Feedback ?

[DJStevie]

Bought a wirelsss mic a few weeks back and when trying them out, they are causing a loud howl of feedback from the speakers - has anyone else had the same happen to them? How do you fix it please?

[DazzyD]

Are you connecting the receiver to your mixer with a Jack plug or balanced XLR connector? I find that Jack plugs require more gain to be used to get the same signal as you would using an XLR connector at a lower gain. A common cause of feedback is having the gain too high.

Also, I find reducing reverb/echo also helps to reduce the effects of feedback. Using your EQ to dampen the higher frequencies can also help.

[SamV]

Jack plugs make no difference if they are TRS.

If you are getting loads of feedback try putting the gain on the receiver lower and bump it up on the desk. However if you're using mics, it's a good idea to use graphic/parametric equalisers to ring out the problem frequencies and room nodes.

[paulg]

Bought a wirelsss mic a few weeks back and when trying them out, they are causing a loud howl of feedback from the speakers - has anyone else had the same happen to them? How do you fix it please?

What model / brand have you bought? It helps to know about the adjustment options?

[DJStevie]

What model / brand have you bought? It helps to know about the adjustment options?
The mixer is Numark CD Mix MP3, the wireless mic is a Trantec S4.4 and if it's relevant, the speakers are RCF ART 712-A's.

About once a month, I do outdoor events, where, in between the music, the mic is handed over to the compere, who is walking all over the place, including in front of the speakers.

I am desperate to fix this feedback/howl, so any help is really appreciated.

[katman]

About once a month, I do outdoor events, where, in between the music, the mic is handed over to the compere, who is walking all over the place, including in front of the speakers.



Walking in front of any speaker with a mic is just asking for feedback. As this is an outdoor event my guess is that they are cranked up quite high to get the coverage and the compare is much too close to them, particularly if the horns are around the same height as his head.

If you can get additional speakers try spacing them out more and running them at a lower level to cover the same area but avoiding the hot spots.

You can also buy a device called a Feedback Eliminator such as this one http://www.behringer.com/EN/Products/FBQ1000.aspx which will sense the onset of feedback and apply a sharp notch filter to suppress the frequency that is feeding back.

[Excalibur]

, the mic is handed over to the compere, who is walking all over the place, including in front of the speakers.

I am desperate to fix this feedback/howl, so any help is really appreciated.

I'm tempted to suggest tasering the swine, but that would be naughty. :no:

Get the cabs as high as you safely can. The further you get the HF units above head height, the better.

[DJStevie]

Many thanks - am trying to keep the speakers at the same height and to not have to buy any more speakers, so may go for the suggested feedback eliminator. Has anyone here used one before? Or, is it better to go for an equalizer to somehow get rid of the howl?

[super-hero]

I have used the Behringer Shark feedback destroyers, and they work really well. But your problem, as suggested by SamV, may be gain related.

I had a Numark cd mix as a backup system once, and I found the mic preamp on them to be terrible, so that may be part of your problem also.

Try adjusting the master output level so that it is set to about 25% below max, then you shouldn't need to turn the mic input up too high. This will greatly help reduce feedback. If this fails then you need an eq or a feedback destroyer.

[DJStevie]

Jack plugs make no difference if they are TRS.

If you are getting loads of feedback try putting the gain on the receiver lower and bump it up on the desk. However if you're using mics, it's a good idea to use graphic/parametric equalisers to ring out the problem frequencies and room nodes.
I'm thinking that instead of paying for a feedback destroyer, that I buy an equalizer - would they both get rid of the feedback howl equally well, or would one of them be better at it?

[DJ Jules]

I'm thinking that instead of paying for a feedback destroyer, that I buy an equalizer - would they both get rid of the feedback howl equally well, or would one of them be better at it?

As the name implies, the feedback destroyer would be better at getting rid of feedback. The Eq is likely to need constant manual "tweaking" to get the best results. I think a few people on here have hinted at it, but you might get more bang for buck by investing in a better suited Mic and/or mixer that would be less likely to feedback in the first place (and give you the additional benefits of a cleaner, crisper, sound as well?)

Julian

[paulg]

You've bought a microphone with a basic cardioid capsule. Nothing wrong with that and it'll be OK in most situations but it will be susceptible to feedback and especially in front of speakers because it has a fairly wide pick up pattern when compared to other types of capsule. Trantec themselves describe the mic you have as having a "bargain basement" price tag - hence a basic cardioid capsule. You are also using a preamp that will be next to useless but it looks like there is a balanced XLR connection on the back of that mixer. If you're not using it, get a balanced cable and give it a try.

If you put a feedback destroyer in line, you will get nearly as many problems as you solve. Been there, done it albeit quite a few years ago now. Feedback destroyers filter out offending frequencies (usually high frequency) that cause feedback. With a mic/mixer combo like you have, you will get so many offending frequencies that, after a while, the overall effect of a feedback destroyer will be to muffle the output which then requires more gain and then leads to more feedback but often at a lower frequency etc etc. Feedback destroyers really should be a last resort.

I noticed you said you were outdoors. Is a couple of RCF 712's enough for outdoor use or are you perhaps pushing things beyond reasonable limits. All in all, I don't think a better mic is necessarily what you need. As a first line of defence, ask the compere to stop walking in front of the speakers. IF he / she doesn't, take the mic off them.

[Creature]

I use both the Beringer Feedback eliminator and Peaveys Feedback destroyer and personally I prefure the peavy one.

set up on fast learn - turn everything up and wander around the room - as the frequencys that cause the issues as blocked out then slowely walk right up to the speakers - takes about 10 mins and works great not had an issue, on my large PA even when the comedians let rip or wande around.

the beringer, even tho it has a 2x 15 graphics graphics which the peavey dont. I relegated to my monitors, but altho it did its job, was never comfortable with it, so recently brought another Peavey of a well known auction site for £60.00 and will fit that over the winter instead.

I did have a large graphice unit installed in fact it still is, but its been bypassed for the last few years as not needed :)

[Retrodisco]

You've bought a microphone with a basic cardioid capsule. Nothing wrong with that and it'll be OK in most situations but it will be susceptible to feedback and especially in front of speakers because it has a fairly wide pick up pattern when compared to other types of capsule. Trantec themselves describe the mic you have as having a "bargain basement" price tag - hence a basic cardioid capsule. You are also using a preamp that will be next to useless but it looks like there is a balanced XLR connection on the back of that mixer. If you're not using it, get a balanced cable and give it a try.

If you put a feedback destroyer in line, you will get nearly as many problems as you solve. Been there, done it albeit quite a few years ago now. Feedback destroyers filter out offending frequencies (usually high frequency) that cause feedback. With a mic/mixer combo like you have, you will get so many offending frequencies that, after a while, the overall effect of a feedback destroyer will be to muffle the output which then requires more gain and then leads to more feedback but often at a lower frequency etc etc. Feedback destroyers really should be a last resort.

I noticed you said you were outdoors. Is a couple of RCF 712's enough for outdoor use or are you perhaps pushing things beyond reasonable limits. All in all, I don't think a better mic is necessarily what you need. As a first line of defence, ask the compere to stop walking in front of the speakers. IF he / she doesn't, take the mic off them.


Yep I agree, replaced cheap mic with an better quality FBT unit, and feedback all but gone.

[DJStevie]

You've bought a microphone with a basic cardioid capsule. Nothing wrong with that and it'll be OK in most situations but it will be susceptible to feedback and especially in front of speakers because it has a fairly wide pick up pattern when compared to other types of capsule. Trantec themselves describe the mic you have as having a "bargain basement" price tag - hence a basic cardioid capsule. You are also using a preamp that will be next to useless but it looks like there is a balanced XLR connection on the back of that mixer. If you're not using it, get a balanced cable and give it a try.

If you put a feedback destroyer in line, you will get nearly as many problems as you solve. Been there, done it albeit quite a few years ago now. Feedback destroyers filter out offending frequencies (usually high frequency) that cause feedback. With a mic/mixer combo like you have, you will get so many offending frequencies that, after a while, the overall effect of a feedback destroyer will be to muffle the output which then requires more gain and then leads to more feedback but often at a lower frequency etc etc. Feedback destroyers really should be a last resort.

I noticed you said you were outdoors. Is a couple of RCF 712's enough for outdoor use or are you perhaps pushing things beyond reasonable limits. All in all, I don't think a better mic is necessarily what you need.
The speakers are entirely adequate for the outdoor events I do. Anyways, back at the ranch, I did get a quick chance to try things over the weekend and it seems as though turning the gain down on the mixer has solved it, but need to have more time to try it more fully, but at the moment, it seems as though the mic is good too! If all is not as it should be, I'll report back, but for the moment, as far as the feedback is concerned, it's happy daze!

[SamV]

It's amazing what a proper gain structure can solve.

Anyways, while we're talking about feedback, prevention is better than cure. Get rid of the peaks and resonances and it's less likely to happen.

[Excalibur]

I had a variety night last Saturday, and we had multiple mikes open from time to time, and performers wandering about with radio mikes. Because we'd got the tops as high as possible, we basically had no problems at all with feedback. It really makes a big difference, if you can get the HF units above head height, that will make life a lot easier.

[DJStevie]

I had a variety night last Saturday, and we had multiple mikes open from time to time, and performers wandering about with radio mikes. Because we'd got the tops as high as possible, we basically had no problems at all with feedback. It really makes a big difference, if you can get the HF units above head height, that will make life a lot easier.
Thanks for that. What's the tops and HF please?

[Excalibur]

Thanks for that. What's the tops and HF please?

Sorry, sometimes we forget not everyone is familiar with the terms we use.
Right, a regular setup is what we call subs and tops. The subs ( bass bins, the big ones on the floor ) handle the low frequencies ( LF ) and usually ( though increasingly not nowadays, but that's with the new types of cabs ) send the higher frequencies ( HF ) to the ones on the poles above them. Although we often call them tops, a more correct term is mid/ highs, as there are usually two speakers inside these cabs, a big one doing mids and the really small one doing the high frequencies. This is the one behind the horn flare, and this is what we need to geet above peoples heads.

If you're just running one pair of cabs, ( full range ) the bigger driver is now doing both low and mid, while the HF still gets exactly the same as it did. Hope this helps.

It will also help a lot if you can run the tone controls on the mic channel as " flat" ie no significant bost on bass and treble.

[DJStevie]

Sorry, sometimes we forget not everyone is familiar with the terms we use.
Right, a regular setup is what we call subs and tops. The subs ( bass bins, the big ones on the floor ) handle the low frequencies ( LF ) and usually ( though increasingly not nowadays, but that's with the new types of cabs ) send the higher frequencies ( HF ) to the ones on the poles above them. Although we often call them tops, a more correct term is mid/ highs, as there are usually two speakers inside these cabs, a big one doing mids and the really small one doing the high frequencies. This is the one behind the horn flare, and this is what we need to geet above peoples heads.

If you're just running one pair of cabs, ( full range ) the bigger driver is now doing both low and mid, while the HF still gets exactly the same as it did. Hope this helps.

It will also help a lot if you can run the tone controls on the mic channel as " flat" ie no significant bost on bass and treble.
Many thanks for that. Mine are ART RCF 712-A's and I try to have them at the consumers eye level.

[paulg]

Many thanks for that. Mine are ART RCF 712-A's and I try to have them at the consumers eye level.

Sat down or stood up?

[Excalibur]

Many thanks for that. Mine are ART RCF 712-A's and I try to have them at the consumers eye level.
In the imortal words of Brucie: "Higher, higher ". ( Smilies gone AWOL, Big grin )


Sat down or stood up?
Cabs on the floor, if the punters are blind drunk.