
Ringing out your room can get rid of feedback problems.
Photo provided by sachyn
You can get rid of that pesky feedback once and for all! Discover the three ways for ringing out the room and the one that you can perform today.
Ringing out a room is a process for eliminating problem frequencies wherein those frequencies are prone to feedback in your room. You might hear it called “tuning the system” or “tuning the room.” The last phrase “tuning the room” is actually a wrong phrase to use. You aren’t tuning the room, you are tuning the house EQ to work in the room.
Additionally, tuning the system and ringing out the room are a little different. Ringing out the room focuses on feedback frequencies whereas tuning the system includes dealing with feedback frequencies but is also aimed at sculpting the house EQ so your system sound is in line with your needs. For example, a house EQ for a country music setup will be different than a house EQ setup for heavy metal music.
There are three methods for ringing out the room;
- ($$$$) Hire a professional. An experienced audio professional can use a real-time audio spectrum analyzer and adjust the house EQ to obtain the desired sound. Not only can they deal with problem frequencies but they can also sculpt the house EQ to be better suited for your needs. Go this route if you can afford it. They can ring out the room but they can also tune your system.
- ($$$) Use an automated solution. An automated room equalizer like the DBX DriveRackPA can be used to eliminate those problem frequencies for your system. It’s effective but not the best. Yes, I know DBX claims it a miracle in a rack component but nothing beats your ears (or the ears of a pro). I’ve known people who have used these types of rack-based solutions for portable systems. In my experience of working on portable systems, I tweak the house EQ during the sound check based on what I hear.
- (FREE) Ring out the system on your own. The cheapest option and one you can do. You won’t get the sound qualities that a professional would get using #2 but if you’re dealing with feedback frequency problems, it’s a great place to start.
The nine steps to ringing out the system on your own
- Set up your board for a proper master volume level.
- Set up a microphone on the stage for a person to use for speaking.
- Have the person talk into the microphone and set up the proper gain structure for their channel.
- Turn up the master fader until you begin to hear feedback as a slight ringing.
- Identify the frequency by ear or use a spectrum analyzer. Only use a spec analyzer if you know how to properly use it.
- Cut that frequency in the multi-band house EQ until it goes away.
- Repeat steps 4 through 6 until many frequencies tend to feed back at the same time. Then….
- Reduce the master volume back to the normal level. The person’s voice should still sound natural. If it doesn’t, tweak your house EQ changes appropriately by giving a little boost to those frequency bands you cut.
Going through this process, you’ll eliminate those problem frequencies while also gaining more headroom in your system before experiencing feedback.
Perhaps #2a with one $ sign – there are so many apps for generating pink noise as noted in the prior post, and inexpensive Real Time Analysis (RTA) mics that it is worthwhile to consider spending a bit, likely less than $100, to be able to ring out your venue yourself.
And in the #1a category, $$$: an approach we are now able to take thanks to ongoing concerts and local professional musician support: purchase a sound board/mixer which builds in RTA support.
if you are in the market for upgrading your sound system, look into sound boards/mixers with integrated “pink” noise sources and equalizers. The Midas M series/Behringer X series and Presonus StudioLive consoles support this and are “hybrid” analog-digital boards. There are others; these are the ones we got our hands on.
We have found a hybrid board gives the physical “feel” to mixing that so many sound engineers need to connect with their mixing tasks. Behind the scenes the digital signal processing foundation of these devices support so much more than the dbx Automatic Feedback Suppressor (AFS) single task of “feedback killer”! (But yes, we have a dbx AFS2 in line most of the time, too!)
As nearly everyone has a smartphone or tablet, there are some great apps that will show you freqency and amplitude. Most are not really good for tuning a room but some are great for ringing it out. I use “AudiiSpectrumMonitor” for Android as it shows keybord notes and the freequency of the loudest note.
Richard, thanks for the info on the apps and the one you use. I taught a church audio session this weekend at a local church and mentioned the advantages of having an SPL meter. During a break, a guy bought an SPL meter app for his iphone and was using it during the next instruction period.
Researching the web led me to this thread, even though I am on your email/newsletter and it is great stuff. My question is, the above example works great when using a digital board as there are completely digital eq’s for each channel and once can really carve in our out what needs to be heard. What is your recommendation for ringing out mikes when you have an analog board and the FOH speakers’ equalization is done through Ashley Protea software (that I don’t have access to -just the guy that installed my churches system.) I will try the above steps, but am imagining that it can cut in 4 areas (we have Allen-Heath GL2400 board with 4 band-parametric EQ for each channel), but I may end up needing to boost more and undo the needed cuts I made to counter feedback ring. Any thoughts? Thank you.
If you have a house rack EQ, use that. If it’s only via the software…how good are you with software?