HDTV Forum

Will my receiver, (Yamaha RX-V667) with 90wx7, total 630w drive my 5.1 surround speakers (Speakercraft AIM 7 Three's) at 6 ohms? Would this sound better than the default 8 ohms setting? I'm trying to learn a little bit more than just using the auto set-up.
Thanks!

Without looking up your owners manual it appears you are saying you have a choice to set the amp for 8 ohms or 6 ohms? If so, use the 6 ohm setting. This changes the feedback loop on the amp to better match that impedance.

I don't think your receiver will have an issue with your speakers!

As for auto setup, that is a different facet altogether. From the Cnet review...

http://reviews.cnet.com/av-receivers/ya ... ag=rvwBody

Yamaha's Parametric Room Acoustic Optimizer (YPAO) automatic speaker calibration system determines speaker sizes and volume levels, measures the distances from the speakers to the listener, sets the ideal subwoofer to speaker crossover point, and confirms that all of the speaker cables are correctly hooked up.

... unless you are saying the impedance selection is automated as well and part of this routine. If so, that is very interesting...

Both the receiver and the speakers can be set to 8, 6, or 4 ohms. The default on each is 8ohms. I am questioning if this a more of a marketing ploy or can I get actual performance out of changing the impedance to 6 or 4ohms. Also, if the 90wx7 is at what impedance setting 8 or 4?

The specs don't define an impedance for the power. What I do know is, like most, your receiver is not a power house and will not double power into 4 ohms. Such correct behavior is unfortunately rare. If it did, there would not be a selection for the output impedance. That is all about forcing an amp to do what it cannot really do with the least amount of error.

I did download the manual on the speakers. It says:
When adjusting the bass frequency, the impedance will be affected as indicated below. Be sure to stay within the impedance guidelines of the amplifier you will be using to power your system.
-3dB: The impedance is 8 ohms
0dB: The impedance is 6 ohms
+3dB: The impedance is 4 ohms

This is not an impedance adjustment, it is a passive crossover EQ adjustment and that always has an effect on impedance for the frequencies used on that driver. That's all they are trying to point out here.

Speaker Craft has no control over the variety of amplifier designs that may be used with their product. This is a CYA statement in case an owner has an amp having trouble with low impedances. BTW, the default setting is flat and that creates a 6 ohm impedance.

Based on real world experience I suggest you set the EQ for the speakers as you wish and let it go. Set your amp for the closest value, in this case 6 ohms. Another option would be setting the speaker controls for a flat response and let the receiver handle the EQ but as noted yours does not provide that feature. You could use the bass control instead.

Due to the way the amp operates he won't be melting it down. Now if the speakers were hitting 2-4 ohms this would be another discussion about getting a better amp.