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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Wireless and Communications => Topic started by: Carrie Snide on May 23, 2017, 11:41:32 PM

Title: Wireless mic feedback
Post by: Carrie Snide on May 23, 2017, 11:41:32 PM
I have what I think is a unique problem. Maybe not tho. For my church we have a Mackie analog board, not sure the brand of 15 band graphic eq (dod), and a sennheiser Freeport wireless mic. All somewhat old equipment. We have the mic eq'ed really weird cuz it's the only way we can get it not to feed back or ring. I have tried pulling out certain frequencies on the graphic eq, tried to change the settings on the board, tried moving the receiver. Yet still cannot get the darn thing to not have a ring when someone is preaching. There are NO feedback or ringing problems with any other mics. Just the one wireless. Any suggestions on a next step or something I missed. I am a self taught sound person so I know there are thingo I don't know. Always wanting to gain knowledge, thanks for any help.
Title: Re: Wireless mic feedback
Post by: Scott Holtzman on May 24, 2017, 01:40:06 AM
I have what I think is a unique problem. Maybe not tho. For my church we have a Mackie analog board, not sure the brand of 15 band graphic eq (dod), and a sennheiser Freeport wireless mic. All somewhat old equipment. We have the mic eq'ed really weird cuz it's the only way we can get it not to feed back or ring. I have tried pulling out certain frequencies on the graphic eq, tried to change the settings on the board, tried moving the receiver. Yet still cannot get the darn thing to not have a ring when someone is preaching. There are NO feedback or ringing problems with any other mics. Just the one wireless. Any suggestions on a next step or something I missed. I am a self taught sound person so I know there are thingo I don't know. Always wanting to gain knowledge, thanks for any help.

You need to update your name before we can help you.   This forum requires your real name.

A little hint.  What is the pattern of the wireless?  Gain staging is critical, there are gains on the mic and on the receiver. 
Title: Re: Wireless mic feedback
Post by: Henry Cohen on May 24, 2017, 07:53:13 AM

You must use your real name for your display name. Kindly go to the registration section and make the change.

Thank you.
Title: Re: Wireless mic feedback
Post by: Paul G. OBrien on May 25, 2017, 07:51:36 PM
  and a sennheiser Freeport wireless mic.
Is that a handheld or lav? 2 possible causes here. If it's a lavalier and it has an omnidirectional capsule it will be much more feedback prone, the solution is to substitute a unidirectional(cardiod) capsule. And in both cases(handheld or lav) if the gain on the receiver is set too high these things go off way too easily, so just turn down the receiver. I find they work best with the receiver gain at the 11-12 o-clock position.
Title: Re: Wireless mic feedback
Post by: Carrie Snide on May 25, 2017, 10:22:33 PM
Thanks for the reply. It is a handheld. I hadn't thought of the gain on the reciever. Good idea. It used to work fine but over the last 6 months or so started acting up. We make it work but it sure is touchy. I'll check that out on Sunday.
Title: Re: Wireless mic feedback
Post by: Karl Winkler on May 26, 2017, 05:43:25 PM
Are you certain that it is acoustic feedback and not something else? The reason I ask is that once I saw a well-known band performing a big show, and the IEM transmit antenna was placed very close (on the same stand) with the receiver antennas, and it was causing a ringing sound in the main mix.

So, it could be a radio problem rather than a feedback problem. Are there any other radio sources nearby? The Freeport is a cheap system, and probably doesn't have very good filtering in the receiver.

Then, one other possibility is a hearing aid. Does the pastor wear one? I've encountered that as well - a hearing aid that is on the verge of feedback gets sent over the edge when in the sound field of a PA system.
Title: Re: Wireless mic feedback
Post by: Ray Aberle on May 26, 2017, 09:55:55 PM
Are you certain that it is acoustic feedback and not something else? The reason I ask is that once I saw a well-known band performing a big show, and the IEM transmit antenna was placed very close (on the same stand) with the receiver antennas, and it was causing a ringing sound in the main mix.

So, it could be a radio problem rather than a feedback problem. Are there any other radio sources nearby? The Freeport is a cheap system, and probably doesn't have very good filtering in the receiver.

Then, one other possibility is a hearing aid. Does the pastor wear one? I've encountered that as well - a hearing aid that is on the verge of feedback gets sent over the edge when in the sound field of a PA system.

That, and coupled with this comment:
It used to work fine but over the last 6 months or so started acting up.
-- something's changed, somewhere, somehow.

-Ray
Title: Re: Wireless mic feedback
Post by: Carrie Snide on May 28, 2017, 06:49:01 PM
It turns out the gain on the back of the receiver was cranked. Thank you for your comment, I made the adjustments today and it was much less sensitive after that. I appreciate the comments! Our head sound guy recently stepped down, and left, and I'm trying to make some necessary improvements. Thanks again.
Title: Re: Wireless mic feedback
Post by: Mike Caldwell on May 28, 2017, 11:46:52 PM
The receivers output level / gain control position in it self will not cause feedback, the mixers channel trim will adjust for the level coming out of the receiver. Of course if the receivers output level had always been set at say half and it got turned all the way up without re-adjusting the mixer channel gain trim it would feed back "quicker" in relation to the fader position on the mixer.

Double check the gain setting on the transmitter, if the wireless mic sounds distorted from time to time and is not the mixers input being over driven check that the peak light on the receiver is not coming on, if so you need to turn the gain down on the transmitter.

   
Title: Re: Wireless mic feedback
Post by: Paul G. OBrien on May 29, 2017, 09:47:19 PM
The receivers output level / gain control position in it self will not cause feedback, the mixers channel trim will adjust for the level coming out of the receiver. 
Normally I would agree gain is gain right.. adding some at one stage just requires less at another stage. But with the gain all the way up on these things the signal is really hot, a pad would be necessary on most mixers to produce any functional range of use on the channel strip that isn't over driving everything, so there is really no need for it to be set that high.

Double check the gain setting on the transmitter,
Strangely in this series the body pack has an output trim control but the handheld does not.. it's output level is fixed so it can't overload the receiver. Makes it easier to use I guess.
Title: Re: Wireless mic feedback
Post by: Mike Caldwell on May 29, 2017, 11:18:30 PM
Normally I would agree gain is gain right.. adding some at one stage just requires less at another stage. But with the gain all the way up on these things the signal is really hot, a pad would be necessary on most mixers to produce any functional range of use on the channel strip that isn't over driving everything, so there is really no need for it to be set that high.
 Strangely in this series the body pack has an output trim control but the handheld does not.. it's output level is fixed so it can't overload the receiver. Makes it easier to use I guess.

At a church I was doing some service call work had a couple Freeport body packs and those did need the gain adjusted on the pack. The handheld was fine so I never opened it up to look for a gain control. I did not notice anything crazy as for the output level into their small Soundcraft board when I turned the receivers up. I set the levels full up to prevent little fingers from turning them up since they had the receivers setting out in the wide open on shelf in their sound booth.