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Old 21st December 2011, 04:04 AM   #19511
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Folks,

Speaking on this whole Feedback gig and all, in the early 90's we had a box in our FX rack called a Sabine FBX. This technology has become quite common nowadays (like in the Behringer Feedback Destroyer).

I have always found at the rock concerts that most of the feedback came from the monitor system, often the Drummers or side fills more than the floor wedges. In fact I always found the monitor mix by far more of a headache than the main FOH Mix...

So when we could afford a few more Sabine boxes I put them set quite aggressively into the monitor lines and left the one in main PA feed as final line of defence. It rarely did anything.

I cannot remember anything we did not try for the monitoring set-up. We tried little cubes bolted to mike stands at one time, but we always ended up back with side fills and floor wedges turned way too loud or most musicians would complain.

In this day and age feedback control is getting easy, it was a bit of a PITA in the 80's, where I had to stick multiple parametric EQ's on the monitor lines and try to catch all feedback frequencies and be quick on the mixing desk gain to catch the rest.

Ciao T
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Old 21st December 2011, 05:05 AM   #19512
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Quote:
Originally Posted by ThorstenL View Post
In this day and age feedback control is getting easy, it was a bit of a PITA in the 80's, where I had to stick multiple parametric EQ's on the monitor lines and try to catch all feedback frequencies and be quick on the mixing desk gain to catch the rest.
It is what I am going to try: high-end kicks with analog EQs personalized for each monitor, buried inside so nobody can touch controls from outside.
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Old 21st December 2011, 01:39 PM   #19513
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Let me just say that most folk music for a small audience of 20 or so people shouldn't need any sound amplification. That's how we listened to folk music back in the very early '60's. And any sound system that became necessary, might be because of higher background noise, talking etc. I built my first PA system in a Coffee House in 1963 (I bet that is before many of you were grown up '-) called 'The Pawn' near the San Jose State college campus. I used a single Electrovoice 12" speaker (wizzer cone for extended bandwidth) with a custom made 'sheet-rock' speaker face angled into an upper corner, making a rather large infinite baffle, driven by a Bogen tubed PA amplifier and a single Shure Unidyne directional microphone. Worked OK, too. Yes, small systems can sometimes be useful.

Last edited by john curl; 21st December 2011 at 01:55 PM.
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Old 21st December 2011, 02:04 PM   #19514
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But is that a "real" concert?
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Old 21st December 2011, 03:20 PM   #19515
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Quote:
Originally Posted by Chris Hornbeck View Post
Is it a line source floor kick? I built a pair once when Leo Kottke was coming to what was "my" theater. Spent all day ringing 'em within an inch of their lives. They have a kinda strange sound but a *very* sharp horizontal focus.

Mr. Kottke (the most consumate gentleman and professional I ever met) took less than five minutes to do sound check ("Give me 3Db less 7 kiloHertz" - exact quote, and he was right!) and decided he didn't need the floor kicks. Oh, well.
He did a great, great show.

Thanks,
Chris
It turns out I probably met Leo busking in the midwest around 1966. All I remember is someone asking "Why the 12 string?" and he answered "Because it's twice as hard to play". No one else could have said that AND play like that.
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Old 21st December 2011, 03:29 PM   #19516
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LK is amazing. He apparently was good friends with my wife's first husband (a guitarist in LA), used to hang out at their place and play in their living room. She tells me that the stream-of-unconsciousness patter that he does between songs is pretty much the way he is.
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Old 21st December 2011, 03:58 PM   #19517
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OK let us talk about what acoustic feedback really is! When the amplified sound from the loudspeaker is louder into the microphone(s) than what you are trying to amplify. Now if the frequency response has a peak in that loop that is where feedback will occur. Equalization will reduce that but it will not allow the return sound to be louder than the source.

Differential microphones will do that if the source can be coupled into them.

A comb filter and pitch shifter will allow the returned sound into the system but will not amplify it a second time, thus breaking the feedback loop!

This is very useful for many live situations. The first market is referee microphones. Here you have a lavalier microphone that can be from 100' to 500' away from the loudspeakers, but the throw of the speakers may need to be 800' and the background noise level may be above the referee! Now the last time someone tried to use a headset mic on the unskilled user it was deemed unmanly!

The next use is in live theater productions where a microphone may be concealed in a wig and the throw for the loudspeakers 150' or greater.

Then there is the church market, talk about unskilled users!
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Old 21st December 2011, 05:11 PM   #19518
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Quote:
Originally Posted by john curl View Post
Yes, small systems can sometimes be useful.
John, the question is not about usability of small or big sound systems. The main problem is till the same, is the system small, or big. The difference is, for small sound system the main attention has to be paid to main speakers. For big system the main attention has to be paid to on-stage monitors. But still, what has to be equalizer, bumps on frequency response of _speakers_.

Quote:
Originally Posted by simon7000 View Post
Then there is the church market, talk about unskilled users!
Yes, churches are very reverberant and cause problems to sound reinforcement. But here as well flat frequency response helps. Here is an example: Hidden in Plain Sight conference in Francis Bacon auditorium of Rosicrucian Order, in San Jose. First day in-house system was used: stock Fender PA, couple of big rectangular speakers hanging from the ceiling made traditionally as 15" driver and horn. Shure lapel wireless microphones. It was a nightmare... Also, the building was old, and ventilation/cooling system did not work, so many big fans were standing along walls making noise. It was almost impossible to hear lectors.

I brought there still the same my system, with pair of line arrays, pair of large diaphragm condenser microphones, equalized everything carefully, and as the result everything went smooth, despite microphones were not on lapels anymore, they were standing on 3 feet distance from lectors who could move freely in front of hem.

Here is the record. You can still hear noise of fans, you can hear echo from stone walls, but at least you can hear now what is said. Equalization of frequency response is the key.

http://wavebourn.com/HIPS/SoundSystem.mp3
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Old 21st December 2011, 05:32 PM   #19519
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Now please let's come back from churches, stadiums, theaters, to our listening room, carrying with us the experience we got there. What did we get there in common? Bumps on frequency response of speakers have to be equalized. Yes, reflections from walls cause bumps and dips, but when they are diffused they don't add artificial coloration. Placing microphone in different places in the room we can discover which exactly bumps are caused by speakers: they will be visible in all positions, equalize them and them only, and enjoy the music...
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Old 21st December 2011, 06:05 PM   #19520
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Actually I prefer not to try to equalize for the room. I find small close reflections add to the listening environment. If you have ever been in an anechoic chamber you quickly understand why small amounts of reverb sound better.

Now if you have a bad room and are trying to fix it with equalization then you have a built in level indicator. (See drummer joke.)
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