Category Archives: Microphone techniques Ancient & Modern

LABOR W MD7 Omnidirectional Dynamic Microphone Circa 1950.

A Short History Lesson.

In 1945, just a few weeks after the end of World War 2 Fritz Sennheiser and 7 fellow engineers from the University of Hanover set up a business designing and producing a range of electrical equipment in a laboratory called Laboratorium Wennebostel (“LABOR W” for short). The laboratory was named after the village of Wennebostel in the municipality of Wedemark, where it had been relocated during the war. LABOR W began building microphones in 1946 and by 1953 (see catalogue below) they had developed a whole range of microphones, including the legendary MD 21 which is still in production today. By 1955 the company had expanded to 250 employees and in 1958 changed its name to Sennheiser.  

These days microphones from the early LABOR W period are becoming increasingly rare, so when this unusual looking MD7H turned up on eBay, ‘untested’ but very cheap, I immediately clicked ‘Buy Now’.

LABOR W MD7H   front view
LABOR W MD7H  front view 2
LABOR W MD7H rear view
The ‘H’ indicates that this is the High impedance version.

The photograph on eBay however, gave no sense of scale and it wasn’t until the microphone arrived that I realised just how small it is! I was reminded of the anecdote of the person who buys a gorgeous sofa online at a bargain price and when it arrives it turns out to be for a dolls house! Had I seen the LABOR W advert below that might have given me a clue.

LABOR W MD7 Advert early 1950's
‘Our most powerful moving coil microphone
MD7 for speech’

Below are the microphones featured in the 1953 LABOR W Catalogue.

Microphones featured in the 1953 LABOR W Catalogue. Page 1
Microphones featured in the 1953 LABOR W Catalogue. Page 2

(Translation of catalogue description above)

‘MD7 Speech microphone

Particularly good speech intelligibility due to emphasis on high frequencies. Therefore recommended for announcement and dictation systems. The soft rubber housing makes the MD7 insensitive to rough handling. Available in low and high impedance versions.

Dimensions: 76 x 48 x 48mm.’

For a sense of scale here below is the baby MD7 along with its Senneiser cousins the MD21 , MD421 and the mighty MD441.

LABOR W MD7 along with its Senneiser cousins the MD21 , MD421 and the mighty MD441.

Innovative design

In the early 50’s the soft rubber housing of the MD7 was an innovative design feature, and indeed made it very robust and resistant to rough handling. I haven’t tried it, but I think it would probably bounce if dropped from a height! It therefore came as no surprise once I had soldered a jack plug on to the cable it burst into life working perfectly.

So what does it sound like? CLICK HERE

LABOR W production came to an end in 1958 and the name changed to SENNHEISER. The rest is history!

The Capac BIN-AURAL (1936- c1960) ‘The accurate and simple equipment for testing the internal condition of mechanism “by sound” .

Although we are all familiar with the medical stethoscope used by doctors to listen to the internal condition of the patient’s heart and lungs etc., few will be familiar with the use of stethoscopes in other industries.

In 1936 British engineer Charles Edward Noel-Storr, Managing Director at Capac Co. Ltd in London, came up with an interesting variation on the stethoscopes that were available at the time.                                            

 The Capac BIN-AURAL 

Capac BIN-AURAL oak case
Who can resist a gorgeous oak case?
Capac BIN-AURAL in its oak case
WOW!
Capac BIN-AURAL in oak case with tray removed.

Capac Company’s BIN-AURAL was somewhat similar in appearance to a medical stethoscope and was used to detect faults and assess the condition of a variety of mechanical devices and structures.

Capac BIN-AURAL with single tectoscope.

The long probe called a tectoscope can be put in contact with the outside part of a machine/engine/structure and the sound from inside is transmitted back to the earpieces via a metal diaphragm. In this way the skilled mechanic can identify specific problems. Virtually no sound is picked up from outside, making it perfect for isolating faults in noisy environments such as factories and machine shops.

The Author. Listening to car engine using Capac BIN-AURAL with single tectoscope.

So what made the Capac BIN-AURAL different to its competitors?

Apart from the single tectoscope illustrated above the user could also employ a second tectoscope. This enables the operator to listen to the mechanism from 2 different points simultaneously.

Capac BIN-AURAL with two tectoscopes.

A further option is also available in the form of the Tectophone.

The tectophone (illustrated below) is a small exponential horn which is screwed on to the diaphragm. This can be used to listen in close proximity to the outside of a mechanism in the particular location where faults are suspected. It can also be used in conjunction with a tectoscope to listen to the outside and inside simultaneously or to compare.

Capac BIN-AURAL with tectophone and tectoscope.

For a detailed explanation of the uses of the Capac BIN-AURAL I have reproduced below the original manual that came in the box.

01 CAPAC BIN-AURAL Manual Cover
02 CAPAC BIN-AURAL Manual Page 1
03 CAPAC BIN-AURAL Manual Page 2
04 CAPAC BIN-AURAL Manual Page 3
04 CAPAC BIN-AURAL Manual Back Page

CONCLUSION

In the build up to World War 2 aero engine makers such as Armstrong Siddeley Motor Limited, Bristol Aeroplane Company Limited, D. Napier & Son Limited and many other British engineering companies adopted the Capac BIN-AURAL as an effective diagnostic tool. With the aid of the BIN-AURAL, a mechanic could pinpoint the source of a sound, or listen to that sound from 2 different perspectives.

P.S. Whilst the Capac BIN-AURAL is not itself a microphone, a microphone can be easily attached, making it a great tool for gathering unusual sounds from inside engines and machines and other structures.

Capac BIN-AURAL with Sennheiser MKE2. Insert into tubing.
Capac BIN-AURAL with Sennheiser MKE2. Insert into tubing. Closeup.

The following ‘collage’ recording of bits of my car engine has been made with a Sennheiser MKE2 inserted into the rubber tubing which connects to the tectoscopes.

CLICK HERE to listen

Omnidirectional Dynamic Vocal Microphones

Up until the late 1960’s, cardioid, omnidirectional and figure of eight dynamic microphones were all commonly found in use on public address systems. Singers were able to choose whichever pattern suited their particular style of delivery. Figure of eight ribbon mics, for instance, were enormously popular with the jazz singers and ‘crooners’ of the 40’s and 50’s because of their smooth response and rich proximity effect which enhanced the low end of the voice. Omni was preferred by singers who required a more ‘open’ sound and the ability to move around without altering tone. Unfortunately, with the development of high power PA systems and the introduction of wedge monitoring in the late 60’s, only cardioid microphones had the required rejection characteristics to deliver a suitable amount of gain before feedback. Consequently, within a few years figure of eight and omni all but vanished from the stage and were pretty much banished to the studio!

I recently acquired a number of vintage omnidirectional dynamic mics from the tail end of the last century. Although the primary purpose of these mics was originally news gathering, my attention was drawn to the following excerpt from the AKG Engineering Data sheet for the D130. It perfectly describes the numerous benefits that an omnidirectional microphone offers the vocal performer.

AKG D130 Data Sheet.

A wide-range instrument, the D-130E offers “open”, natural reproduction of speech and music -without harshness, popping or bass emphasis. Moreover, the D-130E ‘s omnidirectional pattern and consequent absence of proximity effect enable the microphone to retain this natural quality -regardless of the relative position or distance of performers working into it. Together with its handling comfort and attractive styling, these same characteristics also lend the D-130E to a variety of hand-held on-camera applications in the studio -especially to pop-free coverage of vocalists who do not desire proximity effect.

Many singers (especially male vocalists) have an uncomfortable relationship with cardioid microphones because of their inclination towards ‘boomy’ bass and unpleasant popping plosives. I have also worked with performers who are in the habit of pulling away from the mic when delivering the loud bits leaving their voices sounding suddenly thin and weedy (N.B. Proximity effect works in both directions i.e. moving away reduces bass). With omni the bass remains constant with the desired reduction in volume.

And another thing………

For performers whose vocal style involves ‘cupping’ the back of a cardioid dynamic, maybe an omni would be a better choice? It comes ready ‘cupped’!

SM58 cuppingBeyer M58 2 N (C)

 

 

 

 

 

 

 

So…….. Here’s a thought…….

With the rise of in-ear monitoring many performers and bands are dispensing with their cumbersome (and feedback prone) on-stage wedges. So it would seem to me that for cardioid averse vocalists, perhaps now would be a good time to consider bringing back the considerable benefits of the

Omnidirectional Dynamic Vocal Microphone.

AKG D130

Electro-Voice DO56L Dynamic Shock Mount Omni circa 1980

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

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

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

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

Phil Donahue Edit

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

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

What else can it be used for?

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

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

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

 

JrF ‘D’ Series Hydrophone.

JrF D Series Hydrophone and matching transformer

The optional matching transformer is well worth buying to use with XLR inputs.

JrF D Series Hydrophone

Expanding on my recent forays into the wonderful world of outdoor recording I am now starting to explore the possibilities of recording underwater using my newly purchased JrF D-Series Hydrophone. These are handmade to order in the North of England by the acclaimed sound artist Jez Riley French. I was looking for a high quality, lightweight device that is quick and easy to deploy. It is also very reasonably priced!

Hydrophones and the world underwater.

Hydrophones utilise piezoelectric transducers to detect underwater vibrations and pressure differences. A piezoelectric transducer is a device that produces an electric current when a mechanical force is applied to it. No external power source is required. Piezoelectric materials are able to flex under pressure, converting mechanical energy into electrical energy. Because sound is a form of pressure wave that physically moves particles, it produces a mechanical force as it comes in contact with a hydrophone. The first widespread use of hydrophones was during WW1 when they were used to detect enemy submarines. This 100 year old technology is still alive and well! Today they also have wide ranging use in underwater exploration, seismology, aquatic research, and deep sea recording. Apart from these important scientific functions, hydrophones can also simply be used to capture fascinating and unusual sounds with which to delight the ear!

My first Hydrophone Recording

Some friends of ours have a pond in their garden and this seemed like a good place to start. Dropping the hydrophone into clear open water the initial results fell somewhat short of the whales and dolphins I had been imagining…………….  absolute silence!!

However, we persevered. Moving the hydrophone into a patch of water weed suddenly produced this strange sound!  Perhaps some alien life form sending code?   CLICK On Photo

The Ford

This next recording features a delivery van driving through a shallow ford across a stream. The hydrophone is positioned in the middle of the weir about 2 feet out into the stream. As the van passes we hear the initial waves caused by the wheels followed by a strange ‘phasing’ sound produced by the reflected waves bouncing back off the wall on the opposite bank.

The Duck

This final recording is a strange one from another local pond. I dropped the hydrophone into the water close to a large rock just below the surface about 3 feet out from the bank. Along came a duck and started to rub it’s beak on the stone only inches from the hydrophone. I thought at first it was sharpening it’s beak but I am informed by knowledgeable folk that this is in fact a sort of conditioning that ducks carry out. Who knew?

To Conclude

The JrF D-Series hydrophone is a great addition to my microphone collection and has opened up a whole new world of sound exploration. Thoroughly recommended.

 

 

An Audio Postcard From The COVID-19 Lockdown 2020

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

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

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

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

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

AKG C451E with old style logo

AKG C451E no serial number

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

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

AKG C451 CMS Technical Specifications

Technical Info AKG CMS microphones.

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

C451E original case interior AKG C451E Original case

My C451E

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

So What Does it Sound Like?    

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

Meanwhile Stay safe!

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

 

Recording Marimba a New Experience!

One thing I really love about this job is that there is always something new to learn! Having worked as a Sound Engineer for more than 30 years, until last week I had never recorded a Marimba.Marimba One

What an amazing instrument! With a very wide frequency response and huge dynamic range the marimba produces a stunning variety of colour quite unlike any other percussion instrument I can think of. Such tonal subtlety coupled with a battery of rapid transients requires a careful choice of microphone/s.

I did consider using a pair of Sennheiser MD441 dynamics as they have the required frequency response and have an excellent track record on other varieties of percussion, producing a big ‘punchy’ sound with plenty of attack.  I also considered going down the condenser route with a pair of AKG C414s. Great frequency response and bags of detail.  But………… In the end I realised that what was really needed to capture those rapid transients and subtle detail was a high quality stereo ribbon!  In many respects a ribbon microphone has the best of both worlds. Being a variety of dynamic it can pack a great deal of attack and ‘punch’ and on the other hand has an incredibly light diaphragm (ribbon) which can react to transients and fine detail with incredible precision. There is also an intangible ‘smoothness’ to ribbons that even the best condensers just don’t seem to have.

Extinct Audio’s ‘Valkyr’ BM9x2 Stereo Ribbon Microphone was placed on a tall stand, stage centre, about 2m away from the instrument.  The mic set in M-S configuration.

CLICK HERE to hear an excerpt from virtuoso percussionist 18 year old Darcy Beck (winner of Gloucestershire Young Musician of The Year 2020) performing ‘Prism’ by Japanese composer Keiko Abe.Darcy Beck marimbaDarcy Beck marimba

In Conclusion

Apart from capturing the fine detail of even the most rapid passages the ‘Valkyr’ also delivers a very pleasing impression of the reverberant acoustics of the hall.

Season’s Greeting to All My Readers! (Just in case you need some more Christmas Music!)

Usually at this time of the year I post a slightly crazy photo, but this year I thought you might like an audio Christmas card! This video is a piece of Christmassy joy captured by the Extinct Audio BM9x2 ‘Valkyr’ Stereo Ribbon Microphone. Apart from the fabulous audio quality and detailed stereo image this microphone is also extremely unobtrusive (see pics), making it perfect for this type of live performance.

No EQ or processing has been used.

Many thanks to Pam Smith at http://www.petalpics.co.uk/ for the great photos.

Martin Mitchell’s Music For 3 Saucepan Lids and Spatula ! Recorded by the Gaumont-Kalee Type 492. 😊

Inspired by washing up! I did this recording for a bit of amusement on a cold rainy Saturday morning (crazy sound engineer’s idea of having fun!) ……… but I really love the way this beautiful old ribbon mic reproduces the ring and detail of these sounds. I suspect that the 492 would also make a great drum overhead. Anyhow, enjoy!