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Author Topic: Help me double check my constant voltage system  (Read 5545 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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Hal Bissinger/COMSYSTEC

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Re: Help me double check my constant voltage system
« Reply #10 on: April 03, 2013, 04:15:10 pm »

... Funnily though, in this scenario the two speaker lines are labelled Left and Right on the wall.
Not funny at all. Obviously it's designed by someone who doesn't understand the concepts. After all, this is the person who said to use a home stereo amp remember?
 
-Hal
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Ivan Beaver

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Re: Help me double check my constant voltage system
« Reply #11 on: April 03, 2013, 07:40:01 pm »

Not funny at all. Obviously it's designed by someone who doesn't understand the concepts. After all, this is the person who said to use a home stereo amp remember?
 
-Hal
Because any "audio" guy "knows" that stereo is better than mono-right?
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Brad Weber

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Re: Help me double check my constant voltage system
« Reply #12 on: April 04, 2013, 07:37:18 am »

Yeah, that is true, and good thinking. Funnily though, in this scenario the two speaker lines are labelled Left and Right on the wall.
Regardless of whether someone thought the resulting system would be 'stereo', is there any chance that could simply be referring to the left and right sides of the room?  You mentioned the speakers wired as two zone, if one zone is the speakers on the left half of the room and the other the speakers on the right half then would the labeling not only be accurate but also possibly useful?
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Ivan Beaver

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Re: Help me double check my constant voltage system
« Reply #13 on: April 04, 2013, 07:48:04 am »

Regardless of whether someone thought the resulting system would be 'stereo', is there any chance that could simply be referring to the left and right sides of the room?  You mentioned the speakers wired as two zone, if one zone is the speakers on the left half of the room and the other the speakers on the right half then would the labeling not only be accurate but also possibly useful?
Of course that is a very real (and useful) possibility.  I didn't think of that-I guess because I have simply run into to many cases where people wanted a "stereo" ceiling speaker install. 

Because they thought "stereo" was better.

But then again-it could be wired up so that every other speaker was on the right or left-so it could be "stereo"-but only for the people sitting in just the right spots.

S shame on me for jumping to conclusions-based on limited information.  But then again-without further testing-who knows how it is wired.

Of course it is VERY easy to test-even without a 70V amp.  Just hookup any amp and put some signal into ONE side and see what speakers produce sound.

A quick and easy test will revel quite a bit about the system.

So people can speculate for days-but a 1 minute test can revel the TRUE answer.

As a wise man (Don Davis?) once said.  Even the best analyzer on the market cannot tell what is being said from a waveform.  But a $2 plastic speaker can.  So what is better?  It depends on what you are doing and want to know.
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BenGibbs

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Re: Help me double check my constant voltage system
« Reply #14 on: April 05, 2013, 04:28:37 am »

Regardless of whether someone thought the resulting system would be 'stereo', is there any chance that could simply be referring to the left and right sides of the room?  You mentioned the speakers wired as two zone, if one zone is the speakers on the left half of the room and the other the speakers on the right half then would the labeling not only be accurate but also possibly useful?

This is a real possibility, though I will have to test it out. The problem being, though, that is is a workout room, with no clearly defined direction of orientation, ie. there are mirrors and LCD displays on all walls, so left and right have no reference point.
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Hal Bissinger/COMSYSTEC

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Re: Help me double check my constant voltage system
« Reply #15 on: April 05, 2013, 05:37:15 pm »

...this is is a workout room, with no clearly defined direction of orientation, ie. there are mirrors and LCD displays on all walls, so left and right have no reference point.

You know that and we know that but dollars to donuts I'm still betting on that designer splitting it right down the middle for stereo. Is this the one with RCA jacks labeled left and right that you changed to Speakon or are these similar threads confusing me?  ;D
 
-Hal
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BenGibbs

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Re: Help me double check my constant voltage system
« Reply #16 on: April 05, 2013, 08:09:29 pm »


You know that and we know that but dollars to donuts I'm still betting on that designer splitting it right down the middle for stereo. Is this the one with RCA jacks labeled left and right that you changed to Speakon or are these similar threads confusing me?  ;D
 
-Hal

Hal, you're right, same system
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Re: Help me double check my constant voltage system
« Reply #16 on: April 05, 2013, 08:09:29 pm »


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