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Author Topic: Help me double check my constant voltage system  (Read 5550 times)

BenGibbs

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Help me double check my constant voltage system
« on: March 27, 2013, 07:09:01 am »

Hi all,

I'm putting in a constant voltage system in a fitness centre on a school campus and I would like to double check my thinking, since it has been a little while since I had to deal with constant voltage sound. Being in Australia we run "100volt" systems. The ceiling speakers have already been installed and wired by construction contractors and when the building is handed over, we the client supply our own rack of sources (radio, cd, paging mic etc) and amplification.

So, the speaker configuration is as follows: 8 ceiling speakers, each with a 15watt tap on the transformer. The speakers have been wired in 2 sections of 4 speakers each, terminated with 2 speakon sockets at the wall. Having 2 "zones" is pointless in this scenario because it is one room, and is not a requirement from the users.

Where I am second guessing myself is the next step. It works out simpler, space saving and more cost effective to instal a mixer amp, but they pretty much all come with a single channel amp output. My understanding is that, assuming I am providing enough wattage output, I should be able to connect both sets of 4 speakers to the single channel amp output. Is this correct? Or do I have things terribly wrong?

Regards,
Ben
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John Roberts {JR}

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Re: Help me double check my constant voltage system
« Reply #1 on: March 27, 2013, 09:16:46 am »

Yes, CV speaker loads are all connected in parallel.

8x15W is 120W while it is common to use a somewhat larger amp than 120W for a safety margin.

JR
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BenGibbs

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Re: Help me double check my constant voltage system
« Reply #2 on: March 27, 2013, 04:42:49 pm »

Yes, CV speaker loads are all connected in parallel.

8x15W is 120W while it is common to use a somewhat larger amp than 120W for a safety margin.

JR


Thanks, that's what I thought. I will be supplying a 200w amp, as it really only seemed a choice between 100w and 200w models.
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Mac Kerr

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Re: Help me double check my constant voltage system
« Reply #3 on: March 27, 2013, 04:59:35 pm »


Thanks, that's what I thought. I will be supplying a 200w amp, as it really only seemed a choice between 100w and 200w models.

As JR said, go bigger for safety and to make up for the small insertion losses of the transformers. It is OK to go bigger because the "wattage" tap on the transformer is really an impedance tap, with higher impedance meaning less watts. The power matching on the amp is so you don't go below the minimum impedance load the amp can handle. Speakers tapped for more watts than the amp is rated for means the amp is seeing a load impedance that is less than it can deliver full power to.

Mac
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Ivan Beaver

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Re: Help me double check my constant voltage system
« Reply #4 on: March 28, 2013, 07:45:51 am »

Hi all,

I'm putting in a constant voltage system in a fitness centre on a school campus and I would like to double check my thinking, since it has been a little while since I had to deal with constant voltage sound. Being in Australia we run "100volt" systems. The ceiling speakers have already been installed and wired by construction contractors and when the building is handed over, we the client supply our own rack of sources (radio, cd, paging mic etc) and amplification.

So, the speaker configuration is as follows: 8 ceiling speakers, each with a 15watt tap on the transformer. The speakers have been wired in 2 sections of 4 speakers each, terminated with 2 speakon sockets at the wall. Having 2 "zones" is pointless in this scenario because it is one room, and is not a requirement from the users.

Where I am second guessing myself is the next step. It works out simpler, space saving and more cost effective to instal a mixer amp, but they pretty much all come with a single channel amp output. My understanding is that, assuming I am providing enough wattage output, I should be able to connect both sets of 4 speakers to the single channel amp output. Is this correct? Or do I have things terribly wrong?

Regards,
Ben
I think you need to clarify something-you said a "mixer amp".  Exactly what "type" of amp?  Are you talking about a 100V amp or an 8 ohm amp.

It is NOT only the wattage you are interested in here-but also the voltage.  If you are talking about a 8 or 4 ohm "mixer amp" then 200 watts would be fine.  If you are talking about a 8 or 4 ohm output then you will need one about 2500 watts @4 ohms to get the 100V level you need.

Just making sure all the bases are "covered".
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BenGibbs

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Re: Help me double check my constant voltage system
« Reply #5 on: March 30, 2013, 08:08:20 pm »

I think you need to clarify something-you said a "mixer amp".  Exactly what "type" of amp?  Are you talking about a 100V amp or an 8 ohm amp.

It is NOT only the wattage you are interested in here-but also the voltage.  If you are talking about a 8 or 4 ohm "mixer amp" then 200 watts would be fine.  If you are talking about a 8 or 4 ohm output then you will need one about 2500 watts @4 ohms to get the 100V level you need.

Just making sure all the bases are "covered".

Ivan, I was referring to 100v mixer amp. The model I'm actually getting is the Australian Monitor AMD200
http://www.australianmonitor.com.au/products/product/amd200
More inputs than I need, but it has the appropriate power, dsp and 3rd party control, and I have the budget.

I guess if I were to really frame my question with a bit more thought, I'm wanting to know if connecting the the two sets of four speakers in parallel at the amp is correct?
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Lee Buckalew

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Re: Help me double check my constant voltage system
« Reply #6 on: March 30, 2013, 08:13:16 pm »

Ivan, I was referring to 100v mixer amp. The model I'm actually getting is the Australian Monitor AMD200
http://www.australianmonitor.com.au/products/product/amd200
More inputs than I need, but it has the appropriate power, dsp and 3rd party control, and I have the budget.

I guess if I were to really frame my question with a bit more thought, I'm wanting to know if connecting the the two sets of four speakers in parallel at the amp is correct?

All of the speakers need to be in parallel.  How you accomplish that matters very little to not at all.

Lee
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Ivan Beaver

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Re: Help me double check my constant voltage system
« Reply #7 on: March 30, 2013, 08:15:19 pm »

Ivan, I was referring to 100v mixer amp. The model I'm actually getting is the Australian Monitor AMD200
http://www.australianmonitor.com.au/products/product/amd200
More inputs than I need, but it has the appropriate power, dsp and 3rd party control, and I have the budget.

I guess if I were to really frame my question with a bit more thought, I'm wanting to know if connecting the the two sets of four speakers in parallel at the amp is correct?
One of the "beauties" of a "constant voltage" (even though it is anything BUT constant voltage-but I digress----)
is that due to the high impedance-you just keep paralleling loudspeakers untill you get within 10% of the rating of the amp.

It doesn't matter if they are in "sets" or not-they are all still in parallel.
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Alan Clayton

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Re: Help me double check my constant voltage system
« Reply #8 on: April 03, 2013, 12:18:02 pm »


Having 2 "zones" is pointless in this scenario because it is one room, and is not a requirement from the users.

Regards,
Ben

Pointless from a functional perspective, perhaps, but any time you can get multiple home runs, take them. Even if you just parallel things at the amp. It makes troubleshooting easier.

Scenario: Amp blows up. You put your impedance meter on the line and find the load on the speaker line is way more than the amp can handle. There are 8 speakers (Or 16, or 50, or 100) on that line. Where is the problem? With 2 runs, you just cut the number of possibilities in 1/2.

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BenGibbs

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Re: Help me double check my constant voltage system
« Reply #9 on: April 03, 2013, 03:59:24 pm »

Pointless from a functional perspective, perhaps, but any time you can get multiple home runs, take them. Even if you just parallel things at the amp. It makes troubleshooting easier.

Scenario: Amp blows up. You put your impedance meter on the line and find the load on the speaker line is way more than the amp can handle. There are 8 speakers (Or 16, or 50, or 100) on that line. Where is the problem? With 2 runs, you just cut the number of possibilities in 1/2.

Yeah, that is true, and good thinking. Funnily though, in this scenario the two speaker lines are labelled Left and Right on the wall.
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ProSoundWeb Community

Re: Help me double check my constant voltage system
« Reply #9 on: April 03, 2013, 03:59:24 pm »


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