Is this thing on?

Sound systems are a lot like sewers - you can only get out what you put in. With this important truth in mind we take a look at the leading microphone brands to see what the options are for the AV integrator.

It’s been a recurring theme amongst the audio fraternity that AV does not in fact stand for audio-visual but for “all video”. This probably arises at least partly from the fact that there are still a few AV dealers and integrators around who consider the sound system as some kind of inconvenient necessity rather than an integral part of a system design.

A conversation with an audio distributor last week only served to reinforce the feeling that not everyone in AV takes the A part as seriously as the V part. Frankly this is wrong-headed thinking. There’s absolutely no point in having a beautifully lit videoconferencing suite or a crystal clear projected image if there’s poor quality sound to come over the top of it.

Back to that slightly provocative introduction then – the first link in the sound chain is the microphone. You can have the best-positioned speakers and highest quality amplification or processing money can buy, but if the initial pickup via the microphone is poor then it’s all a waste of time.

All of the major manufacturers offer a pretty wide range of microphones suitable for installation use. We asked them what was on offer, and also what advise they could offer integrators when selecting microphones.

What type of mic?

Crown International’s Bruce Bartlett is microphone engineer for the company. He recommended the company’s PCC (Phase Coherent Cardioid) boundary range for boardroom or conferencing applications, in addition to the MB series of mini boundary microphones. These are very low profile products that won’t ruin the look of that expensive boardroom whilst still giving good pickup. Crown’s omnidirectional offering is the PZM series.

Boundary microphones in general are great for boardroom or conference tables because they take advantage of the boundary layer effect to give a free boost to pick up levels. The choice is then between pick up patterns – an omnidirectional one for good all round levels or a cardioid type for more directional pick-up.

Other boundary offerings come from beyerdynamic. Its MPC series offers a pretty comprehensive set of solutions, from microphones that can be bolted through a table such as the MPC 22 and MPC 23 to the more conventional MPC 65 and 66, which sit on the surface. The choice between through- or on-table solutions is really down to aesthetics, and whether your client will allow you to drill through their expensive boardroom table! Clock Audio also supplies boundary layer solutions. Again in both cardioid and omni configurations. These all form part of the COO series.

Amongst Audio-Technica’s extensive Engineered Sound and UniPoint ranges are several boundary solutions – ES945 and ES947 and the U85 range being the chief ones. Many of these also being equipped with the company’s UniGuard RF shielding technology. If Shure is your brand of choice then there are plenty of options in the MicroFlex and EasyFlex ranges.

Recognising the value of the installation market, even DPA has entered the boardroom with the BLM4060, an omindirectional boundary solution with a nice brushed aluminium finish and the high-quality that the performance industry has enjoyed from its products for many years.

Sennheiser’s boundary solutions are mainly aimed at music market but the e912s is a half-cardioid designed specifically with speech pick up in mind.

However, boundary mics are not always the ideal solution. For presentation podiums or conference style set-ups the gooseneck is often a preferable solution. Many of the manufacturers offer modular solutions allowing the integrator to select the kind of attachment, the length and shape of the gooseneck itself, whether its flexible or fixed and finally the kind of capsule in the top. This leads to almost infinite possibilities with product selection. Since these modular systems are so flexible there really isn’t any excuse for coming up with the ideal microphone for a job.

Such modular systems are again available from the major players. Austrian veteran AKG offers a massive number of options in the shape of its Modular Series, which features a choice of 15 different goosenecks, in four different lengths and a choice of five capsules.

Audio-Technica’s Engineered Sound products, whilst not being modular, are all aimed specially at the installation market and the range of solutions is just as comprehensive. In Sennheiser’s installation range, the ME, MZH and COM solutions are available with a variety of different mounting solutions with push-to-talk and other functions available on table-top stands.

Beyerdynamic’s goosenecks are available in short neck versions – the SHM 22, designed for more discrete applications or in the full blooded SHM 200 or SHM 800 versions. The 200 is designed to give optimum speech quality with its cardioid design. If more directivity is needed then the 800 range features a hyper-cardioid pick-up.

EasyFlex (EZ) and MicroFlex (MX) from Shure cater for the more budget conscious or higher quality application respectively. Both ranges include a variety of gooseneck lengths and different capsule options.

There are of course other alternatives. Another common microphone solution is the suspended one, often found in the performance space but used in installations when there is no convenient table or lectern to use as fixing point. They can also help when getting an appropriate distance from mouth to microphone is tricky with a conventional solution or if aesthetic considerations mean that a gooseneck isn’t an option.

Away from traditional offerings beyerdynamic have introduced the much touted Revoluto. Eschewing conventional design, the array of microphone capsules instead of a single one give much better off axis pickup, whilst producing a more discrete looking solution.

Interference issues?

One hot topic concerning microphone users, is radio frequency interference or RFI. The all too familiar sound of someone’s mobile phone, blackberry pager or other device interfering with the system. Several microphone manufacturers now include some kind of shielding in their products. Audio-Technica introduced its UniGuard technology in 2005, and has since spread it to cover the whole Engineered Sound range. Shure’s MX and EZ microphones are designed with CommShield – the company’s brand name for RF protection. Similiarly named technologies are available from beyerdynamic (RFI-Proof) and AKG has built in what it terms high RFI immunity into its latest GN ESP microphones.
Clock Audio’s solution is the RF Series, which cuts across its range of microphones and accessories to eliminate interference from GSM devices.

Sound advice

Choosing the right microphone for the job is often a matter of trial and error. Even the most advanced software modelling can’t help you with an unusual set of acoustic conditions or unexpected problems. This is why the modular systems are so attractive, because you can mix and match capsules, until you get a good sound from the system. Thomas Stubics, product manager for installed sound at AKG points out that choosing the right mic can solve a lot of other problems:

“There are wonderful DSP-based systems which improve the quality of sound, but it all begins with the sound waves which are coming into the microphone. It is the first element of the sound transmission path. If there is something missing you cannot reconstruct it at the same level as the original. Moreover, if your microphone has a bad polar pattern then it can be hard to get a decent level on the PA system even with appropriate EQ.”

So what is the right microphone? That’s not really sensible question since it various from site to site, however there are certain characteristics one should be looking at when making a choice. Crown’s Bruce Bartlett reckons that, “to get natural, hi-fi reproduction of speech, look for a voice-range, smooth frequency response, for example at least 80Hz to 12kHz +/- 3dB. The frequency response should roll off below the voice range to reduce pickup of air-conditioning rumble.”

The capsule choice is also crucial. A directional polar pattern such as cardioid, supercardioid or hypercardioid will help to reduce pickup of room acoustics and feedback. An omnidirectional mic will be suited to a small table where you want to pick up audio from a number of people at once, perhaps in a videoconferencing situation.

Durability is an important consideration for situations such as meeting rooms, with a lot of through traffic. In these cases one should be looking at microphones with a 100% metal construction, and probably avoiding flexible necks which can be fiddled with / bent. Security goes hand in hand with this, and most manufacturers offer secure attachments for goosenecks.

As with everything, you get what you pay for. The same price / performance compromises exists for microphones. A bit more budget will get you smoother pick up patterns, better frequency response, RFI shielding and all round better sound quality.

There is also the issue common to all installations that the end user is not likely to be a trained microphone user. Therefore systems need to be as forgiving as possible. beyerdynamic’s Revoluto comes into this category with its array pattern, but also things like the new Sabine phantom mic-rider. This is a clever, phantom powered device, which performs basic DSP functions. It’s simply plugged in line with the microphone and features automatic gain control amongst others.

Such devices can compensate for inexperienced users but not for poor equipment selection or installation. “In the last few years we’ve discovered more and more that people try to compensate for bad acoustical conditions as well as misplacement of speakers and microphones with electronic devices. This can only lead to a suboptimal solution and does not solve the actual problem. A key issue is often not in the product itself but in the person installing it. We should return to the roots of audio and think more about the physics in a system. Only this can lead to the best possible performance.” – The conclusion of Johannes Kampert, product manager for presentations and conferencing at beyerdynamic.

A final thought, all of the manufacturers mentioned in this piece have excellent web sites full of information about choosing microphones, and using them. For example, DPA Microphones has the Microphone University full of explanations of obscure terms and information about the various pickup patterns. Shure provide a huge bank of information about all things audio, including white papers and FAQs, whilst Crown has a section called Application Guides. This article should have given you some idea where to start, but there’s a lot more information available. Go read it.

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