Yes that would work for more than adequate use. Turns out 3K to 6K actually would be a bit better, but when the telephone system was designed 300 to 3K was much easier to achieve!
So which is more important in a sports arena, frequency response, coverage uniformity of the frequency response or speech recognition?
An excellent question! People would go nuts if they heard the test signal for any length of time. But if what you really wanted to know is how does speech recognition change, then that is reasonably well understood.
Good speech recognition requires the speech (or signal) to be louder than the noise. What makes it easier is that speech information occurs over a fairly wide frequency range and at a syllabic rate of 3 to 5 per syllables per second. So there actually are rating systems that look at the signal to noise (S/N) ratio over a group of 1/3 octave bands and give a percentage of contribution from each to the total score.
The STI system gives a maximum rating if the signal is 15 db above the noise for each measured frequency band. At a signal to noise level of 0 db where the noise is equal to the signal at all frequency bands of interest you get the just passing score! (.5 STI or 70% on the NFPA measurement of Common Intelligibility Scale.)
There are two major noise sources. One is what you would recognize as noise, HVAC fans, crowd noise etc. The second is from reverberation or echoes. Reverb time is the measure of how fat sound takes to decay 60 db in an enclosed space. Early Decay Time is for the first 5 db and is similar but more useful.
So when people are added to the room. The fuzz on them (Clothes, hair... if ya got it, etc.) decrease the amount of reverberation. The people however increase the noise level! So if the sound system can be increased in projected energy the speech recognition will go up. The system in question can deliver more than 105 dba to the seating areas. Half of 18,000 people talking at 70 dba/3' to the average reflection distance of around 100' would create 119 dba of noise! So that is why 80% of the folks talking have to shut up before an announcement really can be understood by most folks!
The issue of how to serve those with acknowledged hearing problems is a different isuue.
d) none of the above. The most important thing is the end of the crappy canned pop music, the banishing of the stupid bugle calls, and most importantly, the death of the organ player.
From these three, speech recognition is for me, but the excitement in these areas comes from the real power in the middle bass. Power in high freq causes fatique. Anything above 5kHz doesn’t matter there IMHO.
Freq. band limiting on the set up and phase shifting on mikes for eliminating acoustic feedback makes life easier for the audience, the engineers and the equipment.
George
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jneutron
Why did you end your endeuvor in this thread?
http://www.diyaudio.com/forums/parts/134500-ground-loops-containment.html
I don't think that the low traffic location was an issue, on the contrary
Threads with a specific topic of interest, provide a lot of benefits to the members
George
Why did you end your endeuvor in this thread?
http://www.diyaudio.com/forums/parts/134500-ground-loops-containment.html
I don't think that the low traffic location was an issue, on the contrary
Threads with a specific topic of interest, provide a lot of benefits to the members
George
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Boy, you don't know how lucky you are. There was the guy who picked the music to play in a stadium located in "Music City" who only chose music he heard played in other stadiums. That pretty much just left the music from the ESPN distributed "Jock Rock" collection!
In most of the venues I have done, the players request much of the music! It has gone as far as players producing their own mixes to be played during practice!
As to bugle calls. My first large venue was then called the "Jake." During the season they would play the bugle call and the crowd would then shout "Charge." The team made it to the World Series. During a home series game Atlanta was at bat and suddenly doing very well. The crowd was completely silent. I woke up from my nap, looked at the control room crowd and asked why they weren't harassing the batter? They got of their A's and played the bugle call. The crowd snapped to life. They realized silence was only good for Atlanta. Of course Atlanta still won. But the Atlanta team was really impressed by how the crowd had rallied behind the home team. So Pavlov was right. ( I of course wonder what would have happened if I woke up a few minutes earlier!)
I added subwoofers to the first large venue (Not called for in the design) I did and all of mine since then. There announcer however does not go through the subwoofers!
I would disagree about the high frequencies. They are needed for many Asian languages! The problem in a large venue is that the air absorbs so much high frequency energy most systems cannot reach the audience with any energy above 8k!
The problem with announcers is often they do not actually talk into the microphone! Headsets are often used, but some refuse even that!
As to processing the microphone signal, that gets into secret stuff!
John,
Watch "Magnetic Levitation in Pumps from Levitronix" Video at Engineering TV
Just popped up on my email!
ES
Watch "Magnetic Levitation in Pumps from Levitronix" Video at Engineering TV
Just popped up on my email!
ES
what do you mean? a compessor , maybe side-chained EQed + a ducker?
its sound pretty textbook to me.
but thats because I'm a sound guy too.
also the 4558 can some other things the 741 doesn't: being able to bias up the first stage, with a 8k to 10K resistor tied to the + rail and the signal output bias up the first stage. This has a nice sound in certain circuit applications.
there is a point to where number haggling of thd/sn/cmrr/slew/the humidity condensation on my head - means nothing. If it sounds like it should be then thats it. No smoke, no mirrors, no snake oil capacitors need to apply here.
p.s. anything surface mount technology still does not gel with me. It is too "throw it away" quality. Digital mixing boards are not professional quality, just makes it easier to move compared with the 540 lb FOH and 600 lb monitor mixing boards. And the DSP plugins don't sound like they should. I had someone rent my Yamaha PM3000 and my outboard gear because the Digidesign Venue board that they callously traded for sux. its all flat. no life. They wish they never gave up their Soundcraft Series Two Board.
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No, None of that. A compressor in a reverberant space reduces speech recognition! Some folks play with the fancier EQ. We just suggest a change of announcer! A push to mute switch works a bit better than a ducker.
There really is secret stuff to getting more gain before feedback and upping speech intelligibility.
Fun stuff, no?
What's interesting is how the guy answers the questions posed. He really doesn't answer any of the technical Q's, like how the magfield is rotated. He mentions 50K computations per second, but not how the rotation is done. He could have just said it was a 3 phase brushless drive embedded in an active feedback magnetic positioning scheme, but nahhh...
I'd be afraid of it in a heart pump...sheesh, too many components to fail... at least heart pumps are ROHS exempt...no whiskers..(pest is of course, not an issue in a human..unless that human is an EE...
)Cheers, John
Here we mostly agree. But surface mount is fine with me. There are a number of good parts available and there is some analog stuff that works better with the smaller parts!
We just sold off a rebuilt PM3k! Got it from a church, fixed it, used it to train churchies, and then sold it to rockers!
you can overcome it easily. if the speakers are in the correct space. sometimes you might have to play with phase and time delay, but that would require more data (room specs, speaker placement, ect. ).
The secret stuff to getting more gain before feedback and upping speech intelligibility is a combination of the correct mic and compessor settings. For instance, Band A has a nominal stage noise of 135 db. Your monitors need to punch the vocals through. your monitor is a bi amped monitor 1100 watts on the 15 and 500 watts on the 2" compession horn tweeter. Before the show, monitors and overall gain structure was tweaked so that they reach 145 db before feedback. as the crowed filled in, humidity and temperature changes, but now the feedback happens at 140db due to the changes in sound conduction in the air. I can still monitor well within the bands comfort range of boosting the vocals 3db above stage noise, but my nice headroom above the band is almost gone. People wonder why I created aggressive monitors. I got tired of the musicians saying they can not hear the monitors. Well they can now.
if you have a decent comp with a good graphic eq on its sidechain, you can fix alot of bad mic use.
but bad mic use is bad mic use.
Gain structure + compession + microphone selection is the major ingredients
and don't over eq your monitors, that leads to mud land.
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Fun stuff, no?
What's interesting is how the guy answers the questions posed. He really doesn't answer any of the technical Q's, like how the magfield is rotated. He mentions 50K computations per second, but not how the rotation is done. He could have just said it was a 3 phase brushless drive embedded in an active feedback magnetic positioning scheme, but nahhh...
I'd be afraid of it in a heart pump...sheesh, too many components to fail... at least heart pumps are ROHS exempt...no whiskers..(pest is of course, not an issue in a human..unless that human is an EE...
Cheers, John
OT but I think an interesting tale.
I was doing a disco in 79 or so. The owner was a bit preoccupied. It seems his niece was seriously ill. (No father around I gathered). She was going to have a heart transplant. Now for those not around back then, the first transplant was done in 67 and the patient died 12 weeks later. Quite a few followed after that. The first ideas about why so short was that only the very seriously ill got transplants so naturally the survival rate was low. So healthier but still ill folks got them and died shortly thereafter. It seems organ rejection by the host was now coming into play. So the operation rate slowed down quite a bit.
Well the local transplant center Doc had an idea he called Chimerism. He though that if you had the transplant long enough the body would both replace the original cells and also adapt some of the new ones. He thought this would work best in children who did not yet have fully developed immune systems. Now at that time my feelings were to let the poor unfortunate very young lady enjoy her short remaining time, not spend it in a hospital. (I did not ever mention this.) Well she had the surgery and was having a great deal of difficulty recovering.
Just then the same Doc got to be among the first to do clinical trials with the then new immunosuppressor drugs. Well the Disco failed and so I did not get much news after that until the young lady was in the news when they were celebrating her (I think) 17th Birthday or ten years of survival.
So John, it may seem like a bad idea for a heart pump, I wouldn't try it, but you never really know what is going to happen!
Ah, fun days. I was the house DJ at a club in those days..
Um, actually, I was only talking about reliability. Running a 3 phase maglev object requires active circuitry with position monitoring capability to maintain the suspension distance, as well as the active stuff to modulate the pump speed...so many little itty bitty semiconductor widgits which all have to work for the lifetime of the wearer...
Cheers, John
ps..sometimes the phrase "guaranteed for the life of the owner" just doesn't seem to be good enough..
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