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The AKG C414 LDC Condenser microphones On February 09, 2016

IF YOU HAVE FOUND THIS PAGE THEN YOU MOST LIKELY ARE LOOKING FOR INFORMATION ON THE AKG C414 AND IT’S MANY VARIATIONS OVER 40 YEARS:

The AKG 414 is dual sided LDC solid state multi-pattern microphone. Unlike the U87 multi-pattern microphone which has two electronic variations since it was released in 1968, the 414 has had nearly a dozen incarnations since its first inception as the C414 comb in 1971.

These variations have significantly changed the sound and circuit designs over the last 4 decades garnishing many opposing opinions on its sound.

All versions of the C414 from the “EB” to present day were fitted with a 4   pattern variation switch on the front of the microphone which allowed the polar or directionality of the microphone’s pickup pattern to be switched between OMNI, CARDIOD, SUPER CARDIOD and FIGURE 8.

All version since the C414eb featured a -10db and -20db attenuation switch plus a 75hz and 150z low cut. Also known as a rumble or HP filter. This HP or low cut filter will reduce the proximity effect which is the phenomenon of the low frequencies building up as the source is addressed closer than 30cm from the front of the microphone.

The first changes from the 414 comb to the 414eb were more subtle. Within 5 year of its inception the size was reduced and the more durable XLR 3 pin connector became standard. But for all practical purposes the capsule and circuit remained the same except for an improvement in the bass response by redesigning the output transformer in the 414eb compared to the 414 comb. The C414eb was released in 1976 and I remember buying a matched pair for our studio, Ocean Sound located in Vancouver circa1977 at a price of $400 each CDN.

WHAT ADVANTAGE DID THE 414eb HAVE OVER THE U87 FOR MUSIC RECORDING?:

The 414eb proved invaluable on acoustic instruments and it could be placed very close to the hammers of a grand piano or used as drum overheads because of the extra headroom and dynamics that is provided by the -10/-20db pad switches and the 2 stage emitter/follower circuit.

The emitter follower circuit used in the early 414 microphones increased the headroom of the electronics compared to the venerable U87. This improved transient response of the 414 on percussive sources allowing the 414 to be used over the hammers of a grand piano. This was very useful when the piano and drums were recorded in the same time in the same room. The emitter follower circuit had a much lower output impedance compared to the single FET circuit used in the U87 allowing a transformer with 14db less loss to be be used. This means the first stage of the 414 required 14db less gain to provide the same final output level as the U87.

The 414eb microphones were often favoured for percussion recording and drum overheads. Several examples can be found on-line including Paul Horn and Ralph Dyck’s Jupiter 8 album that this writer recorded in 1980. Track #5 the title track called Jupiter 8 features an original 414eb on all the percussion overdub. This is a good example of an early 414eb on different percussion as the conga, shaker, scraper and wood block was all recorded in one take with the 414 in the centre of the room.

WHAT IS THE DIFFERENCE IN SOUND BETWEEN A U87 vs the 414EB?:

Both the U87 and 414 had an extended top end above 10khz but rather than de-emphasize the high frequency rise with active EQ like the 87 circuit the 414eb had an amplifier circuit that could more easily handle this extended HF response. The U87 was a bit more mid forward having more rise at 3khz while the 414e did not start to rise till and octave later but having a greater rise above 10khz creating an “airy” sound signature.

The c414 offers and alternative for acoustic guitar recording compared to the U87. For example, the difference between a U87 and 414eb on acoustic guitar is a bit like the difference between a Martin D28 and a Gibson J200. The Martin sounds wonderful on a simple folky/blues arrangement but in a pop tune the jangle of the J200 helps the guitar sound cut through a busy mix.

Likewise, the 414 tends to capture more of the pick striking the strings sound while the U87 captures more of the body. The 414 would often be used on BG vocals as it tended to let the vocals cut through the mix even though they were mixed further back in the track. This wasn’t always the case but it gives the reader a closer idea of how the 414 could be used in a recording situation.

WHEN DID THE SOUND OF THE 414 CHANGE MORE SIGNIFICANTLY?:

In the late 70’s the capsule’s construction was dramatically changed to drop the price and time taken to manufacture the very complex CK12 capsule.

Recording professionals including this writer believe that the sound of the original 414e and its class “A” discrete solid state circuit provides a sound signature that is often preferred for music recording and drum miking compared to later variations of the 414.

The sound of the original CK12 seems a bit more open and the use of the teflon pressed capsule seems slightly darker sounding than the original 414eb microphone. Engineer/producer Hugh Padgham preferred the 414eb to record the vocals for Sting’s “Every Breath You Take”.

By 1980, the 414eb-P48 was introduced which optimized the 414 power circuit for 48 volt operation. Earlier versions could be powered from 9-48v by changing a jumper wire inside the microphone. The 414-P48 power circuit re-design increased the signal to noise ratio by 6db to take advantage of modern digital recording techniques with its better noise ratio.

The 414eb-P48 remained in production until 1986 when the C414B-ULS was released. The 414b-ULS circuit reduced the noise floor even further but the this contributed to the microphone becoming even darker sounding compared to the early 414eb with its CK12 capsule. The 414b-ULS had a more “compressed” an less clear sound compared to earlier versions.

However, the 414 remained popular as it was still more affordable than the more expensive U87 which costs nearly 3 times the price of a 414.

In 1993 a capsule with a brighter response was added to the 414 and a transformerless circuit was introduced. This model became the C414 TL-II. It was a brighter, sounding microphone with a better transient response but again fell slightly short of the sound produced by the earlier 414eb versions. It was characterized by some engineers as sounding too bright.

The latest C414 XLS/XLII versions have the brighter teflon capsule. AKG has improved the capsule mount in the new version but the circuit still remains transformerless with surface soldered components making the microphone nearly impossible to repair but much cheaper to manufacture.

The current list price of the C414XLII is $1549 USD but the microphones can can be purchased at a street price around $1000 with shock-mount.

The 414 still remains a multi-pattern solid state LDC microphone which has become a workhorse of the recording business. However, recording engineers still look for alternate versions that more closely represent the more favoured sound of the original 414eb manufactured in the early 70’s.

On the left is the early CK12 capsule which was very time consuming to manufacture having over 50 individual parts. On the right is the Teflon 2072z which has a slightly “darker” response curve.

HERE IS A PICTURE OF AN EARLY C414EB

Here is a picture of the darker ULS which still incorporated an output transformer and components that are soldered through the circuit board.

CAN A MORE ECONOMICAL VERSION OF THE VINTAGE 414EB BE DESIGNED WHICH INCORPORATES THE MUSICAL SOUNDING CLASS “A” TRANSFORMER COUPLED CIRCUIT AND THE “AIRY” CAPSULE RESPONSE OF THE ORIGINAL MICROPHONE?:

 

Designing the Advanced Audio CM414 multi-pattern professional LDC microphone.

The Advanced Audio CM414 features a dual diaphragm edge fed brass capsule with a response within 2db of the original CK12 capsule used in the original 414eb. The Advanced Audio AK12 capsule has the same “airy” lift found in the original 414comb and early 414eb microphones loved by recording engineers.

 

 

CAN A COMPLEX EDGE FED CAPSULE BE MADE TODAY THAT HAS THE “SOUND SIGNATURE” OF THE ORIGINAL CK12 WHILE REMAINING COST EFFECTIVE TO MANUFACTURE?:

Modern CNC “computer controlled milling machines” allow nearly twice as many very accurate holes to be drilled in the capsule’s back-plate negating the need for two resonator disks that have to be accurately hand fitted and aligned under each of the mylar diaphragms of the original CK12 capsule. This gives the Advanced Audio AK12 capsule a response which delivers a very similar sound as the original capsule while allowing its to be manufactured for much less cost than the vintage CK12 capsule.

 

 

 

 

The body of the CM414 is also manufactured via computer control milling machines reducing production costs significantly plus the construction is much more ergonomic and efficient in its construction. It much faster to fit the capsule and circuit board components into the CM414 body. The CM414 also uses more reasonable priced rugged metal toggle switches compared to the custom made switches used in the original 414.

LEARNING FROM THE EXPERIENCE OF USING THE 414EB:

While reviewing the use of the 414eb on sessions over a 20 year period we discovered the -20db pad was never used. So, in the design of the CM414, only a -10db pad was incorporated for use with high SPL sources. It is possible to use the CM414 just a few centimetres above a snare drum with just the -10db pad. This is because of the CM414’s emitter/follower circuit having 14db more headroom than a U87 before its 10db pad is engaged. Also, the more complex 3 position HP filter switch was replaced with a much more economical and sturdy SPST metal toggle switch engaging a roll-off frequency of 10ohz, 1/2 way between the 75hz and 150hz roll-off frequency of the original 414. Also, we discovered that hyper-cardiod pattern was under utilized and the CM414 was designed with just 3-patterns like the U87. This also means a lower cost and more rugged 3 position metal toggle switch could be used to choose the polar pattern.

These design considerations allow for a microphone to be built that accurately captures the sound signature of the vintage 414eb microphone for a price of $379 complete with a HD shock-mount and flight case.

The CM414 has high quality components that are solder through on the circuit board and can be much more easily and economically replaced than modern day surface soldered components. The CM414 also uses high quality and more expensive tantalum capacitors in the audio chain just like the original 414eb and the U87 vintage microphones.

The CM414 has become a popular choice for percussion, grand piano, vocals from professional to project studios alike.

 

1 Comment

Gary Cable On 02/29 at 09:54 AM

Hi Dave,
Hope you are having fun in Baja! When do you return? I have some documents for the minute book.
I was looking at my original 414 and it appears to be an early black B-ULS like the one in your photo. If I read you correctly, it would have to be post-1986 and would have the teflon capsule and is ‘darker’ than the original E. As such, probably not the best sonic match for your 414s?

Something to say?