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  1. #11
    Black out curtains are designed for acoustic dampening, as well as privacy. They are found in hotels, theaters, etc.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  2. #12

    feedback

    So frustrating to get on this board the first time tonite, and see problems posted from last November...Ivan, have you been struggling with this all this time?

    First: what kind of service do you have? If it's traditional/liturgical with a pipe organ and everything, you're not going to get away with hanging up padding. But if it's a more full-gospel type thing, acoustically deader is better.

    Tapestries and cloth banners can help, but be sure they're liberally padded behind them, and hung at least 6" away from walls. (Acoustic absorption installed smack on a wall only absorbs the highest frequencies.)

    Second: can you elevate the speakers so they're too high for the pastor to walk in front of them?

    Third: pattern control is very important. If you might be thinking of different speakers, be very careful to choose and place them so they cover the seating area but bounce as little sound as possible off the walls and ceiling. Many times, when the congregation has trouble hearing what is being said, the sound people think it needs to be louder. Maybe it's loud enough. Maybe it could be twice as loud, and people would still have trouble hearing, because the sound isn't clear.

    Speech clarity depends on suppressing echoes. Hanging up padded materials will help, but getting speakers with the right pattern and placement will help more. If you don't spray a lot of sound at the side walls, you won't have to hang up padding to soak it up.

    Fourth: your pastor needs a 2X4 across the forehead. If he believes God created the Universe, then he should be able to understand that the physical laws which govern the Universe are as much God's laws as anything in the Bible, and neither he nor you change them. If he walks in front of the speaker, he's going to get feedback. Period.

  3. #13
    Quote
    Quote: karl eilers
    View Post
    So frustrating to get on this board the first time tonite, and see problems posted from last November...Ivan, have you been struggling with this all this time?

    First: what kind of service do you have? If it's traditional/liturgical with a pipe organ and everything, you're not going to get away with hanging up padding. But if it's a more full-gospel type thing, acoustically deader is better.

    Tapestries and cloth banners can help, but be sure they're liberally padded behind them, and hung at least 6" away from walls. (Acoustic absorption installed smack on a wall only absorbs the highest frequencies.)

    Second: can you elevate the speakers so they're too high for the pastor to walk in front of them?

    Third: pattern control is very important. If you might be thinking of different speakers, be very careful to choose and place them so they cover the seating area but bounce as little sound as possible off the walls and ceiling. Many times, when the congregation has trouble hearing what is being said, the sound people think it needs to be louder. Maybe it's loud enough. Maybe it could be twice as loud, and people would still have trouble hearing, because the sound isn't clear.

    Speech clarity depends on suppressing echoes. Hanging up padded materials will help, but getting speakers with the right pattern and placement will help more. If you don't spray a lot of sound at the side walls, you won't have to hang up padding to soak it up.

    Fourth: your pastor needs a 2X4 across the forehead. If he believes God created the Universe, then he should be able to understand that the physical laws which govern the Universe are as much God's laws as anything in the Bible, and neither he nor you change them. If he walks in front of the speaker, he's going to get feedback. Period.
    Hi, thanks for this reply, even though this is an old post. Yes, I have been haveing to deal with this feadback issue for about 6 months now, and it really has not goton any better. I was going to move the speakers, but I was told that they are inside the roof. Do you have any more suggestions? I tryed the curton thing, even got the guy a new mic, I still get feedback! This is so frustrateing!
    Regards,
    Ivan Fegundez. Recording Technician, live sound technician, and mastering technician.

  4. #14
    By "inside the roof" I assume you mean permanently installed in the ceiling, where they can't be moved.

    If you have given the pastor an ear-worn or glasses-worn mic, so the mic is only a couple of inches from his mouth, that's all you can do from a mic standpoint.

    If you shut down all other mics when he's talking, so there are no other open mics picking up feedback, you have minimized the mic pickup problem as best you can. (If you aren't, you gotta. Feedback sensitivity is proportional to how many mics you have open. When the pastor is speaking for long periods - i.e. the sermon - all other mics should be shut off.)

    If you've chased down the main feedback frequencies and notched them out with a graphic equalizer, that's all you can do in the EQ department without buying special feedback eliminating equipment.

    If you haven't, here's what you can do without hiring a consultant: between services, enlist the aid of two assistants. Have one assistant wear the mic and walk around where the pastor does. The other assistant should be a piano player and a good musician. Run the system up until it feeds back. Have the piano player find that note on the piano.

    Here are the frequencies corresponding to the middle-C octave:
    C:262Hz C#:278 D:294 D#:311 E:330 F:349 F#:370 G:392 G#:415 A:440 A#:466 B:494 If the feedback tone is in the middle-C octave, now you know its frequency and you can notch it out.

    If it's in the octave above, double the number I just gave you - for example, if it's G in the next octave, instead of 392Hz the frequency is 784Hz. If it's two octaves above, then the frequency is 4X the above frequency and so on. The frequency of a note doubles every time you go up an octave.

    This is a quick-and-dirty method of notching out the worst two or three feedback frequencies. That's about as far as you can go with this method.

    Sabine and others make computerized feedback killers. They are based on teleconferencing technology and continually monitor feedback modes. Consider getting one for the pastor's mic.

    You should not simply EQ the whole midrange down. Frequencies between 1kHz and 3kHz are where the speech sounds lie that we need to understand what someone is saying. Attenuating these frequencies will ruin speech intelligibility. Then you'll be tempted to turn up the gain and we're back where we started. And in general, use as little EQ as you can get away with. Over-EQ'ing tends to make things worse.

    Okay, let's assume all the above has been attended to. Now: Speakers.

    Simply put, speakers should not aim any part of their sound directly at the microphone. That's guaranteed trouble. This means the speakers should be placed so the pastor is always behind them, no matter where he walks. If he's going to walk out into the middle of the congregation, then he has to use a handheld mic and keep it half an inch from his mouth.

    So, back to the speakers you have. If they're in the ceiling, that's not necessarily bad. The question is, do they cover the area where the pastor is walking around? If so, you may have to abandon them and put up different ones. Maybe you can borrow some to try them out and see if different speakers cure the problem.

    One last thing - do you have a band, and if so, does the band have monitor speakers? Is the pastor's mic fed thru the monitors? If so, turn that feed way down. As a matter of fact, for a test, shut it off and see what happens. Feedback from monitors rather than main speakers is very often the source of the problem. In a complicated system, you need to run a test where you shut off one thing at a time to be sure you know where the problem lies.

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