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Author Topic: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.  (Read 12527 times)

Wim Strydom

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Hi there,
I am managing sound for a church, and at the moment there is a slightly strange in my opinion setup going on here(regarding how everything is hooked up to each other). So due to this right and left channels are not even separate.

To much better explain everything I have attached 3 detailed diagrams, the first is a blank diagram with just all of our equipment and no connections, the second is of our current setup and the third is what I am proposing to setup, but I am really quite new to sound(found out the other day that a mic cable is called an XLR cable) so I really don't know that much but from what I've been able to gather on the internet the third diagram should work.

If anyone can give me some advice on this it would be greatly appreciated
Thanks
Wim Strydom
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Wim Strydom

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #1 on: July 29, 2014, 10:40:07 AM »

I just checked online and the amps aren't XTi series, they're XTi 2 Series.
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Jamin Lynch

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #2 on: July 29, 2014, 10:55:26 AM »

I just checked online and the amps aren't XTi series, they're XTi 2 Series.

Why don't you just use the processing that is built into the amps?
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Wim Strydom

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #3 on: July 29, 2014, 11:02:39 AM »

Why don't you just use the processing that is built into the amps?

I am not sure I understand what you mean by that, I would like to know if the diagram labeled proposedweb.jpg would be a viable way connecting everything.
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Jamin Lynch

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #4 on: July 29, 2014, 11:12:11 AM »

I am not sure I understand what you mean by that, I would like to know if the diagram labeled proposedweb.jpg would be a viable way connecting everything.



The Crown xti2 series amps have built in DSP. Digital Signal Processing. You have EQ, crossover, time delay, limiters available.

I guess I was looking more at the speaker placement and the EQ you mentioned. From that drawing it appears you will need to time align which is built in. You could EQ each separately if needed rather then an EQ for all.
« Last Edit: July 29, 2014, 11:22:07 AM by Jamin Lynch »
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Wim Strydom

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #5 on: July 29, 2014, 11:22:24 AM »

The Crown xti2 series amps have built in DSP. Digital Signal Processing. You have EQ, crossover, time delay, limiters available. Might make your set up easier.

Okay thanks, I will look into that.

Do you have any suggestions regarding the way the amps are connected to the mixer, would my diagram work? If so any advice or things to keep in mind, if not then how do you suggest?
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Jamin Lynch

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #6 on: July 29, 2014, 11:46:42 AM »

Okay thanks, I will look into that.

Do you have any suggestions regarding the way the amps are connected to the mixer, would my diagram work? If so any advice or things to keep in mind, if not then how do you suggest?

From looking strictly at the wiring schematic,  it appears it "will work" but is it the best way to go? That would be a matter of opinion. It's hard to tell from this if it would be the best for your application.

It looks like the 2 larger speakers are pointed in the opposite direction from the others. How are the speakers used?
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Wim Strydom

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #7 on: July 29, 2014, 11:59:48 AM »

From looking strictly at the wiring schematic,  it appears it "will work" but is it the best way to go? That would be a matter of opinion. It's hard to tell from this if it would be the best for your application.

It looks like the 2 larger speakers are pointed in the opposite direction from the others. How are the speakers used?

Ah regarding the speakers,  the first two appear larger mostly because of a sloppy drawing. They are actually monitors (JBL, JRX-100[EDIT: JRX112M]) and the other six are speakers(JBL AC-26)

Is there any more info I can give that might help? I would very much like to set this up in the best way possible.
« Last Edit: July 29, 2014, 12:04:56 PM by Wim Strydom »
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lindsay Dean

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #8 on: July 29, 2014, 01:41:35 PM »

Ah regarding the speakers,  the first two appear larger mostly because of a sloppy drawing. They are actually monitors (JBL, JRX-100[EDIT: JRX112M]) and the other six are speakers(JBL AC-26)

Is there any more info I can give that might help? I would very much like to set this up in the best way possible.

Is there an issue that makes you think of changing  the current set up ?
« Last Edit: July 29, 2014, 01:55:43 PM by lindsay Dean »
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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #9 on: July 29, 2014, 01:59:12 PM »

How does the system perform in its present config and why do you want to change?  There's some nice, capable gear there and I would hope whoever put it in knew how to take advantage of the processing capabilities.  Given that you're unaware of the built-in DSP, I would question whether you should be digging in and re-configuring things without professional help on-site.
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Wim Strydom

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #10 on: July 29, 2014, 02:19:07 PM »

Is there an issue that makes you think of changing  the current set up ?

Well, because all the amps are connected in bridge to speakers on opposite ends of the room there is no distinction or separate control for L and R(making stereo impossible).

That and, we are using one aux for the monitors, one GRP for one set of speakers and then the L and R main outputs for four others, which is quite inconvenient for when having to bring down the overall volume.


Are there any drawbacks or disadvantages with the proposed diagram?
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Mike Christy

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #11 on: July 29, 2014, 02:38:04 PM »

Well, because all the amps are connected in bridge to speakers on opposite ends of the room there is no distinction or separate control for L and R(making stereo impossible).

That and, we are using one aux for the monitors, one GRP for one set of speakers and then the L and R main outputs for four others, which is quite inconvenient for when having to bring down the overall volume.


Are there any drawbacks or disadvantages with the proposed diagram?

The wiring diagram is fine, if you figured this out on your own with little audio experience, congrats. Im not a Crown amp owner, but you make need to change the settings from bridged to stereo in the DSP, someone else who knows more can probably comment on that, Are those speakers in the DSP?

Im guessing that the installer wired it up in bridge mode to get the most out of and match the peak power ratings of the amps with the speakers. Not knowing your typical app or program material, you may want to leave it like it is - with wide dynamic/peak handling potential, or switch to lower power averaged output in stereo.

Mike
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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #12 on: July 29, 2014, 02:49:38 PM »

Well, because all the amps are connected in bridge to speakers on opposite ends of the room there is no distinction or separate control for L and R(making stereo impossible).

That and, we are using one aux for the monitors, one GRP for one set of speakers and then the L and R main outputs for four others, which is quite inconvenient for when having to bring down the overall volume.


Are there any drawbacks or disadvantages with the proposed diagram?

You do not need to have "stereo".  It has been discussed on this and other forums ad nauseum, bot the bottom line is that true stereo sound reproduction in an enclosed area borders on the mythological.

The single thing that matters most in your situation is time-aligning the "down-hall" speakers via the digital delay available in the amplifier DSP's.  This has likely been done by the original installer.

Is the original installer known and available for consultation? 

If it ain't broke, don't fix it...
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Wim Strydom

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #13 on: July 29, 2014, 03:24:41 PM »

You do not need to have "stereo".  It has been discussed on this and other forums ad nauseum, bot the bottom line is that true stereo sound reproduction in an enclosed area borders on the mythological.

The single thing that matters most in your situation is time-aligning the "down-hall" speakers via the digital delay available in the amplifier DSP's.  This has likely been done by the original installer.

Is the original installer known and available for consultation? 

If it ain't broke, don't fix it...

The original installer never enabled DSP, it's been off for the entire time. Also all the equipment was bought on recommendation, but weren't installed by the same person who recommended it.

I would like to set the DSP but I have zero experience with DSP so I am a bit wary of just going into it and doing things, but if I have a good idea of what I need to do and how to do it then I'll give it a shot.

The current configuration was set up in a way by me because we recently extended the back wall and added the last two speakers at the back, and I moved the sound equipment to the new sound desk at the back(using countless photos I took before disconnecting anything at the old sound desk)

As for the stereo, I would at least like to be able to pan some of the channels on the mixer, and it would be more convenient to output everything(except monitors and recording etc..) through the main outputs, but if it has any drawbacks or disadvantages then I'll just leave it be.
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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #14 on: July 29, 2014, 03:49:15 PM »

Every pair of speakers down the sides needs to be delayed in relation to the initial speakers such that the sound from the "repeaters" is synchronized with the initial wave front.  Each succeeding pair will require a longer delay.

It's not hard to figure out.  You just measure the physical distance and read the delay value from a chart or figure it from a formula based on the speed of sound.  Simple, really.

Go to the Crown website and bone up on what you need to interface with the iTechs, then set your delays accordingly.  of course, this requires one amp per pair of speakers, so your cabling will increase...

I may have missed it, but how far apart are the pairs and what are the over-all dimensions of the room?  Do you require the delays for just speaking coverage/intelligibility or for music as well?

I think there's a lot yet to know.
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Jamin Lynch

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #15 on: July 29, 2014, 06:14:32 PM »

The original installer never enabled DSP, it's been off for the entire time. Also all the equipment was bought on recommendation, but weren't installed by the same person who recommended it.

I would like to set the DSP but I have zero experience with DSP so I am a bit wary of just going into it and doing things, but if I have a good idea of what I need to do and how to do it then I'll give it a shot.

The current configuration was set up in a way by me because we recently extended the back wall and added the last two speakers at the back, and I moved the sound equipment to the new sound desk at the back(using countless photos I took before disconnecting anything at the old sound desk)

As for the stereo, I would at least like to be able to pan some of the channels on the mixer, and it would be more convenient to output everything(except monitors and recording etc..) through the main outputs, but if it has any drawbacks or disadvantages then I'll just leave it be.

Where are you located? Maybe there is a PSW person in your area who could take a look.
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Rob Spence

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #16 on: July 29, 2014, 06:51:43 PM »

As others have said, your audience is not going to benifit from stereo. Most people are only going to hear one speaker so unless the whole program is coming from each speaker people will not hear it all.

Changing the amplifier configuration runs a risk of ending up with much lower maximum volume. You are running amps in bridged mode because your designer wanted to save your church from having to spend much more on larger amplifiers.

Getting back to the problems you want to solve...
Can you list them?

Also, as others asked, room dimensions and distances between speakers is needed.


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Stephen Swaffer

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #17 on: August 02, 2014, 10:23:35 PM »

Rob and Dick both have far more experience than me, but from my experience I will chime in and say stereo is not useful.  I have run sound in our auditorium for over 20 years-it is wider than it is deep and you would think that during a musical drama like we do every year, with actors far stage right and left-literally in the front corners of the room that stereo and panning would be useful.  My experience is that people perceive the sound coming from the actors, even though it is coming from a central cluster.  My guess is that in a room with multiple reflections from walls, the mind relies more on visual cues to localize the source of the sound than on confusing aural clues.

The only time I have experienced an odd sensation is when I have been sitting under the front edge of a balcony and the under balcony fill speakers are too loud and the sound comes from behind you.  Given that your current setup requires separate level adjustments for each pair of speakers, I would think that keeping them adjusted properly would be nearly impossible on the fly.  From that standpoint, changing your setup to allow all the house speakers to be fed from the main output makes sense-then they could be tweaked until the system sounded right and the relative levels left alone.  I see no advantage to changing the bridging setup of the amps, though. 
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Steve Swaffer

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #18 on: August 02, 2014, 11:16:24 PM »

Rob and Dick both have far more experience than me, but from my experience I will chime in and say stereo is not useful.  I have run sound in our auditorium for over 20 years-it is wider than it is deep and you would think that during a musical drama like we do every year, with actors far stage right and left-literally in the front corners of the room that stereo and panning would be useful.  My experience is that people perceive the sound coming from the actors, even though it is coming from a central cluster.  My guess is that in a room with multiple reflections from walls, the mind relies more on visual cues to localize the source of the sound than on confusing aural clues.

Also, quite possibly the Haas effect (or "precedence effect") comes into play in this sort of situation. With multiple arrivals (direct source, PA, reflections), the perceived location of the sound source is dominated by the first arrival, even if subsequent arrivals are up to 10 dB louder. If the PA is flown high enough, the first arrival could easily be direct sound from the actor rather than the PA.

The only time I have experienced an odd sensation is when I have been sitting under the front edge of a balcony and the under balcony fill speakers are too loud and the sound comes from behind you.  Given that your current setup requires separate level adjustments for each pair of speakers, I would think that keeping them adjusted properly would be nearly impossible on the fly.  From that standpoint, changing your setup to allow all the house speakers to be fed from the main output makes sense-then they could be tweaked until the system sounded right and the relative levels left alone.  I see no advantage to changing the bridging setup of the amps, though.

Are you sure the balcony fills were properly delayed relative to the main PA? If not, everything I just said about the Haas effect above applies again, and the perceived sound source is localized to the fills even if the main PA is a good deal louder.
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Stephen Swaffer

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #19 on: August 04, 2014, 01:12:17 PM »

Since our actors are usually actually "lip synching",  there is no direct sound.  But it is interesting that people not "in the know" don't notice when we switch from live mic'd to prerecorded-obviously direct sound would be present when live and the PA is flown high enough for direct to get there first for much of the audience.

Balcony fills I have no idea.  I was visiting, but I am reasonably certain both places I have noticed this were professional installs.  Maybe low bid pro installs, but its not that hard to do delay properly so anyone getting paid to install should get it right.
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Steve Swaffer

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #20 on: August 22, 2014, 03:11:04 PM »

Hi Wim

I'm a little late on this, however I am going to assume that with that name and surname you are from South Africa...

Depending on which province you are in I can possibly lend a hand with setting the delay's and tuning.

PM me...
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Shake & Bake

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Re: Connecting 8 speakers to 4 amps to 2 Graphic EQ's to one mixer.
« Reply #20 on: August 22, 2014, 03:11:04 PM »


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