LABOR W MD7 Omnidirectional Dynamic Microphone Circa 1950.

A Short History Lesson.

In 1945, just a few weeks after the end of World War 2 Fritz Sennheiser and 7 fellow engineers from the University of Hanover set up a business designing and producing a range of electrical equipment in a laboratory called Laboratorium Wennebostel (“LABOR W” for short). The laboratory was named after the village of Wennebostel in the municipality of Wedemark, where it had been relocated during the war. LABOR W began building microphones in 1946 and by 1953 (see catalogue below) they had developed a whole range of microphones, including the legendary MD 21 which is still in production today. By 1955 the company had expanded to 250 employees and in 1958 changed its name to Sennheiser.  

These days microphones from the early LABOR W period are becoming increasingly rare, so when this unusual looking MD7H turned up on eBay, ‘untested’ but very cheap, I immediately clicked ‘Buy Now’.

LABOR W MD7H   front view
LABOR W MD7H  front view 2
LABOR W MD7H rear view
The ‘H’ indicates that this is the High impedance version.

The photograph on eBay however, gave no sense of scale and it wasn’t until the microphone arrived that I realised just how small it is! I was reminded of the anecdote of the person who buys a gorgeous sofa online at a bargain price and when it arrives it turns out to be for a dolls house! Had I seen the LABOR W advert below that might have given me a clue.

LABOR W MD7 Advert early 1950's
‘Our most powerful moving coil microphone
MD7 for speech’

Below are the microphones featured in the 1953 LABOR W Catalogue.

Microphones featured in the 1953 LABOR W Catalogue. Page 1
Microphones featured in the 1953 LABOR W Catalogue. Page 2

(Translation of catalogue description above)

‘MD7 Speech microphone

Particularly good speech intelligibility due to emphasis on high frequencies. Therefore recommended for announcement and dictation systems. The soft rubber housing makes the MD7 insensitive to rough handling. Available in low and high impedance versions.

Dimensions: 76 x 48 x 48mm.’

For a sense of scale here below is the baby MD7 along with its Senneiser cousins the MD21 , MD421 and the mighty MD441.

LABOR W MD7 along with its Senneiser cousins the MD21 , MD421 and the mighty MD441.

Innovative design

In the early 50’s the soft rubber housing of the MD7 was an innovative design feature, and indeed made it very robust and resistant to rough handling. I haven’t tried it, but I think it would probably bounce if dropped from a height! It therefore came as no surprise once I had soldered a jack plug on to the cable it burst into life working perfectly.

So what does it sound like? CLICK HERE

LABOR W production came to an end in 1958 and the name changed to SENNHEISER. The rest is history!

5 responses to “LABOR W MD7 Omnidirectional Dynamic Microphone Circa 1950.

  1. Fascinating as always. It is interesting how they talk about “emphasis on the high frequencies”, which might mean something completely different in a musical/HiFi context. Since this is a speech mic, they probably mean sth like frequencies from 2 to 5 kHz, or perhaps up to 6 or 8 k. The birds in the sample don’t sound muffled, so I wonder what the actual freq response is. Also, how much of it the typical connected recording device would have been capable of reproducing.

    Liked by 1 person

    • My guess is 2 to 5kHz. The overall response I think is something like 100Hz to 12kHz (though I can’t find any published tech spec). It is certainly a lot better than I was expecting! In the early 60’s my Dad had an office dictation machine which sounded truly dreadful with a very limited frequency response. I think at this point Sennheiser was rapidly progressing to greater things.


  2. A ‘sleeper’ mic for sure. To my ears, it sounds better (less like a canned 50s mic) than the well-known MD4. I imagine the MD21 still beats it for things like vintage-style guitar amp miking? But, maybe not? Have you compared the two?

    Liked by 1 person

    • PS: is it just me, or does birdsong sound good on almost any mic? Condensers, dynamics, even ribbons (with good wind protection) –the birds always come out on top!

      Liked by 1 person

    • MD 21 is definitely a better microphone. More top and bottom end but it does have a very similar ‘feel’ in the mid range. Capsules are probably very similar.


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