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connecting 2 amps to speaker pair?

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Anonymous
August 19, 2005 6:42:28 PM

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

I have a pair of Celestion Ditton speakers in the family room, currently
connected to the B channel of my Yamaha RX-596 stereo receiver which is
upstairs.

I want to now use those same speakers as the front channel to a new home
theatre system, powered by a Yamaha RXV-657. As long as both amps are not
on at the same time, can I connect the 2 amp outputs to these same
speakers? If not, is there some sort of easy inexpensive isolator I can
use?


Larry Gagnon
--
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Anonymous
August 19, 2005 9:42:48 PM

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

"Larry Gagnon" wrote ...
>I have a pair of Celestion Ditton speakers in the family
> room, currently connected to the B channel of my
> Yamaha RX-596 stereo receiver which is upstairs.
>
> I want to now use those same speakers as the front
> channel to a new home theatre system, powered by
> a Yamaha RXV-657.

> As long as both amps are not on at the same time,

You likely don't have any practical way of ensuring this.
But even if you did....

> can I connect the 2 amp outputs to these same speakers?

No. The amplifier that is "off" is NOT inert(*). If you were
really lucky you might get away with it, but I would never try it.

More likely, the "off" amplifier may cause extra distortion,
and it is quite possible that the "off" amplifier could be damaged
by feeding speaker-level audio INTO its output.

> If not, is there some sort of easy inexpensive isolator I
> can use?

Simplest would be a switch. If you really want to get fancy,
you could wire a line-powered relay into the power strip of
your home theatre system. Then when you power-on the
HTS, it would transfer the speaker connections. With all the
HTS accessories out there, I'd bet that somebody already
makes/sells this kind of thing. If not, maybe I'll start! :-)

(*) On second thought, the powered-off amp COULD
be inert if it has a relay in it to protect the speakers from
power-on "thump". However, that doesn't protect you
from someone upstairs inadvertently turning on the system
while someone downstairs is watching a movie, etc.
Anonymous
August 19, 2005 11:04:46 PM

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

On Fri, 19 Aug 2005 14:42:28 -0700, Larry Gagnon
<lagagnon@fakeuniserve.com> wrote:

>I have a pair of Celestion Ditton speakers in the family room, currently
>connected to the B channel of my Yamaha RX-596 stereo receiver which is
>upstairs.
>
>I want to now use those same speakers as the front channel to a new home
>theatre system, powered by a Yamaha RXV-657. As long as both amps are not
>on at the same time, can I connect the 2 amp outputs to these same
>speakers? If not, is there some sort of easy inexpensive isolator I can
>use?

You cannot/should not since one amp can shunt the other, sometimes
even if it is unpowered. Besides, can you assume that you will NEVER
forget and have them both on?

Get a switch or run one receiver through the other.

Kal
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Anonymous
August 20, 2005 4:37:01 PM

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

Richard Crowley wrote:

> "Larry Gagnon" wrote ...

>>can I connect the 2 amp outputs to these same speakers?

> Simplest would be a switch. If you really want to get fancy,
> you could wire a line-powered relay into the power strip of
> your home theatre system. Then when you power-on the
> HTS, it would transfer the speaker connections. With all the
> HTS accessories out there, I'd bet that somebody already
> makes/sells this kind of thing. If not, maybe I'll start! :-)

You mean there are people out there who haven't made one?

My HT amp has a 2-prong power outlet that powers a 2-way 4-pole relay.
You could also use a master-slave mains extension block so when you
switch on the HT amp it also switches on the relay and the subwoofer amp.

A 4 pole relay is best so it switches the amp's ground outlet as well.
I used a 12v relay and an old 12v psu, as it was what I had in the junk box.

--
Eiron

I have no spirit to play with you; your dearth of judgment renders you
tedious - Ben Jonson.
Anonymous
August 20, 2005 9:38:05 PM

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

"Larry Gagnon" <lagagnon@fakeuniserve.com> wrote in message
news:p an.2005.08.19.21.42.28.520907@fakeuniserve.com...
> I have a pair of Celestion Ditton speakers in the family room, currently
> connected to the B channel of my Yamaha RX-596 stereo receiver which is
> upstairs.
>
> I want to now use those same speakers as the front channel to a new home
> theatre system, powered by a Yamaha RXV-657. As long as both amps are not
> on at the same time, can I connect the 2 amp outputs to these same
> speakers? If not, is there some sort of easy inexpensive isolator I can
> use?

If the output of one amplifier ever gets connected to the output of the
other, you will very likely blow up one set of output transistors.

Instead, connect the speakers to the new home theater system, and run a
line-level cable from the tape out of the upstairs receiver to a suitable
input on the downstairs receiver. So the speakers are always driven by the
downstairs receiver; but that receiver can take as in input whatever the
upstairs receiver is playing.

Tim
!