A/V Receiver Impedance Selector Switch

[Trebdp83]

It’s still a heat switch. When running 4 ohm speakers, set it at 6 ohm or higher in winter and back to 4 ohm in summer.

 

[PENG]

Well I was talking about that...
Low Impedance (Z) Mode .... loudspeakers rated below 8-ohms. (This mode limits the output voltage, and therefore the maximum current any given speaker can demand of it).
High Impedance (Z) Mode ... loudspeakers rated at 6-ohms or higher....

And I suppose that would be right...
Low Impedance (Z) Mode .... loudspeakers rated below 6-ohms. (This mode limits the output voltage, and therefore the maximum current any given speaker can demand of it).
High Impedance (Z) Mode ... loudspeakers rated at 8-ohms or higher....

That's splitting hairs though.. The nominal impedance figures should be used as a general guide/approximation. For more details one would have to look at the impedance vs frequency curve. For amplifiers, owner's manual, typically simply go with 4, 6 and 8 ohms only when refer to their output ratings and/or impedance selector settings.

 

[dlaloum]

Both my Onkyo TX-SR876 and Integra DTR 70.4 had the "6ohm+ / 4ohm" switch.

My speakers drop down below 2 ohm at both the high end and at the woofer/midrange crossover.

Under all circumstances, the amps sounded best on the 6ohm+ setting - it may have run a bit warmer - but the sound was definitely better/cleaner, and it never seemed to drive the amps into their nanny mode (if pushed too hard they self protect by automatically placing themselves in the 4 ohm mode).

Given my experience with speakers providing a difficult load to the amp, I cannot fathom why they bother with that switch - all it ever does, is degrade the sound... with the sort of low impedance speakers that match the 4 ohm tag, it neither protects the receiver, nor improves the sound.

P.S. I even ran the Receivers in bridged mode for front L/R, which effectively meant the amps were seeing loads below 1 ohm (it halves the effective impedance!) - and still the amps ran fine. (but they sounded better in standard mode, rather than in bridged mode - no surprises... the sub 1ohm load pushed the amps a bit too hard!)

 

[lovinthehd]

Both my Onkyo TX-SR876 and Integra DTR 70.4 had the "6ohm+ / 4ohm" switch.

My speakers drop down below 2 ohm at both the high end and at the woofer/midrange crossover.

Under all circumstances, the amps sounded best on the 6ohm+ setting - it may have run a bit warmer - but the sound was definitely better/cleaner, and it never seemed to drive the amps into their nanny mode (if pushed too hard they self protect by automatically placing themselves in the 4 ohm mode).

Given my experience with speakers providing a difficult load to the amp, I cannot fathom why they bother with that switch - all it ever does, is degrade the sound... with the sort of low impedance speakers that match the 4 ohm tag, it neither protects the receiver, nor improves the sound.

P.S. I even ran the Receivers in bridged mode for front L/R, which effectively meant the amps were seeing loads below 1 ohm (it halves the effective impedance!) - and still the amps ran fine. (but they sounded better in standard mode, rather than in bridged mode - no surprises... the sub 1ohm load pushed the amps a bit too hard!)

The switch isn't about performance, it's about regulatory compliance....