<s>
A	O
valve	B-Algorithm
microphone	I-Algorithm
is	O
a	O
condenser	O
microphone	O
which	O
uses	O
a	O
valve	O
amplifier	O
rather	O
than	O
a	O
transistor	B-Application
circuit	O
.	O
</s>
<s>
The	O
387	O
model	O
,	O
with	O
its	O
0.0017	O
inch	O
thick	O
gold-sputtered	O
diaphragm	B-Device
,	O
was	O
the	O
best	O
of	O
these	O
early	O
designs	O
.	O
</s>
<s>
It	O
was	O
followed	O
by	O
the	O
improved	O
model	O
600	O
in	O
the	O
early	O
1930s	O
,	O
and	O
the	O
double-button	O
became	O
recognised	O
worldwide	O
as	O
a	O
standard	O
in	O
broadcasting	B-Operating_System
.	O
</s>
<s>
In	O
this	O
period	O
valves	O
were	O
also	O
then	O
incorporated	O
internally	O
into	O
microphones	O
and	O
valve	B-Algorithm
microphones	I-Algorithm
were	O
hence	O
commercially	O
available	O
.	O
</s>
<s>
In	O
the	O
late	O
1920s	O
,	O
Dr.	O
Harry	O
F	O
.	O
Olson	O
of	O
RCA	O
began	O
development	O
of	O
the	O
ribbon	B-Algorithm
microphone	I-Algorithm
,	O
eventually	O
using	O
permanent	O
magnets	O
.	O
</s>
<s>
marketed	O
a	O
bi-directional	O
ribbon	B-Algorithm
microphone	I-Algorithm
,	O
the	O
44-A	O
.	O
</s>
<s>
Ribbon	B-Algorithm
microphones	I-Algorithm
are	O
still	O
in	O
demand	O
today	O
and	O
come	O
in	O
many	O
styles	O
.	O
</s>
<s>
In	O
June	O
1948	O
the	O
Neumann	O
model	O
U47	B-Algorithm
was	O
introduced	O
,	O
and	O
distributed	O
by	O
Telefunken	O
.	O
</s>
<s>
The	O
U47	B-Algorithm
was	O
the	O
first	O
condenser	O
microphone	O
switchable	O
between	O
cardioid	O
and	O
omni-directional	O
pick-up	O
patterns	O
.	O
</s>
<s>
In	O
1958	O
Neumann	O
took	O
over	O
the	O
sale	O
of	O
their	O
own	O
mics	O
from	O
Telefunken	O
and	O
made	O
many	O
small	O
changes	O
to	O
the	O
U47	B-Algorithm
design	O
,	O
but	O
this	O
mic	O
perhaps	O
more	O
than	O
any	O
other	O
embodies	O
the	O
valve	O
or	O
tube	O
sound	O
.	O
</s>
<s>
There	O
are	O
many	O
reasons	O
why	O
valve	B-Algorithm
microphones	I-Algorithm
have	O
become	O
so	O
important	O
in	O
today	O
's	O
recording	O
and	O
home	O
studios	O
;	O
partly	O
they	O
are	O
fashionable	O
due	O
to	O
their	O
early	O
use	O
by	O
influential	O
composers	O
and	O
musicians	O
such	O
as	O
the	B-Application
Beatles	I-Application
,	O
Pink	O
Floyd	O
,	O
the	O
Rolling	O
Stones	O
,	O
etc	O
.	O
</s>
<s>
but	O
also	O
because	O
the	O
sound	O
quality	O
they	O
reproduce	O
has	O
pleasing	O
sonic	O
qualities	O
,	O
even	O
though	O
more	O
technically	O
perfect	O
reproduction	O
is	O
possible	O
by	O
transistor	B-Application
microphones	O
which	O
have	O
less	O
self-noise	O
.	O
</s>
