Category Archives: BBC Microphones

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.

‘The Beatles Mic’ Reslo RB/L Black Label (Circa 1961)

Reslosound Ltd were a British company based in Romford, Essex, manufacturing microphones and electrical equipment throughout the 50’s and 60’s. In recent years the Reslo RB has become known as ‘The Beatles Mic’ because of its association with The Beatles early days at The Cavern Club.

However, as I recall (‘cos I’m that old), the Reslo RB was simply a popular vocal mic with many up-and-coming young beat groups in the clubs and pubs around Liverpool and Manchester. Like the Shure SM58 today, the Reslo RB was not, perhaps, the greatest vocal mic in the world, but it wasn’t bad either, and most importantly it was pitched at a price that gigging musicians could afford! In 1962 the Reslo RB/L could be purchased for £9.12s, which was less than half the price of an AKG D19B. A Sennheiser MD21 cost £16gns, or if you couldn’t quite afford the Reslo you could always settle for a Grampian DP4 L at £8. For their first gig at The Cavern in 1961 The Beatles were paid £5.

So how on earth did a delicate ribbon microphone survive whilst an enthusiastic singer (straining to get heard through a 50watt Vox PA) screamed ‘Twist and Shout’ at a distance of half an inch? (Or in the case of my mate’s band, an old valve amp built into a re-purposed rabbit hutch!) Reslosound clearly knew their market and gave this problem some thought. To avoid instant annihilation of the ribbon, Reslo had a cunning plan! Firstly the RB was designed with the ribbon motor facing backwards i.e. with the ribbon nearest the back of the microphone and thus somewhat shielded by the magnet. Secondly the RBs were supplied with a set of fine fibreglass ‘ acoustic correction pads ‘.

Reslo Filter Pads Kit 1961

These had a range of functions, described in detail in the Reslo Instruction Manual. However, the most important purpose of the pads was to prevent the implosion of breath on the ribbon.

ResloRB_INSTRUCTIONS_TECHDATA

In the almost inevitable event of catastrophic failure Reslo also had ‘Plan B’ in the form of replacement ribbons which came mounted on a plastic frame ready to do a quick swap.  It was also not uncommon for musicians to replace a blown ribbon themselves using the thin aluminium foil that came in cigarette packets! Having heard the results this is not to be recommended……… but it worked!

Rolling Stones 1963

Another bunch of likely lads with a Reslo RB. The Rolling Stones in 1963

The BBC Connection

In 1961 the BBC were looking around for small, unobtrusive microphones to use on TV. After serious deliberation, and thorough testing of the Reslo RBM/T, the Research Department concluded that ‘The performance of the microphone fell short of broadcasting standards’ (a night out at The Cavern would have told them that!).  However, the cheapness and robust construction of the RB was also noted, and they therefore suggested implementing a number of simple changes to the design which would bring it up to broadcasting specification. The full report can be read here…….

 1961 BBC Modifications.

The modified broadcast microphone is known as the Reslo VRM/T

The VRM/T was sold to the BBC for the princely sum of £10 per microphone.BBC TV Grandstand Reslo VRM/T

Home Taping

The Reslo RB was also popular with amateur tape recording enthusiasts. Once again, it gave good results without breaking the bank. The British tape recorder manufacturer Ferrograph sold Reslos with some of their machines and made their own in-line transformers to match them to the input. Here is a review of the RB by Fred Judd, who edited Amateur Tape Recording magazine for a number of years……. ResloRB_review by F Judd

Reslos also appeared in re-badged versions for various equipment manufacturers including VOX and GEC.

Conclusion

Fronting many famous (and not-so-famous) names of the 60’s the Reslo RB has rightly earned a place in rock ’n’ roll history, and thanks to its solid design there are many examples still in circulation. With a bit of a clean and a new ribbon they will probably carry on rocking for another 60 years.

So what does the Reslo RB/L sound like?

CLICK HERE Pete Gill with Reslo RBL

P.S.    If your Reslo RB needs re-ribboning or if you fancy upgrading to BBC spec http://xaudia.com/ do a fantastic job.

 

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/

Wind Shield 4001.A. to fit STC4032 and 4035

In the post yesterday came a small cardboard box  containing a very pleasant surprise. On reading my last post on the STC4032, one of my readers had observed, that I didn’t have the 4001.A. wind shield. These days they are extremely hard to find. He happened to have 2 and so he sent me this as a present! That is very kind and made my day. So, a big thank you to John Machling

Wind Shield 4001.A to fit STC4032 and 4035

And it is in absolutely perfect condition!

The construction of the wind shield is interesting, consisting of a cleverly designed dome of fine wire mesh packed with rubberised hair and other fibres. (Even the thickness and spacing of the wire and hair/fibre is critical! ) An airtight rubber seal easily attaches the wind shield to the mic.

Inside view of STC4001.A. Wind shield

No. It is not a nest for an extremely small bird!

Inside rim of STC4001.A. Wind shield.

To understand exactly how this slightly crazy-looking piece of vintage British technology works it is worth reading the original patent application which explains all. 

Patent Application for STC4001.A.

STC4032 with 4001.A. Wind Shield.STC4032 with 4001.A. Wind ShieldSTC4032 wit 4001.A. Wind Shield

With the wind shield in place, the level of noise caused by winds in the range of 10 – 30 mph  is reduced by up to 16 db, with surprisingly little effect on the frequency response. It also provides a valuable additional layer of waterproofing. It certainly looks like it should be very effective, and as soon as we have some really bad winter weather I will get outside and record a demonstration!

 

STC4032-D Outside Broadcast Microphone Ex BBC Circa 1955

STC4032-D

STC4032-D

STC4032C Advert

From the earliest days of outside broadcasting and recording, keeping the microphone dry has always been something of a challenge. Condenser microphones in particular don’t function well in damp conditions, and pretty much any mic can be completely ruined by a good soaking.

These days’ companies such as Rycote make windshields and water resistant protection to cover a wide range of different professional microphones. Back in 1955 STC came up with their own neat and convenient solution to the problem.

Advertised rather grandly as being ‘an all weather instrument’ with ‘full marine and tropical protection,’ the STC4032 is a robust hand-held, omnidirectional, dynamic microphone with a moisture resistant black Bakelite body. The grill is a dual layer of fine stainless steel mesh and an optional windshield (pictured above) may be added to give an additional 15db noise free performance in high winds and additional protection from the rain. The handle incorporates a switch, which can be wired to provide muting or remote start/stop function for a tape recorder (such as the E.M.I Midget).

EMI Midget Tape Recorder

This super lightweight setup was used by BBC outside broadcasters from 1955 until the mid-60’s and weighed a mere 14lbs!  You may laugh…….. But this was a vast improvement on carting round the previous equipment…….. a BBC Type C portable disc recorder weighing 44lbs!!!   (see pic below)   Perfect for recording in a gondola!                                                                                                     BBC OB Disc cutter Venice 1946Michael Reynolds reporting for the BBC in Venice 1946.

Can’t imagine the rocking of the boat helped the disc cutter very much. The mic is an STC4017c and none of this gear is waterproof (apart from Michael’s sturdy military raincoat!)

Legendary sports comentator David Coleman

Legendary sports commentator David Coleman with his trusty STC4032 in hand.

The following is a hilarious period piece, almost like something out of Monty Python:

Alan Whicker interviews Beatniks in Newquay in 1960  (STC4032 appears at 5min 50secs)

https://www.youtube.com/watch?v=W3WfXA9JL9w&t=350s

Actress and opera singer, Rosalina Neri.

This picture of actress and opera singer Rosalina Neri being interviewed for the BBC really deserves a suitable caption!                       ………………………………………………………………………………

STC4032-D

STC4032-D

Although it looks somewhat like a World War 2 battlefield telephone, in terms of technical performance the STC4032 is exactly the same as the STC4035 studio microphone, and very similar to the famous Apple & Biscuit STC4021. It has a notably smooth frequency response from 30Hz to around 10 kHz, with a presence peak of around 5db at 6.5kHz . The only difference with the 4032 is the water resistant case.

Technical Specifications.

STC4032

Here is a short demonstration of the STC4032-D

In Conclusion.

Although ostensibly designed for outside broadcasting, the STC4032 is a high quality dynamic microphone that could be used for many different tasks.

Click Here for a short except from Suite for Soprano Saxophone and Church Organ – ‘In Remembrance’ composed and performed by Patsy Gamble with Jonathan Hope on Sat 11th Aug 2018 in Gloucester Cathedral. Photograph by Duncan Laker.

Click Here for a short clip of Acoustic Guitar. Many thanks to Joe Martin for the brief impromptu solo.

P.S.

For those who are interested in the history of broadcast recording I would thoroughly recommend these 3 sites which are a rich source of fascinating information:-

http://rfwilmut.net/broadcast/recording.html

http://museumofmagneticsoundrecording.org/StoriesBBCEMI.html

http://www.orbem.co.uk/repwar/wr_recorders.htm

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!

 

BBC Engineering Training Manual. MICROPHONES. (1951)

I was born on January 20th 1951 at St Mary’s Hospital for Women and Children in the centre of Manchester,  just across the road from the Palace Theatre. Less than a mile away, at the BBC Studios in Piccadilly, engineers were avidly thumbing through their copies of the very latest BBC ENGINEERING TRAINING MANUAL . MICROPHONES!

BBC Training Manual 1951

My copy arrived yesterday! (courtesy of eBay). It is in nearly new condition and sadly it’s unmarked pages have all the ‘vibe’ of a book that has never been read!

In recent years I have often regaled students with my reflections on how much audio technology has changed during my lifetime. Reading through this book really brings it home! It is a window into a long-gone world of engineers in brown lab coats and announcers at the microphone in evening dress. For me, as a child, it was the world of ‘Listen with Mother’ and ‘Children’s Hour’ and seeing the valves glowing in the back of the mahogany veneered wireless set on a shelf next to the fireplace in our living room.

My earliest memory of a microphone was standing on a box in front of a huge Marconi AXBT ribbon mic having won a prize in a BBC Children’s Hour competition at the age of 7 or 8. (It looked just like a giant ice cream cone!) I was presented with a silver propelling pencil by the producer Trevor Hill. I said ‘Thank You’ in the general direction of the mighty Marconi, and was escorted back to my seat.

BBC Children's Hour Competition Prize 1958


Anyhow, back to the book. 

What is most striking is how slender this volume is (114 pages). Most of it is taken up with detailed information about the propagation of sound and the physics involved in microphone design and construction. Much of this is still useful knowledge. However, only 7 different microphones are described in detail and most of these had already been in service since the mid 1930’s.

Here, (to give you a flavour of this informative little book) are some of the illustrations.BBC Marconi Ribbon Mic

In the BBC Studio of 1951 the Marconi AXBT Ribbon Microphone (first introduced in 1935) was the principal tool for drama, announcement and music. Broadcasting  was in Mono. With a frequency range from 20Hz-16 kHz, this figure of eight device was very often the only mic used!  One useful piece of advice offered to the engineer, in order to avoid ‘an excessive bass response’ (caused by proximity effect), is that ‘The microphone should never be used at a distance less than approximately two feet.’


BBC STC4017C

From 1938 to 1953 the STC 4017C was the main BBC outside broadcast microphone. Built like a tank, with a solid copper body and an aluminium diaphragm, it was a very robust dynamic. Although, in theory omnidirectional, it did exhibit some frontal directionality at higher frequencies.


BBC STC4021

The STC4021 , nicknamed the ‘Apple and Biscuit’, was a high quality dynamic mic which, due to its spherical shape, was truly omnidirectional. It was mounted vertically and was used for a variety of purposes including ’round table’ discussions and interviews. It was also used as a talkback mic.


BBC EMI Moving Coil

Developed by Holman and Blumlein working for the Columbia Gramophone Company (later E.M.I.) , it was used extensively by the newly formed BBC Television service at Alexandra Palace from 1936.The unusual thing about this microphone is the fact that it’s diaphragm is made of thin balsa wood enclosed between two sheets of aluminium foil! Interestingly, the description in the book ends with something of a warning……..  ‘the instrument is less suitable when high quality is a major consideration’  !!!!!


BBC Marconi Condenser Mic

BBC Marconi Condenser Element

The Marconi Condenser Microphone with built-in amplifier was a large and extremely rare beast, introduced experimentally in the mid-1930’s.  Even at the BBC it was not commonly used. Early condensers were prone to suffer with crackling caused by moisture.When it was employed it was mostly to be found at concerts.


BBC Brush Crystal Mic

BBC Brush Sound Cell

I have never seen a BBC studio picture with one of these. Not sure what it’s duties might have been. Perhaps, included in the manual simply because it is an example of a crystal mic? These were quite common at the time as PA and announcement mics. Also quite popular with amateur tape recordists.


BBC Marconi Lip MicBBC Marconi Lip Mic Back view

The Marconi Lip Ribbon Microphone (designed by the BBC in 1937) is a noise cancelling device which was used for sporting commentaries and broadcasting in noisy environments. It was designed for very close speaking with the ribbon protected from the impact of the speaker’s breath by the enclosing magnet. (see pics above)  One of the most important features of this microphone is the mouth-guard, which is pressed up against the speaker’s jaws, thus maintaining a constant distance between the mouth and the ribbon. This ensures against changes in frequency response, and volume, caused by fluctuations in distance. A variation of this microphone is still made today for the BBC by Coles (formerly STC).

BBC Training Manual 1951012BBC Training Manual 1951013

Foot Note.

In 1953 BBC Television broadcast live the Coronation of Queen Elizabeth II. Amongst the most notable features of this historic broadcast was the commentary delivered by Richard Dimbleby inside Westminster Abbey. The microphone used on this occasion was the latest Marconi L.2 Lip Ribbon mic. The perfect choice! The closeness of the speaker to the microphone, and the rich tone of Dimbleby’s voice, served to give the listening audience an intimate, sense of the grandeur of the occasion. The isolating characteristics of the lip microphone also served to focus attention on his voice. Dimbleby was the undoubted master of this technique of close-mic’d delivery which became a hall-mark of British State occasions.

Richard Dimbleby at the Coronation of Elizabeth II 1953

Richard Dimbleby with the Marconi L.2 Lip Ribbon microphone in the specially constructed commentary box in the Triforium of Westminster Abbey


 

In Conclusion

Within a decade of this manual the BBC microphone cupboard would be rapidly filling with exciting new models from the likes of AKG, Sennheiser and Neumann. In the following years alongside the growth of television and multi-track recording came a whole range of microphones designed for different purposes. Stereo mics, shotgun mics, lavaliers, parabolic, contact, binaural, ambisonic…………….. A whole new world!


Here are some useful links for more information.

http://www.coutant.org/bbc/index.html   (Some great photos of the Marconi Ribbon Mic)

http://www.coutant.org/marconi/    (Pictures and information on this extremely rare condenser mic)

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