Was Stereophonic Recording Invented During World War II?

Given the widely published assumption of the subject at hand, does anyone ever wonder how many audiophiles know that stereo recording was actually introduced during the height of World War II?

By: Ringo Bones

Contrary to popular belief, stereophonic or stereo recording wasn’t introduced or even invented during the mid 1950s during the beginnings of the “Golden Age of Stereo”, but in actuality, during the “dark days of World War II – in Nazi era Germany of all places! Given that – from a historical perspective – war intends to initiate the strongest impetus of progress in scientific and technological developments, the how’s and why’s of the development of stereophonic recording / stereophonic sound in Nazi era Germany seems to elude the interests of tenured historians until a few years after the fall of the Berlin Wall.

The Haus des Rundfunks (Broadcast House) in Berlin, which later became known as Das Berlin Funkhaus, the radio station building of the Reichs-Rundfunk Gessellschaft or RRG when Adolf Hitler got elected as Chancellor of Germany - that was inaugurated back in 1931 was the first ever building in Europe specifically designed for recording and broadcasting. Part of the structure was then devoted to the Grosser Senesaal – a large hall from which symphony orchestra concerts frequently were transmitted live. By 1942, after some years of development by the Reichs-Rundfunk-Gessellschaft (RRG) technicians, the AEG/Magnetophon R22 magnetic tape recorder for recording and broadcasting was pressed into service.

Sound quality wise, the AEG/Magnetophon R22 magnetic tape recorder for recording and broadcasting was an audio engineering tour-de-force during its day because during the height of World War II, the Allies thought the Nazis had successfully developed a very high speed aircraft because live broadcasts of Adolf Hitler speaking in Berlin were followed a short time later by similar broadcasts from Hamburg and Munich. Given the excellent sound fidelity – at the time – of the magnetic tape recorder used by Nazi era broadcasters at the time, the Allies were not aware – until after World War II – that they were hearing magnetic tape recordings of Adolf Hitler’s speeches – one’s at the time totally indistinguishable from live radio broadcasts.

By 1943, one of the Reichs-Rundfunk-Gessellschaft (RRG) technicians by the name of Helmut Krüger, regularly made magnetic tape recordings of symphony orchestra concerts from the Great Hall in the Berlin Broadcast House a then newly upgraded AEG magnetic tape recorder that ran at 30-i.ps. (77-cm/sec.)  in which high frequency premagnetization or a.c. bias, then recently patented by its inventor – Walter Weber, was used – affording far better performance compared to contemporary recording machines. Imagine – back in 1943 – a magnetic tape recorder with a frequency response of 50-Hz to 10,000-Hz with a dynamic range of 60-dB and a harmonic distortion of 1.5%. An audio engineering feat that American broadcasting and recording engineering firms were only able to replicate – let alone exceed – at the start of the 1950s.

The two-channel recording head upgrade to one of the AEG/Magnetophon R22 magnetic tape recorder for recording and broadcasting for the RRG was the very impetus that made Helmut Krüger “experiment” and test out his own ideas on stereophonic sound. Although, the two-channel recording heads were originally intended to reduce harmonic distortion in monophonic taping sessions by recording two channels in push-pull.

Ironically, Krüger’s “unauthorized” experimental pioneering stereophonic audio recordings were – for all intents and purposes – actually bootleg recordings! This became so because during regular monophonic with the orchestras, Krüger ran separate signal cables from his microphones and directed them to a small input console with four potentiometers and thence to his “modified” AEG stereo recorder set up in an isolated room in the Broadcast House.

Believe it or not, Krüger was using a spaced-array mike pickup – where one mike is placed to the left of the conductor, another to the right, and a third in the center – which Krüger fed to the left and right channels of the recorder. The mikes were 2 meters in front of the orchestra and 1 meter above the conductor’s head. This set-up, with slight variations, was used by Bob Fine in his Mercury recordings, by Bert Whyte in his Everest recordings during the Golden Age of Stereo of the 1950s – and even Jack Renner frequently used it until today in his Telarc recordings.

According to surviving records, by the end of World War II, Krüger had made between 200 and 300 stereophonic tape recordings – which were stored in a bunker in the Broadcast House and in several other locations. Sadly, when the Stalin-era Soviet troops occupied Berlin took shelter in the Broadcast House, almost all of the tapes there where either lost or destroyed. Of all the stereo tapes recorded by Krüger, only five of which are known to have survived and it wasn’t until 1993 during the 94^th AES convention which was held in the first time in post-Cold War era Berlin were mere “civilian” audiophiles had the chance to hear the pioneering tapes first hand with their own two ears. Some had even to wait a few months later when Krüger’s pioneering stereo tape recordings were transferred to CD.

After hearing CD transfers - mastered via an early 1990s version of Sony’s Super Bit Mapping technique - of Krüger’s pioneering stereo tape recordings back in 1995. The residual tape hiss is only slightly louder than those of 1950s era stereo analog tape recordings of orchestral concerts form the mid 1950s. But what fascinated me most was their warmth and pristine tone that 1980s era fully digital recordings of Classical Music orchestras still fails to capture – even during the mid 1990s! The very first Classical Music orchestral recordings may have been made in various places during the mid 1950s at the start of the Golden Age of Stereo – but Helmut Krüger truly deserve the credit for pioneering stereophonic tape recording during the dark days of World War II.