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Mic Pickups

Discussion in 'Sound, Music, and Intercom' started by Schniapereli, Dec 13, 2006.

  1. Schniapereli

    Schniapereli Active Member

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    What is different in the manufacturing of a cardioid mic as apposed to an omnidirectional, etc.? Do they just place the insides of the mic differently, or are there different parts entirely? What the gravy is the difference between how they work? (this question goes for all lavs, PZM's floor mics, handhelds, etc.)
    I've always wondered about how they do that...
     
  2. SHARYNF

    SHARYNF Well-Known Member

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    On relatively simple terms
    all the mic elements start out as omni, ie the pick up sound from all directions.

    If you place the element in a tube and block off the rear, you get a cardioid, from there if you can also manipulate the rear signal to get super or hyper cardioid. You can but in two elements and depending on how you set them up can also create different patterns.

    That's the simplistic explanation
    Sharyn
     
  3. cutlunch

    cutlunch Active Member

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  4. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    Actually, you're backwards, Sharyn. A port behind the element is what gives the element a cardioid pattern, since the port is what creates the physical cancellation that creates the null. This is why if you cover the port on a cardioid mic (for example, holding a handheld mic around the back of the grille), you'll turn the pattern omni.

    The most clear example of this is Crown's GLM-100 and -200 lavaliers, where the omni one (I believe that's the 100, but don't quote me) is literally identical to the cardioid, except for the addition of a small rubber plug in the port.

    --A
     
  5. Schniapereli

    Schniapereli Active Member

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    Why are the patterns always messed up on the right side especiallyfor lower frequencies?

    Is it related to the port behind the element that creates the null? (a side affect)

    Why is it not symetrical?
     
  6. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    It is on every cardioid mic I've ever come across in my career. I've never heard of a mic that isn't rotationally symetrical. What mic(s) have you used that exhibited this?
     
  7. Schniapereli

    Schniapereli Active Member

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    I've been looking online at Sennheiser, Shure, and Blue mics, and have also seen them like that a lot in the past.

    I have never been able to tell from listening though.
     
  8. SHARYNF

    SHARYNF Well-Known Member

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    Andy is correct, I mistyped what I meant, and the point about gripping the rear and that causing feedback by closing off the port is a very real problem, that is why you will see people ringing out a monitor system cup the mic in their hands to see if it induces feedback.

    Now of you place the element in a long tube with the tube in FRONT OF the element,with opening on front and sides you will get a shot gun mic
    thanks for pointing that out
    Sharyn
     
  9. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    I'm still not understanding where you're getting the impression that they're different left-to-right from. Perhaps you're misinterpreting the diagrams you're looking at? If you've got a link to what you're looking at that's giving you that idea, perhaps we can sort out where the confusion's coming from :)

    I can tell you as a fact that neither Shure, Sennheiser, nor BLUE make any mics that are different sounding from the left then from the right, although they make many, many mics that are different from front to back.
     
  10. Andy_Leviss

    Andy_Leviss Active Member Premium Member

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    No sweat, Sharyn. And a great point about shotguns, which work on similar physics to cardioids, but in a much more complex manner!

    If anybody's interested, doing some research on how these different methods of cancellation cause the different patterns of mics can be a really cool exploration of physics and sound, and it's actually not all that "rocket sciencey" if you get down to it. Where it gets really crazy is with multi-pattern mics, which use multiple mic elements together in different ways to create a pattern that can be switched from omni to cardioid to hypercardioid to figure-8. Way cool.
     

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