Tag Archives: Microphones for Television

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.

1962 BBC Training Manual

In the 1951 BBC Microphones training manual we saw that the corporation functioned with a small selection of British manufactured microphones, most of which had been in service since the 1930’s.  So when I saw this Manual from 1962 I was curious to see how ‘Auntie’ had moved on into the swinging sixties.

BBC Training Manual 1962

Old favourites continued in use.                                                                                         BBC Training Manual 1962 STC Dynamic Microphones

The STC4021 ‘Apple and Biscuit’ first appeared in 1935 as did the famous Marconi A series ribbon microphone pictured on the page below. (The AXBT is the 4th generation).  The STC4035 was a lighter, updated replacement for the old STC 4017, which had been phased out in the mid 50’s. The 4032 is identical to the 4035 but housed in a neat handheld Bakelite body making it suitable for outdoor use in all weathers. The 4037 was designed for TV and has a rather more modern look (slim lightweight body and matt black finish). However, the capsule is still pretty much the same as the good old ‘Apple and Biscuit’. STC’s dynamic models were the tried and tested backbone of general purpose and outside broadcasting. The noise-cancelling STC4104 lip ribbon mic was used for sports commentary and noisy events. This was an updated version of the older Marconi lip ribbon microphone. More recently manufactured by Coles, the 4104 continues in production to this day.

BBC Training Manual 1962 Ribbon Microphones

So what was new?

FM broadcasting by the BBC began in 1955 and the audio frequency response was thereby extended from 5 kHz up to 15 kHz. The new FM system was also considerably less susceptible to noise and interference than AM. Although the old favourite microphones from STC and Marconi were still fine for everyday transmission of speech, when it came to the broadcasting of high quality music, mics with improved high end response were now required. With this in mind the BBC Research Department designed 2 new ribbon microphones (pictured above). First came the PGS (Pressure Gradient with a Single magnet) and from this developed the 4038. Manufactured by STC these new microphones were considerably smaller and lighter than the old Marconi AXBT, and had an almost flat frequency response up to 15 kHz. This was around ½ an octave higher than the mighty AXBT. Now manufactured by Coles the 4038 continues in service to this day and is still recognised as one of the finest ribbon microphones available.

The photograph below is rather bizarre. In real life the STC4033 is around 3x bigger than the Reslo! The Reslo was small and convenient for use on TV (as mentioned in my previous blog post). The STC4033 is an unusual hybrid, similar in design to the classic Western Electric 639 ‘Birdcage’. It has an ‘Apple and Biscuit’ type omni dynamic element, and a ribbon element. This gives a choice of switchable polar patterns. Using the elements separately we have Omni or Figure of Eight and by combining the outputs of both we obtain Cardioid. Nevertheless, by 1962 the STC4033 was a somewhat antiquated design and no match for the more sophisticated competition coming out of Germany and Austria.

BBC Training Manual 1962 Reslo and STC4033

Enter AKG and Neumann……….

A number of high quality condenser microphones now appeared in the BBC microphone locker. The legendary AKG C12 quickly became a firm favourite for the broadcasting of concerts and was very often the only microphone used to capture a symphony orchestra in glorious Mono! The AKG C28, C29 and C30 were perfect for solo performers on live TV. The variable extension pieces made it easy for unobtrusive positioning.

BBC Traing Manual 1962 AKG C12.jpgBBC Traing Manual 1962 AKGC28 .jpg

The Neumann KM54 cardioid, and the multi-pattern KM56 were also popular choices for high quality broadcasting.

BBC Training Manual 1962 Neumann KM54BBC Training Manual 1962 Neumann KM56

Other Microphones.

A number of other microphones are given a mention but not honoured with a photo. The Corporation was still very much dominated by BBC Radio and most of these microphones are from the rapidly evolving new world of BBC Television. TV presenters very often needed to keep their hands free and microphones ‘in shot’ needed to be small and unobtrusive.

BBC Training Manual 1962BBC Training Manual 1962BBC Training Manual 1962

The Placing of Microphones
The diagrams and explanations on the pages below provide an interesting insight into the lost world of recording and broadcasting in Mono.

BBC Training Manual 1962 Microphone Placement 01

The BBC philosophy for the broadcasting of classical music is best summed up in the opening sentence of the page below.  In the manual there is a clear distinction between music which requires the engineer to simply reproduce a ‘true balance’ created by the conductor and the performers (captured by one microphone), and more popular forms of music which require the engineer to create the balance from a number of microphones. Today this distinction has been all but lost.

BBC Training Manual 1962 Microphone Placement 02BBC Training Manual 1962 Microphone Placement 03

 Modern Dance Bands

BBC Training Manual 1962 Microphone Placement 05

Setups for Dance Bands.

BBC Training Manual 1962 Microphone Placement 06

The section above on Modern Dance Bands contains no mention of the latest Beat Groups, Rock’n’Roll or Skiffle. BBC thinking was clearly lagging at least 5 years behind the latest trends in popular music. If you were a teenager in 1962 the ensembles mentioned above are the sort of music your Mum and Dad would have liked! Within a couple of years British teenagers were under the bedclothes every night with a transistor radio listening to their favourite music coming from pirate radio stations such a Radio Caroline and Radio London, illegally broadcasting from offshore. It wasn’t until 1967 that the BBC threw in the towel and set up Radio 1 to cater for a younger audience!

STEREOPHONY

The final chapter of the manual is devoted to describing the basic principles of ‘STEREOPHONY’. Even though stereophonic records had been around for several years, by 1962 stereo broadcasting was still in it’s infancy. Around this time there were a number of experimental BBC broadcasts. In our house I can remember my Dad following the instructions for a particular broadcast by setting up 2 radio sets tuned to different programmes, one carrying the left-hand channel and one carrying the right !! Unfortunately the 2 radios were very different sizes and so the effect was somewhat less than perfect! It was not until 1973 that Radios 1,2 and 4 finally broadcast in stereo.

In Conclusion.

Although a small amount of space is given to sound in the context of television, this manual is firmly focused on ‘High-Quality Sound Production and Reproduction’ for BBC Radio. Tape had pretty much replaced 78 rpm discs as the primary means of recording and storing programmes. FM broadcasting was a huge technical leap forward and the arrival of some new condenser microphones further improved the quality of the output. Nevertheless, in many respects, even by 1962 ‘Auntie’ still had one foot firmly in the 1930’s !

 

 

 

 

‘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.

 

Sennheiser ”Telemike” (Circa 1976) with ME20, ME40 & ME80 capsules.

Sennheiser ''Telemike'' Operating Instructions. 1976

Sennheiser Telemike with ME80, ME40 and ME20 Capsules

My eBay bargain with K2-U powering module and MZF 802-U 100Hz filter.

Below, page from ‘Telemike’ manual.Sennheiser Telemike Operating Instructions 1976Spezial Teleskop MZS 802

Sennheiser’s ‘Telemike’ is an extremely versatile, high quality, modular, electret microphone system originally designed for reporters and film makers. It consists of a powering module K1, K2 or K3, a metre long telescopic boom arm MZS 802, (how cool is that?) and a choice of 3 interchangeable microphone modules (ME-20 Omni, ME-40 Super-Cardioid or ME-80 Shotgun) There were  also a number of accessories such as the 100Hz filter, windscreens and various clip mounts and table stands.

Unlike all of the other Sennheiser microphones in my collection ‘Telemike’ is extremely light. Even with the ME80 attached to the telescopic boom it adds very little weight to a camera or portable tape machine, making it an attractive tool for location recording. Back in the 70’s an additional benefit of the telescopic boom was that it kept the microphone at a distance from the motor noise of the camera or tape machine.

Apart from professional users ‘Telemike’ also attracted an army of amateur video camera owners and tape recording enthusiasts. It was easy to use and came with a handy booklet of instructions on how to connect Sennheiser mics to a huge range of tape recorders from 51 different manufacturers!! (No that isn’t a typo!) My Dad was a tape enthusiast with an interest in local history, and so when I was a child we always had at least 2 tape recorders in the house! The microphones that were supplied with domestic machines were usually of poor quality. These Sennheiser mics offered the keen amateur a huge improvement in sound quality. They also produced excellent results with more professional machines such as the Revox A77 and B77 which did not provide on board phantom power.

CLICK HERE  for a short voice demo of ”Telemike” featuring all 3 capsules.

Original Users guide and Technical SpecificationsSennheiser MKE 202 User manualsennheiser mke202 manual002sennheiser mke202 manual003sennheiser mke202 manual004sennheiser mke202 manual005sennheiser mke202 manual006sennheiser mke202 manual007sennheiser mke202 manual008sennheiser mke202 manual009sennheiser mke202 manual010

Sennheiser MKE 202. (with K2pre-amp)Sennheiser MKE 202Sennheiser MKE803 (K3 pre-amp with 3 position bass roll-off)Sennheiser MKE803

These versatile modules can also be simply used either hand held or stand mounted. All in all, a very useful set of microphones!

 

 

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 Parabolic Microphone.

In the Beginning.

The notion of using a parabolic reflector to pick up sounds from afar has been around for many years.

With the advent of aerial warfare in the First World War, the British military started developing acoustical devices to provide early warning of incoming enemy aircraft. The first ‘sound mirror’ was erected in Maidstone in April 1915. During the 1930s, in the run-up to World War 2, a number of these enormous concrete parabolic reflectors appeared along the South coast of England and at other strategic locations. The largest of these structures could detect aircraft at a distance of 25 miles. However, the whole project was abruptly abandoned in 1938 with the invention of Radar!

WW1 30ft Sound Mirror

The listening ‘trumpet’ seen on this dish could be rotated to find the strongest signal. This would enable the listener in the control room beneath the dish to calculate the direction of the incoming aircraft. The information could then be relayed to anti-aircraft batteries.

Parabolic Ears

A ‘stereo’ device like this could be used to pick up activity in enemy positions and provide early warning of attack. (That is if you could hear anything above the sound of your mates laughing their heads off!)

The Parabolic Microphone

In the post war years with the rise of television and the increasing popularity natural history broadcasts on both wireless and TV, sound recordists were quick to adopt the parabolic microphone i.e. an omni or a cardioid microphone, mounted facing inwards, at the central focal point of a portable parabolic dish.


Parabolic MIcrophone

The author recording birds in the trees down at the bottom of the garden.  CLICK HERE to share in the joy!

A parabolic reflector has one significant advantage over other sound pick-up devices: it is a noiseless acoustic amplifier. The frequency response and polar pattern are a function of the size of the dish used. The enormous concrete military dishes of the 1930’s were often 30ft in diameter or more, enabling them to detect the lowest frequencies of an aircraft engine over huge distances. For the modern wildlife recordist a somewhat smaller portable dish is something of a compromise! For a narrow forward beam of 10 degrees a 60cm diameter dish gives around 14db (x5) gain to frequencies above 500Hz. A 1m dish will give 20db (x10) gain to frequencies above 300Hz. The forward gain of a reflector is defined as the difference in output level between a microphone which is reflector-mounted compared to the same microphone unmounted. Even with a modest sized reflector, the on-axis sound of the chosen subject is greatly magnified without adding any of the hiss and hum associated with electronic amplification. However, given the narrow beam characteristics of the dish, one thing that the recordist should bear in mind is that if the subject moves off axis the tonal quality of the sound will change. This can be difficult if for instance the subject is moving around in a group of birds. For that reason I would suggest that the parabolic dish is at its best when recording an isolated single subject.

Frequency/ Directional Response Plot for a typical parabolic reflector for wildlife recordingParabolic Dish Frequency plot

Using an unmounted microphone there are many wildlife recording situations in which it is simply not possible for the sound recordist to get close enough to achieve a good signal to noise ratio. As you creep up with your microphone the subject simply flies off or runs away! ……..Or in the case of dangerous wild animals it may be the sound recordist who does the running! The parabolic dish enables the sound recordist to record from a safe distance without risk of disturbing the subject or getting eaten!

One of the most common problems with wildlife recording is that quite often the perfect recording opportunity comes up without warning. Animals and birds are not predictable. Hence, my minimalist, rapid response kit, illustrated below is light, portable and very fast to set up. I can be in record in a matter of seconds!

The Parabolic Microphone. Minimalist Wildlife Sound Recording Kit

  • Extremely light weight, flexible, 50cm plastic parabolic dish available from new UK company innercore
  • Aluminium handle on the back which can also be screwed on to a tripod
  • Simple microphone mount marked at the focal point.
  • HMN Sound MicroLav. N.B. to prevent wind noise a Rycote Furry windshield is recommended. (Not pictured.)
  • M-Audio MicroTrack II set to record in mono at 96kHz 24bit.
  • M-Audio in-ear headphones with industrial ear defenders over the top for isolation.

Walking by a local lake the other day I came across a small flock of Canada geese about 40ft away quietly pottering about on the grassy bank. Suddenly one of them started squawking/honking. I started recording and within a few seconds it flew high into the air and passed straight over my head. On the recording the strange creaking sound of the bird’s wings and the movement of air can be clearly heard. It sounds close up, even though the bird is at least 30ft above me. It then flies round the lake and lands back with the others and carries on honking very loudly. Definitely not a bird you would want to get close to! Would probably make a good guard dog!                                                                           CLICK HERE to take a listen.

Other Uses for the Parabolic Microphone.

When listening to sporting coverage on radio or TV you may have enjoyed the additional excitement of hearing the ball striking the bat or the racket. You may hear the close-up thunder of the horse’s hooves in a race or the grunts and shouts of a rugby scrum and…… Not a microphone in sight!

In Conclusion.

My purpose in writing this post has not been to advertise the merits of a particular set of equipment but merely to suggest some of the possibilities and fun to be had recording sound using a parabolic dish.

P.S. (Nov 2019)  I have just come across this fascinating patent by British Acoustic Films Ltd from 1931 ( !! ) for a Parabolic Microphone for use in film production, recording and broadcasting.  Parabolic Microphone B.A.F Ltd 1931       It even includes a setup whereby sound can be recorded (and mixed) from 3 independent reflectors aimed at 3 different sound sources simultaneously using a single microphone!  Wow!