Category Archives: 1980’s Microphone

UNITRA Tonsil MCU-53 Cardioid Condenser (1970’s/80’s)

History

In the early 1970’s MB Electronic (now known as MBHO) produced the MB C540. This was a high quality battery powered condenser microphone. It boasted an almost flat frequency response from 20Hz to 20kHz with a slight dip at the low end. The MB C540 was modular in construction and had the option of 2 capsules (omni or cardioid).

MB C 540 AdvertMB C 540 Frequency response

In the UK it appeared as the PEERLESS MBC-540.

Reviewed here in Studio Sound May 1977.Review. Peerless MBC 540 - Studio Sound - May 1977

Meanwhile in Communist Era Eastern Europe.

This German design was also manufactured under licence by the Polish state owned electronics company UNITRA Tonsil and marketed as the MCO-30 (omni) and the MCU-31 (cardioid). According to Polish sources, the only difference between the German and Polish versions appears to have been variation in quality control at the Tonsil factory. This lead to some Polish mics reputedly sounding rather better than others.

Around 1980 the design was modified and updated. Whether this was done by MB Electronic or by Tonsil’s own engineers is not clear. (MB licenced a number of different designs to Tonsil but sadly MBHO now have no records relating to this microphone !)…….. Anyhow, the resulting microphone was somewhat shorter in length, the battery powering was changed from 2 x 15v to 1 x 6v and the previously unbalanced output was upgraded to balanced. The WCU-31 and WCO-30 capsules were retained and the frequency response appears pretty much the same. The new model was the UNITRA Tonsil MCU-53 (cardioid) / MCO-52 (omni).  The Tonsil 50 series continued in production through the 1980’s. In the late 80’s a further modification was carried out to provide 48v phantom power. This model was the MC-265.

UNITRA Tonsil MCU-53

UNITRA Tonsil MCU-53UNITRA Tonsil MCU-53 exploded view

A clever modular design. Well constructed and finished in shining nickel plate.

Tonsil WCU-31 Cardioid capsule. Front view

WCU-31 Cardioid capsule.

WCU-31 Cardioid capsule. Rear view.

Unusual 5 pin DIN connection.  (below)

Pins 4&5 in the plug are shorted together to provide a ‘switch’ for the battery. When the cable is plugged in the power is thereby switched on. N.B. This also means that if you accidently leave it connected when not in use you end up with a flat battery!! Arrrgh!

5 Pin DIN socket on Tonsil MCU-53 5 Pin DIN plug Tonsil MCU-53 Tonsil MCU-53 5 pin DIN Plug

Technical Specifications.

Pages from MCO-52/ MCU 53 Owner’s Manual UNITRA Tonsil MCU-53 ManualUNITRA Tonsil MCU-53 Manual P2UNITRA Tonsil MCU-53 Manual P3

In Conclusion.

Being battery powered made the MCU-52 /53 suitable for use with cameras and tape machines which in the 70’s and 80’s often did not provide phantom power. This made it a popular choice for wildlife and location recording.

When there is once again an opportunity to record music I will be interested to see how the MCU-53 compares to the AKG C451E as their frequency responses appear to be somewhat similar. I suspect the Tonsil may have a bit more self-noise but tonally may give the AKG a run for its money. Let’s wait and see…………

Credits.

Many thanks to Adam Wilma for sending me this pristine example of the UNITRA Tonsil MCU-53. Very generous. And thanks to my old mate blues guitarist Keith Thompson for bringing it back from Poland. His March tour was sadly cancelled after only 2 shows as Poland went into COVID-19 lockdown. Luckily for me the second gig was in Adam’s home town of Torun and he kindly dropped the mic off for Keith to bring back before the borders closed!

 

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

 

Acel GM-17B. A ‘Mystery’ Polish Microphone (Circa 1987)

This wonderfully shiny and somewhat obscure vintage microphone was kindly sent to me as a Christmas gift by Adam Wilma, one of my Polish readers!

It is interesting, not because of its fabulous quality, but because it provides a small window into a fairly grim chapter of Polish history.

Acel GM-17B Cardioid Dynamic Microphone

GM-17B Cardioid Dynamic Stage Microphone

GM-17B Box

After 30 years of Communist misrule, the Polish economy was in an extremely precarious state with serious shortages of many goods. Shops were empty with long queues in the streets. In March 1979 the Ministry of Internal Trade listed 280 products for which demand was difficult to satisfy and the list grew longer in the following year. 1980 saw the formation of the free trade union Solidarity and the end of Communism seemed to be in sight. However, in 1981 General Jaruzelski declared martial law and Solidarity was banned. The USA imposed sanctions and for the next 10 years the Polish economy struggled along in a state of collapse. This lead to the rapid growth of a black or ‘grey’ market. In these conditions a ‘second’ or ‘parallel’ private sector economy flourished.

Acel GM-!7B Dynamic MicrophoneSmall scale private businesses were broadly tolerated and allowed to function supplying demands that could not be met by the ‘official’ economy. However, if a company became too large and successful it risked attracting unwelcome attention from the Communist bureaucracy and might be shut down and its assets seized. This probably explains why the Acel GM-17B microphone pictured in this post, with its original packaging, gives away little clue about the company who made it or their whereabouts! So far all attempts to trace the manufacturer have failed! Goods like this were sold through local craft associations/co-operatives, which was a way of avoiding the many permits and licences that were officially required. All we know is that this particular microphone was sold in 1987 by the Multi-Branch Co-operative in Leszno. The previous owner informed me that it cost 15,330 old zloty. (For comparison, in the same year a kilo of carrots cost 50 zloty, and a kilo of tomatoes 200 zloty).

1980’s Polish Music Scene

For musicians this was a difficult time and few could afford good quality equipment imported from abroad. The electrical industry had been particularly affected by shortages of raw materials, components and machinery. Local manufacturers did their best to meet demand with limited resources. Sadly the resulting equipment was often somewhat less than ideal! Paradoxically, this decade saw a flowering of rock music in Poland. In no other communist country was there such freedom for musicians. It was not by accident – the communist authorities calculated that for young people it would be a good way to neutralize frustration. Freedom for various subcultures also served to draw young people away from the Catholic Church, which was perceived to be their greatest threat. It was not by chance that the dates of the biggest music festivals coincided with important dates in the Catholic calendar.

Polish Plug Problems!  

One Acel GM-17B Connector.slightly annoying feature of Polish-made gear of this period is the non-standard connector! Although this may look like a standard Klein Tuchel socket (as found on German and Austrian mics of the 60’s and 70’s), the locking ring is slightly larger with a different thread. I am told that Polish-made guitars often came with non-standard jack sockets. Slightly bigger or smaller! Presumably this meant that you would have to purchase a special lead from the maker at extra cost. Or maybe it was to avoid patent infringement? Who knows?………….Anyway, an ordinary Tuchel plug on the GM-17B can be kept in place with a piece of gaffer tape!

So What Does it Sound Like?  

During the Communist era, here in Western Europe we were always lead to believe that products made in the USSR and Eastern Europe were bound to be inferior to anything made in the West! Indeed, even now I am assured by a musical connection in Poland that Polish-made gear of this period was very poor and that this microphone can probably be summed up by one word: ‘CRAP’!!  Anyhow, I don’t like to jump to conclusions so I thought I would give it a fair trial……………..

CLICK HERE TO HEAR THE GM-17B in action…….. and reach your own verdict!

Many thanks to Keith Thompson for the tasty guitars and vocals (I played shaker and programmed the kick!) and thanks once again to Adam Wilma for sending this interesting and unusual microphone.

 

AKG C747 More Than Just A Podium Conference Mic.

AKG C747

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.
  • AKG C747 Frequency Response GraphAKG C747 Polar Pattern

It didn’t take engineers long to realise that this neat, pencil sized miniature shotgun microphone has many uses away from the conference hall!

AKG C747 Matched Pair

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 …………

CLICK HERE for Symphony Orchestra sound clip.

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!

AKG C747 Crossed pair at 65 degrees

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!

C747-manual

AKG_C747_Service_Documentation

AKG_C747V11_Manual

AKG_C747V11_Polar_Patterns

AKG_C747V11_Cutsheet

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 ‘ !

AKG C747 Hi-pass filter