Ohms. What's important, a per channel load or total amp load? (1 Viewer)

[Charles J P]

I have a question about impedance. I am toying with the idea of building an Adire Audio kit, and I did some posting over at HTT but one of my questions kind of went unanswered. If I build two 281s for mains and a sealed 281 center and kit 81s for surrounds, then I will have three 4 Ohm speakers and two 8 Ohm. My amp (Yamaha RX-V1200) is rated as being able to have two 4 Ohm mains and three (or 4 if you use the rear center channel) other 6 Ohm speakers connected at once. My question is, how bad will it be if I use three 4 Ohm speakers and the rest 8 Ohm? Will this be a similar load as all 6 Ohm speakers or two 4 Ohm and three 6 Ohm speakers? I dont want to burn up my amp, but I would think the Yamaha would have sufficient build quality to handle the load. Any ideas?

 

[Patrick Sun]

For the most part, in HT, the center speaker is getting most of the duty, so I think you'd be okay with hooking up three 4 ohm speakers and two 8 ohm speakers to the set-up.

 

[Charles J P]

Thanks Pat. I'm going to do some more research and check how the Yammie's power supply compares to others that are well known for being robust (like H/K) and see if they are at least close. Maybe Yamaha is just being conservative.

 

[Charles J P]

Well, after some prelimenary research, I did notice that Yamaha lists this as one of their features on the 1200...

LOW IMPEDANCE DRIVE CAPABILITY AND IMPEDANCE SWITCHING Yamaha's famed low impedance drive circuitry is included in this receiver so that it can handle virtually all loads and a wide variety of speakers. For further speaker matching, the amplifier can set for either 4-or 8-ohm speakers.

That is pretty non-specific considering the manuel cites specific impedance for various channels, but it does indicate that they do design the amps and power supplies are designed for somewhat challenging loads.

 

[Earl Simpson]

Charles! This opens a whole bag of worms I wish someone would clarify. How independent are the amps in these rcvrs? Are they totally discrete independent amps???? If they are, then each amp is tied to its own load. I don't know, and I wish some really smart person would jump in.

 

[Charles J P]

Well, I guess regardless of how truly independant they are, they get their power from the same power supply, as I've never seen a mid to high-end receiver with more than one power supply in it.

 

[Chris PC]

You know what? Unless you research some more and find out from someones experience, you'll never know until you try. I don't think that your proposed setup would destroy the amplifier, BUT you might have to switch the thing to 4 ohms which reduces performance, while eliminating the chance of blowing something. Thing is, it depends how you listen aswell. I listen to 6 ohms speakers all around hooked up to my receiver and its not a problem, but my main speakers are very efficient and so I rarely listen to them at their and the receiver/amp limits.

Add up all of the variables.

If the speakers you are building are less efficient than average and you listen to music very loud and the speakers will also have to reproduce the lower bass, then actually, I'd say you better be sure to switch the receiver to the 4 ohm setting or you'll risk damaging your amp. But if your speakers are very efficient and you're using a subwoofer for the bass, then I'd say you are likely to be ok without having to switch to the 4 ohm setting.

Consequently, my center channel speaker is 8 ohms while my others are 6 ohms. Don't know if that design was intended for a purpose or what.