Calibrating Monitors on stage

Mauricio Guillen

Freshman
Jun 12, 2014
25
0
0
Hi, this is my first post, although I've been reading and learning a lot from you guys regarding the X32 and audio stuff and i would like to thanks all for your suggestion that everyone over here makes (I'm sorry for my English, this is not my main language, it is Spanish, so any mistake that i write pls., bear with me, and I'm still learning a lot your language), as i mentioned, I've bought an X32 and everything is working well with it, however; i know somebody who does work with a Mc7l, and he use an ipad with it, its not my friend so i can't ask him how does he do this; I've had to work in 2 times with him, he was doing the sound stuff and i was doing all the light, but i noticed that he calibrates the stage monitors with a pink noise generator and then (i don't know how?)he change the pitch of the noise generator in tones and semitones like if you were playing keyboards and then he analize the monitors and correct them before for not making feedbak.... so anyone over here knows how or what soft is using with it?

Regards

Mauricio
 
Re: Calibrating Monitors on stage

but i noticed that he calibrates the stage monitors with a pink noise generator and then (i don't know how?)he change the pitch of the noise generator in tones and semitones like if you were playing keyboards and then he analize the monitors and correct them before for not making feedbak.... so anyone over here knows how or what soft is using with it?
Mauricio,

The software Smaart (and several others)has both pink noise generator and sine wave generators, the sine wave generator can be manually set to any frequency (tone) , or specific frequencies can be typed in.

Pink noise can be helpful for "roughing in" monitor EQ, but to get maximum gain before feedback requires talking in the mic, as the microphone responds quite differently when there is a mouth and head, (possibly wearing glasses and a hat) reflecting the monitor sound back at the mic than if the mic is left open as you described.

Art
 
Re: Calibrating Monitors on stage

Thanks a lot Art for your kindly response, so I have to look then for sine wave generators to set the tone or frequency or as you've mentioned,

Thanks for your input....
 
Re: Calibrating Monitors on stage

Thanks a lot Art for your kindly response, so I have to look then for sine wave generators to set the tone or frequency or as you've mentioned,

Thanks for your input....

Hi Mauricio-

Art is discussing 2 concepts, one uses a pink noise or swept sine wave and an "analyzer" product or computer program, the other uses YOU, speaking into the microphone and making the same actions as the performer (like a rapper 'cupping' the microphone, or the TV personality who points the microphone into a monitor wedge). The latter technique is sometimes called "ringing out", because you want to gradually bring up the level until feedback is just beginning to "ring" (before it becomes a big howl or squeal), then reduce the appropriate band on your EQ; then you bring it up again until the ringing begins, find the frequency band and bring it down. Once you have done this for 3 or 4 frequencies, you've done about all you can do without adversely affecting the sound.

Both methods are often used. Frequently the analyzer is employed first and used to identify things that need general correction, then the ringing out is done to maximize the available level while emulating the performer's actions, choice of hat/eyeglasses, or desired tonal qualities.
 
Re: Calibrating Monitors on stage

Mauricio...

To reinforce what Tim said:

You can simply use an open mic (or mics) to quickly find the 3 or 4 "hot" frequencies of a room/system or stage/system setup. Put your mic(s) in the area of concern and set them to a good input level. Raise the mic/main level until the system starts to ring, then back off a tad. You can then simply "boost to identify" by raising the EQ faders one at a time (starting from the LF end), returning each fader to the neutral position if no ringing is encountered. If you hear a frequency start to "go" when boosting, you can then apply an appropriate cut to bring the response into a friendlier "ball park". If you have any EQ which is sweepable, you can put a 9dB boost on a filter, then sweep through the spectrum setting filters as needed...again starting with the LF end of things. As Tim said, find the 3 or 4 worst offenders and call it a day.

Practice makes perfect. After getting comfortable with the process, you should be able to do this with a mix in a matter of minutes. It is admittedly unsophisticated but served many of us well over the years and is still valid. Much insight in how frequencies reinforce/cancel can be gained using this basic method.

Please feel free to come back with any questions. Boost to identify, cut to taste...
 
Re: Calibrating Monitors on stage

Thanks again Tim, Dick, Art; very clear your response into this matter, i understand the concepts doing it with a mic and a person who speaks into it, however i was wondering about the analyzer; but its understood very well; thanks again guys, I'll appreciate your help on this specific point
 
Re: Calibrating Monitors on stage

Thanks again Tim, Dick, Art; very clear your response into this matter, i understand the concepts doing it with a mic and a person who speaks into it, however i was wondering about the analyzer; but its understood very well; thanks again guys, I'll appreciate your help on this specific point

The dual FFT analyzers like Smaart or SIM or SysTune do their measurements in the time domain (and time is frequency and also distance). From the impulse response, both magnitude and phase (not just polarity) responses can be determined. Or they can be used as simple RTAs, looking for an obvious magnitude peak or to provide a quick visual confirmation of something the operator is hearing. How the tool is used depends on what the operator is looking for and what other tools he has to apply to any problems he encounters.
 
Re: Calibrating Monitors on stage

Mauricio...

To reinforce what Tim said:

You can simply use an open mic (or mics) to quickly find the 3 or 4 "hot" frequencies of a room/system or stage/system setup. Put your mic(s) in the area of concern and set them to a good input level. Raise the mic/main level until the system starts to ring, then back off a tad. You can then simply "boost to identify" by raising the EQ faders one at a time (starting from the LF end), returning each fader to the neutral position if no ringing is encountered. If you hear a frequency start to "go" when boosting, you can then apply an appropriate cut to bring the response into a friendlier "ball park". If you have any EQ which is sweepable, you can put a 9dB boost on a filter, then sweep through the spectrum setting filters as needed...again starting with the LF end of things. As Tim said, find the 3 or 4 worst offenders and call it a day.

Practice makes perfect. After getting comfortable with the process, you should be able to do this with a mix in a matter of minutes. It is admittedly unsophisticated but served many of us well over the years and is still valid. Much insight in how frequencies reinforce/cancel can be gained using this basic method.

Please feel free to come back with any questions. Boost to identify, cut to taste...

Mauricio,

As a general practice, using Smaart or a similar analyzer on monitors would be something one would do while in the shop, not in real time at an event. I would rather work out issues with the monitors in question like this first, getting them voiced and corrected to taste, preferably outside with no walls around.

At the gig, I'd check by ringing out the monitors as Dick describes, looking for problems that are inherently native to the location and specific setup.

One thing I've added to my method is a handy app on my iPhone that identifies a frequency that is feeding back. If I'm at a mic, I can see instantly what the exact frequency feeding back is, and match it in the processor for that wedge. This allows one to also use very narrow filters, which won't affect the overall sound(that you've dialed in back at the shop with Smaart) nearly as much.

Best regards,

John
 
Re: Calibrating Monitors on stage

Mauricio,

As a general practice, using Smaart or a similar analyzer on monitors would be something one would do while in the shop, not in real time at an event. I would rather work out issues with the monitors in question like this first, getting them voiced and corrected to taste, preferably outside with no walls around.

At the gig, I'd check by ringing out the monitors as Dick describes, looking for problems that are inherently native to the location and specific setup.

One thing I've added to my method is a handy app on my iPhone that identifies a frequency that is feeding back. If I'm at a mic, I can see instantly what the exact frequency feeding back is, and match it in the processor for that wedge. This allows one to also use very narrow filters, which won't affect the overall sound(that you've dialed in back at the shop with Smaart) nearly as much.

Best regards,

John

John, et al...

After decades as a musician I have developed a sensibility I'll term "relative pitch", not perfect pitch. I use my normal voice range as a base line and can get pretty close to a step of the scale in comparison. It is close enough so that I can name a pitch in terms of a piano keyboard within a half step...allowing for seasonal colds and such. I then count the octaves from my voice pitch to the feedback pitch and go from there. I know the frequency of your basic pitches of the scale, but I keep a pitch to frequency chart on whatever digital device I happen to tote along....laptop or iPad. I find this to be as quick as anything but do sacrifice pinpoint accuracy. But considering available filter width, drift and other variables, I'm comfortable with the ball park in which I work.

I suspect that the various ear training programs shoot for the same result. I just happen to have gotten there through the music over the years. And if I can do it, certainly anyone has a good chance of developing the ability with effort over time.

PS

The SMAART overlay of the GEQ on the StudioLive boards is brilliant for this, but you do have to be at the board to use it.
 
Re: Calibrating Monitors on stage

I suspect that the various ear training programs shoot for the same result. I just happen to have gotten there through the music over the years. And if I can do it, certainly anyone has a good chance of developing the ability with effort over time.
Dick,

Danley's Feedback Trainer and other apps are very handy and helpful. I think they're working on an Android version, but don't remember where I saw mention of that. Currently, I believe they are only for Apple iOS devices.
 
Re: Calibrating Monitors on stage

Dick,

Danley's Feedback Trainer and other apps are very handy and helpful. I think they're working on an Android version, but don't remember where I saw mention of that. Currently, I believe they are only for Apple iOS devices.


The techno-phobe/DIY side of me wonders if you could train folks simply by dividing the 31 bands in half, then in quarters, then in finer and finer increments...learning in which area/division the hot frequency lay. Continue until you have 31 divisions and you're as good as you can get...

First stage: here or there.

Etc.

Etc.

Etc.
 
Re: Calibrating Monitors on stage

The techno-phobe/DIY side of me wonders if you could train folks simply by dividing the 31 bands in half, then in quarters, then in finer and finer increments...learning in which area/division the hot frequency lay. Continue until you have 31 divisions and you're as good as you can get...

First stage: here or there.

Etc.

Etc.

Etc.

That's kind of how a few of them work, from my experience. I'd send links your way but I'm drawing blanks on the names of ear trainers right now.
 
Re: Calibrating Monitors on stage

Thanks again for everyone who has jumped over here, like Tim and Jhon were saying, it's better to work with a mic and a person to ring the monitors, that's what I do on my rig, but I was wondering about this person who does pitch the frequency with a pink noise generator and I was wondering if I can do that with my X32, altought I have an RTA in the mixer, however it doesn't have an anti feedback built on it, can you help me with the name of an app that shows wich frequency is the one who is bothering, for an Android tablet? Besides the RTA on the mixer
 
Re: Calibrating Monitors on stage

So you need an app for this? Seems like common sense and practice would suffice...

Make sure to wear ear plugs when ringing out monitors on stage, especially if you don't know the engineer driving the console.

After a loud blast on stage a few years ago, my right ear ended up with some serious damage. Plugs would've minimized it.