Yamaha RX-V1500 (minimum impedance setting)


Standard Member

I own a Yamaha RX-V1500 AV Receiver/Amplifier. I'm using it with B&W CM1 speakers (rated at 8 ohm - minimum 5.1 ohm and 84dB sensitivity).

I've noticed quite a difference between setting the minimum impedance on the RX-V1500, between min 6 ohm and min 8 ohm. But I can't find any information about what exactly this setting does to the way the RX-V1500 performs.

If I set it to min 6 ohm, the speakers produce deeper low frequencies (bass) and maybe a little more ressonance. At 8 ohm, the sound is a little more clear and bass is less present.

Why does this happen? What is the best, most effective setting I should use on the Yamaha receiver, to drive these speakers?

I found some information about this at http://www.audioholics.com (even if the article focus on the Yamaha RX-V4600), where the reviewer says:

"Editorial Note about the Impedance Selector Switch

I recommend the "Minimum 8-ohms" setting even for 4-ohm speakers of moderate efficiency (>89dB SPL). Yamaha includes a" 6-ohm" setting to satisfy UL heat dissipation requirements when driving 4-ohm loads, as well as easing consumer concerns about driving low impedance loads. These switches step down voltage feed to the power sections which can limit dynamics and overall fidelity. My advice is to keep the switch set to "Minimum 8-ohms" regardless of the impedance of your speakers and ensure proper ventilation of the Receiver. To illustrate this point further, I have tabulated my measured differences between the 8-ohm and 6-ohm setting for driving 8-ohm and 4-ohm loads.

8 Ohm Setting

134wpc into an 8-ohm load @ 0.1% THD
210wpc into a 4-ohm load @ 0.1% THD

6 Ohm Setting

95wpc into an 8-ohm load @ 0.1% THD
180wpc into a 4-ohm load @ 0.1% THD"

Does this make sense? Is the 6 ohm setting just limiting the performance of the amplifier?

Please help me understand the impact of this setting.

Thank you very much!

Top Bottom