Impedence switches necessary? (1 Viewer)

[ShaneH]

Seeing as how the yamaha rxv-420 65x5 has an impedence switch on the back, would you use it with 6 ohm psb speakers or say screw it and just leave it on the 8 ohm setting? Doesnt the impedence switch basically limit the power output of the receiver, meaning less volume , which means turning the volume up even more?

 

[Nicholas A. Gallegos]

Some speakers are designed to receive low-impedence loads like 4-ohms, for example. In that case, you need a receiver capable of driving that kind of load.
Late-model Yamaha receivers usually have two settings on their impedence switches: 6/8-ohm and 4-ohm. Lower impedence loads have less resistance and therefore the amplifier is allowed to pass more power. This is why a power rating on an amp or receiver is significantly higher when being driven at a lower impedence.
If you have 8-ohm (which the majority of speakers are), I'd keep your impedence selector at the default setting. They might not be capable of handling a 4-ohm load, potentially damaging your speakers if you do so.
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[Chuck Kent]

See this thread for more info...
http://www.hometheaterforum.com/uub/...ML/039643.html
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[DaleB]

If you want a current limiter circuit in your amplifier, the switch solution is fine.
I have used 3 different recievers over 15 years with the same 4 ohm speakers. All receivers were rated for a minimum of 6 ohms, I never had a problem. None of the receivers had impedance selectors.
My understanding is the biggest reason for the switch is so manufacturers can meet the industry standard whhch unrealistically requires an amp to run with a fixed load over a prescribed time.
I now run a receiver (NAD) that is rated for 4 ohms. My new 5.1 setup has 4 ohm speakers at L, C, and R, so I think this is the best solution.