Forums / Archive / Thread
Author: Posted by Jeremy Darby
Date: 01/10/1999
Author: Posted by Donald James
Date: 01/10/1999

The 'Neumann' UM57 is really a Gefell (East German) mic with a large M7 capsule and 3 patterns, selectable at the power supply. It was introduced in 1957, and was the first variable pattern mic to be introduced by Gefell.
In many ways its appearance is similar to the UM 92 by Microtech Geffel. It is similar in concept to the M49 and C12A, in that the one diaphragm is connected to earth, the back-plate is connected to the input of the tube, and is at 60volt, and the second diaphragm is varied from 0 - 120volts from the power supply to give you the various patterns. Make sure you have the power supply as the pattern switching is on it, and not on the mic. It uses an EC92 triode for the tube.
Apparently the power supplies were poorly made. Thus, the price is much lower than the Western German mics of the same era.
Donald James Donald James Productions New York, NY. www.voice-overs.net
Donald James's NEUMANN UM57 MICROPHONE comments
Author: Posted by Klaus Heyne
Date: 01/11/1999

I would like to offer a correction, a suggestion and an optinion regarding Donald James's post. A correction: Neither Neumann's M49 nor any other Neumann-Berlin tube mic are 'similar in concept' to Gefell's UM57, by 'connecting one diaphragm to earth' as James claims. To the contrary, Neumann's more elaborate circuitry avoids connecting any capsule part to ground potential, thereby providing a direct wire connection between diaphragm and tube grid. More primitive circuits like Gefell's UM 57 require a DC- decoupling capacitor in the signal path between capsule and grid, which, to good ears, is one audible capacitor too many.
A suggestion regarding the often encountered confusion betweenNeumann/Berlin and Neumann/Gefell: Could Berlin's historians at Neumann's website please set the record straight about the real and perceived corporate connections between two companies with the same name AND logo? What little I know from telephone conversations with some of the old Berlin Charlottenstrasse - crew, is that there never any cross-breeding of product, and that at no time has any 'M7' capsule from East Germany ever been allowed into any U47 or M49. (Berlin made its own capsules, so did Gefell. When Neumann/Berlin found out that these PVC capsules self-destruct over time, they immediately stopped production. Gefell, and its successor company, Microtech Gefell GmbH, produce PVC 'time-bombs' to this day).
Which brings me to my opinion regarding the troublesome situation old Neumann/Gefell-product faces in the U.S.: Greedy gray-market equipment dealers rushed into east block countries after 1989 and flooded the U.S. market with product bearing the 'Neumann' logo, taking advantage of the name-recognition and a very favorable exchange rate, and reaping hefty profits. I say greedy, because these folks could not care less what happened to these mics once sold. They did not inform their buyers that, unlike similarly priced studio condenser mics from 'legitimate' companies, there are no parts supplies, no importer or authorized service centers to take care of defective Gefell mics in the U.S..
Why are these mics so cheap if they are so good? I wish it was just 'the poorly made power supplies' as James contends. In fact, the company situation and resale price development is similar to Yugo automobiles: Microtech Gefell's U.S importer, G-Prime will not touch product or sell parts for mics manufactured prior to their involvement (1990). Neumann/Berlin certainly does not have any connection to the East German Company, old or curent. So: Where will a customer get a replacement 'M7' capsule for that Gefell mic?
That 'great deal' to get a real Neumann tube mic real cheap is not a deal in the end. Gefell mic prices are not appreciating as Neumann/Berlin products' prices because of the obvious reasons stated. My advice: If you like the sound of Neumann/Gefell, buy two of each model you contemplate getting. One for work, the other for parts.
Klaus Heyne  
Paging Martin Schneider + Karl Winkler
Author: Posted by Donald James
Date: 01/11/1999

It's not 'solely' because of the power supplies that they haven't held their price, though the reputation of the power supply hasn't been the greatest. Let's all visit http://www.gprime.com/microtech/history/ history.htm for some history.  
Re: History is relative
Author: Posted by M Lemaire
Date: 01/12/1999

When I read this from Gprime: '1989...Neumann, Berlin tests the various Gefell microphones and, much to their surprise, finds technolology more advanced than that in the West.' I remind myself that the Gprime website is interesting, but 'history' is always a mix of fact and the historian's viewpoint, including their self-interest. Still, there is much information there that is unavailable elsewhere.  
Re: Donald James's NEUMANN UM57 MICROPHONE comments
Author: Posted by M. Schneider / Neumann
Date: 01/11/1999

Some additional info:
1. True, the UM57 has one diaphragm directly on ground potential. The middle electrode is connected via 1nF capacitance to the grid. The M49 has one diaphragm connected directly to the grid, the potential of which is close to 0 Volts and is drained to ground via >100Megohms. The back diaphragm is connected via 1nF capacitance to the front. A dispute, which is 'the best topology' could be difficult to settle. The M49 certainly has the 'direct-to-grid' appeal. But both circuitries have some pros and cons, engineering-wise.
2. Re: Neumann + Gefell: Some cooperation existed after the war, but grew increasingly difficult after 1953, and was finally disrupted in 1961 with the Berlin Wall. PVC was used in the 30s and 40s, then metal diaphragms were used for the 50's series. PVC showed the tendency to become brittle over the decades, leading to 'cobweb cracks' in the gold layer. With improved PE quality, the switch was made from PVC to PE in the late 50s, at Neumann Berlin. Thus, late U47s and M49s, and all the mics from U67 (1960) on were built with PE diaphragms. As we're quite satisfied with the quality, we'll stick to that material. About the long term behaviour of Gefell's current M7s I have no specific knowledge.
3. Re: Spare parts. The Berlin and Gefell productions were different things altogether. This went down to connectors, which had similar configurations, but different threads in the East and West. As the industrial situation was quite critical in East Germany, a lot of parts were produced by Gefell itself. Thus, no maintenance or repair of Gefell microphones can be performed by us in Berlin, or our repair centres.
4. True, some people must have made some profit with buying up studio and broadcast equipment in the old Eastern block. As to the worth of the material, well, it always depends on the state of the insides, if it was worth the price.
5. Finally, there IS a distinction between the Neumann and the Gefell logos: the post-war Neumann Berlin logo was always the rhomb (tilted square) around the vertical 'Neumann'. Gefell just used the 'inner' logo, until the early 70s approx.
Best regards, Martin Schneider Neumann Mic. Development