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ATAUDIO 10th February 2013 07:25 PM

Basic Sound Engineering manual / literature
 
Do not get me wrong, I had some Sound exams at the university at my times, (I am EE) but a lot of theory, FFTs, psycoacoustics and so on.
I often help some of my artists friends with their live setups, when there are free or caritative events, but on the practical side, I am less than a diletant.
However I have good practical skill on my job, with measuring instruments and so on.
So I am looking to some literature on the practical side of the job, to improve myself, mostly for respect of my friends, that are truly good artists.
An aspect of special concern is how to sistematically measure and setup the equalization of a small (150/800 p.) venue, usually a theater or an outdoor ( I know, this last is though). Right now I am doing "at hear" using the help of some really good ones (my arenīt so much) and the results are so and so. I have no problem to get some reasonably priced microphone and portable instrument in case, but I would like to start with the absolute basics.
Any help, espcially "first hand" will be highly appreciated.

Jsixis 10th February 2013 11:27 PM

the biggest problem I see is no one reads the manual to the mixer and one can see boards clipping all the time. When you point that out the response is, I read the manual it says when the red light flashes I still have 3db left (it says flash not stay on for seconds)

Most boards have a PSL or solo button that lets you adjust just that input.
You set the slider at 0 or Unity, then with the PSL button pushed down you adjust the trim to where the power meters read 0 (you can leave the sliders down during this to keep from scaring the audience)
You want everything at 0 for the peak, the kick drum is the hardest to set at 0 but it is the most important because it needs that head room.
After everything is set for 0 on the output meters I usually start off with vocals at unity gain and the instruments -12db below unity. (depending on how loud they play) and the power sliders about 1/2 way.


Once the band starts playing I just try to widen the sound and bring everyone up to the loudest player on stage.
Then check the settings again using the meters because during a sound check no one plays their loudest.

If the board has sweepable mids on vocals I will turn that up to 3-6increase and sweep the frequency until I find their voice. I usually turn the bass (80hz) down on all vocals and usually roll the highs (12khz) back since no one sings that high or low. On instruments I normally do not eq anything unless it is to cut a frequency.

One thing to remember is everyone in the audience has more experience running a sound board then the sound man :) (inside joke)

ATAUDIO 14th February 2013 08:06 PM

Thatīs helpful for the mix side, thanks.
What about room (ambient) equalization? How you measure the levels ad various point of the audience? My experience is that there is tiny fraction that hears well (usually in the front/center) and the most that hear quite muddy/bad.
General complain is that the bass is not strong enough and the highs are not clear.

Jsixis 15th February 2013 04:44 PM

""hears well (usually in the front/center) and the most that hear quite muddy/bad.""

That is always a problem, if possible get the main speakers farther apart, if you have a sub it is recommended center stage is the best place for it but live sound is live sound, 10 or more sound sources you have sounds bouncing off of everything in every direction. Then you have monitors which really muddy up the sound but getting musicians to learn to listen is impossible.

I am the wrong person to ask about EQ as I never use them. My sound gigs are loud rock and roll bands and the room acoustics are out of our control. We walk around and we notice there are areas that sound bad but 99% of the rooms we run sound in were never designed for sound in the 1st place.

I do know a couple of sound guys who EQ a room by feeding a sine wave into the system and adjusting the EQ to eliminate squeals but once the band shows up all of that goes out the window.

Sub woofers have been debated since they were made, I believe they should be next to each other, preferably as center to the room as you can get or right against a wall. I know 2 completely theories there but every room is different, one can do the math and go crazy or just keep experimenting.

I do use a couple of external units
I use a Rane AC22 crossover that can add up to a 2ms delay to the sub and that seems to help the low end.
I also have a BBE 442 that lets me clear up the highs (not sure if it delays or advances the high end) by turning the high control knob on that up 2-3 clicks over the low setting it lets the horns on my peavey SP2G speakers really shine. Usually my low volume knob will be on 4 and the high volume knob will be around 6 the BBE changes the phase relationship of the drivers.

cyclecamper 15th February 2013 05:35 PM

Making your own graphs from sines will take all day. For room EQ, the traditional tool is the RTA (real-time analyzer) with a pink-noise signal generator (equal energy in all frequency bands) and a 1/3 octave equalizer. You can pick up a used Behringer for $150 with a calibrated instrumentation condenser mic. I search and get them even cheaper. That will do all 3 jobs digitally. If fact, it will do all 3 jobs automatically at the push of a button. Personally, that "auto" mode never works all that well in the real world, but the RTA lets you take and average readings at multiple locations, add stored EQs, etc. It's a fundamental tool. On the other hand, it doesn't tell you much your ears can't tell you; its more like giving your ears a reality-check reference; tweeking by ear does a decent job of high/low balance, but feltcher-munson and personal tastes etc. can get you confused and into thinking a mid-scoop that sounds impressive is really flat.

That gives you energy EQ, but doesn't really tell you what's going on in the time domain. Really basic info you still need to tell what's going on is the reverberation time at different frequencies, something that gives you a real waterfall plot including the time domain. That also helps time-align your crossovers and speakers. But finding out what's going on and doing something about it are two different things. All too often it shows up room problems that you can't do anything about.

Then, once you have an accurate 'reinforcement' system, then you can start to work on each input and the mix. There a meter or LED bridge helps a lot, but your ears are really important.

cyclecamper 15th February 2013 05:40 PM

Sorry, I don't know the good lit anymore. In the old days, it was "Audio Encyclopedia" by Howard E. Tremaine.

ATAUDIO 16th February 2013 12:11 PM

Quote:

Originally Posted by cyclecamper (Post 3371215)
Making your own graphs from sines will take all day. For room EQ, the traditional tool is the RTA (real-time analyzer) with a pink-noise signal generator (equal energy in all frequency bands) and a 1/3 octave equalizer. You can pick up a used Behringer for $150 with a calibrated instrumentation condenser mic. I search and get them even cheaper. That will do all 3 jobs digitally. .

Thank you for the reply,
Could you please elaborate more on the subjext?
I understand the pink noise , but why 1/3 octave?
And which 3 jobs you mean?
Again a manual or some lterature would help I am real noob.
I did once some tests with a FFT scope and a pink noise generator, but with uncertain results..

I will look for that book maybe at the Uni library. What year is it about?

mickeymoose 16th February 2013 01:20 PM

I believe the yellow bible, as it once was known, "Sound System Engineering" by Don and Carolyn Davies is still the best reference. I hope it was updated! E

cyclecamper 16th February 2013 03:43 PM

I'm sure there's good books now; "Audio encyclopedia" original edition is from 195-something.

A RTA is usually a 1/3 octave 2-dimensional bar-graph array of volume in each 1/3 octave band. Which corresponds conveniently to a 1/4 octave equalizer.
3 jobs:
1) Signal generator that can make pink noise.
2) RTA that can display what the mike picks up.
3) Equaizer.

cyclecamper 16th February 2013 03:52 PM

Pick up a Behringer DSP-8024 and matching mic. Pretty cheap, pretty effective. Or the DSP-9024. like this one: Behringer Utlracurve DSP 8024 w Mic | eBay


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