7.1 setup with two fronts 4ohms the rest 8ohms

[petenad]

I am curious about this I am waiting for my Onkyo nr905 to come in and I've never had 5.1 or 7.1 I was looking at picking up the Axiom m80's and using them as fronts however they are showing 4ohms vs 8 on my others. Can I set the fronts for 4ohms setting with this receiver? And how will it affect the other speakers set at 8 or do they all have to be set either 8ohm or 4ohm and you don't get a choice? Anyway any insight would help thank you.

[Slec]

Originally Posted by petenad

I am curious about this I am waiting for my Onkyo nr905 to come in and I've never had 5.1 or 7.1 I was looking at picking up the Axiom m80's and using them as fronts however they are showing 4ohms vs 8 on my others. Can I set the fronts for 4ohms setting with this receiver? And how will it affect the other speakers set at 8 or do they all have to be set either 8ohm or 4ohm and you don't get a choice? Anyway any insight would help thank you.

looks like the 905 is certified for 4 ohm usage. I think the setup will be EXTREMELY important with this. I'm not sure how mixing 8ohm surrounds will act with 4ohm fronts. Check out Big Daddy's How To: on setup with an SPL meter. This will be critical if using speakers with different impedence.

ultimately I think this is something you would want to avoid... Let me see if I can get BigDaddy, Crackinhedz or some of the more knowledgeable guys over here.

edit: The impedance isn't really a setting. it's a rating that lets you know how much the speaker 'impedes' the power flow. Using the Onkyo 905, power output into 8 ohms is 140 watts. Power output into 4 ohms (1/2 the resistance), doubles the output to 280 watts per channel.

[Woody]

Originally Posted by Slec

looks like the 905 is certified for 4 ohm usage. I think the setup will be EXTREMELY important with this. I'm not sure how mixing 8ohm surrounds will act with 4ohm fronts. Check out Big Daddy's How To: on setup with an SPL meter. This will be critical if using speakers with different impedence.

ultimately I think this is something you would want to avoid... Let me see if I can get BigDaddy, Crackinhedz or some of the more knowledgeable guys over here.

edit: The impedance isn't really a setting. it's a rating that lets you know how much the speaker 'impedes' the power flow. Using the Onkyo 905, power output into 8 ohms is 140 watts. Power output into 4 ohms (1/2 the resistance), doubles the output to 280 watts per channel.

If you run Audyessy it will sound fine. Make sure you follow the manufacturer's recommendations on adequate ventilation for the unit. I personally don't recommend running 4 ohm speakers with any receiver, but it usually isnt a problem if you don't play it obnoxiously loud constantly.

On a side note, the 905 actually does not double in power when the impedance lowers, it does raise the load on the receiver and increase the power output, but it doesnt double the power.

Lastly, to be 100% honest, you should be using very similar speakers (ideally the same speaker if possible) for your main 3 channels for timbre matching if you can. A least speakers from the same manufacturer.

[musicman1999]

That is correct it would require a serious high current amp to double its power output into 4 ohm.

bill

[petenad]

Originally Posted by Woody

If you run Audyessy it will sound fine. Make sure you follow the manufacturer's recommendations on adequate ventilation for the unit. I personally don't recommend running 4 ohm speakers with any receiver, but it usually isnt a problem if you don't play it obnoxiously loud constantly.

On a side note, the 905 actually does not double in power when the impedance lowers, it does raise the load on the receiver and increase the power output, but it doesnt double the power.

Lastly, to be 100% honest, you should be using very similar speakers (ideally the same speaker if possible) for your main 3 channels for timbre matching if you can. A least speakers from the same manufacturer.

Ok on the ventilation as the receiver will be on a low stand on the top. I talked to axiom I can run them at 8ohms but not sure if that would affect the sound? I do listen to loud music when I have the place to myself. I ran a club with live bands and the average band was 108db to 115db and the loudest was April Wine at 121. Anyway I understand the damage caused by prolonged listening at those levels ......still like it loud though. My system is a miss mash of speakers. Paradigm M9's Paradigm cc290, Cerwin V sub cls12, Yamaha NS-10m's with frankensteined woofers in them, and 2 tower pioneers js-825Q's. Anyway these M80's look like something I want and just want to make sure what I have will make them preform. My budget is well a budget which I know thousands can be spent I just can't seem to win the lottery!

[richteer]

Originally Posted by petenad

I am curious about this I am waiting for my Onkyo nr905 to come in and I've never had 5.1 or 7.1 I was looking at picking up the Axiom m80's and using them as fronts however they are showing 4ohms vs 8 on my others. Can I set the fronts for 4ohms setting with this receiver? And how will it affect the other speakers set at 8 or do they all have to be set either 8ohm or 4ohm and you don't get a choice? Anyway any insight would help thank you.

Set your receiver to the 4 Ohm setting (i.e., the most difficult load). Hooking 8 Ohm speakers to a 4 Ohm tap will have no ill effect.

[David Craig]

Don't worry if the ohms don't match. Just read the manual for the receiver to see if it supports it.

At one time I had a set of 5 PSB speakers.

Center - 8 ohms
Front L & R - 4 ohm towers
Rear L & R - 6 ohm bookshelfs

It was fine with a Yamaha receiver that documented it could work with those combinations.

[Woody]

Originally Posted by richteer

Set your receiver to the 4 Ohm setting (i.e., the most difficult load). Hooking 8 Ohm speakers to a 4 Ohm tap will have no ill effect.

+1

If there is an impedance setting, setting them all to 4 should be ok.

This receiver should be ok with 4 ohm speakers, I just said that depending on the application I typically wouldn't do it.

Recommending the same 3 speakers for the front isnt a requirement, it is just recommended for surround sound.

To the OP, the 905 is a nice receiver and if you like the sound of the sound of the speakers, go for it. Who knows, maybe down the road you can even add a matching center if you want to.

[moviefan]

Originally Posted by petenad

I am curious about this I am waiting for my Onkyo nr905 to come in and I've never had 5.1 or 7.1 I was looking at picking up the Axiom m80's and using them as fronts however they are showing 4ohms vs 8 on my others. Can I set the fronts for 4ohms setting with this receiver? And how will it affect the other speakers set at 8 or do they all have to be set either 8ohm or 4ohm and you don't get a choice? Anyway any insight would help thank you.

WHY? Why does anyone anyone want to mix speakers like this?
Home theater can get complicated enough without introducing unnecessary variables!
There are dozens if brands with 8 ohm speakers ... get some of those!

[petenad]

Originally Posted by moviefan

WHY? Why does anyone anyone want to mix speakers like this?
Home theater can get complicated enough without introducing unnecessary variables!
There are dozens if brands with 8 ohm speakers ... get some of those!

To tell ya the truth I feel like it's an experiment and it's like one of everything should be good I've never had home theater before only ever 2 channel with A/B speakers and usually running all 4 at the same time. All was good until I introduced the sub and put the rears through the sub and well the receiver is dead so it was good timing I wanted a new setup anyway. Anyway what the worst that can happen? I'll have great fronts without breaking the bank. I was going to give my kids the Pioneer and the Yamaha's and the two older receivers I have and I'll replace those older ones with either paradigm or axiom not sure yet but don't forget the receiver can be used for 2 other zones hence I may use everything! I like options Lol. Anyway I really appreciate everyones point of view I'm glad I found this site.