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- 1930s Microphone
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- A Rare Siemens (?)/ Telefunken (?)/ Klangfilm (?) Microphone.
- BBC Microphones
- Boundary Layer Microphone
- Christmas Posts
- Conference/Podium Microphone
- Extinct Audio
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- Line Array Microphone
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- Microphone Tech Specs
- Microphone techniques Ancient & Modern
- Mititary Microphones
- New Microphones
- Noise- cancelling microphones
- Parabolic Microphone
- Presidential Microphones
- Recording in stereo
- Ribbon Microphones
- Russian Microphones.
- STC Microphones
- Stereo Microphone Techniques
- Stereo Pair
- Vintage Broadcasting
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- Vintage Microphones
- Vintage PA Microphone
- WW2 Microphones
First introduced in 1987 the AKG C747 was originally designed for ‘unobtrusive speech applications when mounted on a podium or lectern, or for teleconferencing activities’. From this somewhat uninspiring start, these days the C747 is widely acknowledged as one of the most versatile microphones AKG ever produced!
Just a glance at the tech spec tells you that this was not a microphone simply doomed to deliver the Chairman’s annual report!
- Smooth frequency response from 30Hz -18kHz.
- Rapid transient response produced by tiny, low-mass, capsule.
- Tight hypercardioid polar pattern, giving excellent separation.
- SPL rating of 133db.
It didn’t take engineers long to realise that this neat, pencil sized miniature shotgun microphone has many uses away from the conference hall!
I recently acquired a well-matched pair of old C747s and it occurred to me that although advertised as having some ‘shotgun’ characteristics, these neat little condensers do in fact behave pretty much the same as any other hypercardioid microphone. I therefore wondered how they would get on as a crossed stereo pair. I have seen them occasionally used like that in a conference speech setup, but never recording a large symphony orchestra! (Frequently used as spot mics but certainly not as the main pair!) So here goes …………
The mics were crossed at 65 degrees (at the capsules) and positioned on a tall stand about a metre behind the conductor. N.B. To get the full effect of this recording you need to download it in full resolution and play it on speakers at the sort of volume that will really annoy your neighbours!
Here below are the Tech specs for both the AKG C747 and the current model the C747 11. It is interesting to note that in the C747 11 literature various instrumental applications are also illustrated. (guitar, saxophone, snare, drum) The newer model also has a slightly different frequency response, more tailored towards speech. Either way these are fabulous, unobtrusive, little mics that will blend seamlessly into almost any situation!
N.B. The Hi-Pass filter on these mics is hidden away in the XLR plug (also containing the mic preamp) I included this last photo because, in conversation with the previous owner, he told me that he never realised that the 747 had a hi-pass switch!! When working close up he ‘Always found them a bit too bassy ‘ !
Is it just me? For the last year, every time I see this mic setup I can’t help laughing. The enormous hot air filter and the unusual ‘cantilever’ (upside down) mount. The donut shock absorber, the quirky gooseneck stand, and at the heart of it all………… is that a ‘Made in Mexico’ Shure SM57?
The Shure VIP Mount used by previous US presidents was an image copied by politicians all over the world. It will be interesting to see if this somewhat ‘eccentric’ new look ever catches on. Somehow, I doubt it!
If you are looking for a small diaphragm condenser microphone that will add extra sparkle to your high end, more presence to your mids, and greater weight to your bass………… then the Oktava MK-012 is definitely not for you!! However, if you are looking for an accurate microphone which simply reproduces what it hears, then the Oktava MK-012 is definitely worth considering.
I bought a matched stereo pair about 10 years ago (direct from Oktava) and they have earned me more money than any other mics I own! I have used them on hundreds of live shows for many different purposes, including drum overheads, hi-hat, Latin percussion, grand piano, acoustic instruments, and as ambient mics. However, it is on classical music recording that they really excel. I have used them in a variety of stereo configurations and in each case they provide a clean accurate account of the performance, capturing the finest nuances of timbre and texture.
Here below are my favourite stereo microphone techniques illustrated with the Oktava Mk-012s
These microphones have not been ‘modified’ in any way and the recordings linked below have not been EQ’d or processed. Although the streaming quality is reasonably good, for more detailed listening most of the tracks can be downloaded off Soundcloud in their original full resolution wav format.
Near-coincident X-Y crossed pair at 90 degrees gives a phase-coherent stereo image with excellent positionality. The angle between the mics can be altered to suit the width of the subject and the relative distance of the mic placement. Particularly useful for chamber music and small ensembles. Cardioid or hyper-cardioid capsules can be used.
Oktava do now make a dedicated figure of eight capsule. In which case a pair of those would be another option.
N.B. The shock mounts are Rycote InVision INV-7 and (below with piggyback clips)
M-S pair using the Oktava figure of eight adapter which utilises 2 cardioid capsules back to back, in opposite phase. The Mid mic can be cardioid, hyper-cardioid or omni. As with the X-Y array, the M-S pair produce an accurate phase-coherent image. Works exceedingly well on wide subjects such as orchestras and choirs, particularly when the mic position needs to be close to the performers. Has the additional advantage that the relative levels of the mics can be manipulated in post-production. (Reducing the level of the Mid mic and raising the Side channels widens the image. Increasing the Mid and lowering the Sides ends in Mono!)
ORTF pair. Cardioid capsules set at 55 degrees and spaced 17 cm apart. Emulating the inter-aural time differences between our ears this configuration produces a detailed but somewhat more diffuse stereo image than the previous examples. This array produces a good sense of depth and perspective. Many engineers argue that ORTF pairs give a more ‘musical’ sound. (?) Excellent for choirs and orchestras.
The Jecklin Disc takes the principles of the ORTF pair one step further and introduces a foam and fur covered 12”disc between the microphone ‘ears’, emulating the reflective, and shading characteristics of the human head. This array utilises a spaced pair of omni capsules angled slightly outwards. The Jecklin disc with a pair of MK-012s produces a remarkable sense of ‘being there’. Excellent in situations where, along with the performance, you want to capture the acoustics of a great sounding hall or church. Good with subjects of any size and can be positioned at a distance without losing ‘presence’.
Some years ago whilst recording a live performance of Monteverdi Vespers, I was somewhat taken aback at the start of the concert by the following occurrence. As the choir processed in from the back of the church, they suddenly started singing!! Arrgh! With almost any other array this would have been a recording disaster. As it was, the pick-up of the Jecklin disc with its MK-012 omnis is pretty much the same from behind! The choir processed down the length of the church and filed past on either side of the mic stand and took their positions in front still singing! Sounded great!
One thing I particularly liked about my MK-012s when they arrived, was the inclusion of individual printouts of the response characteristics of each of the 6 capsules. Below is the printout comparing the matched frequency response of the 2 cardioid capsules, complete with handwritten details!
Having provided a neat wooden box it is commendable that Oktava didn’t waste money on fancy, glossy, printing on the packaging! No hype, no bullshit, no celebrity endorsements, just a great sounding pair of mics !
Made in Paris between 1948 and 1958 by Mélodium Société, 296 rue Lecourbe 15eme.
Although visually the design harks back to the 1930s it has a surprisingly modern sound. This is borne out by the frequency graph, which shows a smooth response from 50 Hz to 10 kHz.There is a presence lift of 5db at around 4.8 kHz which lends clarity and crispness, particularly to speech and vocals.
The 75A boasts a very light duralumin diaphragm and voice coil (30mg), giving good transient response. It is also claimed that the microphone is impervious to wind, making it an excellent choice for outside broadcasting and sports reporting.
The grill design featured in the technical leaflet above was used on the earlier models.
If you buy a Mélodium 75A it is worth noting that it has very low impedance (10 ohms) and will require the services of an appropriate preamp.
Also, the plug socket on the 75A is peculiar to Mélodium! (N.B. The earliest models have 3 screw terminals.)
N.B. Right hand pin is ‘hot’. Left hand pin ‘cold’. Centre pin is earth.
The Mélodium 75A was employed extensively by French broadcasters and was used by many famous entertainers and politicians, including the singer Edith Piaf and President Charles de Gaulle.
Even with this slightly creepy, wax works figure of Edith Piaf, at Musée Grévin in Paris, the Mélodium 75A takes stage centre!
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!
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.
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.
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.’
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.
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.
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’ !!!!!
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.
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.
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).
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.
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)
The Controlled Reluctance microphone (aka Controlled Magnetic) was developed by Shure during World War 2 to fulfil the need for a battle announce microphone that could operate reliably at extremes of temperature and humidity. (Subsequently also perfect for Korea and Vietnam!)
Although the Controlled Reluctance design was in some respects similar to a conventional dynamic in other ways it was significantly different.
The 2 diagrams below illustrate the differences.
Here, in response to an email enquiry, is an explanation from Shure of the working of this microphone
On 3 May 2017 15:06, “Shure Europe” <firstname.lastname@example.org> wrote:
Response By Email (Michael P) (05/03/2017 09:06 AM)
Controlled reluctance is a variation of a dynamic mic. The controlled reluctance mic diaphragm connects to a small lever made from ferrous material. The other end of this lever is positioned inside of a stationary coil of wire. Surrounding the coil of wire is a stationary magnet. As the ferrous lever is moved by the mic diaphragm, the lever disturbs the magnet field. This induces an AC signal (the audio signal) in the coil of wire.
This type of mic was originally designed for military applications.
The CR/CM elements have a high output (making them suitable for transmission over large distances) and require no additional transformer. They are therefore cheaper to manufacture than a conventional dynamic.
After WW2 Shure introduced several models for the civilian market, including the famous Green Bullet (still popular with harmonica players to this day). These were mostly budget PA mics intended for speech applications such as paging and announcements. Whilst not being particularly noted for high quality audio, their main selling points were cheapness and reliability. It is therefore not hard to see why these sturdy, affordable mics soon found favour with musicians and singers.
Apart from being highly profitable, Shure’s military communications contracts had the additional spin-off of enhancing a lasting reputation for reliability. Indeed, the company have often boasted that all of their products are tested to military standards (MILSPEC). Even though the Model 430 was made for the civilian, domestic market it nevertheless trades on its military heritage with the name ‘Commando’ and it’s distinctive, camouflage green head!
Data Sheet for the Shure Commando series.:- us_pro_415_ug
Shure Microphones :- 1957 Catalogue
So what does it sound like? CLICK HERE for a short clip of spoken word and Blues Harmonica.