of the AKG
must start this journey by looking at AKG's
A microphone of quite simple design, early
examples were based around the 12AY7
high-mu double triode, together with the large V2148
output matching transformer. This combination
along with the excellent CK12
"Brass" capsule, enabled this design to
work so well.
- For more in depth and detailed information on
the design and construction of the AKG CK12
"Brass" capsule, please see the "AKG's
CK12 Capsule" page.
versions of the C12 were to use the smaller T14/1
output matching transformer. As that also used in
the AKG designed Elam
250 and 251 series microphones. The
"Cross sectional area" of laminations
used in the T14/1, is considerably smaller than
that of those in the V2148 transformer. Therefore,
despite the small value coupling capacitor, just
0.5uF in the C12, the T14/1 would offer less
magnetic/flux "Headroom" than the V2148,
being somewhat prone to saturation at LF. This
could make the microphone sound slightly
"Compressed" at the bottom end, when
used on very loud signal sources.
is worth noting, due to the lack of available
space and physical size, the C24
both use the T14/1 transformer(s), together with a
coupling capacitor of 1uF and 3.2uF respectively,
to a 12AY7 (6072)
valve. Therefore, due to the larger value coupling
capacitors, these microphones are even more prone
to LF saturation than the C12. Of course, this is
all part of a microphone's "Sound
Signature", useful or not, it is down to
- The C28c, with the 7586
"Nuvistor", uses a different transformer
to the T14/1, therefore the associated problems of
the T14/1 transformer are not applicable the this
most things in this world, change is inevitable,
and so it was that the C12
was superceded by the C12A. Rather
then using the 12AY7 (6072A) valve, as in the C12,
the C12A utilized a miniature "Nuvistor" type
valve. The "Selected" low noise Nuvistor,
type 7586, plugging into a socket
on the PCB. This, together with smaller/modern components
mounted on a PCB
enabled the body of the C12A to be very much
smaller then it's predecessor. The C12A was our
first introduction to the famous rectangular box
shape that we have
come to recognize as a kind of
"trademark" from AKG.
AKG C12a also appears under the name of Philips,
as the LBB
9061/00, and Norelco
C12a. "Norelco", being the North American
Electric Company, who where distributors for
the AKG C12a in America.
worked very well, but for some applications i.e.
when working with very high SPL's, the
microphone could be prone to
overload/distortion. This problem was overcome,
with the introduction of the C12B. Whereby the addition of a
"Pad" switch, between the capsule and the
valve (Nuvistor), could attenuate the signal by -20dB. Thus allowing the
recording of far louder sound sources, without
encountering any of the overload problems associated with the C12A. Other
than the pad components i.e. a switch and a
capacitor, the internal PCB
/ capsule of the C12B, are the same as that in the
body of the C12B is slightly larger than the C12A,
being the same shape and size as the C412, which superceded
the C12B. The "Grill" assembly used on
the C12B, was of a molded plastic type of
material, unlike the "Substantial" metal
assembly used on the C12A. Therefore, unlike the
C12A, the wire
mesh forming the grill/screen of the C12B, had to be
"Hard wired" to the earth point of the
microphone electronics to avoid any hum/RF pick-up
problems. This same grill assembly would go on to
be used on the C412 and C414E/C microphones and
was always a "Weak" part of the design.
Either being easily damaged or causing hum/RF pick-up
When AKG introduced
modern semiconductor (FET) designs, the prefix of the
figure 4 was utilised. The first microphone to
carry the new number scheme, being the C412 i.e. a
semiconductor version of the C12B. Still using
the same CK12 capsule as that in the C12, C12A and
The C412, had 2 on board switches. One for polar
pattern selection, the other for attenuation.
There seems to be various "Attenuator/Pad" levels
e.g -10dB &
-20dB, throughout the history of units produced.
However ..... as the attenuator was purely a potential divider
in the output stage of the microphone, there still
were minor problems with distortion, as the FET
amplifier could be still easily be over-driven by
The C412 had only 3 switchable polar patterns i.e.
Omni, cardioid and fig'8. Whereas, the C12, C12A
and C12B had 9 possible polar pattern settings. This was OK for
some users, but many found this a move backwards. The BBC, one of AKG's
customers, found that the C412 was unable to fill
the place of the C12, C12A and C12B, as 3 polar patterns
were insufficient for many applications.
After much back and forth conversation's between
the BBC and AKG, together with other pro-audio users, an up-dated version of the C412
was introduced. Basically the same as the C412,
with an improved attenuator i.e pre-FET amplifier
stage, and more importantly, the addition of a
Hyper-cardioid polar pattern. As this new
microphone had 4 polar
patterns, the last digit of
the older C412, was changed to a 4 i.e C414. Thus
the start of the C414 series of microphones.
was available in 2 versions. Either, the C414E,
with cannon type connector or, the C414C with a
connector to the "Din standard".
Identical in appearance to the C412, the C414
continued to use the AKG "Custom" stand
mount. Indeed, the C414 and the C412, could both
be plugged into the C12A and C12B stand mounts.
Fortunately the wiring arrangement is such, that
no damage can take place to either the microphones
or the power supplies, should the wrong microphone
be inadvertently plugged into the wrong stand
C414 proved be a strong competitor to the Neumann
U77 and U87. The U77, being Neumann's first semiconductor
(FET) version of the U67.
- The U77 was one of
Neumann's earliest microphones with a "Transformer-less" output stage. Mainly
due to the
12volt "T" powering technique used at
that time, and therefore the circuit design
required by that system of powering.
The next version of
the C414, was the C414EB. Much the same as the
C414, with the addition of a 3 position Attenuator
switch (0,-10,-20dB) and 3 position Bass roll-off
switch (Flat, 75, 150Hz). One of the major, long
term, improvements, was that of the connector
type. Since the introduction of the C12A,
including the C12B, C412 and C414, a stand
mount/connector combination had been used for
mounting, and electrical connection, of the microphone. This would
prove to be very unreliable throughout it's life,
so the introduction of a built-in
cannon type connector on the C414EB, was of great benefit
to all users.
the production years of the C414EB, manufacture of
the "original" CK12 capsule ceased and a
modern nylon version (2072-Z-0005) was introduced.
This replacement would never live up to the
standard of the "Famous"
CK12, that had previously
made AKG large capsule microphones so wonderful.
The tonal qualities of the nylon CK12, are just so
different from it's predecessor.
remote control version of the C414EB was produced.
Known as the C414E1. This would be very useful in
"Fixed Rig" situations, as the polar
patterns were remotely adjustable via the S42E1
remote control box. The S42E1, offered 9 polar
patterns and facilities for 2 microphones. The
C414E1 looked identical to the C414EB, without the
polar pattern switch. The housing used, was that
of the C414EB. Hence it still had C414EB stamped
on it, with the addition of the word Remote, where
the polar pattern switch would have been.
The capsule and pre-amplifier, were the same as
that used in the C414EB. However, the polarising
voltages, for both sides/faces of the capsule,
were derived from a DC/DC converter in the phantom
powered S42E1 box.
"Digital Age" was now upon us, and the
need for quieter microphones was very apparent.
Enter the C414EB-P48. Until this time, the
previous C412 & C414 series of microphones,
could be powered from any "Phantom"
power supply, offering +12 to +52 volts. However,
the C414EB-P48, was designed to work purely on
+48v phantom supplies. The polarising voltage for
the capsule, is taken from the +48v supply via
very high value resistors and high voltage tantalum
reservoir capacitors., rather then the previous
way of using a DC/DC converter. The tantalum
capacitors were to be a fault liability in the
new model, the C414B-ULS,
was the next microphone to emerge. The suffix ULS,
denoting that the microphone had a "completely
linear transfer characteristic of all transmission
parameters". Looking just like a black/matt
version of a C414EB, the C414B-ULS offered better
performance figures and reliability, then the
C414EB-P48. The electronics took on a highly
complex design. Utilising no less then 17
transistors, as opposed to the previous 4
transistors in earlier designs. Whether or not this maze
of components could improve the sound quality, would be food for thought. However, we did
see the return of the DC/DC converter for
polarising the capsule.
the iron out of the audio signal i.e. no coupling
transformers, was all the rage at this time. The C414B-TL
(Transformer Less) version of the C414B-ULS was
introduced. Offering less distortion at high SPL's
then the C414B-ULS. Sounding somewhat dryer and
more clinical then it's predecessor.
were to re-create/emulate the sound of the original CK12
capsule, in a new nylon version (2072-Z-0009),
similar to the (2072-Z-0005)
already in production. This new
capsule was to be used in the "Gold Grill"
version of the C414B-TL, to be known as the C414B-TLII.
The electronics being identical, in both the TL
and TLII microphones i.e. Just a different capsule
and cosmetic changes. The only audible
difference, between the TL and TLII, being a
capsule would also be featured in the AKG C12VR (Vintage
Revival), valve microphone. For those who can remember the AKG
"The Tube" (Brown), using the original 2072-Z-0005
nylon type capsule
..... well the C12VR
(Green) is exactly the same microphone, with the
2072-Z-0009 capsule and an additional 3G ohm
resistor. The latter wired in parallel with the
capsule, front to rear diaphragm, coupling
- The AKG "The
Tube" should not to be confused with the AKG "Solid
Tube" valve microphone, which is totally
it is farewell to the old square edged C12A shape
we have known for so long (nearly 50 years), along
with the associated reliability these older models
gained over the years. It is also the demise of
the output coupling/matching transformer, that
added/subtracted something from the sound
obtained. Apparently, it is all about progress
came the "New Look", rounded edged, C414B-XLS,
which will hopefully earn the same positive virtues
of earlier designs. Many new features are found on
this electronically balanced, "Transformer-less",
output design. The
capsule being mounted on a internal elastic
suspension system, rather then the previous fixed
block method. The frame of the microphone,
especially where the cage joins the main body,
looking somewhat sturdier than that of it's predecessors.
All PCB's being held together via their
interconnecting plug/socket system. Logic circuitry is used for
switching of all parameters. With LED display of
chosen settings and overload. All switch settings
are "Lockable" to avoid accidental
changes, or tampering, of the selected settings.
A useful addition, is
the provision of a 5th polar pattern i.e. Soft
Cardioid. Therefore, I wonder why the microphone
was not called the C415B, following the tradition
of the last digit being the amount of fixed polar
patterns available. Who knows ?
is cosmetically and electrically identical to the C414B-XLS, other
than the "Gold Grill" and gold print on
the microphone together with a different capsule. The capsule used in the C414B-XLII
offers the same advantages as that of the capsule
used in the C414B-TLII. A "Usefull" audible
difference, between the XLS and XLII, being a
slight "Presence" boost above 3KHz on
the later model.
latest range of C414 microphones are, cosmetically
and electrically, much like the C414B-XLS and XLII
above. They both offer no less than nine (9) switchable
polar patterns i.e. the addition of the four
intermediate patterns between the five found on
the previous C414B models, together with a few other
improvements over their predecessors.