From: The Post Quartermaster on
I've never quite caught on to the Ohms thing. If I am running two
speakers (I forget the terminology - series or parallel) in a system
in which the speaker cable runs from the power amp to the first
speaker, and then another cable runs from that speaker to the second
speaker, what must I calculate in order to safely run yet another
cable from the second speaker to a third speaker?
--
Careful how you respond. I have people!

JC

From: Krooburg Science on
On Jul 16, 12:09 pm, "The Post Quartermaster"
<quartermasterextraordina...(a)postfiftyone.org> wrote:
> I've never quite caught on to the Ohms thing. If I am running two
> speakers (I forget the terminology - series or parallel) in a system
> in which the speaker cable runs from the power amp to the first
> speaker, and then another cable runs from that speaker to the second
> speaker, what must I calculate in order to safely run yet another
> cable from the second speaker to a third speaker?
> --
> Careful how you respond. I have people!
>
> JC

Daisy chaining speakers is a *parallel* connection which is
electrically the same connection is hooking all the speakers directly
to the amp terminals. The disadvantage to daisy chaining is that cable
resistance is higher and electrical damping is lower since all the
speakers go through a single cable to the amp. Anyhow, every time you
take two identical speakers (loads) and connect them in parallel to
the amp by either method, you effectively cut the impedance of the
load that the amp "sees" in half. So two 8Ù speakers nets a 4Ù nominal
load - nominal meaning average. Speaker impedance varies with
frequency which can be very important depending on the amp and how
well it can handle dips in impedance below nominal. Now adding a 3rd
speaker requires the use of a formula since you're dealing with an odd
number. The formula is Rt = 1 / [ (1/R1) + (1/R2) + (1/R3). I suffices
to say that the load with three 8Ù speakers is ~2.66Ù. If your amp
channel is rated to handle 2 ohm loads (four 8Ù speakers in parallel
or two 4 ohm speakers in parallel), then 2.66Ù should work fine. If
it's rated for 4Ù minimum, don't do it.

- K
From: The Post Quartermaster on

"Krooburg Science" <krooburg(a)gmail.com> wrote in message
news:b6655c0d-5d42-481a-9cc9-92a6ac196193(a)z34g2000pro.googlegroups.com...
On Jul 16, 12:09 pm, "The Post Quartermaster"
<quartermasterextraordina...(a)postfiftyone.org> wrote:
> I've never quite caught on to the Ohms thing. If I am running two
> speakers (I forget the terminology - series or parallel) in a system
> in which the speaker cable runs from the power amp to the first
> speaker, and then another cable runs from that speaker to the second
> speaker, what must I calculate in order to safely run yet another
> cable from the second speaker to a third speaker?
> --
> Careful how you respond. I have people!
>
> JC

Daisy chaining speakers is a *parallel* connection which is
electrically the same connection is hooking all the speakers directly
to the amp terminals. The disadvantage to daisy chaining is that cable
resistance is higher and electrical damping is lower since all the
speakers go through a single cable to the amp. Anyhow, every time you
take two identical speakers (loads) and connect them in parallel to
the amp by either method, you effectively cut the impedance of the
load that the amp "sees" in half. So two 8� speakers nets a 4� nominal
load - nominal meaning average. Speaker impedance varies with
frequency which can be very important depending on the amp and how
well it can handle dips in impedance below nominal. Now adding a 3rd
speaker requires the use of a formula since you're dealing with an odd
number. The formula is Rt = 1 / [ (1/R1) + (1/R2) + (1/R3). I suffices
to say that the load with three 8� speakers is ~2.66�. If your amp
channel is rated to handle 2 ohm loads (four 8� speakers in parallel
or two 4 ohm speakers in parallel), then 2.66� should work fine. If
it's rated for 4� minimum, don't do it.

- K

Thanks. Our local chamber of commerce wants to run an outdoor speaker
off of their system, which is
http://www.americanmusical.com/Item--i-BEH-PAPACK

It's a small town chamber and they just needed something lowpriced
that had the capability to project sound both inside and outside
during small festival and fleamarket type events. This one can be run
both series and parallel so I guess it could be run with two speakers
on one side and then use the other side for outside speakers. If that
is the case, as long as I ran four speakers of the same ohms, I'd be
alright? And, thanks for your response. A whole town of 3000
appreciates ya.
--
Careful how you respond. I have people!

JC

From: George's Pro Sound Co. on

"The Post Quartermaster" <quartermasterextraordinaire(a)postfiftyone.org>
wrote in message news:Krydne_cAKN0I93RnZ2dnUVZ_tSdnZ2d(a)giganews.com...
>
> "Krooburg Science" <krooburg(a)gmail.com> wrote in message
> news:b6655c0d-5d42-481a-9cc9-92a6ac196193(a)z34g2000pro.googlegroups.com...
> On Jul 16, 12:09 pm, "The Post Quartermaster"
> <quartermasterextraordina...(a)postfiftyone.org> wrote:
>> I've never quite caught on to the Ohms thing. If I am running two
>> speakers (I forget the terminology - series or parallel) in a system
>> in which the speaker cable runs from the power amp to the first
>> speaker, and then another cable runs from that speaker to the second
>> speaker, what must I calculate in order to safely run yet another
>> cable from the second speaker to a third speaker?
>> --
>> Careful how you respond. I have people!
>>
>> JC
>
> Daisy chaining speakers is a *parallel* connection which is
> electrically the same connection is hooking all the speakers directly
> to the amp terminals. The disadvantage to daisy chaining is that cable
> resistance is higher and electrical damping is lower since all the
> speakers go through a single cable to the amp. Anyhow, every time you
> take two identical speakers (loads) and connect them in parallel to
> the amp by either method, you effectively cut the impedance of the
> load that the amp "sees" in half. So two 8� speakers nets a 4� nominal
> load - nominal meaning average. Speaker impedance varies with
> frequency which can be very important depending on the amp and how
> well it can handle dips in impedance below nominal. Now adding a 3rd
> speaker requires the use of a formula since you're dealing with an odd
> number. The formula is Rt = 1 / [ (1/R1) + (1/R2) + (1/R3). I suffices
> to say that the load with three 8� speakers is ~2.66�. If your amp
> channel is rated to handle 2 ohm loads (four 8� speakers in parallel
> or two 4 ohm speakers in parallel), then 2.66� should work fine. If
> it's rated for 4� minimum, don't do it.
>
> - K
>
> Thanks. Our local chamber of commerce wants to run an outdoor speaker off
> of their system, which is
> http://www.americanmusical.com/Item--i-BEH-PAPACK
>
> It's a small town chamber and they just needed something lowpriced that
> had the capability to project sound both inside and outside during small
> festival and fleamarket type events. This one can be run both series and
> parallel so I guess it could be run with two speakers on one side and then
> use the other side for outside speakers. If that is the case, as long as I
> ran four speakers of the same ohms, I'd be alright? And, thanks for your
> response. A whole town of 3000 appreciates ya.
> --
> Careful how you respond. I have people!
>
> JC

JC that 518 mixer is not suitable for your stated use

George


From: George's Pro Sound Co. on


>
> JC that 518 mixer is not suitable for your stated use
>
> George
>

see manual here
http://www.behringer.com/EN/downloads/pdf/PMP518M_P0672_M_EN.pdf

look to page 7 section 2.4

you can use 2 x8 ohm speakers TOTAL, this is sound system at its most basic
do not try to hook 4 speakers up to this mixer or the magic smoke will leave
this unit and leavee it for dead


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