Mic Gain

[MrStitch]

Is there a step by step somewhere that shows how to reach 0 db with a dynamic microphone, without inducing feedback?

I don't know if I should be messing with the fader (slider), the gain knob, eq settings, etc.

I should also mention that I have a cheap behringer mixer (16 channel), so maybe there is some really hi-end noise that's causing the problem.

Suggestions?

 

[boingoman]

Turn your monitors down.

 

[snow lizard]

Turn your monitors down.

Or off for that matter.

If you're on a stage or anywhere where you need to have speakers on, try to set up so that the null of the microphone is facing the speaker.


sl

 

[MrStitch]

Yep, tried turning monitors down, but then they go so low that you practically can't hear them. As far as the mic position.... i'm stuck in a bad spot, and can't do anything about it. 'Sometimes', the mic gets pointed directly at the speaker.... frickin drunks! hahahah

 

[Vagodeoz]

The best ways to keep feedback as away as possible, is to aim the null side to the speakers (as someone already said earlier) and moving the position. The closer it is to the sound source in comparison with the speakers, the more gain before feedback you get.
Also very directional speakers/microphones will help.

 

[MrStitch]

I'll just have to do the best I can with speaker position....

Anyways, to my main point - How do you go about setting up the mic on the mixer? Do you set the slider at 0db, and then adjust the 'gain' knob as far as it can go before feedback?

I should also mention that the system is tied to a 31 band eq.... of which, I'm not really sure how to operate all that well, and I'll post something in another thread about this... many questions.

 

[Fishmed]

Can't you just use headphones to track if you cannot isolate the mic from the monitors?

 

[RightOnMusic]

i think he's talking about live sound.

 

[eyeteeth]

For live sound, I've always turned up the preamp, EQ'd the channel, then final adjust the preamp gain to just below peak. This ends up giving me the greatest flexibility and range with the fader for mixing.

In the studio, it comes down to the sound. I'll vary between running a lot of gain and little fader, or a little gain and a lot of fader depending on how hard I want to push the preamps for a specific "color" or effect. Occasionally I'll purposely peak the preamp for the effect.

Live... a good Multi band EQ is going to be a necessity. You usually need to shape the sound as many monitors (especially cheap ones) can overload freqs around 3000hz. The super cheap monitors with the piezos for HF drivers are the worst for that. the room will also have certain freqs it likes to enhance and every room is different, plus it will change once people show up. It's a constant moving target.

 

[Fishmed]

i think he's talking about live sound.

Ok...

When it comes to mixing live sound, it is partly up to the performer to know how to handle the mic and where they can go on the stage with the mic. I have had singers just drop their hard holding the mic when they stop singing during the song, and the mic would then be right next to the monitors on stage and feedback. I am thinking, "You idot, keep your hand up or put the mic back on the stand."

* If you do not have control of what the singer does with the mic on stage, you might want to put a gate on it so when they stop singing it closes.
-or-
* If the singer sings too softly, then you are forced to crank the mic, which then increases the background noise into the mic, in turn feedback. Have the singer sing louder or have the band play not as loud.
-or-
* If posible, EQ the vocal send to the stage monitors, but that is tricky if you have multiple singers performing back to back and you don't have the time to do that part of the sound check (basically have to do it on the fly).

I find stage systems with inadequate power/speakers tend to feedback more often than those with the right amount of power/speakers.

 

[Vagodeoz]

What I have done with the 31 band eq is to put a mike aiming at the PA. The mike is connected to an spectrum analizer. And start doing the usual soundcheck. When you have feedback the spectrum analizer will tell you in which band it was, so you dip it a little bit with the EQ. This should give you a couple more dBs overall before feedback.
Usually my reference point for gain is the recorder I'm using, but since you are on live sound I guess just before peak is a good option. Just leave a little headroom for dynamics.

 

[MrStitch]

Yeah... I've got all the worse problems working against me on this, see siggy

1) Live sound

2) People that don't know how to handle a mic

3) Live sound and people that don't know how to handle a mic hahahahah

However, I've encountered this problem in band practice, and I've heard of 'finding the right frequency' to kill the feedback, but I don't have a spectrum analyzer.

The only thing I guess I could do, is induce feedback and let it ring until I find the right knobby to turn down.... yeah... that'll go over well at a show. hahahah

Doesn't help that I'm running an SM58 (known to be hot) with a behringer mixer (god only knows what it's throwing in there for noise).

I was thinking of investing in some beta 58's, as I've heard some good reviews... anyone here know different?

The host actually uses a different mic. He uses an Audio Technica, with some sort of feedback eliminator/reducer. The mic sounds DAMN GOOD, and we never have trouble with feedback. Problem is, the thing costs $350. Could be cheaper by now tho.. haven't checked recently.

 

[boingoman]

Go to a big bookstore and read a basic PA setup book. Not so much for the whole gain structure thing, but for speaker placement, and other basics. If you do have an EQ, consider tying it into the monitors instead of the mains, or running in mono and using one side of the eq for mains and the other for monitors.

 

[MrStitch]

actually... right now one channel is set up for mains, and the other for mono.

Will get into the eq in another thread, as I got some knobs I don't understand. When we do a show saturday night, I'll take some notes on what I've got.

 

[mixsit]

Anyways, to my main point - How do you go about setting up the mic on the mixer? Do you set the slider at 0db, and then adjust the 'gain' knob as far as it can go before feedback?

Back up a bit. You're setting the first gain stage for the inputs here first. This has nothing to do with how loud you might be able to get the speakers.
Set the chanel fader to 0' with the speakers (mains and monitors) off, eq's should be zeroed out initially. Then set the gain/trim so that each input at it's loudest signal is hitting 0' on the mixer.