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Omni versus Cardioid (Directional) microphones, How many do I need?

5/10/2013
RevoBlog
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One of the best decisions you can make for the design of any given conference room is deciding on using Revolabs microphones to provide an exceptional audio experience.  Now that the most important decision has been made, let’s talk about some of the other ones you need to think about when designing a space with Revolabs microphones.

As a Field Application Engineer, I am often tasked with assisting on helping a consultant, an end-user, or integrator decide on which microphones are going to be the best fit.  One of the most common questions I get is, “Should I use omnidirectional or directional tabletop mics?”  Typically, I always answer this question with several more questions (something I believe Socrates would approve of).  What I am most keen on knowing is, “What does the room sound like when no one is making any noise?”  This is a leading question to tell me more about the ambient or background  noise (HVAC, projector fans, street traffic) in the room. Another important factor is how easily sound is reverberated throughout the room based on construction and furniture materials.  Does the conference room have three glass walls and/or windows that face a busy street?  Often architects want rooms that look nice, but sometimes that architectural design translates in to rooms that have less than desirable acoustic properties.  Knowing these properties will point you in the right direction when choosing a microphone.  Lastly, I will also ask if any local voice reinforcement is going to be done as well as this need can dictate what mic you want to choose.

When it comes to using Revolabs tabletop mics, the question becomes – omni or directional?  Well, both have their advantages.  Omnidirectional mics have a unique quality to them where their biggest asset can sometimes also be their biggest drawback.  They have a 360 degree pickup range that covers a large area.  If you’re in a large room that has low levels of ambient noise, this is great!  If you’ve got loud HVAC, glass walls, or trucks zooming by on the street all day, well then this can make the overall quality of the audio coming from the room suffer because based on their 360 degree design they could be picking up a lot of the unwanted ambient or background noise in the room.

  Omni.png

The directional tabletop microphone has a much more focused pickup pattern, which helps mitigate ambient noise and allows the mic to be more directly aimed at the person you are trying to "hear".  This more focused, precise pickup pattern can help minimize any unwanted background noise that is inherently in the room.

Cardioid.png

Often, the answers to my questions about the ambient noise levels in a room are unknown.  Whether it is a new construction, a bid, or whatever the case may be – sometimes we can’t know the answer.  If this is ever the case, I always urge that people err on the side of caution and use directional mics so that there are no “surprises” once a room is finished and fully operational.

Based on what type of mic you decide on, this then also dictates how many channels you will need.  Our rule of thumb here is that an omnidirectional mic can pick up 4-6 people sitting on either side of a table where the mic is at the center.   If going with a directional mic, we suggest that it cover 2-3 people that the mic is facing toward.

Another important thing to note is there is occasionally the need to locally amplify the microphones, what is commonly referred to as “voice lift”.  When the situation calls for voice lift, we always suggest that you use our directional mic as using the omnidirectional can cause feedback problems due to its larger pickup pattern.

In the end, I hope that you find this helpful in deciding which Revolabs microphone best suits your needs.  A little definition of how they work goes a long way, and in the words of Socrates, “The beginning of wisdom is the definition of terms.”  Please feel free to contact me by emailing support@revolabs.com

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