Grundig GDM-311

Wow, a “temperature resistant microphone”? Yup, that’s what the marketing blurb has to say about the Grundig GDM-311! It is a dynamic omni for use with the TK 14L and TK 17L series of Grundig tape recorders. It is made out of plastic and comes in a plastic case, yup! That plastic case does have a trick up its sleeve, though, as it not only serves to store the mic and its cable, but also as a makeshift table stand. If you don’t use it, the GDM-311 will lie flat on the table and will not budge, as it has four rubber feet. If you crank up the gain, you can use it to talk on Skype, so hey presto! Or you can also use it ham radio style, as it is a dynamic omni, it will not get mad at either treatment.

Temperature resistant as it may be, the Grundig GDM 311 is not made of heat-resistant space grade plastics, so I didn't turn on the stove, obviously.

Temperature resistant as it may be, the Grundig GDM 311 is probably not made of heat-resistant space grade plastics, so I didn’t turn on the stove.

Like so many other mics of that era, it contains one of those AKG pillbox style capsules which doesn’t sound too bad at all, rather pleasant and warm. It’s not very useful for studio purposes, though, as it does not have a screw thread. One quite nice application is hanging it over your guitar amp Sennheiser MD 409 style, even for stage work. It’s an omni, though, so feedback might just nip that lovely idea in the bud…it has balanced wiring, though, so that’s a plus.

There’s a similar mic which is not white, but black and light blue, called Stuzzi DM5/200, a model by an Austrian company which got its capsules from AKG as well. The back of the Grundig GDM-311 says “Made in Germany”, but the Stuzzi says “Made in Austria”. And the plastic case on both says “Made in Austria”. Fascinating stuff, right?

  • polar pattern: omnidirectional
  • frequency range: 150 – 12.000 Hz
  • impedance 200 Ohm
  • sensitivity: 1,5 mV/Pa
  • weight: 80 g
  • size: 50 x 80 x 35 mm
  • cable length ~1,5m
  • price ca. 1965: 28 DM,-

Extra fun:

I’m not really sure why you would need that (maybe to rewire the mic to XLR really, really professionally?), but I found a neat schematic diagram of the GDM 311, courtesy of AndiiT on the Vintage Radio forumsSchematics Grundig GDM 311

Style: (2.0 / 5)
Sound: (3.0 / 5)
Uniqueness: (2.0 / 5)
Usefulness: (2.5 / 5)

Trash:Gold ratio – 1:1

  1. Hello there :-)
    Thanks for sharing all this info!
    I would like to replace the old DIN-connecter with an XLR-plug, as you mention. But I am puzzled about which wires to solder where. Is it simply that the wires going into number 1,2,3 in the old DIN-plug should be soldered to 1,2,3 in the new XLR-plug?

    • Hi Adrian! The pins assignments are different – the 3-pole Din plugs are wired like this: 1 = (+), 2 = GND, 3 = (-). XLR uses 1 = GND, 2 = (+), 3 = (-). Your adapter should look like this: DIN –> XLR = 1 –> 2 / 2 –> 1 / 3 –> 3.

      I’ve been planning on drawing up some schematics for that for basically forever, I hope I’ll get around to it someday…

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