American Microphone Company D9A/ D9AT ‘Skyscraper’ (1938- circa 1958)

Where’s Wally/Waldo?

When the American D9A was launched in 1938 it was notable because of its fashionable Art Deco ‘look’ inspired by the skyscraper skyline of New York and other great American cities. Indeed the side elevation of the mic appears to directly reference Manhattan’s famous Chrysler Building constructed in 1930.

This was the age of Jazz, and Rock’n’Roll was just around the corner. Microphones increasingly appeared centre stage in photographs and on screen as part of the performer’s visual image. Over the following couple of decades the American Microphone Company kept ahead of the game producing a number of stunning designs which appeared in movies and featured in commercials.

Katharine Hepburn, Spencer Tracy, Van Johnson, and Angela Lansbury in State of the Union (1948)

The transducer design of the American D9 is also interesting and unusual.

The D9A /D9AT is often incorrectly identified as a ribbon microphone! This matter can simply be resolved by undoing 4 screws!!

Does this look like a ribbon motor??!!  In the advertising blurb below it is described as being ‘a pressure-velocity combination microphone’ which may have led some folks to think that the ‘velocity’ element must be a ribbon (like the Western Electric/Altec 639). However, the 2 elements are clearly both dynamic. One pressure element (omni) sealed at the back, and one velocity element (Fig of 8) open at the back. The signals from these 2 elements are combined to produce a cardioid directional response. I can’t off hand think of another microphone that is configured in this way using 2 separate dynamic elements.

Although I can accept most of the description given above, the notion that the DA9 has ‘qualities of ruggedness’ is somewhat farfetched. Sadly, the bodywork appears to be cast in a cheap zinc alloy which is brittle and easily damaged. The yoke is also made of the same material. These days it is hard to find one without bent, cracked or broken ribs.

Some years ago I was working on a theatre show in which an over-excited actor, (playing the part of Jerry Lee Lewis) unintentionally launched my treasured Electro-Voice EV664 right across the stage. It landed 30 feet away with a sickening thud. Apart from a slightly damaged switch the mic was unmarked and still worked perfectly! That is rugged! I wouldn’t want to try that with my D9AT. This is definitely not a mic to drop by accident. As well as the fragile body the chrome plating is remarkably thin. Even though my D9AT is from the tail end of production in the mid 50’s much of the chrome has worn away. Nevertheless it is still a stylish looking object.

BUT………….. More importantly what does it sound like?  CLICK HERE for Voice Recording

The American Microphone Company D9A / D9AT was not designed as a high quality studio instrument. It was recommended for P.A. and installation use. In 1938 most dynamic P.A. mics were feedback-prone omnis. American’s dual element cardioid with its promise of higher gain before feedback could therefore be seen as an exciting new development. However, the following year Shure launched their game changing Unidyne 55 featuring a single cardioid capsule. The new single capsule design was soon adopted by most manufacturers as it was clearly cheaper to make and capable of producing excellent results. American carried on manufacturing the D9A/ D9AT for another 15-20 years. In 1955 the company was bought by Elgin-Neomatic,Inc. whose main business was watch making. At the time Elgin had the notion that they would develop miniature parts for microphones but this idea soon faded. My D9AT featured here is from the Elgin period.

Around 1960 American was sold again to General Cement Company Rockford, Il (AKA G.C.Electronics). Several years later the company was finally bought by Electro-Voice who soon retired the brand.

In Conclusion

Although the American Microphone Company D9A/AT may not win any prizes for its audio quality it nevertheless provides an interesting link in the development of directional microphones in the first half of the 20^th century.

Remembering D-Day June 6th 1944

CLICKHEREJohn Snagge announces the D-Day Landings in France 75 years ago today.

The STC4017c was used by the BBC throughout World War 2 to broadcast many momentous events and speeches. Possibly the most important communication tool of the 20th century it was the first microphone robust enough to withstand the rigors of serious outside broadcasting in a war zone.

For more information https://martinmitchellsmicrophones.wordpress.com/2013/06/21/stc-4017c-dead-or-alive/

World War 2 M.T.L.L.No2 Throat Microphone

Found in a garden shed where it had been for at least the last thirty years, this WW2 British military throat mic looks a bit sad and dilapidated. The paint is falling off and the steel fittings are rusting, the elastic is past its best, and a hungry woodworm has been drilling into the crumbling leather. So imagine my surprise when I plugged it in and it immediately burst into life!

The M.T.L.L. No 2 was used by the RAF and by the army. The mic was worn around the neck and was designed to pick up vibrations direct from the voice box. The two leather covered sensors were pressed against either side of the throat. The great advantage of the throat mic was that it could be used effectively in very noisy environments, such as inside a tank or an aircraft in combat. Even loud sounds around the wearer would be largely rejected. Although the audio quality is not fabulous, speech has a high degree of intelligibility.

This view below is of the back of one of the sensors with the plastic cover removed. Inside there is a magnet, the polarity of which is marked on the metal case ‘N’ and ‘S’.  The wires are identified with red and blue cotton thread. (Hot and cold?)

Below, (pinched from an ebay listing) is a photo of the front side of the mic, without its leather covering. Here there appear to be a couple of coils.

Below, the strip of steel which picks up vibrations from the throat is sitting on top of the coils and magnet. This assembly is held in place by the leather covering. The result of this ingenious arrangement is a small electrical (audio) output signal appearing at the red and blue wires.

 

CLICK here to hear a short voice test of this unusual creation.

Conclusion.

It would be hard to exaggerate the importance of military communications during World War 2 and the crucial role played by the M.T.L.L. No 2 throat microphone.

 

The STC4001B Acoustic Baffle for the STC4021 (Apple & Biscuit) circa 1935.

The very first post that I wrote for this blog back in 2012 was about the STC4021 (Apple & Biscuit). Still one of my favourite microphones.  I even made a YouTube video to go with it! In the course of the video I mentioned the STC4001B Acoustic Baffle. According to the STC brochure this could be purchased to modify the frequency response and directionality of the microphone. These days the 4001B Acoustic Baffle is very hard to find. So imagine my surprise when a brand new old stock 4001B (still in the box) appeared on eBay. 

So I thought I had better ‘Buy it now‘ and make another video to celebrate the occasion!

 

Electro-Voice Rags To Riches. T45 Noise-Cancelling Microphone (1944)

In 1942 after America entered World War 2, the US military estimated that only 20% of radio communications in combat were successful. Failure in the other 80% was mainly due to the voice of the radio operator being drowned out by the surrounding cacophony of war. Like no other conflict before, success on the battlefield relied on communications. Spotting a gap in the market Al Khan and Ed Burrows, the owners of Electro-Voice, came up with a brilliantly simple, ingenious and cost effective solution to this problem.

Even in 1942 the single button carbon microphone was a piece of old fashioned tried and tested technology, having been in use in telephones since the tail end of the previous century. Although the audio quality of the T45 is little better than it’s telephonic predecessors it is extremely reliable and very robust. It also has a high output making it ideal for long distance communication. Even if the microphone gets wet you can simply dry it out (as per the instructions above) and it will carry on working! However, the really clever part of this design utilises 2 small holes of equal size on the front and back of the mic.

These allow the surrounding noise to enter the microphone on both sides of the diaphragm. The sound striking the back of the diaphragm is 180 degrees out of phase with the sound at the front. This causes a very impressive cancellation of the unwanted noise whilst the speaker’s voice, which is less than a 1/4 of an inch from the front opening, dominates the transmission.

In terms of manufacturing costs it would be hard to produce a cheaper microphone.  A carbon button is a very small tin of glorified coal dust (carbon granules) with a simple diaphragm attached.  A bit of wire and some lightweight plastic fittings and that is it! Pure genius !

After some initial military skepticism the product was thoroughly tested and a first order came through to Khan and Burrows  for 100,000 units! The T45 was soon taken up by all branches of America’s armed forces and  the success rate of combat communications rose to 90%.

Rags to Riches.

Prior to World War 2 Electro-Voice was a small struggling company, with 20 employees, manufacturing a handful of dynamic and velocity microphones per week. By the latter part of the war Electro-Voice had 500 employees working in 3 shifts  producing more than 2,000 T45 microphones a day! After WW2 it was also adopted by commercial aviation and remained in service for several decades.  The T45 was also used on the Mercury, Gemini and Skylab space missions.

Over the entire production run more than a million were produced placing the T45  among the highest selling microphones ever made.

During the war many small firms went out of business due to a shortage of manpower and materials, but for those involved in the war effort fortunes were to be made. In 1946 Electro-Voice moved into an impressive new factory at Buchanan Michigan where they continued to manufacture  innovative and exciting audio products  for the next 60 years.

 

Footnote 

Circuit for powering a carbon microphone.  

 

Vitavox Admiralty Pattern No1359 (1944 D-Day)

 

 

Whilst the BBC was broadcasting and recording many of the momentous events of World War 2 using the STC4017C, and American radio stations continued to use the original trusty Western Electric 618A, out on the high seas the British Royal Navy were issuing orders and communicating using the Vitavox Admiralty Pattern No 1359.

Because it looks very similar, I had previously thought that the Vitavox was simply a re-badged STC, but this is not the case. Having finally managed to unscrew the grills on both it is easy to see key differences.

1) The STC4017 (on the right) is very slightly larger than the Vitavox No 1359. 2) The Vitavox diaphragm is, however, a good deal larger than the STC. 3) The Vitavox has no equalising tube running from the front to the rear chamber . 4) The grill components are quite different.

CLICK HERE for Sound Clip.

The Admiralty Pattern No1359  is also mentioned in the Australian Royal Navy Fleet Orders for 1945 for use with radio & disc recording equipment. It is suggested here as an inferior alternative to the STC4021  (which has a much flatter frequency response).N.B. Coarse groove, direct cut, disc recording equipment was used extensively by broadcasters  and the military throughout WW2.

 

STC 4017-C Dead or Alive ???

My freshly unwrapped STC4017C

Bought ……. ‘sold as seen’……’not known if working’….. from a house clearance sale on ebay. This microphone was previously owned by Kenneth Chaplin, who worked for the BBC from 1935 to 1981. Question is……. will my newly purchased STC 4017-C turn out to be:-

a)  A Classicic World War 2 BBC Outside Broadcast microphone in perfect working order…………’We will fight them on the beaches’… etc etc.

OR

b) An expensive  copper paperweight/doorstop!!!

What’s your guess?   a) or b)                                                                           

All I’ve got to do now is make up a special lead and find out!!!

2 Days Later ……… To find out what happens when I plug it in  CLICK HERE!

I was going to write some technical blurb on this mic, but the information on Stan Coutant’s wonderful ‘Welcome to Microphones’ site is so comprehensive I would thoroughly recommend reading that!

http://www.coutant.org/stc4017c/index.html

Many historic 20th century broadcasts and recordings were made with the STC4017 (probably more than any other microphone) and many famous people have had their picture taken with it! Here is a great photograph of the writer George Orwell

Marlene Dietrich 1944 performing for the BBC Allied Expeditionary Forces Programme.

Here is another famous user:-

The 14 year old future Queen makes her first broadcast in 1940

More PicsLucky to find this elegant, original BBC stand for a bargain price on ebay!

Another sound clip CLICK HERE>

also

Live concert Solo violin recording

Tasty guitar clip.

STC4017-C Delivering the famous ‘Peace in Our Time’ speech. Sept 30th 1938 Chamberlain returns from Munich with agreement from Hitler!

‘Mark my words, that Adolf Hitler is a very naughty boy!’ Headmaster Neville Chamberlain Declares War on Germany 1939
P.S. I wonder why they mic’d up his right hand??

Here below are links to to more interesting information :-

war time use of the STC4017 by the BBC.

John Snagge reporting D-Day landings June 6th 1944

America Declares War on Japan. President Roosevelt’s Speech using the original  Western Electric 618a. (Same as STC4017a)

A variation of this microphone also used by the Royal Navy in the form of the Vitavox Admiralty Pattern No 1359

Following the years of wartime reporting, below a battery of  STC4017s assists in cementing the peace.  

The first session of the United Nations General Assembly opened on 10 January 1946 at Central Hall in London. Here, Secretary-General Trygve, speaks at his installation ceremony. (2 February 1946) UN Photo/Marcel Bolomey