On Dec 22, 12:02*am, David Nebenzahl wrote:
On 12/21/2010 7:36 PM Jeff Thies spake thus:





On 12/21/2010 2:25 PM, Sam Takoy wrote:

This is offtopic, but related to home improvement and this is where I
get my best information.

I want to connect my ipod - amp - speaker selector - speakers

My amp is 4 Ohms (Pyle PTAU45)

My speakers are 4 Ohms (Pyle PWRC51)

But the speaker selector that I want to buy (Pyle PSS6) says "with
speakers systems that are 8 Ohms minimum".

We aren't matching impedances, what we are doing is making sure that the
amp doesn't blow up! (Impedance matching is tube stuff)

Odd thing to say: actually, transistor amps care about impedance
matching too. In fact, it may be even more important with solid state,
as there's no output transformer as in a tube amp to isolate the load
from the final stage. Very easy to smoke transistors (or to cause the
angry gods to activate the shutdown circuit or blowenfusen). In
transistor amps, speakers are (more or less) directly coupled to the
output stage, usually with a large capacitor to block DC.

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Agreed, impedance matching applies all over the place.

As others have noted the most likely reason fo rthe 8 ohm minimum is
that the selector switch probably supports turning on two pairs of
speakers. And it likely does it by connectng them in parallel. That
results in a 2 ohm load if you have 4 ohm speakers which some amps
can't handle. But a lot of newer amps can so check your amp manual.
Or don't turn two sets on at the same time.