Feedback in your PA

[dmatthews]

I recently acquired a Bose L1 model 2 with B2 and Tonematch.
I struggled last night with some feedback issues. This will be based on numerous things such as placement/vol/blah blah.
That being said, I started to think a bit outside of the box.
I found this app for my Android phone called Audio Spectrum Monitor.
This is the most accurate app I've found to listen to and display frequencies.
I wanted a RTA app to help me find offending feedback frequencies. This is it.
As an example, I hooked a mic up to my Zoom L-12 mixer/recorder, and stuck the mic in the woofer of my Yamaha HS80M monitor.
The app showed feedback around 100hz.
I then dialed that freq range on that input on the L-12 and lowered the low end. Boom! Feedback gone!
I then repeated the experiment with the mic in the tweeter.
1000hz, same method and feedback gone!
The app shows the frequency along with the note, therefore 440 = A.
That's how the Bose works.
Winning!

So... lesson for me is that if you are gigging, or even in your regular practise space, you can use this app to find the nasty offending feedback frequencies and knock them out by yourself, or at least tell the sound guy where the freqs are.

 

[László]

I love this stuff.

 

[gush]

I've spent a lot of time with my Rane RTA at shows. The most frustrating thing is dealing with people yelling "turn it down" when dialing in a room.

Sometimes you gotta hate people! Lol

 

[alantig]

I recently acquired a Bose L1 model 2 with B2 and Tonematch.
I struggled last night with some feedback issues. This will be based on numerous things such as placement/vol/blah blah.
That being said, I started to think a bit outside of the box.
I found this app for my Android phone called Audio Spectrum Monitor.
This is the most accurate app I've found to listen to and display frequencies.
I wanted a RTA app to help me find offending feedback frequencies. This is it.
As an example, I hooked a mic up to my Zoom L-12 mixer/recorder, and stuck the mic in the woofer of my Yamaha HS80M monitor.
The app showed feedback around 100hz.
I then dialed that freq range on that input on the L-12 and lowered the low end. Boom! Feedback gone!
I then repeated the experiment with the mic in the tweeter.
1000hz, same method and feedback gone!
The app shows the frequency along with the note, therefore 440 = A.
That's how the Bose works.
Winning!

So... lesson for me is that if you are gigging, or even in your regular practise space, you can use this app to find the nasty offending feedback frequencies and knock them out by yourself, or at least tell the sound guy where the freqs are.

Nicely done.

That reminds me of a Michael Hedges bootleg video I have. Can't remember which show it is, but he strummed his guitar to check his tuning while he was introducing the next song. He stopped talking and hit it again, and there was just this bit of woofy feedback. All of this in about three seconds or so - hit the chord, looked up at his tech and said something like, "Turn 480 down 2 db." Hit the chord again - gone. That dude was a freak with what he could hear and identify.

 

[bodia]

Nicely done, Dave. Needs a pun, though!

 

[dmatthews]

Nicely done, Dave. Needs a pun, though!

Bwahahahahaha!!!
Damn it... now I have pun/stage fright!

 

[bodia]

Bwahahahahaha!!!
Damn it... now I have pun/stage fright!

Like standing next to another guy at a urinal?

 

[Deleted member 5962]

I love this stuff.

Me too. As a sound man at a big church, I've been chasing feedback without a tool like this for YEARS. Using only my ears to "guesstimate" what range to get the parametric EQ too and then dialing around til I find it. I'm going to look now to see if they have the same app for iphone.

Edit: they do and I got it. I'll check it out tomorrow and tell my brother to get it as well.

 

[dmatthews]

Like standing next to another guy at a urinal?

Peezacly!

 

[dmatthews]

Me too. As a sound man at a big church, I've been chasing feedback without a tool like this for YEARS. Using only my ears to "guesstimate" what range to get the parametric EQ too and then dialing around til I find it. I'm going to look now to see if they have the same app for iphone.

Lots of the ones I tried use a bar graph system that encompasses a range, say 1000 - 1500 or something which I found to be less than useful.
This app zeros in on the freq exactly!
Here's a screen shot of the app finding 1000hz generated by my PC speakers



You can go here to generate a freq of choice to test

http://onlinetonegenerator.com/

 

[Rusty Chops]

Not for me!
If you get all the hum and feedback out, the vocals might wind up out front and people will expect me to remember lyrics!

 

[Axis39]

I use a Behringer XR-18. It has a built-in RTA and the graphic EQ

Here's a video on doing it on Android for the Behringer. But with your app and an EQ you can use this on any PA

 

[gush]

This may seem odd but I've put my RTA in an aux on my board to get a visual of an individual source.

I did sound for a band once where one guitar had a line 6 head and he had some super obnoxious freqs coming through system. I had a really hard time sweeping to find the most offending frequency because there were so many mics on stage and their stage volume was loud.

By putting it through the aux I could isolate his channel to the RTA and get a visual of what was goingoing on.

 

[DickBanks]

Line 6 digital speakers have feedback suppression. My L3Ts have it, and it works well. The squeal will start, and then rapidly cut out, with no loss of volume/tone.

Frightfully simple technology really; just a low-pass filter that dynamically kicks in when needed. Surprised more speakers don't have it.

Did a wedding last spring, handed the mic off to the Maid of Honor to do her bit, and showed her the "feedback line." She insisted on walking forward of it, and would get the start of the squeal, and then rapidly jump back. She did this a number of times, all to the same effect. Her dad was yelling, "you better take that mic from her before she kills your speakers!"

Me: "I ain't worried about it."

Very satisfying.