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DVD Sound...?

Discussion in 'Sound, Music, and Intercom' started by Schniapereli, Mar 8, 2007.

  1. Schniapereli

    Schniapereli Active Member

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    Our school's next musical is Crazy for you, and today I was talking to the directot about sound. She says that the music that we will be using will be on a DVD, and that we will be getting a special DVD player to use it. I have never heard of this before, and I don't know what to expect. Can anyone tell me anything about this? I just want to know more about it.
     
  2. Cooze

    Cooze Member

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    I have never heard of such a thing, are you sure its not MP3, you could use a DVD player for that, not sure why but you could, well either way you could probabaly convert the files and use them on a CD player, post what you find out, I am curious as to what this is
     
  3. Schniapereli

    Schniapereli Active Member

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    I did a little more research, and I think it is known as "DVD-Audio". Its supposed to be really high quality (192kHz at 24 bit stereo) but, Wikipedia also says that experts aren't sure that it is perceptible by the average listener...

    But, none of the sites told much more about it...
     
  4. Footer

    Footer Senior Team Senior Team Premium Member

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    They have been around for a very long time, basically its high def audio. Its the only way to get multiple tracks on one disc, CD players and CD's as a content carrier are not set up to do that.
    http://en.wikipedia.org/wiki/DVD-Audio
     
  5. avkid

    avkid Not a New User Fight Leukemia

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    All you need is a mid-line DVD player.
     
  6. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    The real question is do you have the high tech sound system to make it worthwhile. Most schools barely have good enough audio gear to make CD sound better than Cassettes to the average listener. I hope it isn't costing you that much extra because odds are really good your audience won't know the difference over a CD.
     
  7. Van

    Van CBMod CB Mods Premium Member

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    Yeah, but it'll be cool !:twisted:
     
  8. Schniapereli

    Schniapereli Active Member

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    Well, we have a Mackie SR32 board, with Crown ComTech 410 and 810 amps, and EV Xi 22/85 speakers.

    Would it be worth it?

    Our speakers also have a few problems with bass on the right. (Wierd impedance plug ins.)
     
  9. avkid

    avkid Not a New User Fight Leukemia

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    Huh, what, who??
     
  10. gafftaper

    gafftaper Senior Team Senior Team Fight Leukemia

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    Explain your problem and let's see if we can fix it.
     
  11. Schniapereli

    Schniapereli Active Member

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    Well, I have asked a question about it on here before, but it didn't get very many answers.

    Our speakers are set to a lot of different impedances. (They are the EV Xi 22/85) I have attatched a rough sketch of our auditorium, and the speakers including their position, way they are pointed, and their impedances.

    Our front right speakers (and possibly others) have not ever gotten much base. I talked to another sound guy who helped us out a little, and I told him about the difference in the impedance. He said that to him, it sounded like that speaker had been blown, but since I told him that that particular speaker was set to high impedance, he is not sure. He said he thinks he remembers there being some problem at the amps. (He was a tech there in High School a while ago, and has helped there for a long time)

    He thinks there might be some reason why it was like that, but he's not sure, and I don't know of any time when you would want them all on different impedances.

    If you need any other information, when I go back to school, I can look at the setup better.
     

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  12. mbenonis

    mbenonis Wireless Guy Administrator

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    I'm not sure I understand the setup here. Are you sure you mean impedance and not frequency? It sounds to me more like you have a crossover, separating the low frequencies from the high frequencies, and that things are wired up or configured wrong.

    Can you give us a more detailed diagram, including any signal processing between the console (gates, compressors, crossovers), amplifiers, and what speakers are connected to what amplifiers and to what terminals on the amplifiers. Also include whether speakers are connected together in parallel.
     
  13. Schniapereli

    Schniapereli Active Member

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    I went to the school, and found out more information. Yes, I am sure that it is the impedance setting. The speakers have to plugs in the back, and I used a S4 to look at them. There were some other speakers of the same type in the closet, so I could tell all plugs on the left of the speaker where Lo-Z, and on the right was Hi-Z

    Attatched is the new correct layout of the speakers with their impedances.
    The Hi impedances are 1200w, and the Lo's are 300w. The amp assignment is now also on there.

    Our amps are Crown Com-Tech 410 for the high freq channels, and Com-Tech 810 for Lo freq. We have no crossovers. They are just daisy-chained up the rack. If it makes a difference, a cord leads from the graphic EQ, and then leads to the 1st XLR plug, which also has another cord coming out which leads to the second plug. Looks like /UUUUU as one cord, and where the ends of the U's meet, is an XLR connector. I drew it on the attatchment. (is there another name for this type of cable, or would it also be considered just daisy-chained)

    There are no crossovers used. Amps are connected up the line regardless of frequency output.

    I do not know what you mean exactly by "terminal". Lefts are on Channel 1, and Rights on Channel 2 if that is what you mean...

    We use a Mackie SR 32 VLZ pro. The mains go straight to the Graphic EQ (Behringer GEQ 3102)


    We are probably going to do some major sound work on the speakers system since we are using DVD-Audio, and will probably finally get to EQ the system, and use an RTA. Should we set all the speakers to the same impedance along with this process? Or, is there any possibility that there was some valid reason for the impedances being the way they are?


    Sorry if the drawing is weird, and my explanations are faulty. It's kinda late at night...
     

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  14. SHARYNF

    SHARYNF Well-Known Member

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    Something seems to be missing in your description. If you go to http://www.ev-concert.com/wEvcs_en/prod_html/xi.php?navid=28 you will see the Xi line, and I cannot find your model numbers see if you can look at it more closely and see which it is

    These were sort of derived from the concert line, an all of them except for one model are all active, meaning that they need a signal processor to actively split the frequencies, but since you are using Comp tech amps, there are option cards that do this in the amp
    http://www.djdepot.com/info/comtechseries.shtml

    The impedance connections are for a few options one is 70 volt (typically used for running a bunch of ceiling speakers, and 140 volt where they have done a design to allow you to run higher power over lower awg cable for the speakers (this series is designed for pro installs

    SO you are correct each amp is chained on the input, but what you don't see is the internal cards that set the frequency splits for the crossover. (most people are familiar with either a crossover that goes infront of the amps, like an ashly for instance, or a passive crossover that goes in the speaker, the third option is a processing system like the bss or drive rack, and the fourth is where the amp has it built right in.

    For your use, the impedance settings are really irrelavent, as they are really just set up for wiring. The input connections are either balanced or unbalanced and I am assuming you are going to use balanced.

    It sounds reversed that you have the high power amp connected to the upper end, IF this was done in the last setup, my guess, and this is just a guess, is that someone got it reversed, and you probably have blown out something, at the same time, on the low end you will not get any bass, since the internal filter is going to think it is driving the upper end and filter out the bass

    SO, you need to determine from each amp what the internal filter/crossover in the Crown is set for, then you need to see what amp is connected to what speaker,

    My guess, and again just a guess is that some how someone connect the higher power amps, that should have been powering the bass to the mids/high, and the lower power amps that filter out the bass, to the bass speakers.

    If the install was done properly there should be a book somewhere that shows the configuration but that might have long gone missing

    Re dvd and audio.

    there are a few possibilites, one is that infact you are getting dvd-audio, in which case you are not likely to hear any difference, since on most systems you need a digital decoder to take full advantage, and when you take the analog outs and feed it in to the mackie all the high def audio stuff is going to be lost

    Other is that instead of using multple cd's the audio was put on a dvd, and what you have is just a big dvd, with no video and all audio that you will have to play, typically, this is a custom dvd-rom and the files will be wave files etc, and they will expect you to be playing them back from a pc based system

    Hope this helps

    Sharyn
     
  15. mbenonis

    mbenonis Wireless Guy Administrator

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    I was able to find your speakers on EV's website, see here:
    http://www.electrovoice.com/products/232.html

    According to the data sheet, the NL4 (Speakon) connectors on the back of the speaker are wired in parallel, and thus the labels by them do not refer to the connector but rather to the speaker's specifications (300W peak for HF, 1200W peak for LF). The 1+/1- pins are for the high-frequency driver, and the 2+/2- pins are for the low-frequency driver. As Sharyn said, it is likely that your amplifiers have option cards built-in that cross the signal over at the appropriate frequency and delay it.

    So it appears that your system is wired correctly based on a cursory inspection. This leaves two possibilities to explain the problems you're having. First, it is possible that someone blew out one of the bass drivers. Second, one of the NL4 connectors on the speakers is wired incorrectly. The only way to determine which of these is the problem is to get up next to the speaker and connect it directly to a pair of amplifiers that you know is wired correctly and listen to the output - if it is still distorted, then it is the speaker; if it is fine, the connection from the amplifier to the speaker is incorrectly wired.

    Now, a short note on impedance. Impedance is composed of two parts: reactance and resistance. Resistance is simply the total opposition to direct-current flow. Reactance is defined as the total opposition to alternating-current flow. In layman terms, it is a kind of resistance than can vary based on the frequency of the ac. Impedance is actually a complex number, with resistance being the real part and reactance being the imaginary part. All of these things (resistance, reactance, and impedance are measured in Ohms (abbreviated as a capital Omega). If you're not too comfortable with imaginary numbers, take a look at this introduction to refresh yourself: http://www.purplemath.com/modules/complex.htm

    In terms of speakers (technically cone drivers here), the speaker's total impedance is composed to two parts, resistance and inductance (one of two types of reactance). The resistance comes from the length of wire used in the speaker, and the inductance comes from the wire being coiled around inside the driver. You'll note that I said above that reactance changes with frequency. Thus, the impedance of the speaker is NOT a fixed number. If you look at the spec sheet for your speaker, you'll see a graph on page 2 at the top right that shows you the total impedance of your speaker across the audio spectrum. To come up with the number printed on the back of the speaker (typically somewhere between two and sixteen ohms), the manufacturer takes the average across the audio spectrum and uses that.

    There are two basic ways to connect speakers together, in parallel and series. When you connect two speakers in parallel, the total impedance of the speaker system is half of the original impedance (if both speakers have the same impedance). When you connect two speakers in series, the total impedance is double the original impedance (once again, assuming both speakers have the same impedance). It is indeed possible to have a parallel/series connection or a series/parallel connection, and this is often done to keep the impedance at a reasonable value when over three speakers need to be connected to one amplifier (although this typically not a good idea because you’ll need a really powerful amplifier to do this).

    Now, a short note on power.

    Power is the total amount of energy used by a speaker second, and is measured in Watts (W). This seems simple enough, but manufacturers love to quote different types of power rating for amplifiers and speakers. There are three main types of power ratings floating around: peak, program, and continuous. Good manufacturers will quote all of these ratings and will also describe how each one is derived.

    Continuous power (also called RMS power) is based on the power drawn by the speaker by a steady signal, such as a sine wave. While this is a fairly easy and safe way to measure the capabilities of a speaker, it has two drawbacks. First, because impedance changes with frequency, so does power. Second, nobody actually feeds a speaker a sine wave! Thus, this is a fairly useless measurement.

    Peak power is another metric used by equipment manufacturers. Manufacturers like it because it is a big number. However, it is also quite useless. First, how long can the speaker withstand this peak power? What frequency is this at? Additionally, peak power has no real bearing on how loud a show is. Again, we have a useless measurement.

    Program power is the final measurement given to us by manufacturers. This metric has the benefit of being the most representative of how we will use the speaker. While it seems to be the most useful, it too has a drawback: what kind of program was fed to the speaker?! If the manufacturer uses bluegrass music to test and rate their speakers, the program rating means nothing to a sound engineer about to do a heavy rock show.

    The bottom line with speaker power rating is that they must be taken with a grain of salt. The program rating is probably the best one to use, but just remember that the manufacturer doesn’t test their speaker with your program material, and if you think you’re going to need more power, buy a more powerful speaker!

    I hope this helps someone!
     
  16. Foxinabox10

    Foxinabox10 Active Member

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    As far as the troubleshooting goes, you said you have a speaker just like it in a closet, so I would suggest going up with that speaker (if possible) and hooking it up. If it sounds the same, it's the cable. If it sounds better, the driver is blown.
     
  17. SHARYNF

    SHARYNF Well-Known Member

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    Couple of things to add to the discussion now that I have seen the specs.

    It is always possible that the low frequency driver is blown, usually the highs go first, but if someone has overdriven the low end amp to overload distortion it could have fried the voice coil. If you have a meter you can also test the ohm rating for the low driver, it will read open if the driver is blown probably 6 ohms or so if the voice coil is intact.

    Also since these use all 4 connections of the nl4 make sure that the right connections are being made at the amp side of things, again, it depends on how the amp is set up both channels could be filtered at the same freq or they could have the hi and low split on the same amp.

    Sharyn
     

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