In a massive room last night speakers spread apart but still got mic boom, what is the cause and what devices are available to eliminate, its getting very annoying. I have good gear and use only one sm58 and backing

In your other thread you are looking for an anolog mixer. If you were to buy something like an Allen and Heath cq12t you could get a built in feedback eliminator plus way better EQ options than any anolog mixer.

Mic boom is caused by a resonant frequency within the room you're playing in. Smaller rooms have higher resonant points (or none at all), larger rooms have lower resonant frequencies and are more prone to mic boom.

Curing the problem can be done with any reasonable EQ device -- graphic EQ, parametric EQ, even cheesy tone controls. What you want is a narrow filter at whatever the resonant frequency for that venue might be.

What are you using for a mixer?

Was that just a boomy sounding vocal or run away rumble with no one speaking? In live settings mics almost always need to be high passed, my default on an analog console is to engage the high pass filter and add some low EQ cut on any mic channel, those that prefer a big booming vocal sound are SOL.
Controlling microphones is one area where a basic analog console really shows it's limitations, far far better results are possible with a digital mixer.

Are you talking about a boomy sound or about feedback and ringing?

Room resonances and boomy sounds caused by close-in mike placement can be compensated for with equalization. That's why the console has EQ controls.

Feedback is caused by the output of the speaker leaking into the microphone. Either due to direct leakage from the speaker to the mike, or due to the sound reflecting off a surface and coming back into the mike. Feedback is often a side-effect of something else, like poor coverage of the audience from the speakers being too low to the ground (so the volume has to be cranked up so the people in back can hear, while the people in the front get blasted out), monitors pointed at microphones and not the performers ears, slap echoes from the room directing sound from the mains back to the stage, etc.

A good introduction to this stuff can be found in the Yamaha Sound Reinforcement Handbook which I highly recommend.
--scott

Boomy sound rumble of low end

I dont want a digital desk, i can be doing with the hidden setup, is there a feedback eliminator on any analogue desks?

Was using a flow 8 behringer but im switching back to analogue, i cant be fiddling with apps when performing

No, but your analogue desk probably has high-pass filters on all the channels. What happens when you engage them all?

I still can't tell if your problem is that it is feeding back at low frequencies or if it just has too much low frequencies, but equalization is the first step of defense in either case.

A feedback eliminator is really just a fancy automated EQ that makes very tight notches in the frequency response. It's for people in situations where the microphones are moving around all the time so the notches need to move around with them. It's not anything that you should care about under normal conditions.

But you SHOULD wonder how those low frequencies are getting into the microphones.... and it is likely through vibrations conducted from the speakers through the stage into the microphones. Shock mounts are a good help along with the high-pass.... so is adding mass to the stage and stands with sandbags.

And if it's coming in through the monitors vibrating the stage, cutting _all_ the low end on the monitors with really aggressive EQ is likely to help a lot, and it's likely to make the sound a lot better for the audience too since they won't be hearing thumpy stuff leaking out of the back of the monitors.
--scott

So feedback eliminator should do the trick? at what point in the setup is it used? is it used after the desk or before?

After following this thread for a while, as well as all of your others, may I offer some advice?

You have a relatively sophisticated mixer already, but are still looking for another device.

Perhaps you should invest the time in learning to use the gear you already own? Lots of good tutorials on youtube on setting up the Flow 8, and there are other tutorials on how to EQ a room, and so on.

My suggestion is to invest the time to learn to ring out the room before starting your performance. It's not hard, and it usually only has to be done once.

If you can't hear what's going on because you're performing, maybe bring along a pair of friendly ears? I do that for my solo/duo performer friends all the time. A bit of EQ, compression, chorus and reverb and they sound like a million bucks with their Flow 8s.

Or, if you have a recording of yourself, play it through your system at the venue ahead of time, walk out into the room, and make adjustments as necessary.

Yes, there is a learning curve. With a bit of practice, you can train your ears to hear what's going on in the room vs. how you'd like it to sound.

Otherwise, you're gonna end up with a bunch of gizmos that are hard to manage and still don't sound the way you'd like them to.

The mixer I recommended has a screen. Will work better than any anolog mixer becausecit has better channel EQ and output EQ

No, it's exactly the wrong tool. Go back and read what I wrote.
--scott

Way to complex for what i need, i use wav backing tracks and 1 microphone

And yet you are still having difficulties. The Allen and heath mixer you are looking at has bass and treble for EQ options. If you encounter the same type of feedback again your options will be to turn down the bass EQ knob or turn down the whole mix. With the CQ12t you have built in feedback eliminator and parametric EQ or a 20 band graphic EQ. This will allow you to make surgical cuts instead of taking a chainsaw to the whole mix. The CQ12t has a about the same footprint as the ZED 6FX. They made the CQ series to be easy to use. Maybe watch a few videos on You tube before dismissing it as too complicated.

ZED 6fx looks ideal

Then your problem is made easier to locate.... how is the sound from speaker leaking into the microphone? Engage the high-pass on the microphone channel and see how much better it is.
--scott

How is ideal? Bare bones mixer with not enough EQ options. Its obvious you don't know what you are doing but I'm through offering any advice

It's the way you hold your mouth when you sing .

Seriously .....

The room (as others have said) can have resonant frequencies. All you can do is trim them out with filters on your mixer. A digital mixer has these tools built in and with its RTA graphic overlay makes this job a breeze.

Other things you can do .....

The SM58 is NOT the best microphone to reject live feedback. Try something like the Sennheiser e945 (or for less money the e845) or another decent supercardioid microphone.

Keep your microphone at least 4 feet behind the speakers.

Be careful, even when behind the speakers (especially if you have subs) not to be standing in a peak comb filter of low frequencies. Low frequencies have a way of concentrating near the back wall behind the speakers. Move your station away from the back wall 4 feet. It will keep you out of the bass node that develops near the wall between the speakers.

I was using a digital mixer with all that boom

Flow 8 behringer

You will find a cheap analogue mixer easier to learn on. The Flow 8 does everything you need and a lot of other things too, but you're going to have to use a laptop in order to turn the high-pass filters on the channels or adjust the channel EQ. It is entirely fine for the job, but if you haven't done this before you may find that having a console with a "HI PASS" button on each channel is easier to start.
--scott

Regardless whether you use an analog or digital board you need to do the same thing to fix your issue.

The reason the digital console is the better option is because it gives you the tools you need to fix the issue built in whereas the analog mixer would require you buy more equipment to take up space to do the same thing.

First...As mentioned, based on what you describe, you may be able to fix this issue just by using a high pass filter.

Analog and digital mixers will both have these built in.

However, if this is a sound system you bring with you and setup in different venues...A high pass filter may not be the fix in every room.

You may need to "ring" the room. What that means simply is you place the mic where it will be used and turn it up until it starts feeding back. Then using a GRAPHIC EQ on the MASTER FADER/BUS you pull down whichever frequency is feeding back...Then you turn it up more until it feeds back again and you pull down that frequency and so on...I would look into this more on youtube...I am sure there are great more in depth tutorials than the brief one I just gave.

The point of ringing the room is to balance the resonant frequencies in the room. For example, the room you have described in this thread seems to have some build up in the low frequencies...Meaning the room reproduces the lower frequencies better than the higher ones and thus the louder frequencies are much louder. To a point where they just sound boomy...Or they are so loud that they are starting to feedback.

A digital mixer (most anyway) will have a graphic EQ built in.

An analog will require you buy a graphic EQ separately to do this.

Your notion that you "can't be fiddling with apps while performing" is a bit silly to me.

The fiddling should all be done BEFORE the performance. Perhaps you would make minor adjustments throughout but nothing crazy.

And I would argue...the reason you are fiddling with anything at all during the performance is because you haven't taken the time before the performance to do things like ring the room and you are constantly trying to manage the consequences of that.

On top of all that, I understand that your setup is simple. Backing track and vocal. However...

Assuming you are singing...perhaps you want some compression on your mic (which you should)...analog mixer doesn't have that...digital does.

Maybe you want some reverb...Most analog mixers do not have this...digital will.

You are leaving a lot on the table trying to go analog...seemingly because you don't want to spend the couple of hours it would take to learn the digital mixer. And if you take your performances seriously...you should want to learn the tools you have digital or analog or better yet. hire someone to mix for you while you are performing.

If it matters to you (your performances) then invest in them!