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70 volt pa system wiring

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Anonymous
April 14, 2004 4:35:47 PM

Archived from groups: rec.audio.tech (More info?)

Math question, I am attempting to hookup a 70 volt pa system for
mainly background music. Mixer amp has a 20 watt output, there are 8
speakers with built in transformers. I am going to set the taps to the
2 watt setting on the speakers that adds up to 16 watts allowing for
the 20 percent margin is this correct? Can i get away with running
just a single pair 16 ga cable and tapping off it from speaker to
speaker(should be very low current right?)or do i need home runs from
each speaker back to the amp, parallel across the 70v tap???

More about : volt system wiring

Anonymous
April 15, 2004 1:49:01 AM

Archived from groups: rec.audio.tech (More info?)

"G.B." <cbandtech@yahoo.com> wrote in message
news:c742cc1.0404141135.3b4b96ea@posting.google.com...
> Math question, I am attempting to hookup a 70 volt pa system for
> mainly background music. Mixer amp has a 20 watt output, there are 8
> speakers with built in transformers. I am going to set the taps to the
> 2 watt setting on the speakers that adds up to 16 watts allowing for
> the 20 percent margin is this correct? Can i get away with running
> just a single pair 16 ga cable and tapping off it from speaker to
> speaker(should be very low current right?)or do i need home runs from
> each speaker back to the amp, parallel across the 70v tap???

The wire gauge required depends on the length of the
run and how much IR loss you can tolerate.
Anonymous
April 15, 2004 3:16:45 AM

Archived from groups: rec.audio.tech (More info?)

That stuff is made to be daisy chained, you should be fine with the load
too.
Phil
"G.B." <cbandtech@yahoo.com> wrote in message
news:c742cc1.0404141135.3b4b96ea@posting.google.com...
> Math question, I am attempting to hookup a 70 volt pa system for
> mainly background music. Mixer amp has a 20 watt output, there are 8
> speakers with built in transformers. I am going to set the taps to the
> 2 watt setting on the speakers that adds up to 16 watts allowing for
> the 20 percent margin is this correct? Can i get away with running
> just a single pair 16 ga cable and tapping off it from speaker to
> speaker(should be very low current right?)or do i need home runs from
> each speaker back to the amp, parallel across the 70v tap???
Related resources
Anonymous
April 15, 2004 9:42:04 AM

Archived from groups: rec.audio.tech (More info?)

"Richard Crowley" <rcrowley7@xprt.net> wrote in message news:<107s5206bqpgl78@corp.supernews.com>...
> "G.B." <cbandtech@yahoo.com> wrote in message
> news:c742cc1.0404141135.3b4b96ea@posting.google.com...
> > Math question, I am attempting to hookup a 70 volt pa system for
> > mainly background music. Mixer amp has a 20 watt output, there are 8
> > speakers with built in transformers. I am going to set the taps to the
> > 2 watt setting on the speakers that adds up to 16 watts allowing for
> > the 20 percent margin is this correct? Can i get away with running
> > just a single pair 16 ga cable and tapping off it from speaker to
> > speaker(should be very low current right?)or do i need home runs from
> > each speaker back to the amp, parallel across the 70v tap???
>
> The wire gauge required depends on the length of the
> run and how much IR loss you can tolerate.

Thanks for the replays, i think the max cable run will be 300 feet.
With that short a run the end speaker should be about the same level
as the others right?
Anonymous
April 17, 2004 8:57:21 AM

Archived from groups: rec.audio.tech (More info?)

> > > Math question, I am attempting to hookup a 70 volt pa system for
> > > mainly background music. Mixer amp has a 20 watt output, there are 8
> > > speakers with built in transformers. I am going to set the taps to the
> > > 2 watt setting on the speakers that adds up to 16 watts allowing for
> > > the 20 percent margin is this correct? Can i get away with running
> > > just a single pair 16 ga cable and tapping off it from speaker to
> > > speaker(should be very low current right?)or do i need home runs from
> > > each speaker back to the amp, parallel across the 70v tap???
> >
> > The wire gauge required depends on the length of the
> > run and how much IR loss you can tolerate.
>
> Thanks for the replays, i think the max cable run will be 300 feet.
> With that short a run the end speaker should be about the same level
> as the others right?


School intercom systems, which typically run on 25 volts, are
typically wired with 22 ga. cable. The typical class room speaker is
tapped at 1/2 watt.
What you are trying to do is entirely practical and your choice of
cable is perfectly acceptable.

Lee Salter
Anonymous
April 18, 2004 4:00:41 AM

Archived from groups: rec.audio.tech (More info?)

"G.B." <cbandtech@yahoo.com> wrote in message
news:c742cc1.0404150442.2ca68dce@posting.google.com...
> "Richard Crowley" <rcrowley7@xprt.net> wrote in message
news:<107s5206bqpgl78@corp.supernews.com>...
> > "G.B." <cbandtech@yahoo.com> wrote in message
> > news:c742cc1.0404141135.3b4b96ea@posting.google.com...
> > > Math question, I am attempting to hookup a 70 volt pa system for
> > > mainly background music. Mixer amp has a 20 watt output, there are 8
> > > speakers with built in transformers. I am going to set the taps to the
> > > 2 watt setting on the speakers that adds up to 16 watts allowing for
> > > the 20 percent margin is this correct? Can i get away with running
> > > just a single pair 16 ga cable and tapping off it from speaker to
> > > speaker(should be very low current right?)or do i need home runs from
> > > each speaker back to the amp, parallel across the 70v tap???
> >
> > The wire gauge required depends on the length of the
> > run and how much IR loss you can tolerate.
>
> Thanks for the replays, i think the max cable run will be 300 feet.
> With that short a run the end speaker should be about the same level
> as the others right?

**You'll experience no problems. What I do, for higher power/longer runs, is
to loop the cable back to the amplifier.


--
Trevor Wilson
www.rageaudio.com.au
Anonymous
April 24, 2004 6:03:33 PM

Archived from groups: rec.audio.tech (More info?)

(G.B.) wrote
> Math question, I am attempting to hookup a 70 volt pa system for
> mainly background music. Mixer amp has a 20 watt output, there are
> 8 speakers with built in transformers. I am going to set the taps
> to the 2 watt setting on the speakers that adds up to 16 watts
> allowing for the 20 percent margin is this correct?

Yes.

> Can i get away with running just a single pair 16 ga cable and
> tapping off it from speaker to speaker(should be very low
> current right?)or do i need home runs from each speaker back
> to the amp, parallel across the 70v tap???

These systems are designed to be teed off almost any old how. I don't
know what 16 ga cable is but I'd suggest that as long as its as heavy
as table lamp cable it will be good enough. One caveat: 70V wiring may
be required to be to the same standard as mains wiring depending on
your local electrical regulations.

Owain
April 26, 2004 2:17:04 AM

Archived from groups: rec.audio.tech (More info?)

spuorgelgoog@gowanhill.com (Owain) wrote in message news:<ba44ae3.0404241303.7b148997@posting.google.com>...
> (G.B.) wrote
> > Math question, I am attempting to hookup a 70 volt pa system for
> > mainly background music. Mixer amp has a 20 watt output, there are
> > 8 speakers with built in transformers. I am going to set the taps
> > to the 2 watt setting on the speakers that adds up to 16 watts
> > allowing for the 20 percent margin is this correct?
>
> Yes.
>
> > Can i get away with running just a single pair 16 ga cable and
> > tapping off it from speaker to speaker(should be very low
> > current right?)or do i need home runs from each speaker back
> > to the amp, parallel across the 70v tap???
>
> These systems are designed to be teed off almost any old how. I don't
> know what 16 ga cable is but I'd suggest that as long as its as heavy
> as table lamp cable it will be good enough. One caveat: 70V wiring may
> be required to be to the same standard as mains wiring depending on
> your local electrical regulations.
>
> Owain


"One caveat: 70V wiring may be required to be to the same standard
as mains wiring depending on your local electrical regulations."

Definitely check with the relevent building inspector department.
They'll probably want you to use "plenum cable", which is supposed to
not put out as great a level of poisonous fumes as regular wire does
when the insulation burns up in a fire.

Lamp cord, specifically the kind actually used on lamps, is usually
16 or the slightly smaller 18 gauge.
!