Category Archives: Microphone techniques Ancient & Modern

Shure 430 ‘Commando’ Controlled Magnetic / Controlled Reluctance Microphone (Circa 1957)

Shure Model 430 CommandoShure 430 Commando grill

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.

  • DYNAMIC MICROPHONEDynamic-moving-coil-diagram
  • CONTROLLED RELUCTANCE/MAGNETIC MICROPHONE (2 slightly different versions)Controlled Reluctance Microphone Sectional Diagram

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” <support@shure.eu> 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.

Answer Link: Difference between controlled reluctance and controlled magnetic

This type of mic was originally designed for military applications.

Michael Pettersen

Shure Historian

 


2 pin Ampenol Connector

If you buy a 430 make sure it comes with one of these as 2 pin Amphenol connectors are hard to find.

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!

Shure 430 Commando head

Data Sheet for the Shure Commando series.:-     us_pro_415_ug

Shure Microphones  :-  1957 Catalogue

 430 Commando Original Box

So what does it sound like?  CLICK HERE for a short clip of spoken word and Blues Harmonica.

 

Dynamic Microphones for Classical Recording?!

In the late 1950’s Electro-Voice ceased production of both ribbon and condenser microphones. In an article in his series ‘MICROPHONE FACTS for the operating engineer’ Electro-Voice founder Lou Burroughs explained the decision and presented reasons why dynamic microphones were, in every way, superior. The feeling at Electro-Voice was that ribbons and condensers were too fragile and prone to failure and that dynamics were solid and reliable and sounded better. Towards the end of the article (referring to dynamics) Burroughs declares that ‘These are the microphones of the future’.

Today, although dynamic mics are still revered for their robustness and ability to handle high SPLs they are not generally considered to be sonically superior to all other microphones! Indeed, I can’t imagine many engineers taking a pair of dynamics out to record an orchestral concert of classical music instead of their usual selection of condensers and ribbons.

Compared to condensers Burroughs claimed that dynamics have a ‘smoother high frequency response’ and so, here (by way of an experiment) are a  couple  of clips from an orchestral concert I recorded recently using a pair of Soviet Era, Russian, Oktava MD186 dynamics! I was simply curious to see if Lou Burroughs maybe had a point?

CLICK HERE for End of Beethoven’s Fifth

CLICK HERE for Mozart Piano Concerto

Electro-Voice EV642, 643, & 644 Cardiline Microphones , (circa)1960

Ever since the advent of the ‘Talkies’ sound technicians have struggled to pick up speech in motion pictures with sufficient clarity. For many years the problem of getting the microphone close enough to the performers without it being in the camera shot was a constant challenge!  On the other hand if the mic was too far away the sound was often ruined by the pickup of unwanted surrounding noise.

Seeking to address this problem, in October 1959 Wayne A. Beaverson of Electro-Voice filed for a patent on a new type of directional microphone which could be successfully operated at a distance from the sound source.  At low frequencies this microphone exhibits the directional characteristics of a cardioid mic, with excellent rear rejection. As the frequency response rises it becomes a line mic with considerable attenuation of unwanted sound from the sides. Thus the new ‘Cardiline’ design provides excellent directivity right across its operating frequency range.

Electro-Voice Patent for Unidirectional Microphone 1963

The success of the new microphone was such that in 1963 Electro-Voice received an Academy Awards “Oscar” for the development of the model 642 Cardiline, The award, in part, read “To Electro-Voice for a highly directional dynamic line microphone… capable of picking up sound in situations where a microphone cannot be placed close to the sound source and where unwanted sounds are to be discriminated against.”

Although the Academy Award went to the 642, the microphone drawn and described in the original patent application was in fact its close cousin the EV644. At this point you might be wondering about the 643?  Well ……… The 643 was pretty much the same as the 642 except in one significant detail ……… it was just over 7 feet long!  All three of these mics were of the Cardiline pattern but they were aimed (excuse the pun) at different areas of the market. As we know, the 642 was tailored very much for the film and TV industry and came with an elastic mount for attaching to a boom.

EV642 Advert 1963

EV643  Advert

Electro-Voice_643 Advert

electrovoice_643_2

Although extravagant claims are made for the mighty 643 in the advert above, I suspect that this mic was in fact quite awkward and unwieldy to use (even sighting along the barrel!!) It is certainly hard to find any fond recollections of it. I came across one report from some poor sod who once spent an afternoon standing on the roof of a football stadium trying to follow the ball round the field!! Anyone who has ever operated a theatre follow spot will appreciate just how ludicrous that must have been!

Which leaves the 644. (My latest eBay bargain!)

electro-voice-ev644

Designed for use on stage, in theatres, auditoriums and churches,  the EV644 Sound Spot came with a microphone stand mounting and was finished in classic Electro-Voice chrome. You could also buy it with a dull matt paint finish,(non-reflective under lighting), but why do that when the chrome version just looks so rock’n’roll cool !

Allied Catalogue 1960

List Price $110. A bargain at $64.68 ! (Not cheap in 1960!)

ev644-back-end ev644-body-and-stand-mountev644-end-grillev644-original-box-insideev644-original-box

CLICK HERE for Voice recording at a distance of 12ft

CLICK HERE for Glockenspiel Recording

In Conclusion

The 1963 patent shown above acknowledges a number of earlier inventions relating to directional microphones. In particular the patents of Harry Olson dating back to 1939. However, the earlier inventions, (mostly involving complex arrangements of multiple tubes of differing lengths), were awkward and cumbersome. In contrast, Beaverson’s Cardiline microphone, using a single multi-path tube feeding a single cardioid capsule, was an uncomplicated work of genius. It was both effective and easy to use.

To this day the elements of Beaverson’s patent can to be seen in shotgun microphones all over the world.

Below are the Techincal Specification Sheets for all 3 microphones.

Electro-Voice 642 Spec Sheet

Electro-Voice 643 Tech Spec.

Electro-Voice 644 Tech Spec

Experimental Line Array Microphone

making-line-array-mount

Improvising the mount for a 4 Element Line Array Microphone.

line-array-microphone

My basic 4 Element Line Array Microphone.  (Using 4 x Omnidirectional Karma K-Micro Silver Bullets)

shure-m268-front-panel

A handy little pre-amp for my line array. A Shure M268 4 x channel Mono Microphone Mixer. Surprisingly clean-sounding for its age!

Line array theory has been around since the 1930’s. In the 50’s and 60’s basic line arrays were very popular in the form of the column loudspeaker commonly used for PA. These days we are used to seeing massive line array speaker systems flown above the stage at festivals and concerts.

On the other hand the line array microphone is a rare breed and the few that are around, such as the impressive Microtech Gefell KEM970, tend to be expensive. The KEM970 is around £10,000.

In common with the shotgun microphone, the line array is a phase-reactive device. Unlike the shotgun where the on-axis position is down the length of the interference tube, with the line array the on-axis position is side-on at 90 degrees to the vertical column. Sound arriving at 90 degrees will be in phase at all of the capsules. The electrical output from each capsule will be identical and therefore additive. Sound arriving off-axis will suffer varying degrees of phase cancellation, depending on the frequency and the angle of incidence.

The polar pattern of a line array microphone is therefore wide in the horizontal plane and narrow in the vertical, getting narrower with rising frequency. This enables the mic to pick up over longer distances whilst rejecting mid and high frequency sound arriving off axis ( ie below and above.)

N.B.The longer the array (ie the more elements in the line) the lower the frequency at which it starts to be effective.

line-array-microphone-polar-pattern

Polar Plot at 1kHz

Below about 400Hz my 4 element model becomes increasingly omni-directional.  In this respect it is once again  similar to a shotgun.

Over the next few months I am planning a number of experiments to explore how this array will behave and to see what practical applications I can find for it!  I’ll report back…………..

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ASTON ORIGIN (2016)

It is not often that I buy anything simply on the strength of the advertising, but in the case of the Aston Origin that is exactly what I did! In fact worse than that I bought two! Aston Origin Out of Box As a rule when you make this kind of impulse purchase, the goods arrive and you are doomed to disappointment. However, on this occasion it turns out that Aston microphones are as good in real life as they look on paper and on the website! Every aspect of the product has been carefully considered and designed from the ground up, everything from the unique flexible grill to the eco-friendly packaging.

At the present time the myriad of competitors  in this price range are mostly derivatives of older designs, often vaguely resembling particular vintage Neumann or AKG models. Aston Microphones have launched into this rather tired and jaded market place with product that is radically different.

Designed and built in the UK the Aston Origin not only has eccentric good looks, but it also boasts a distinctive ‘British’ sound. A sound shaped by a panel of 33 well known UK producers and recording professionals, who listened to every element of the audio chain, and by a lengthy process of elimination, chose the very best sounding components. For the full story and technical specifications visit: – http://www.astonmics.com/

The stand mounting options are either the very classy custom Rycote InVision shock mount (left) or simply screwing the mic straight on to the stand.(right)

The stand mounting options are either the very classy custom Rycote InVision shock mount (left) or simply screwing the mic straight on to the stand.(right)

My only criticism of screwing the mic straight on to the stand is that whilst this is quick and easy, it is not always possible to manoeuvre the mic into exactly the right place.

Below is my homemade rotating knuckle joint which allows the mic to be moved into any position whilst screwed directly to the stand.     It is made from the top piece of an old camera tripod. Using Milliput (which sets rock hard) I glued a 3/8 inch thread adapter into the base.  Then over the screw which would normally hold the camera, I glued a 3/8 inch stand adapter to hold the mic. The ball-joint, which can rotate in any direction, is fixed by screwing down the chrome locking ring.

Rotating Knuckle Joint for Aston Origin

So What Does It Sound Like?

CLICK HERE for Rain Stick transient response test

CLICK HERE for Saxophone.

CLICK HERE for Piano and Orchestra

Neumann U87Ai  v  Aston Origin CLICK HERE

Neumann U87AiAston Origin grill

N.B.

The Neumann U87Ai is 8 x the price of the Aston Origin!

Here are my Aston Origins used to record Vocals, Guitars and Harmonica on the title track of Steve Ashley’s new album ‘Another Day’.

FUN WITH FIGURE-OF-EIGHT! Episode 1 Radio and Film.

RADIO

Back in the 1950s the iconic Marconi AX ribbon microphone was the main tool for BBC drama production.  Actors were familiar with its figure of eight characteristics, and would utilise the dead zones at the sides of the mic to great effect. Noisy page turns could be avoided by holding the script to the side of the mic. The impression of going off into the distance could be achieved by simply delivering the lines whilst slowly moving to the side of the microphone. Shouting from a distance could be managed in the same way. Actors were also very conscious users of proximity effect, moving closer or further from the microphone as the script required.

CLICK FOR SHORT VOICE DEMO.

Figure of Eight Marconi AX                                                             BBC Training Manual 1942

Bearing this in mind an elderly ex-BBC producer told me the following delightful tale about a well- known actor of the day.

Whenever a trainee or inexperienced engineer was spotted entering the control booth he would go through the same entertaining routine. On being asked to deliver some lines to test the mic, he would start speaking in a fairly quiet voice whilst very gradually moving his head round the side of the mic. All the while the hapless young knob- twiddler in the control booth would be increasing the gain on the input. When our actor judged that the gain was almost certainly up full he would deftly swing his head back to the front of the mic and inquire in rich, thespian tones, (as if addressing the back row of the gallery)                            ‘HOW’S THAT FOR LEVEL?!!’

 

FILM

In the early days of talking pictures, years before the invention of the shotgun microphone, considerable use was made of the directional characteristics of figure-of-eight ribbon microphones to minimise the pick- up of unwanted noise on the set.  Cameras and other noisy equipment could be positioned in the dead zones. This greatly improved the quality and intelligibility of the end product. It also made it possible (using more than one microphone) to balance the levels of different performer’s voices. This had not previously been possible using Omni-directional models.

Filming in locations with high levels of surrounding ambient noise, a figure-of-eight could be suspended horizontally above the actors’ heads. The back of the mic faced upwards (away from the sound sources) and the front faced downwards towards the actors. In this position the dead zone effectively attenuated 360 degrees of surrounding noise!

These days, when recording studios seem to be generally stuck in Cardioid mode, I thought it might make a pleasant change to revive some of these vintage figure-of-eight techniques. In the following episodes I shall take a look at more uses for this versatile but somewhat neglected polar pattern.

 

Looking for the Perfect Gift?

 One of my favourite recordings from this year. Makes me feel like I’m sitting in a French cafe on a sunny day! Gypsy jazz beautifully played  by AC Woods and Fenner Curtis and captured in authentic mono on my 1930’s  Siemens ribbon mic.  

a3200302581_16

Echoes of France, by Echoes of France