Feedback Eliminators?!?!?

Posted: Tue Jul 10, 2007 11:59 am

hey people!!!

so when im performing im getting feedback and i was just wondering if its worth buying a feedback eliminator, like does it really work or should i just buy something else.

Posted: Tue Jul 10, 2007 2:03 pm

A bit more specific please, what are you getting feedback through? monitors? iem's (ouch)?, foh?

If you have any sort of linecheck/soundcheck, I would just buy a graphic eq for the rack and tune it myself, but if time is something you don't have feedback suppression isn't a bad idea.

Posted: Tue Jul 10, 2007 3:12 pm

You need to learn WHY you are getting the feedback first!!!!! You can't just go out and buy a box and throw it at the problem...
There are just too many interwoven issues that cause this.
Microphones-what kind? How are they positioned in regards to the stage monitors? In regards to the house system? How are you positioning the
various speakers? What types? What type of room and acoustics? How big is the band? How loud?
The main issue, in my mind, is that you need to be cognizant of keeping the sound from any of the speakers from getting into any of the mics. This includes not only the direct sound from the speakers, but also the reflected sound off of the walls, the floors, the ceilings. This means that you have to understand your mics' pick-up patterns and your speakers' dispersion patterns. Then you learn how to tune with a decent graphic.
No matter what the marketing hype from the manufacturers says, these boxes have a very limited benefit. You HAVE to get the basics down first.
Having said that, I've found that the Sabine systems work the best, there are others that like the Peavey. The dbx is looking mediocre, and stay clear of the cheap crap like Samson and Behri^%&ger.

Posted: Tue Jul 10, 2007 5:10 pm

Feedback eliminators work! But they can't perform miracles. They are designed to improve your gain before feedback. Most people don't know that in order to make these units function, you must cause feedback to happen at the sound check. Screaming horrible feedback! Then you have to wait for a few seconds while the feedback eliminators detect the feedback frequencies and notches those frequencies out. So now you get less feedback and frequently, a most unflattering sound since it has screwed up your pristine audio with numerous notch filters sucking out frequencies that have a huge effect on the tonality of your sound. So the less the feedback suppressor has to work, the better your sound is in the end.

Conversely, a omnidirectional and preferably calibrated microphone on a RTA (real-time analyzer) and a 1/3 octave graphic equalizer can be utilized instead of a feedback suppressor. It's what the feedback suppressor automatically does.

Just my feedback
Ms. Remy Ann David

Posted: Tue Jul 10, 2007 5:49 pm

RemyRAD wrote:

Conversely, a omnidirectional and preferably calibrated microphone on a RTA (real-time analyzer) and a 1/3 octave graphic equalizer can be utilized instead of a feedback suppressor. It's what the feedback suppressor automatically does.

You can dispense with the RTA and the test mic if you train your ears to recognize feedback frequencies.

This is potentially a much better method than either the automatic feedback supression or the RTA / mic combo, as (if you get good enough at it) you can hear when a mic is merely on the edge of feedback and can pull back the required frequencies to prevent it without the mic ever actually howling.

Simple Feedback Trainer

Wink

Posted: Tue Jul 10, 2007 6:28 pm

So, wouldn't you want something you can turn to, never sick never congested or drinking and never becoming age 50 with a highend hearing loss? I never was any good at tests so I might fail the test anywho:)

Posted: Tue Jul 10, 2007 7:33 pm

IIRs wrote:

RemyRAD wrote:

Conversely, a omnidirectional and preferably calibrated microphone on a RTA (real-time analyzer) and a 1/3 octave graphic equalizer can be utilized instead of a feedback suppressor. It's what the feedback suppressor automatically does.

You can dispense with the RTA and the test mic if you train your ears to recognize feedback frequencies.

This is potentially a much better method than either the automatic feedback supression or the RTA / mic combo, as (if you get good enough at it) you can hear when a mic is merely on the edge of feedback and can pull back the required frequencies to prevent it without the mic ever actually howling.

Simple Feedback Trainer

Wink

I agree that using an RTA alone is crap. I can use my ears for that. Former bandmates recently told me that they miss me, because they don't get as much sleep as they used to. I would have their wedges tweaked quickly, calling out the frequencies that need cutting, adjusting the wedge positions, etc. It is a matter of time and practice and knowing you gear. It's all about physics.

Feedback eliminators eat headroom and gain, add noise, etc. ALL OF THEM. THEY ARE ALL CRAP compared to a guy that knows what he is doing. They should only be used in installs, where non-audio people operate gear (conference rooms, churches, etc). They are correctly employed where the system is properly installed, has correct gain structure, etc. They are correctly used as a last safety net, not as a primary, constant fix for a poorly engineered, installed and operated system.

Posted: Tue Jul 10, 2007 10:06 pm

Yup, that's right. Most of us with a solid background don't bother with feedback eliminators or real-time analyzers. We know what we're listening to and what we hear. Having been a professional technician and analog tape recorder tweaker, where one has to tweak up the 24 track machines before each and every session, in each of 4 control rooms in a busy NYC recording studio and final test technician and quality control manager for a legendary American tape recorder manufacturer, I could whistle most of the tones from the oscillators and test tapes, in my sleep! Perfect pitch? Nope. Perfect insanity!

1kHz at 250nWb/m OOOOOOOOOOOOOOOOO.........
10kHz at 250nWb/m EEEEEEEEEEEEEEEEEEEEE..........
20kHz at 250nWb/m bark bark woof woof bark!!!!!!!!!!
NO BARK!...............
Ms. Remy Ann David

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