High Efficiency Speaker Asylum: An example of HOW GOOD speakers where nearly 70 Years ago.... by Thorsten

Hi,

In 1943 the German "Reichsrundfunk Gesellschaft" made the first high fidelity stereophonic magnetic tape recordings.

They used Neumann Kondensor Microphones, Amplifiers with Pentode outputs and no feedback (can you say current drive - congratulations to Mr. Pass for reinventing that particular wheel 70 Years later) and Eckmiller Koaxial Speakers (which actually came out as monitors in the late 1930's, but prewar).

The whole chain was evaluated not just with music and the "Voice of the Fuehrer" (considerable research was put into radio & electroacoustics in Germany in the 1930's to ensure that the "hypnotism" in that horrible austrians voice could be transmitted accuratly), but also with such highly difficult to transmit sounds as the jangeling of keys and the tearing of paper, in direct comparison to the original.

Now any part of the recording/replay chain was exemplary in it's own way and has seen very little, if any fundamental improvements since but lets concentrate on the speaker....

First we observe that the Tweeter and Woofer voicecoils share the same airgap. This is a 2-Way Driver that is truely tiomecoherent.

Secondly, the whole woofer sturcture is actually inherently damped, using both an acoustic flow resistance and a "grease bearing", thus the resonance of the driver is critially damped, inherently without relying on electrical damping.

Thirdly, the crossover is a 2nd order series type.

Fourthly, the impedanc eis flat, +/-15% from 70Hz - 10KHz.

Fifthly, the specifi design featurs of the tweeters 1-Piece dome/voicecoil former construction also place a shortcircuit ring in the drivers magnetic airgap, combined with near "current drive" this should havbe made for very low distortion and compression.

Now, this Driver and associated amplifier where state/edge of the art nearly 70 years ago, have we finally managed to get back to something similar with (say) a Seas Coax Driver and a Pass/Firstwatt F1 Amp?

I leave the call to the genteele reader.

A few pictures to oogle at of a post-war variation on the Driver made in Berlin (probably in the russian occupied Sector) in the late 1940's by Konski & Krueger, this substitutded due to material problems the permanent magnet of the original Eckmiller with a Fieldcoil.

BTW, any information about the wherabouts of "System Eckmiller" Speakers (paiurs please) at at least semi-affordable prices are welcome.....

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Ciao T