Impedence help...

Discussion in 'Location Recording' started by LeroyGodspeed, Feb 14, 2006.

  1. man oh man...
    i've found myself in quite a quagmeir... here is what i'm lookin at:

    Im in a touring band (experimental rock, very hi fi) and we just recently put in a TC helicon Voice Works in our chian... it is a nice, but simple vocal effect unit that has a few bells and whistles. We dont play at the nicest of places very often, so we do as much of our own 'mixing and engeneering' ourselves... to eliminate problems associated with bad soundguys at dive bars. That includes having these voice effects on the front end (on stage) and sending an effected signal to the board. Here is where my problem comes in...

    We use Beta 58's (150 ohm Z) that go into the TC Helicon (40 ohm Z output). Where and why does it feedback, why is there signal degredation... can someone help explain to me the 'right course' of Impedence for a chain such as this?

    I have read that you should have a lower Z going to the board's equipment (that is higher Z than yours) if you want to keep this problem away. But i am worked up and confused about WHAT effect impedence, and how that plays into 'balanced and unballenced' lines.

    can anyone offer me up some advise or point me in the direction to find it? thanks so much!
     
  2. Kev

    Kev Well-Known Member

    without knowing a little more detail I can't be sure but I suspect that impedance mismatch is not your problem

    A simple 58 and a standard Mic input arrangement should interface fine.
    This box is likely to have an adequate line output and if you are using a line input to the mixer I think it should work

    I suspect your feedback problem is caused by the use of compression in the presets you are using

    Turn the compression OFF and try again

    Then dial the compression back in slowly untill you find a workable level ...
    This is a live sound / PA issue and experience is required
     
  3. moonbaby

    moonbaby Mmmmmm Well-Known Member

    You also have to be very careful with any EQ presets on the Helicon. These may "fight" the PA's EQ settings, and this will aggravate the feedback issue. So, besides the very good suggestion that you kill the compression, you need to "flatten out" the EQ, and kill any "Exciter" presets as well!
    And then carefully gain-stage your chain:
    Beta58> TC> mixer......watch the output level settings on the TC to the mixer. And if you DO end up using some compression, try setting the "Threshold" level higher, so that it controls the peaks without squashing everything or "pulling up ' the room ambience. That will just aggravate the situation.
    One more thing to watch: Beta 58s are "hypercardioid"in their pattern. Where are your stage monitors in relationship to the mic(s)? Try "11:00"and/or "1:00" instead of "12:00"...
     
  4. RemyRAD

    RemyRAD Well-Known Member

    Microphone output impedance is generally rated at 150 to 250 ohms. The output of equipment is generally from a transistorized output which is always lower in impedance than that of microphones and is completely normal. Normal output impedances average from 10 to 150 ohms but are not affected as much as microphones if you load them down by feeding more than one source. The above posters I believe are correct in their assumptions of equalization and compression causing you greater feedback problems. Less is more. It is difficult to make a PA system sound like a recording, especially in tight places.

    Squeeze me. Please me.
    Ms. Remy Ann David
     

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