Powering 19 ceiling speakers

[PepsiFX357]

Hello all, I am trying to power ceiling speakers in my house. I have 19 100Watt 8OHm speakers and they are all wire parallel. What would be the best amp or amps to power them with.

Thanks,
Ben

[Weasel9992]

Originally Posted by PepsiFX357

Hello all, I am trying to power ceiling speakers in my house. I have 19 100Watt 8OHm speakers and they are all wire parallel.

That can't be right. *19* 100W, 8ohm ceiling speakers? All wired parallel? What speakers are these and what are you trying to do?

Frank

[Pascal Sijen]

That would be a .4 Ohm load!

[Weasel9992]

Originally Posted by Pascal Sijen

That would be a .4 Ohm load!

Frank

[theblue1]

When I was 14 or so I conned my folks into letting me wire the house for sound -- although not quite the elaborate, ceiling mounted-infinite baffle set up I envisioned. No holes in the ceiling, wires had to be hidden under carpets, and so on.

It was nothing like 19 speakers [OK... I gotta bite -- why nineteen?!? One center speaker somewhere? ] -- at its peak it got up to 8 speakers. I used a switching matrix to try to manage the impedance, switching certain pairs in parallel and others in series as needed. It was a bit of a logic problem but nothing that couldn't be solved with a couple sheets of paper and some simple math and boolean algebra (symbolic logic, if you will).

[Barnabas]

I'd get an amplifier designed to push a 70-volt line and install a 70-volt transformer at each speaker. Most of the transformers have multiple taps so you can make some rooms louder than others. You can also get a wall-mounted volume control (pad) to put in each room.

[aussie_techie]

Originally Posted by Pascal Sijen

That would be a .4 Ohm load!

a Camco can down to about half an Ohm but the real load when cold is probably lower than 0.4Ohm and im sure you have pretty long cable runs so in reality nothing is going to be able to do it off a single amp.

for this kind of thing are going to need a couple of amps and probably driving 70v/100v lines
the crown commercial series goes up to about 6channels in a single unit and the CT/CD series can also push 100v lines as well. not sure what else is out there off the top of my head but im sure there is plenty.

you probably need to work out some zones first anyway

[PepsiFX357]

Ok, Update. Sorry my internet was down. ok this house I just moved into and the previous owner installed 23 100Watt 8OHm speakers "NHT" (Now Hear This) brand. There is 2 in just about every room and 1 in the hallway. They all have a volume SWITCH in each room for control and from my visit to the attic they are all wired by themselves and run to a central location and bundled together.

[Weasel9992]

Originally Posted by aussie_techie

for this kind of thing are going to need a couple of amps and probably driving 70v/100v lines
the crown commercial series goes up to about 6channels in a single unit and the CT/CD series can also push 100v lines as well. not sure what else is out there off the top of my head but im sure there is plenty.

Can't use 70/100V amps on 8ohm speakers...if they're really 8ohm. If they are, then you'll have to see how they're rated, but you *might* be able to run 4 parallel...probably only 3 though. Also depends on the amp you buy. All the major manufacturers make multi-channel amps (4-8 channels) for use in just such situations, so you might be able to get away with a single amp. The other alternative is to get a bunch of 2-channel amps. If the speakers all have volume knobs already then you won't techically have to figure out zones, though you may want to buy and install some kind of signal processing/control system sometime in the future...at that point you will have to decide how you want to group everything.

Frank

[soundsundergroun]

If 70v transformers are not an option, you can wire them all in series then split them up into groups. for example, 4 speakers wired in series and another 4 in series then join those 2 sets together at the amp and would give you 16 ohm load.

someone correct me if i'm wrong on this, my brain is fried from work right now

[aussie_techie]

sorry i meant with 70/100v transformers not that you would try to do it directly. most cheaper amps arnt going to want to drive a load lower than about 4 ohm, yes many will do 2ohm but you will be working the amp alot harder so its certainly not desirable.

before you work out numbers of how many you can run the first thing you should do is get out a multi-meter and actually measure the resistance of the speakers as you may find they are very different from their rating. in most cases they will be slightly under when cold and warm up to their rating but in some cases you will get drivers that are as far as half or double their rating.

do you know what model speakers they are or only the brand?

[Mylithra]

The way they do commercial overhead sound systems like you see in stores (Im sure places like Sears have more than 23 speakers in their ceiling at their store and only run 1 or 2 amps) is to do it all by transformer. Once you Isolate the the speaker, you can pretty much fake any load to an amp with some creative wiring of some resistors. If transformers arent an option, your only real choice (and by real I mean safe and wont blow anything up in the long run) is to wire out your speakers to to where you get no less than a 4 ohm load. 2 , 8ohm speakers wired in series then 4 sets of the series speakers wired in parallel together should get you 4 Ohms. (2, 8 ohm speakers, series = 16Ohm, 4, 16ohm loads wired in parallel =4ohm. Take 4 channels of amp around 400w a channel and you should be good to go.

Think about it this way, You can run 8, 16ohm 12's (2 stock 412 cabs) off a single guitar amp. You load your amp correctly, You shouldn't have a problem.

[tINY]

You'll want several amplifiers, that way you can have sound in one room and not the next while mantaining a sane load.

Or get a roatary switch and only play a room at a time...



-tINY

[subspace]

Buy 19 70V transformers and install them at each speaker as suggested. I use Crown CTs amps for driving distributed 70V loads, nice amps that share the bulk of their circuit boards with the I-Tech line, but are analog only on the front-end. I use PIP-lite cards in them for remotely monitoring the amps over a network.

[rainsinvelvet]

Originally Posted by subspace

Buy 19 70V transformers and install them at each speaker as suggested. I use Crown CTs amps for driving distributed 70V loads, nice amps that share the bulk of their circuit boards with the I-Tech line, but are analog only on the front-end. I use PIP-lite cards in them for remotely monitoring the amps over a network.

If the speakers are indeed 8 ohm and not 70volt than this is what you will need to do.

If they are actually 70volt than its a piece of cake. Get a 70volt amp of 100watts or so and your good to go.
ERic

[Keystone]

Dukane amps are the grocery store,restaurant variety made for this kind of application.You can find them all over the internet.

[8th_note]

I have speakers wired all over my house so I'm familiar with your situation. I use an Adcom 600 Speaker Selector that allows you to select up to 6 pairs of speakers and it has a switch that you can engage that provides a higher impedence for your amp.

If you use a high quality integrated amp like an Onkyo, Denon, or NAD, these amps will withstand a low impedence without going up in smoke. One thing nice about using an integrated amp is that you can set the amp's volume control so that you will never overdrive your ceiling speakers. In my case I have two separate integrated amps driving several sets of speakers and these are fed a line level signal by a central system in my living room with a separate preamp, amp, and CD player.

[Mege]

You may want to look into something like Control4 or Niles Audio components.
Control4 has a C4-16AMP3-B 16-channel amplifier.
Niles has the SL-1260 12-channel amplifier.
In either case you'll be buying more than one of theses amps and may have to buy something to control them with.

[PepsiFX357]

I'm wanting all of the speakers to work at one time. Since they all have a volume control in every room they can be cut off from there if someone doesn't want to hear them. Now about this 70volt system. What kind of tranny are we talking about? Where do it hook up in relation to the amp? And, how many amps will I need @ what wattage?

Thanks for all your posts

[PepsiFX357]

Also there are two in every room so I was hoping to get Left and Right to every room also.

[Weasel9992]

Originally Posted by PepsiFX357

I'm wanting all of the speakers to work at one time. Since they all have a volume control in every room they can be cut off from there if someone doesn't want to hear them. Now about this 70volt system. What kind of tranny are we talking about? Where do it hook up in relation to the amp? And, how many amps will I need @ what wattage?

Thanks for all your posts

In your original post you said that the speakers were 8ohm; if they are, you can't use a 70.7V amp. If they're 8ohm you'll have to use an 8ohm amplifier, but you can wire the speakers different ways depending on what your'e doing (parallel vs. series parallel, for instance).

Lots of ceiling speakers come with 70.7V transformers on them though, so check and see if that's the case. *IF* the speakers have a 70.7V transformer already, then the forumla is number of speakers*wattage per speaker=amount of amplification necessary. So, if you had ten 30W speakers, you'd need 300W of amp to power them.

Frank

[BadJones]

You can buy the transformers seperately on line. The taps on the transformers determine the wattage, not the speaker! So if you tap the the transformer at say 2.5 watts at an 8 ohm load assuming thats what your speakers are. You will need 19 speakers x 2.5 watts = 47.5 watts total. A 100 watt 70v amp will do it easily. Most transformers will have taps from .5 watts to 10 watts. Don't let the small wattage fool you, the speakers should still get a decent volume.

[Weasel9992]

Originally Posted by BadJones

You can buy the transformers seperately on line. The taps on the transformers determine the wattage, not the speaker! So if you tap the the transformer at say 2.5 watts at an 8 ohm load assuming thats what your speakers are. You will need 19 speakers x 2.5 watts = 47.5 watts total. A 100 watt 70v amp will do it easily. Most transformers will have taps from .5 watts to 10 watts. Don't let the small wattage fool you, the speakers should still get a decent volume.

Sure, if you want to change the trafo's on 100 speakers. If he's never done it before, I wouldn't suggest it. We also don't know what kind of volume controls he's got. The whole system is probably wired for 8ohms if they're in fact 8 ohm speakers, too. In short, I'm not sure it's practical to install new trafo's.

Frank

[BadJones]

He wouldn't have to change the transformers on the speakers themselves, he would just have to add the transformer before the volume control and speaker. This is of course if the speakers aren't already wired with a transformer.

2 wire 70v feed from amp to transformer, out transformer 8 ohm tap to 2 wires leading to the speaker and volume control. As long as the wiring is proper gauge etc. It may be too much for himself to perform and too difficult to explain not knowing how it is actually wired. Are the wires telephone, security wire or speaker wire? How are the volume controls wired to each speaker? It might be best to just hire a sound installation company to look it over and suggest what he needs.

[Mylithra]

If you know how its all wired already, can you draw it all out or post a schematic? Types of wire installed and existing components will be helpful as well.

[PepsiFX357]

Here are the speakers:

NHT - Now Hear This ®

23 of these are what I'm dealing with.

[subspace]

Originally Posted by PepsiFX357

Here are the speakers: NHT - Now Hear This ® 23 of these are what I'm dealing with.

you can drive 11 stereo pairs off one 70v amp if you install transformers at each load. otherwise, you're looking at a dedicted stereo amp for every 4 pairs maximum, assuming that amp is happy driving a 2 ohm load. perhaps one six channel surround amp with 4 speakers/ channel would get it done, assuming you can find one that's stable at 2 ohms per channel. try searching on Audiosource amps and racks for an affordale multi-channel install system, partsexpress.com carries them I believe.

[tINY]

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-tINY