Since I switched mixers my microphones have become more sensitive to feedback rumble. They don't give off the normal shrill high pitched squeal. There is a loud low pitched vibration rumble noise if they get pointed toward the speakers.
Any ideas what causes that?
Low end mircophone rumble....
Re: Low end mircophone rumble....
The preamps in your new mixer are likely more sensitive, with a better frequency response. You could be picking up rumble from the air conditioning. Use your graphic EQ, and experiment with cutting individual bands, one at a time, between 20 and 200 HZ. One of them will likely be the fundamental frequency of the rumble, and you can use that band to filter it out.Bigdog wrote:Since I switched mixers my microphones have become more sensitive to feedback rumble. They don't give off the normal shrill high pitched squeal. There is a loud low pitched vibration rumble noise if they get pointed toward the speakers.
Any ideas what causes that?
Last week, I went to Philadelphia, but it was closed.
Yup, it's basically the same thing happening, but at different frequencies. Graphic EQ is the best tool for eliminating or reducing all those funny noises.Bigdog wrote:It only happens when the microphones are too close to or at the wrong angel to the speakers. Just like when you you get high squeal feedback.
I had a rival KJ scoping me out last night. One of the singers casually propped himself on a speaker (a fairly large twin 15" cab) during a music interlude in a song. The KJ's jaw dropped in disbelief when nothing nasty happened. He asked if I was using a feedback buster, and I told him I just used the EQ to control feedback.
It's not hard to learn - just takes a bit of practice.
Edit: Here's an excellent article on the basics.
http://www.stage-directions.com/backiss ... 2/eq.shtml
Last week, I went to Philadelphia, but it was closed.
Remember, feedback happens because there's too much volume at a particular frequency.Bigdog wrote:OK but...my sound..... music and vocals goes through the same 31 band EQ out of the mixer.
If I start dropping the freqencies to fix the mic rumble, I'll be affecting the sound of the music too.
You're not going to need large adjustments here. it's kinda like Brylcreem - a little dab will do ya. Usually a -3db cut will be enough to make a big difference. The audience likely won't notice a thing except that it sounds "cleaner."
Last week, I went to Philadelphia, but it was closed.
I always do one at a time - if you take a minute before a show you can do a cut on on freq, see if it helps, bring it back up if it doesn't and move to the next higher freq.Bigdog wrote:Do you suggest starting with the low end frequencies? How would you do it? One at a time or several at once?
Since you describe it as a rumble, I'd be guessing it's somewhere below 250 Hz.
Last week, I went to Philadelphia, but it was closed.
Assuming that you are using separate channels for music and each mic, I suggest cutting the low end on your mic channels only.Bigdog wrote:OK but...my sound..... music and vocals goes through the same 31 band EQ out of the mixer.
If I start dropping the freqencies to fix the mic rumble, I'll be affecting the sound of the music too.
One other thing worth mentioning as a side note. Not knowing what brand of mixer you have I can only make this suggestion based on what I have experience on. On each mono mic/line channel, just below each the inputs, I have a "Low Cut" button which does just that. It’s a hi-slope low-cut filter for eliminating unwanted low frequency signal components to reduce or prevent rumble.
If it applies to your mixer it will help as well. If not, disregard.
jr2423 wrote:Assuming that you are using separate channels for music and each mic, I suggest cutting the low end on your mic channels only.Bigdog wrote:OK but...my sound..... music and vocals goes through the same 31 band EQ out of the mixer.
If I start dropping the freqencies to fix the mic rumble, I'll be affecting the sound of the music too.
One other thing worth mentioning as a side note. Not knowing what brand of mixer you have I can only make this suggestion based on what I have experience on. On each mono mic/line channel, just below each the inputs, I have a "Low Cut" button which does just that. It’s a hi-slope low-cut filter for eliminating unwanted low frequency signal components to reduce or prevent rumble.
If it applies to your mixer it will help as well. If not, disregard.
Engage Low-Cut if you have it and use the Channel EQ to cut around 250Hz assuming you have a sweepable mid. You don't need much cut, just a very slight turn.
