Can someone tell me what this? Pics inside

[drmrsdad]

Well I'm just about to start installing my sound sytem in the new house.

It appears the house was "wired for sound" as there are speakers built into the ceilings in a couple of rooms plus a pair of speakers built into the eave of the roof outside. There was a junction box that had what appears to be a speaker wire connection with two grey cables each containing 4 colored wires (Red White, Green & Black) When we removed the ceiling we found what appeared to a transformer that one of the grey cables was connected to, but I can't find any source of power to it, if it is a transformer??

This weekend we start wiring for the sound system and I want to try an utilize some of the wiring that is already there.

Main box in the living room

Cables that come out of the wall one of which connected to the other side of the room and connects to the "transformer". The other cable connected to the 2 speakers that were in that room whcih have since been removed since we have vaulted the ceiling.

 

[C.A.P]

Looks like power transformers to step up or down voltages.

 

[amey01]

Looks like transformers of some description. Not sure. Are you sure it is for the sound system and not for 12v halogen lighting?

 

[Tosh]

Transformer distributed audio system?
(scroll down to Fig.3)

 

[OldMonolith]

That would likely be a 70 volt system.

That is the appropriate way to do a large number of speakers for a background music system. :music:

Often, like in a business installation, each speaker will have its own 8 ohm fader for independant volume control.

OldMonolith

 

[drmrsdad]

Looks like transformers of some description. Not sure. Are you sure it is for the sound system and not for 12v halogen lighting?

Got up into the attic last night and started tracing lines. I'm sure this is for the speaker systems throughout the house.

As you can see from the pic above the Junction Box has inputs of 4. One line went to the speakers that once were in the living room, that have now been removed, the other cable connected to the otherside of the room and then went directly to this "Transformer", From the transformer, 4 lines run out.
1 line to the Kitchen,

One line to the Dining Room

One to the speakers outside

and one to the Masterbedroom and Master bath, but this line has been disconnected from the Masterbedroom and bath as those speakers are being run into a closet in the masterbedroom where a Amp used to be.
There is a control Knob on the wall in each of these rooms to control volume. I opened one of the Control Knob switches and it has a small transformer attached with "Input from Amplifier" and " Volume To Speaker"

I guess what I'm trying to get at is, should I be running the main cable from my amp to this transformer? I guess I need to hook up a source of power and signal and see how it all turns out. I'll let you know.

 

[drmrsdad]

That would likely be a 70 volt system.

That is the appropriate way to do a large number of speakers for a background music system. :music:

Often, like in a business installation, each speaker will have its own 8 ohm fader for independant volume control.

OldMonolith

Tosh, thanks for the link, and the explanation OldMonolith, but please excuse my ignornace. Does this transformer need to be powered? I see no existence of a source of power, unless I'm missing a wire connection somewhere. It just seems like the main cable from the speaker junction box goes in and a few lines come out. COuld this be powered by a very small source of power?

 

[Dreamer]

I would agree with Tosh and OldMonolith. Your wiring and those transformers are for a 70-volt speaker system. This is the sort of system that is used in older office buildings and schools for intercoms, and in commercial installations for "background music".

The transfomers do not require a seperate power supply. But you DO need a special amplifier that is built to provide the 70 volt output signal. The higher-voltage output is so that the sound won't degrade as much due to potential resistance loss through the long lines. The transformers then step down the 70 volt signal to something that a standard PA-type speaker can handle.

You can't really power this type of setup with a traditional "audiophile" type amp. If you hook up your amp to this circuit, you will get a VERY weak signal at the speaker, and no matter HOW loud you crank it, or how powerful your amp is, it will be barely audible. You need an amp that does 70 volt output, and you can only get THAT sort of amp from someone who makes amp specifically for PA-type applications, which pretty much excludes any "high end" manufacturer. I think Carver used to make some that were 70v in their "Pro" line, but that was a LONG time ago. I've heard that Mark Levinson will custom-build amps for pro or PA use, to your spec, but I would imagine that would get pretty pricey...

Of course, if the lines in your ceilings are twisted-pairs or shielded with braiding, you might be able to just use them as-is, if you take those transformers out of the circuit. I mean just plug the wires into your amps, and then run them straight to the speakers. Since these are in-wall and in-ceiling speakers, it's not like they are really designed for "audiophile-grade" listening experience--they are for background music. You'll get a little loss of power and clarity, and you might get some tiny amount of RFI interferance if any of the lines run near flourescent or halogen light fixtures, (which is another advantage to 70v systems--they generate enough of their own magnetic field that they essentially shield themself against stray RFI/EMI from lights) but I mean, DUDE, it's a background music system, not your main "critical listening" rig...

The problem with these super-custom "full-house" music systems is that most of these installers are essentially glorified electricians or General Contractors. Sure, their wiring is pretty and tidy, and sure the speakers are mounted in a very professional, slick, and nearly invisible manner, but the fact remains that these installers (and for the most part their customers too) are NOT concerned with sound quality. They are concerned with 1) how it looks, and 2) how easy it is to use once its installed. Sound quality, at least as people like us view it, is WAY down on the list of priorities with installers (and customers) that deal with this sort of setup. If the speaker makes music, and doesn't buzz, hum, or crackle, then to them it's a successful install...

Wire those speakers direct to your amp. Just take the transformers out of the circuit. They will sound OK.

But you might consider hooking a meter or a continuity tester up to those wires before you hook them up to your amps, just to be SURE they don't have any shorts. You'd hate to lose an amp to some damaged wiring...

--Richard

 

[drmrsdad]

Dreamer! Fantastic! You've explained it clearly and perfectly and I totally understand it all now.

Thanks again!

 

[Speedskater]

Rane Corp. has a nice paper on 70 Volt systems.

www.rane.com/note136.html

A big audiophile solid state power amplifier works pretty well driving a 70 Volt system, even without the voltage step-up transformer.