Category Archives: Vintage Brochures and Tech Specs

Sennheiser MD408 N Super-Cardioid Dynamic Gooseneck Microphone. 1960’s/70’s

Sennheiser MD408N
Sennheiser MD408N

Originally designed for speech and vocals the Sennheiser MD408 N is a solid, reliable, workhorse microphone which is useful for many tasks. It performs well on guitar cabs, delivering a rich beefy sound with plenty of midrange punch. The flexible gooseneck makes it particularly easy to position. It is also useful on snare and a variety of percussion. Once again the gooseneck is very handy for manoeuvring in awkward spaces. Being a super-cardioid it also has excellent feedback rejection.

Some microphones were destined to appear with the stars, glittering centre stage with Elvis or Tina Turner or David Bowie. Others however, never quite made it to the limelight. Back in the 60’s and 70’s the MD408 N was often used as a humble studio talkback mic. Even so, when it comes to dull publicity photos the shot below takes a lot of beating!

Sennheiser Advert 1969 for MD408N
Sennheiser MD408N  Klien Tuchel Connector and standard 3/8 inch stand adapter.
Sennheiser MD408N Klien Tuchel Connector and standard 3/8 inch stand adapter.
Sennheiser MD408N On/Off switch

The MD408 also has a silent on/off switch which is very handy if it is used for talkback or as a lectern mic. The neat square plastic actuator has sadly gone missing on mine but you can see it in the publicity photo.

CLICK HERE to listen to the MD408 on rock’n’roll Guitar at a live show.

Conclusion

Whilst it may not have the kudos and charisma of the more famous Sennheiser Models such as the MD421 and MD441 it is nevertheless a recommended addition to any collection.

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!

RSA Selmer RL1 Ribbon Microphone 1947-1958

Wireless world Advert October 1946

Looking back from the 21st century it is hard to picture a ‘dream’ PA system as being 2 x 8” speakers attached to a 12 WATT amplifier with 2 mic inputs!! However, in the UK this marks the beginning of the age of amplified, modern popular music. Within a few years the wattage and power output of PA systems would be rising rapidly, trying to keep pace with bigger and louder guitar amps!

In 1947 R.S. Amplifiers Ltd was bought by H. Selmer & Co Ltd who were at that time the largest musical instrument manufacturer in England. RSA’s newly launched Truevoice U12 PA system (described in detail below) continued in production until 1958 and formed the starting point for the Selmer Truevoice range of amplifiers. Selmer amps soon became a firm favourite for a whole generation of guitarists and bands.

R.S.A Selmer U12 PA system
Photographs of U12 PA Courtesy of Mario Martins.
R.S.A Selmer U12 PA Amplifier
R.S.A Selmer U12 PA Speaker with Mic compartment.

The handy compartment lined with green baize is where the microphone would be stored in transit.

The RSA Selmer RL1 Microphone

R.S.A. Selmer RL1 Ribbon Microphone.

Designed as a gigging PA microphone the body of the R.L.1. is very solidly cast in aluminium. The styling is distinctive and unusual. Somewhere between Art Deco and Mock-Tudor!  I can’t think of another microphone like it. The design of the grill is also peculiar to this model (and the later RL2) with baffled slots cleverly contrived to prevent the direct implosion of breath on the ribbon.

Inside the R.L.1. the ribbon motor is also further protected by a cotton bag.

R.S.A. Selmer RL1 Ribbon Microphone Interior.
R.S.A. Selmer RL1 Ribbon Microphone Interior case.
R.S.A. Selmer RL1 Ribbon Microphone Grill Interior.
R.S.A. Selmer RL1 Ribbon Microphone Rear View..

Optional step-up transformer 15 Ohms – 50k Ohms (below)

 This enabled the mic to be plugged into a high impedance PA input or even a guitar amp.

R.S.A. Step-up Transformer 15 Ohms- 50k Ohms.

Performance.

In terms of performance the R.S.A. Selmer RL1 is pretty much what you would expect from a ribbon microphone designed to go with the U12 PA system. Although it is somewhat lacking in high end response this would not have been a problem when delivering through 2 x 8 inch speakers! However, it has a pleasing, warm midrange which is flattering for most vocalists.

I had been intending to record a vocal clip to illustrate the qualities of this microphone but current COVID-19 restrictions here in the UK still make it difficult to meet up with performers. Hopefully in the next few months this situation will improve and I will be able to add a suitable recording to complete this post. 

P.S.

Here are a couple of likely lads from Liverpool (circa 1960) with the Selmer RL2. The grill is identical to the RL1 but the bodywork is somewhat different. I wonder what ever happened to these fresh-faced youths?

Tannoy Microphone Circa 1950.

Background.

The Tulsemere Manufacturing Company was founded in London in 1926 by Guy R. Fountain. In 1928 the name was changed to Tannoy. Rectifiers used in the company’s amplifiers utilised an alloy made from lead and tantalum. The name is simply a contraction of TANtalum/allOY.

 In the UK throughout the 1930’s Tannoy built up a considerable reputation for the design, manufacture and installation of industrial public address systems. Tannoy systems appeared in department stores, factories, offices, public buildings, academic institutions and sports grounds. In fact, just about anywhere that public announcements needed to be made- indoors or outdoors. There were even mobile systems fitted to vans!  

During World War 2, Tannoy manufactured installations for the British Army, Navy and Royal Air Force. Orders and day to day communications would be announced over ‘the Tannoy’.

By the end of WW2 the Tannoy brand was pretty much synonymous with any PA system. In 1946 the word ‘Tannoy’ passed into the Oxford English Dictionary as a noun meaning ‘public address system’. This usage is still current in the UK today.

As can be seen on the microphone featured here, Tannoy were not shy when it came to emblazoning the company name on their products. Judging from the tasteful antique bronze and grey paint finish, this gooseneck announcement microphone may well have been mounted on a mahogany desk in a Town Hall or other municipal building.

At first glance I assumed that this specimen, which has no model or serial number on it, was simply a dynamic paging mic in a fancy-looking case. However, when plugged in I was very surprised to hear how good it sounded! I carefully removed the grill and inside this is what I found……………

……. A well-made and neatly constructed, end addressed, ribbon motor. The back of the ribbon is enclosed by the magnet and the rear section of the casing. This produces a pretty much cardioid, directional polar pattern. It is similar in design to the STC4113 featured in a previous post.

So what does it sound like?   Because, here in the UK we continue to be under COVID-19 lockdown restrictions I still can’t get close to any proper musicians. I have therefore put together a slightly eccentric audio ‘collage’ of ‘percussion’ from around my desk to illustrate some of the impressive qualities of this distinctive Tannoy microphone. Marvel at the slightly sinister sound of 2 small terracotta plant pots being rubbed together and check out the creaky floor board! The finest details and complex textures of a variety of sounds are effortlessly reproduced as well as delivering natural speech with a high level of intelligibility.  

 CLICK HERE TO LISTEN.  

Conclusion.

This is definitely a microphone to keep. Apart from vocals and percussion, I have a feeling that it will work well on a whole range of instruments. Ribbons are always great for beefing up guitars! Can’t wait to get back to gigs and try it out!

Tannoy Mic on Rycote shock mount.

P.S.  

Here below are a couple of photos of another Tannoy microphone sent to me by Stewart Tavener at http://xaudia.com/. This mic appears to share the same casing and ribbon motor as mine but has a switch and hinged stand mount.

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

American D9AT Where's Wally

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.

American D9 Side View Chrysler Building

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)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!!American D9AT Interior Front viewAmerican D9AT Rear inside viewAmerican D9AT Interior side view

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.American Microphone Company D9 Advert

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.American D9AT Damage to bodywork

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.American Microphone Company D9AT

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.Badge ELGIN American Microphone Company D9AT

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 20th century.

Electro-Voice DO56L Dynamic Shock Mount Omni circa 1980

Perfect for the socially distanced interview!Electro Voice DO56LElectro Voice DO56L OmniElectro Voice DO56L with original case

Following in the company’s long tradition the Electro-Voice DO56L is a triumph of innovative design and precision engineering. The 11 and a half inch 56L is the Long version of the DO56 and was intended as the perfect tool for TV news gathering or Talk Show Hosts. Even the dull ‘Silver tone beige’ finish was carefully chosen to be unobtrusive and none-reflective under TV lighting.

Electro-Voice advertising material from 1980 featured below explains in detail the design of this exceptional new microphone. The clever arrangement of the internal shock mounting is particularly impressive.

Electro Voice DO56L Literature. page1Electro Voice DO56L Literature. page2Electro Voice DO56L Literature. page 3

Phil Donahue Edit

Can’t beat a bit of subtle product placement/celebrity endorsement!

So What Does it Sound Like?  CLICK HERE for spoken word clip.

What else can it be used for?

Back in the 1950’s when AKG came up with the D12 they fondly imagined that they had designed a general purpose instrument and vocal mic. The marketing blurb featured photos of pretty girls warbling sweetly into the new microphone and indeed it was a great success with singers. Then along came the studio engineers who took a look at the tech spec and said, ‘Hey…. I bet with that frequency response curve and high SPL rating the D12 would sound great on bass drum’!  Within a few years it was on bass drums all over the world! In fact these days it is often referred to as the ‘legendary bass drum mic’ (no mention of vocals). So when I see marketing literature declaring a microphone to have a particular purpose I always find myself imagining (based on the tech spec) what else it might be good for.

Although the Electro-Voice DO56L was very much designed with demands of TV journalism in mind and a frequency response tailored to the human voice, I feel sure that it could also have a range of other uses. So let me see now……………

More Sound Clips to follow as soon as COVID-19 allows!

 

Steane’s ‘Ellipsoid’ Ribbon Microphone Circa 1948. A Sorry Tale!

Steane's 'Ellipsoid' Ribbon Microphone circa 1948

Steane’s ‘Ellipsoid’ was a budget ribbon microphone made in Melbourne Australia in the late 1940’s. The advertising literature from December 1948 declares it to be the ‘World’s Smallest Ribbon Mike’!Steanes-1948-advert

Other claims made in the blurb also raised my curiosity, especially the bit about ‘No boom or puff’!  (Never previously on my list of ribbon mic problems!)   So when my newly purchased Steane’s ‘Ellipsoid’ arrived I had to plug it in straight way. However………….. As I turned up the volume on my headphones I was horrified by the sound that assailed my ears. It had a very unpleasant nasal honk and a gratingly harsh high end! This was not what I was expecting! The previous owner had assured me that this shiny gem was fully working and all original. Hmmm!

On opening it up this is what I found. Whaaaaaaaaat TF!

Astatic MC-127

The ribbon motor and transformer had been removed! The body of the mic was filled with grotty, yellowing, wading and a crudely soldered Astatic ceramic element dumped unceremoniously on the top.The whole horrifying confection was sort of held in place with a couple of random bits of grey foam.

Astatic MC-127 back view.

The grill was also stuffed with wading to stop the lose element from rattling around (and maybe improve the tone?) Perhaps it was an attempt to get rid of some of that legendary Aussie ‘Boom’ and ‘Puff’!   Anyhow, I sadly stuffed it all back together as I found it and bunged it back in the post to the previous owner for a full refund. What a disappointment!

P.S.

If like me you are unfamiliar with Steane’s microphones here is their Microphone catalogue circa 1948/9. The mics listed here offer a range of applications for both the professional and the amateur user. I notice that the Dynacard model also guarantees ‘No Boom or Puff’!  🤣  The Home Studio shown on the last page is interesting as it appears to be an early form of Karaoke system allowing the user to sing along with the radio and thereby add ‘zip’ to any party!

Steane's Microphone Catalogue 1948/9 Steane's Microphone Catalogue 1948 P.1 Steane's Microphone Catalogue 1948 P.2 Steane's Microphone Catalogue 1948 P.3 Steane's Microphone Catalogue 1948 P.4 Steane's Microphone Catalogue 1948 P.5 Steane's Microphone Catalogue 1948 P.6

Anyhow, perhaps one day another Steane’s microphone will come my way.

UNITRA Tonsil MCU-53 Cardioid Condenser (1970’s/80’s)

History

In the early 1970’s MB Electronic (now known as MBHO) produced the MB C540. This was a high quality battery powered condenser microphone. It boasted an almost flat frequency response from 20Hz to 20kHz with a slight dip at the low end. The MB C540 was modular in construction and had the option of 2 capsules (omni or cardioid).

MB C 540 AdvertMB C 540 Frequency response

In the UK it appeared as the PEERLESS MBC-540.

Reviewed here in Studio Sound May 1977.Review. Peerless MBC 540 - Studio Sound - May 1977

Meanwhile in Communist Era Eastern Europe.

This German design was also manufactured under licence by the Polish state owned electronics company UNITRA Tonsil and marketed as the MCO-30 (omni) and the MCU-31 (cardioid). According to Polish sources, the only difference between the German and Polish versions appears to have been variation in quality control at the Tonsil factory. This lead to some Polish mics reputedly sounding rather better than others.

Around 1980 the design was modified and updated. Whether this was done by MB Electronic or by Tonsil’s own engineers is not clear. (MB licenced a number of different designs to Tonsil but sadly MBHO now have no records relating to this microphone !)…….. Anyhow, the resulting microphone was somewhat shorter in length, the battery powering was changed from 2 x 15v to 1 x 6v and the previously unbalanced output was upgraded to balanced. The WCU-31 and WCO-30 capsules were retained and the frequency response appears pretty much the same. The new model was the UNITRA Tonsil MCU-53 (cardioid) / MCO-52 (omni).  The Tonsil 50 series continued in production through the 1980’s. In the late 80’s a further modification was carried out to provide 48v phantom power. This model was the MC-265.

UNITRA Tonsil MCU-53

UNITRA Tonsil MCU-53UNITRA Tonsil MCU-53 exploded view

A clever modular design. Well constructed and finished in shining nickel plate.

Tonsil WCU-31 Cardioid capsule. Front view

WCU-31 Cardioid capsule.

WCU-31 Cardioid capsule. Rear view.

Unusual 5 pin DIN connection.  (below)

Pins 4&5 in the plug are shorted together to provide a ‘switch’ for the battery. When the cable is plugged in the power is thereby switched on. N.B. This also means that if you accidently leave it connected when not in use you end up with a flat battery!! Arrrgh!

5 Pin DIN socket on Tonsil MCU-53 5 Pin DIN plug Tonsil MCU-53 Tonsil MCU-53 5 pin DIN Plug

Technical Specifications.

Pages from MCO-52/ MCU 53 Owner’s Manual UNITRA Tonsil MCU-53 ManualUNITRA Tonsil MCU-53 Manual P2UNITRA Tonsil MCU-53 Manual P3

In Conclusion.

Being battery powered made the MCU-52 /53 suitable for use with cameras and tape machines which in the 70’s and 80’s often did not provide phantom power. This made it a popular choice for wildlife and location recording.

When there is once again an opportunity to record music I will be interested to see how the MCU-53 compares to the AKG C451E as their frequency responses appear to be somewhat similar. I suspect the Tonsil may have a bit more self-noise but tonally may give the AKG a run for its money. Let’s wait and see…………

Credits.

Many thanks to Adam Wilma for sending me this pristine example of the UNITRA Tonsil MCU-53. Very generous. And thanks to my old mate blues guitarist Keith Thompson for bringing it back from Poland. His March tour was sadly cancelled after only 2 shows as Poland went into COVID-19 lockdown. Luckily for me the second gig was in Adam’s home town of Torun and he kindly dropped the mic off for Keith to bring back before the borders closed!

 

AKG C451E (Circa 1970) A Classic from The Golden Age of AKG

Today AKG is little more than a brand name owned by a multi-national corporation. Like a tired old rock star it rests on the laurels of its former glory whilst still churning out a few old favourites.

However, if we go back to the late 1960’s and into the 70’s AKG was a powerhouse of innovative design and high-tech engineering. Major achievements include the D200 series which took dynamic microphone design to a peak which even today sees few competitors. This period also saw the legendary C12 condenser evolve into the C414 which continues to be a favourite in studios across the world.

In 1969 AKG launched its newly developed Condenser Microphone System (CMS) using audio frequency circuitry with Field Effect Transistors. This was a fully modular microphone system based around the C451E, the inherent features of which were claimed to be;

  • Low noise level,
  • Extremely high reliability and
  • Life-long sta­bility.                                                                                                    

AKG C451E with old style logo

AKG C451E no serial number

A selection of interchangeable capsules and extension tubes could be purchased along with a variety of accessories covering a wide range of recording and live sound applications. The CMS proved to be enormously popular with broadcasters, TV companies and studios throughout the 1970’s and beyond, and can be seen on many BBC music programmes of the period.

These contemporary AKG brochures/guides explain the features of the CMS in detail.

AKG C451 CMS Technical Specifications

Technical Info AKG CMS microphones.

AKG CK1 CapsuleAKG C451E with capsule removed.AKG C451E body with CK1 Capsule

C451E original case interior AKG C451E Original case

My C451E

Judging from the old style of logo and the lack of an externally stamped serial number on my newly purchased C451E (see top 2 pics), I think that it must be a fairly early example. It is in perfect condition and even the case is hardly marked. As always it was a bargain!

So What Does it Sound Like?    

Sadly, like many, many other people I am stuck at home at the moment practicing social distancing, and so recording music with my beautiful new C451E will have to wait until the current COVID-19 pandemic dies down and we can all get back to work!

Meanwhile Stay safe!

P.S.   Went for a walk today and recorded this:-    https://www.youtube.com/watch?v=k5MHEL6ZPHI

 

Gaumont-Kalee Type 492 Ribbon Microphone (Circa 1950) A rare piece of British cinema history.

Gaumont-Kalee Type 492 Side viewGaumont-Kalee Type 492 Side view2Gaumont-Kalee Type 492Gaumont-Kalee Type 492 Box

I bought this microphone out of curiosity! It caught my attention because I had never seen or heard of it before (shock, horror!).  It came in its original felt lined wooden box, of the kind normally reserved for valuable scientific instruments. The name Gaumont I recalled from the old UK cinema chain but beyond that I knew nothing.

Researching this microphone has proved to be a challenging task.

It would appear that the Gaumont-Kalee Type 492 was never on sale to the general public. It was marketed along with other Gaumont-Kalee equipment purely within the cinema industry. So far the only contemporary references I have found have been in trade journals such as British Kinematography and Cine Technician.

It was manufactured by British Acoustic Films Ltd (B.A.F.), which by 1947, along with Gaumont-Kalee, was one of the many companies which made up The Rank Organisation.

Specifically designed as a boom mounted microphone, the Gaumont-Kalee Type 492 was most likely used to record dialogue and music for the classic British movies made at The Rank Organisation’s studios in the 1950’s. By this time The Rank Organisation in Britain had become one of the biggest film companies in the world. They owned 5 major studios including Pinewood and Ealing and Denham. Rank also owned and controlled distribution for several hundred UK cinemas.

B.A.F., under the Gaumont-Kalee brand, produced a number of sound recorders for the cinema industry, both optical and magnetic. Below is an advert from Cine Technician March-April 1953. My assumption based on this is that the Type 492 ribbon mic (and the Type 493 condenser not covered here) were designed for use with these machines. A 1947 BBC technical report on The G-K Sound on Film Recorder also makes passing mention of 2 microphones being supplied with the machine.

The Gaumont-Kalee Portable Recording Equipment pictured here features 35mm or 17.5mm sprocketed magnetic film which could be run in sync with a professional movie camera. In post-production this enabled easy editing and transfer.Gaumont-Kalee Portable Recording Equipment

These days when we talk about portable sound recording equipment we are maybe thinking of something the size of a mobile phone. The ‘portable’ equipment described above would have filled the boot of a car and required fairly muscular crew to carry it! However, its mobility nevertheless extended the possibilities of location recording both for TV and film production. (Also worth mentioning that magnetic film made a considerable improvement to the available frequency response.)

From this advert it can be noted that other users included BBC Television, Universal, a number of Newsreel companies, San Angel Inn (Mexico) and Dear Film (Rome).

 

Technical Information on the Gaumont-Kalee Type 492

In the absence of any detailed manufacturer’s literature, below I have made some observations and speculation about the design of this mic.

Noise has always been the enemy of the motion picture sound recordist, whether it be camera and equipment noise, on-set noise, tape hiss, or electrical interference generated by lighting. Trying to obtain clarity, especially in dialogue, has always been something of a challenge. This was particularly true in the age before shotgun mics.

  • In common with all figure of eight microphones the dead zones at the sides of the Type 492 could be directed to minimise unwanted mechanical noise from cameras and other equipment.
  • The yellow wiring around the ribbon is cunningly arranged to form a humbucking loop, helping to reject electromagnetically induced–noise. This is very useful when operating in the vicinity of lighting equipment and large mains transformers radiating strong magnetic fields.
  • In addition, the interior of the grill is lined with ultra-fine wire mesh which not only provides a certain amount of blast protection and back pressure for the ribbon but also creates an effective Faraday Cage.Gaumont-Kalee Type 492 inside 1Gaumont-Kalee Type 492 inside 2
  • The interesting-looking baffle arrangement on either side of the ribbon has the effect of producing a boost to the high end frequency response. This may provide greater clarity to dialogue, especially when recording at a distance (in order to keep the boom mounted 492 out of the camera shot). It was also common practice at this time to boost signals going to magnetic tape at around 4kHz on the way in and cut by the same amount on playback. This returned the desired signal to flat and reduced unwanted tape hiss by several db.Gaumont-Kalee Type 492 inside 3Gaumont-Kalee Type 492 inside 4
  • The connector pictured above is a Reslo. This mic came with a 3 pin Amphenol. When I took the mic apart it became clear that this was a modification as it was chipped and had been filed to fit! Stewart Tavener at Xaudia informed me that the two 492s he had previously repaired had Reslo connectors. The Reslo fitted perfectly. Thanks Stewart!
  • Unlike many of the ribbon microphones of the period which have impedances of 50 ohms or less, this Gaumont-Kalee Type 492 has an impedance of 300 ohms with a strong output signal which requires considerably less amplification than many of its contemporaries.

So what does the Gaumont-Kalee Type 492 sound like? CLICK HERE.

 In Conclusion.

Having emailed academic institutions, museums, collectors and fellow sound engineers all over the world, so far I have only tracked down a handful people who have come across the Type 492. The serial number on mine is 132 and I assume from the complete dearth of information that only a limited number were made. Sadly, much of the recording equipment from that period has long since gone in the bin along with company records, technical literature and drawings. Trying to unearth information about the Gaumont-Kalee Type 492 has highlighted to me the growing problem of vanishing history in the field of audio technology. Living links to the past are dying out and records are being lost. It is therefore important to preserve what we can before it is too late!

NEWS FLASH UPDATE  12 Nov.2019  

   have kindly unearthed this single page ad for the Gaumont- Kalee Type 492 and Type 493  in a May 1951 GB-Kalee product catalogue ‘Everything for the Cinema and Theatre’.  GB Kalee Type 492 Advert 1951

UPDATE 28th Nov.

Stroke of luck! Have just purchased this GB-Kalee Catalogue for 1950 on ebay and here on page 4 are the frequency response graphs for the Type 492 and 493!

GB-Kalee 1950 Catalogue. Cover

Gaumont British-Kalee proudly projects it’s brand across the world! The British Empire is marked in pink. Within a couple of decades the Empire was gone along with GB-Kalee and most of British industry!  (N.B. Even by 1950 the map above was out of date. India got rid of us in 1947 !)

 


Gaumont-Kalee Catalogue Page 4

Useful Links.

https://www.gettyimages.co.uk/detail/news-photo/an-engineer-works-on-a-laboratory-set-up-to-develop-news-photo/90777079?adppopup=true   Taken at B.A.F. factory at Mitcheldean in Gloucestershire in 1953, on the workbench is a Gaumont-Kalee Type 492. The zeppelin shaped mic up in the air is the Type 493 condenser.

http://xaudiaelektrik.blogspot.com/2014/02/motm-gaumont-kalee-type-1492-ribbon-mic.html  It is interesting to note that the microphone featured here has a 1 inserted in front of the 492. Apart from having an impedance of 50 ohms, what the difference was I have no idea.