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Whistling sound from speakers with High EQ

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Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 10:07 am
by Guest
Hi
I have ran a couple of behringer mixers with the High EQ turned up to full, and when I turn it up on bough mixers I get a whistling noise from the speakers. Any ideas on how to avoid please?

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 10:10 am
by Hugh Robjohns
Don't turn the high-EQ up full... simples! :lol:

A flippant answer, perhaps, but frankly you haven't given anything like enough information for anyone to be able to offer any kind of sensible answer.

For starters, is this 'whistle' apparent when you have a live source faded up on the desk -- if so, what is the source? Are we talking open microphones here? Could you be describing a high-frequency acoustic howlround?

Or is the source generating some high frequency noise itself which you are then raising to audibility?

Or is this unwanted whistle there even when all the desk faders are closed?

If the latter, then we need to know how the speakers are wired into the desk. Balanced or unbalanced. Are the speakers and desk running from the same mains outlet, or different outlets? What else is connected to the desk?

Give us a clue....

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 10:33 am
by Arpangel
What Behringer speakers have you got? I use a pair pair of 3031A now and again, I turned up the high EQ switch, no whistling sound. This may be an input/source issue, turn down or unplug your sources and see if it goes away. But this just may be a case of variable "Behringer build quallity" in which case, take Hugh's advice!

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 2:06 pm
by Guest
Hugh Robjohns wrote:
For starters, is this 'whistle' apparent when you have a live source faded up on the desk -- if so, what is the source? Are we talking open microphones here? Could you be describing a high-frequency acoustic howlround?

Or is the source generating some high frequency noise itself which you are then raising to audibility?

Or is this unwanted whistle there even when all the desk faders are closed?


.
I don't know, will have to go and test and report back, but the closer the microphone is too the speakers (s) the greater chance or a whistle or the louder the volume is set on the speakers the greater chance

But some sound tech guy advised that I needed more High EQ and less Low EQ on my voice

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 2:36 pm
by Hugh Robjohns
night ans day wrote:...the closer the microphone is too the speakers (s) the greater chance or a whistle or the louder the volume is set on the speakers the greater chance...

Ah yes. I think the professionals call that a HOWL-ROUND. It happens when the overall gain in the system exceeds unity and so leads to positive feedback. Sound from speaker gets into mic. Signal is amplified and routed back to speaker... and so on.

The only way to prevent it is to reduce the amount of sound from the speaker getting in to the mic!

You can do that in many ways, and normally you will require a combination of them.

Maximise the distance between speakers and the mic.

Optimise the directionality of the speakers and mic to minimise pickup -- which usually means placing the speakers closer to the audience than the mic (so the mic is behind the speakers) , and use a directional mic with its least sensitive sides facing the speakers.

Choose or adjust the PA system and mics to have as flat a frequency response as possible -- howl-rounds occur first at the response peaks.

ALWAYS use EQ cuts rather than boosts .

But some sound tech guy advised that I needed more High EQ and less Low EQ on my voice

Try cutting the bass rather than boosting the HF! Try a different mic. Improve your mic technique. Optimise the setup of speakers on stage relative to the mic... etc...

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 3:50 pm
by Guest
Hugh Robjohns wrote:Ah yes. I think the professionals call that a HOWL-ROUND. It happens when the overall gain in the system exceeds unity and so leads to positive feedback. Sound from speaker gets into mic. Signal is amplified and routed back to speaker... and so on.
will turning the gain knob down not help?

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 3:56 pm
by Hugh Robjohns
Yes... and so would not turning up (so far) the HF boost gain knob!

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 4:51 pm
by Mike Stranks
I found that most feedback problems can be sorted by adjusting the EQ, rather than dialling back the gain. More effective as you're only attenuating the offending frequencies rather than those and everything else too.

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 5:45 pm
by AlecSp
Wonder what sized cones they are...? ;) </twitch>

Re: Whistling sound from speakers with High EQ

PostPosted: Thu Aug 08, 2019 6:41 pm
by Guest
Take a listen to this at 32 seconds you hear ooh ooh ooh ohh ooh ooh, was not sure if it was to much falsetto in my voice or the mixer set up wrong

This was a home recording with no PA speakers present, for the mic channel the High EQ turned up to full and the Low EQ turned to minimum. And the gain and the level bough set to 5/8 turned on

https://www.dropbox.com/s/upxy6m6d83cdv ... o.m4a?dl=0

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 6:45 am
by Sam Spoons
Those peaks are distorting, I can't hear any whistling on my laptop speakers.

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 9:58 am
by Guest
Sam Spoons wrote:Those peaks are distorting, I can't hear any whistling on my laptop speakers.
what do you thinks causing it then?

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 10:36 am
by Mike Stranks
Sam Spoons wrote:Those peaks are distorting, I can't hear any whistling on my laptop speakers.

Yup! Listened on decent monitors in my treated room. No 'whistling', but excessive presence in the vocal causing various artefacts.... but then there would be wouldn't there?

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 10:46 am
by Guest
Mike Stranks wrote: but excessive presence in the vocal causing various artefacts....
Are you saying I am a little loud and should back off the mic then?

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 10:59 am
by Hugh Robjohns
Dialling in maximum boost adds 16-18dB of extra level at high frequencies, and that could very easily result in overloading the mixer's mix bus. If you're going to dial in that much EQ you will probably have to back of the input gain a bit to compensate and maintain headroom in the mixer.

So it's more about setting up a sensible gain structure than backing off the mic.

But as I and others have already said, adding that much HF boost is not ideal, especially in a live-sound situation.

Cutting unwanted frequencies is always better than boosting the wanted ones!

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 11:15 am
by Guest
For that recording you heard the High EQ was set to max and the level and gain set to 5/8. I'll try an experiment this afternoon (after my morning voice has wormed up) by recording the same chord playing around with all 3 knobs to see if there is any improvment

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 7:05 pm
by Guest
I just tried it again as set as before and there is no distortion this time so I don't know.

But as a general rule should the gain and level be set even and set to the middle, and the high EQ set to the middle too?

Re: Whistling sound from speakers with High EQ

PostPosted: Fri Aug 09, 2019 9:52 pm
by Sam Spoons
No, not really, the gain needs to be set to suit the source at each stage of the signal path, it is adjustable at the preamp and via the eq and, sometimes, further down the chain. The crucial thing is to ensure that it is not overloading at any point in the signal path. WRT to mic technique, backing off the mic when 'belting' is standard practice.

Re: Whistling sound from speakers with High EQ

PostPosted: Sat Aug 10, 2019 11:14 am
by Guest
Sam Spoons wrote:No, not really, the gain needs to be set to suit the source at each stage of the signal path,
The crucial thing is to ensure that it is not overloading at any point in the signal path.
Is there a proper way to do a diagnostic test with say a multi meter or something?

Re: Whistling sound from speakers with High EQ

PostPosted: Sat Aug 10, 2019 11:35 am
by Hugh Robjohns
night ans day wrote:Is there a proper way to do a diagnostic test...

Yes!

...with say a multi meter or something?

No!

The correct procedure is to use the PFL (or solo) button on each channel which will display on the meter the signal level as it reaches the channel fader. You can then adjust the input gain to optimise the signal level -- usually so that it averages around the zero mark on the meter.

Do yourself a favour and read a decent book about the practical side of live-sound production. This one's not bad...

https://www.soundonsound.com/shop/books/sos-guide-live-sound