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Two Amps One Pair Of Speakers

I've read posts here on audiogon stating not to connect two amplifiers to one pair of speakers because (as it was put) the stronger amp will win if they are both on at the same time. To me, this means that one amp will likely have a fuse blown - however, I wonder if this is even true at all and I am curious to know if anyone out there has connected two amps to one set of speakers.

Now - I am not talking about bi-amping from a single source. I am talking about two separate systems connected to a single pair of speakers.

Of course having amps sending signal at the same time wouldn't make for good listening but even if they were, wouldn't the speakers just play both sources? Power flows from + ...> - so the positive output of both amps would flow through the speakers into the - of both amps wouldn't it??

Perhaps its just me but that seems more likely than something blowing up... but then again, what do I know?

Even in cases where someone bi-amps in a single system, there are two amps driving the speaker which in many/most cases is connected internally via crossover - regardless of how many binding posts are on the speaker. This is tried and true - lots of people bi-amp but why would it not cause damage but connecting two amps from different sources cause a problem?

Sorry for the rant, I hope someone can shed some technical knowledge on this.
bwhite
pmc's avatar
pmc
36 posts
 
As TW1 put it, Electricity will travel the path of least resistance, ence it will go to the outputs of the other amp.
Output stages can't deal with that, the output will be complitly burn, output transistor are directional they don't work bidirectional, they will blow. unless the other
amp has some kind of output protection circuit that will prevent the signal from entering the output circuit.

P.S. I don't have a EE but I have an AS on Electrical Engineering technology.

So please don't try it. Or you will be sorry you did.
bwhite OP
807 posts
 
Hey - now that makes sense! Thanks guys for your input on this topic. I dislike the idea of a switch box but I certainly dislike the idea of a damaged amplifier more.
hpshps
66 posts
 
Just for the record, there are amplifiers on the market that you can run in bridged mode (a topology that connects two amps to the same speaker with one amp serving the plus pole, the other the minus pole and a connection between the amps).

I believe the Pass X1000 falls into that category. Accuphase has or had a such amp as well (I think it was called the X2000). These amps were designed to be used in that setup. In bridged mode, these behemoths produce a lot more power (and cost a lot more, too).
kr4ef94
208 posts
 
Many amps can do this. Bridged, common ground amps have their output stages, in effect, connected in series, not parallel as the OP suggested.
hpshps
66 posts
 
kr4@nyu.edu, thanks for the correction. Should have looked it up before posting.
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