,	O
a	O
2-way	O
studio	B-Device
monitor	I-Device
with	O
all	O
internal	O
electronics	O
.	O
</s>
<s>
Meyer	O
said	O
he	O
"	O
hired	O
an	O
ad	O
agency	O
to	O
research	O
how	O
people	O
felt	O
about	O
powered	B-Device
speakers	I-Device
for	O
sound	O
reinforcement	O
,	O
and	O
they	O
came	O
back	O
after	O
a	O
survey	O
and	O
said	O
that	O
nobody	O
wanted	O
them.	O
"	O
</s>
<s>
Nevertheless	O
,	O
Meyer	O
kept	O
to	O
his	O
decision	O
and	O
produced	O
the	O
MSL-4	O
in	O
1994	O
,	O
the	O
first	O
powered	B-Device
loudspeaker	I-Device
intended	O
for	O
concert	O
touring	O
.	O
</s>
<s>
The	O
main	O
benefit	O
of	O
active	O
versus	O
passive	O
speakers	O
is	O
in	O
the	O
higher	O
fidelity	O
associated	O
with	O
active	B-Algorithm
crossovers	I-Algorithm
and	O
multiple	O
amplifiers	O
,	O
including	O
less	O
IMD	O
,	O
higher	O
dynamic	O
range	O
and	O
greater	O
output	O
power	O
.	O
</s>
<s>
The	O
amplifiers	O
within	O
the	O
loudspeaker	B-Device
enclosure	I-Device
may	O
be	O
ideally	O
matched	O
to	O
the	O
individual	O
drivers	O
,	O
eliminating	O
the	O
need	O
for	O
each	O
amplifier	O
channel	O
to	O
operate	O
in	O
the	O
entire	O
audio	O
bandpass	O
.	O
</s>
<s>
More	O
specifically	O
,	O
active	B-Device
speakers	I-Device
have	O
very	O
short	O
speaker	B-Device
cables	I-Device
inside	O
the	O
enclosure	O
,	O
so	O
very	O
little	O
voltage	O
and	O
control	O
is	O
lost	O
in	O
long	O
speaker	B-Device
cables	I-Device
with	O
higher	O
resistance	O
.	O
</s>
<s>
An	O
active	B-Device
speaker	I-Device
often	O
incorporates	O
equalization	O
tailored	O
to	O
each	O
driver	O
's	O
response	O
in	O
the	O
enclosure	O
.	O
</s>
<s>
Passive	O
speakers	O
need	O
only	O
one	O
speaker	B-Device
cable	I-Device
but	O
active	B-Device
speakers	I-Device
need	O
two	O
cables	O
:	O
an	O
audio	O
signal	O
cable	O
and	O
an	O
AC	O
power	O
cable	O
.	O
</s>
<s>
For	O
multiple-enclosure	O
high-power	O
concert	O
systems	O
,	O
the	O
AC	O
cabling	O
is	O
often	O
smaller	O
in	O
diameter	O
than	O
the	O
equivalent	O
speaker	B-Device
cable	I-Device
bundles	O
,	O
so	O
less	O
copper	O
is	O
used	O
.	O
</s>
<s>
Some	O
powered	B-Device
speaker	I-Device
manufacturers	O
are	O
now	O
incorporating	O
UHF	O
or	O
more	O
frequently	O
Wi-Fi	O
wireless	O
receivers	O
so	O
the	O
speaker	O
requires	O
only	O
an	O
AC	O
power	O
cable	O
.	O
</s>
<s>
A	O
powered	B-Device
speaker	I-Device
usually	O
weighs	O
more	O
than	O
an	O
equivalent	O
passive	O
speaker	O
because	O
the	O
internal	O
amplifier	O
circuitry	O
usually	O
outweighs	O
a	O
speaker-level	O
passive	O
crossover	B-Algorithm
.	O
</s>
<s>
A	O
loudspeaker	O
associated	O
with	O
an	O
integrated	O
active	O
system	O
is	O
even	O
lighter	O
because	O
it	O
has	O
no	O
internal	O
crossover	B-Algorithm
.	O
</s>
<s>
However	O
,	O
active	B-Device
speakers	I-Device
using	O
lightweight	O
Class-D	O
amplifiers	O
have	O
narrowed	O
the	O
difference	O
.	O
</s>
<s>
Trucking	O
for	O
a	O
sound	O
system	O
involves	O
transporting	O
all	O
of	O
the	O
various	O
components	O
including	O
amplifier	O
racks	O
,	O
speaker	O
cabling	O
and	O
loudspeaker	B-Device
enclosures	I-Device
.	O
</s>
<s>
Overall	O
shipping	O
weight	O
for	O
an	O
active	B-Device
loudspeaker	I-Device
system	O
may	O
be	O
less	O
than	O
for	O
a	O
passive	O
system	O
because	O
heavy	O
passive	O
speaker	B-Device
cable	I-Device
bundles	O
are	O
replaced	O
by	O
lighter	O
AC	O
cables	O
and	O
small	O
diameter	O
signal	O
cables	O
.	O
</s>
<s>
The	O
expense	O
of	O
a	O
large	O
concert	O
active	B-Device
speaker	I-Device
system	O
is	O
less	O
than	O
the	O
expense	O
of	O
an	O
equivalent	O
passive	O
system	O
.	O
</s>
<s>
The	O
passive	O
system	O
,	O
or	O
integrated	O
active	O
system	O
with	O
external	O
electronics	O
,	O
requires	O
separate	O
components	O
such	O
as	O
crossovers	B-Algorithm
,	O
equalizers	O
,	O
limiters	O
and	O
amplifiers	O
,	O
all	O
mounted	O
in	O
rolling	O
racks	O
.	O
</s>
<s>
Cabling	O
for	O
passive	O
concert	O
systems	O
is	O
heavy	O
,	O
large-diameter	O
speaker	B-Device
cable	I-Device
,	O
more	O
expensive	O
than	O
smaller	O
diameter	O
AC	O
power	O
cables	O
and	O
much	O
smaller	O
audio	O
signal	O
cables	O
.	O
</s>
<s>
For	O
high-end	O
home	O
use	O
,	O
active	B-Device
speakers	I-Device
usually	O
cost	O
more	O
than	O
passive	O
speakers	O
because	O
of	O
the	O
additional	O
amplifier	O
channels	O
required	O
.	O
</s>
<s>
In	O
professional	O
audio	O
and	O
some	O
home	O
cinema	O
and	O
hi-fi	O
applications	O
,	O
the	O
active	B-Device
speaker	I-Device
may	O
be	O
easier	O
to	O
use	O
because	O
it	O
eliminates	O
the	O
complexity	O
of	O
properly	O
setting	O
crossover	B-Algorithm
frequencies	I-Algorithm
,	O
equalizer	O
curves	O
and	O
limiter	O
thresholds	O
.	O
</s>
<s>
Cabling	O
is	O
not	O
as	O
simple	O
,	O
however	O
,	O
because	O
active	B-Device
speakers	I-Device
require	O
two	O
cables	O
instead	O
of	O
one	O
(	O
an	O
AC	O
power	O
cable	O
and	O
a	O
cable	O
with	O
the	O
signal	O
,	O
typically	O
an	O
XLR	B-Device
cable	I-Device
)	O
.	O
</s>
<s>
In	O
either	O
case	O
,	O
specialist	O
amplifier	O
designs	O
are	O
needed	O
and	O
so	O
servo	O
speakers	O
are	O
inherently	O
powered	B-Device
speakers	I-Device
.	O
</s>
<s>
Some	O
bass	O
amplifier	O
manufacturers	O
sell	O
powered	B-Device
speakers	I-Device
designed	O
for	O
adding	O
to	O
the	O
stage	O
power	O
of	O
a	O
combo	O
bass	O
amp	O
.	O
</s>
<s>
The	O
user	O
plugs	O
a	O
patch	O
cord	O
or	O
XLR	B-Device
cable	I-Device
from	O
the	O
combo	O
amp	O
into	O
the	O
powered	B-Device
speaker	I-Device
.	O
</s>
