AKG C12 - Siemens SM204/23

AKG C12 - Siemens SM204/23

The AKG C12 and SM204/23 are pretty much the same microphone.
The SM204/23 was marketed by Siemens Austria / WSW who were the distributors for AKG products within Austria at the time. A large percentage of this model was sold to the Austrian Broadcast Company ("Österreichischer Rundfunk" - watch out for a corresponding engraving on the housing tube. These specimen usually had particularly strict quality control).
The main difference to the C12 is the biasing circuitry for the GE 6072 tube and results in a slight difference in timbre and the way transients are processed. The SM204´s circuit was already used for a forerunner of the C12 the C23 and the same type of biasing is also found in other AKG tube mics used in Austrian broadcast (C28, C24, ect.) so the same type of power supply can be used for these mics.

Just as early C12 mics the SM204/23 was originally equipped with a rather linear sounding CK12 capsule (shallow air chambers). Many of these capsules still had the first generation Styroflex diaphragms that failed after few years. When the broken microphones were sent back for repair the capsules were swapped for the updated CK12 which had higher output (due to larger air chambers). That gave the microphones a better signal to noise ratio and as a side effect a brighter sound. Although not originally intended the slight lift in the upper midrange has proven to be very desirable in many recording applications.
The above photograph shows an early SM204/23 with upgraded capsule.

Most SM204/23 microphones can be visually distinguished by a painted ring beneath the grille for colour coding - usually red or blue. This is not common on the C12 where this ring has a plain gloss nickel finish.
Internationally the Siemens SM204 is by far more rare than the C12 and highly sought after.


The year 2018 marks the 65th anniversary of this groundbreaking Viennese development.
To celebrate it a project was launched to finally remanufacture this fantastic recording microphone in its original excellence without compromise or breaking corners like the commercial replica manufacturers need to do. Of course handcrafted in Vienna, Austria.
These will be available only in extremely limited quantity to very few lucky professionals:
https://www.fotocommunity.de/photo/austrian-c12-reissue-2018-markus-sauschlager/40749228
EDIT 2022: Discontinued. Making this microphone in its original glory proved not to be a working business model (the commercial clone-makers are smarter than me ;) If you want original quality get an original mic.



For infos on the C12´s famous condenser capsule - aka "CK12 brass capsule" - click the following links:
https://www.fotocommunity.de/photo/akg-ck12-ck12-brass-capsule-gene-markus-sauschlager/31169829

https://www.fotocommunity.de/photo/patent-akg-ck12-brass-capsule-markus-sauschlager/39210855












































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