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A Nice Pair

Beyer microphones

Want to know how the electret principle functions? Or the difference between pressure and pressure-gradient microphones? Then read the review, as recording engineer Gareth Stuart field tests the most recent additions to the famous Beyer range.


Two new microphones from Beyer Dynamic - the MCE80 Electret Condenser and the M700 Dynamic - come under the close scrutiny of recording engineer Gareth Stuart.

Beyer M700 dynamic vocal mic.

Taking the MCE80 first, Beyer point to the incorporation of phantom power supplies in most stage equipment as their reason for designing this rugged condenser microphone. The idea then is to present us with a microphone that is capable of withstanding knocks and drops on stage and, at the same time, offers the sensitivity characteristic of condenser systems. But, the MCE80 is not just a condenser microphone, it's an electret condenser microphone.

The 'electret' principle has several advantages over the conventional condenser type. As an almost permanent state of charge is achieved by applying a strong DC electrostatic field to the plastic foil of the diaphragm, the need for a DC polarizing supply to the microphone is eliminated. And, instead of having to rely on using a phantom power supply (12-48V) which most, but not all, modern stage equipment offers, a small 4.5V battery is employed to 'drive' an integrated circuit head amplifier. This in turn both simplifies the cabling system and reduces the microphone's physical size. Recommended types of 4.5V batteries for the MCE80 are the Neda 1306, Ever Ready 333, and Duracell PX21 (the latter being supplied with the review microphone).

The M700 Dynamic Vocal Microphone, to quote Beyer - "represents a new generation of Beyer stage mics." It is suitably one of Beyer's top models "because of its true hypercardioid polar pattern, which is completely insensitive to feedback."

Both mics are described as 'cardioid' to a greater or lesser degree - super and hypercardioid. Just think of supermarkets and hypermarkets and you'll never forget which is the greater of the two terms. Please don't get sidetracked... it's not really worth grappling with the idea of a Tesco cardioid!

Anyway, this term cardioid describes the degree to which the microphones are directional, or if you prefer, the degree to which they're able to attenuate any signals picked up from their sides and rear. As well as making use of the 'phase shift' principle, which I covered in the Sennheiser review (SOS Nov 86) - sounds approaching the microphone from 180 degrees arrive simultaneously at the rear and front of the diaphragm, exerting equal amounts of pressure, and do their best to immobilise the diaphragm thus rendering the mic insensitive to those sounds - the cardioid response of the Beyer is primarily achieved by combining two modes of microphone operation - 'pressure' and 'pressure-gradient'.

According to Beyer, "combining the principles of pressure and pressure-gradient operation in a single microphone can produce intermediary polar diagram shapes." The most common is the 'cardioid' (heart shape) which results when the pressure (circle) and pressure-gradient (figure of eight) elements are of equal sensitivity.

The only way I can think of describing this combination of polar responses, rather than have you flick through the pages of your sound recording textbook, is for you to imagine that the front and rear responses of the pressure-operated (omnidirectional) mic are in-phase, whereas the front response of the pressure-gradient mic is in-phase, but the rear response is out-of-phase; consequently, as the two rear responses are superimposed, where they coincide they cancel one another. In so doing, this result produces a microphone which is less sensitive to sounds approaching from the rear.

The reason for the slight difference in cardioid characteristic is due to the fact that condenser mics don't quite achieve the ideal pattern of 'true' pressure-gradient mics, and rather than having a region of zero sensitivity around the 90 and 270 degree angles - or, to be fair to the cardioid shape, at 120 and 240 degrees - they are said to have a 'waist'.

Now, if that still isn't clear, it's first necessary to understand that Beyer intended the two mics to be highly directional - to pick up only those signals hitting the diaphragm directly, and to ignore any signals approaching from the sides or the rear (approaching in the region of 120 to 240 degrees). As the MCE80's polar pattern is described as 'supercardioid', and I've just mentioned that signals at 90 and 270 degrees don't register at zero sensitivity, but instead cause the polar pattern to have a waist, this means that signals to the side are still picked up to a small degree. The M700, on the other hand, claims to be 'hypercardioid' (even more directional), and side attenuation at 120 degrees (for a test frequency of 1 kHz) exceeds 24dB, rendering it virtually insensitive to those signals.

Enough of this 'quasi' techno talk. Alright with you if I report on a few live/studiotests?

ON TRIAL



Again, taking the MCE80 first, due to circumstances beyond my control I could only try out this mic in the studio. Now, although it's essentially a stage mic, believe me, I did my best to recreate a live sound in the studio with exceedingly heavy hands on the faders... lots of volume.

And the verdict? A very 'clear' sound, with a fairly high resistance to feedback. So, what else can I tell you about it? Well, it has a built-in footfall filter (for bass cut), which tails off below 100Hz to compensate for handling noise, and does its job very well. And, oh yes, it's prone to the 'proximity effect', otherwise known as 'bass tip-up'.

The proximity effect is said to happen when an "increase in low frequencies occurs at distances less than about one metre from pressure-gradient operated microphones".

Beyer MCE80 electret condenser mic.

What happens, is that the closer you move the mic to your mouth, the more bassy the sound becomes. Beyer suggest that "the proximity effect gives the professional singer various sound colourations by changing the distance to the mic". That's all very well but, essentially, proximity effect is a by-product of the pressure-gradient principle. If the sound source (singer) is more than, say, two metres from the mic, there is hardly any difference in the time of arrival of sounds reaching the front and rear of the diaphragm. If the source is very close to the microphone, the front of the diaphragm is exposed to sound waves at a higher amplitude than at the rear. This produces a large pressure-gradient and the output of low frequencies is thus increased.

Now, from what I've said about the proximity effect, I'm inclined to think that to make full use of the MCE80's "various sound colourations" - from singing with the mic positioned close to the mouth, and then with it held at arms length - the PA system would have to be of a very high order, to aid the mic's capabilities in holding down feedback. Certainly, a mic costing this much (£299) wouldn't be out of place in such a set-up, but in your run of the mill PA I'm sure you wouldn't be able to take full advantage of its fine capabilities.

The day after I was given the M700 to review, I hurried along with it to the Graduate Centre in Cambridge, where a few friends of mine were putting on a concert. I hoped that I could pleasantly surprise them and persuade them to soundcheck with it, to give me some idea of how it performed.

I'm not really convinced that a soundcheck is necessarily the best moment to try out a new product, as time is short and it makes sense to stick to known and trusted equipment. However, with a mic like this, it should be possible within a fairly short space of time to adjust level and EQ on the desk to suit it to the venue and produce an acceptable sound - clear and full-bodied.

When compared with the mic the band normally use - a Shure SM57 - it seemed to produce a thinner sound, and gave a lower output. In boosting the volume, there were no feedback problems, so at least that's in its favour. And, indeed, in my noisy studio checks, when compared with the MCE80, it proved much more resistant to feedback. But, unfortunately, it wasn't used for the gig. (Many thanks to The Principle... friends who get me by.)

Then from the Grad Pad, Cambridge, back to the studio... with my Beyer. From the bumph (and price) that accompanies the M700, it would appear that this is the mic that Beyer hope will appeal to enthusiasts with limited budgets. I say this because, not only do they suggest that it should be used for stage vocals, but also for recording instruments "due to its frequency response reaching 40Hz."

So, I carried on at high volume in the studio, miking up an electric guitar (with an over-the-top metal sound), then an acoustic guitar.

(Perhaps you should know what set-up I was using to listen to the M700, to understand how I came to the conclusions I did. I used the M700 - Soundcraft mixer - Quad 405 amp - JBL 4311B control monitors.)

Considering the electric guitar first then. For a sound which seemed okay heard through the speaker cabinet, through the JBL monitors it became really 'edgy' - dominated by high frequencies. So, to the desk's EQ. I took out several dBs at 3.5kHz, and after that the sound was great, very true to the original. Incidentally, before equalising the sound I was having feedback problems, but afterwards I was able to really give the sound a tremendous boost, with no ill effects.

The main problem that I've had when miking guitar cabs on stage, is that nearly all guitarists want masses of volume coming from their amp. As a result of this, the poor person at the PA desk has no control over their sound at all. Their level on stage is too high, therefore a satisfactory mix through the PA speakers is impossible to achieve, without turning everything up louder than everything else. Once they're sure that they can have all the volume necessary through foldback monitors, it's normally possible to ask the guitarist to turn down.

Meanwhile, back in the studio, I tried turning my guitar amp down to a minimum, to enable maximum amplification through the monitors. And, because the Beyer M700 mic is so good at not feeding back, I was able to turn a tiny sound into an almost ear-ringing one... impressive.

Before equalising the monitored sound of an acoustic guitar, it tended to boom a great deal. (Be warned, placing the mic directly in front of the soundhole, makes an acoustic guitar into an effective feedback generator.) After a touch of EQ had been added, the feedback problem and boominess disappeared, but finding the right sound and maximum working volume with the M700 proved a little tricky.

CONCLUSIONS



My initial 'in the hand' impressions when I first received these Beyer mics were that both models felt solid, reliable and built to last. I still uphold that view. I think they're well designed, tough and chunky, and on stage should be able to hold their own, depending, naturally, on the standard of stages you're used to working on.

Prices: M700 £149, MCE80 £299 (both inc VAT).

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ART DR1 digital reverb

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Sound Advice


Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

 

Sound On Sound - Feb 1987

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Review by Gareth Stuart

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