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Old 19th June 2010, 12:56 AM   #1
Bigsby is offline Bigsby  United States
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Default Wedge P.A. Monitors w/Early Feedback

I've got a pair of wedge monitors, and at some point in their history, someone put in two way (combined woofer and mid/tweeter) speakers that feedback so early, they're not really usable. Is there any sort of cheap mod I can make that will generally improve the volume before feedback of a speaker and cabinet?
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Old 19th June 2010, 10:36 AM   #2
Xoc1 is offline Xoc1  United Kingdom
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Have you any graphic equaliser's that you could use to adjust the frequency response.
You could then try playing some music that you are familiar with and adjusting the eq to see if there are any peaks in the frequency response that you can smooth out. You also can plug in your mic, find out which frequency bands cause feedback and attenuate them.
Excessive feedback can be caused by poor microphone technique.
This is particularly important with small gigs where the mics and speakers are close to each other!
Ensure that the microphone is in close proximity to the source, to reduce the amount of gain that is needed.
Make sure that the microphone is facing directly away from the monitors to maximise the cardoid directional rejection.
Ensure that the user of the microphone is not covering the rear of the mic basket with their hand (like rap artists seem to prefer) this totally stops the cardoid response from working properly, and causes terrible feedback.
When I am doing live mixing I use a automatic digital eq (Bheringer feedback destroyer) for the foldback monitors. This detects any feedback peaks and attenuates them.
Some people detest the sound of the feedback destroyer, but I have found it very effective used for vocal monitors, Its a lot quicker than me at tuning out any squeals on stage, and allows me to get on with the mix.
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Last edited by Xoc1; 19th June 2010 at 10:39 AM.
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Old 19th June 2010, 01:06 PM   #3
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"Ensure that the user of the microphone is not covering the rear of the mic basket with their hand (like rap artists seem to prefer) this totally stops the cardoid response from working properly, and causes terrible feedback."

Too damn right!
Covering the back of the basket effectively turns a cardioid response mic into an omni-directional response one with the obvious result of massive feedback.

Correct mic technique seems to be a lost art form with most of todays vocalists.
Watch the old guys (Tom Jones for example) and learn!
Minimizes the need for compression too.
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Old 20th June 2010, 06:37 PM   #4
Bigsby is offline Bigsby  United States
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Default compared

Actually, compared to other wedge monitors, this pair of speakers simply feeds back way before any usable volume can be coaxed out of them. Whatever's happening with the interaction of the drivers and cabs, they just don't work like other speakers I use. If there's any way I can stick in a port, or otherwise re-tune the cabinets without too much difficulty, I'd appreciate hearing about it.

Otherwise, I'll turn them into ashtrays.
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Old 20th June 2010, 08:17 PM   #5
Xoc1 is offline Xoc1  United Kingdom
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Default Tell us more?

Premature feedback is caused by a frequency peak in the speaker, the microphone, or the audio system you are using. Since in this case you have compared other monitors it seems a safe assumption that the speakers are the main problem.
If your mixer has sweepable eq. you can turn up the eq. gain, and sweep the frequency range to find out where it rings. Using a separate eq. for the monitor system would allow you to trim the response to suit without effecting the rest of the system.
All we know of the problem is what you have told us. I don't know what else to recommend to you without some more specific information on the speakers, you PA system, and the frequencies that you are having problems with.
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Old 21st June 2010, 04:48 AM   #6
Bigsby is offline Bigsby  United States
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Quote:
Originally Posted by Xoc1 View Post
Premature feedback is caused by a frequency peak in the speaker, the microphone, or the audio system you are using. Since in this case you have compared other monitors it seems a safe assumption that the speakers are the main problem.
If your mixer has sweepable eq. you can turn up the eq. gain, and sweep the frequency range to find out where it rings. Using a separate eq. for the monitor system would allow you to trim the response to suit without effecting the rest of the system.
All we know of the problem is what you have told us. I don't know what else to recommend to you without some more specific information on the speakers, you PA system, and the frequencies that you are having problems with.
Right, thanks. Step one, figure out the offending frequency(ies) via eq cut sweep. Step 2, open one up and see if there's any info on the driver or any circuits inside.

If it's upper mids and above, would some kind of choke be in order? If it's a lower frequency, could porting each cab potentially help?
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Old 21st June 2010, 07:27 AM   #7
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Porting the cabinet will change the low-frequency response. With the stage monitors being so small, it's unlikely to improve. I don't understand how you linked that to feedback problems though...
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