# 9.2 theater system opinions



## rf5000 (Mar 13, 2010)

Hey All,

Building a 9.2 theater system. I have (7) Definitive Technology RLS II in walls that i was using for my mains, center, surround side and surround back. I have (2) Definitive Technology RLS III in walls using for my front highs. For processing, I was going to use my Onkyo tx-nr5007 9.2 receiver.

I have a question about amplification. Since I have read that the rear 4 channels and 2 front high channels don't use much wattage and only periodically, would those be fine to run off the receiver? Then just get a 200 or 250 x 3 amplifier for the mains and center? I'm undecided. The Onkyo flagship receiver boasts a Massive Toroidal transformer for High current drive and 4 Independent Power Supplys, but in the same specifications it lists 145 watts per channel with two channels driven?? So is that to say if all four rear surrounds and two high fronts are driven at the same time, it would be way less then 145 watts each?

I know it would be better to by one or two more seperate amplifiers for the rears and front highs, but will I notice that much of a difference? The speakers are each rated at like 10 to 350 watts. Also, I figured 250 watts from a seperate 3 channel amplifier would be okay for the fronts, or maybe I'm wrong there too? Should I be trying to reach that 350 watt mark? Please help with some input. Thanks.


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## Owen Bartley (Oct 18, 2006)

Let me get my 2 cents in here to fill the time until someone more knowledgeable provides an answer. I think you're going about it the right way, and can definitely run your surrounds from the receiver. You're right about the rear channels not usually being very demanding (at least for most movies, dedicated multichannel audio would be a different story), and in my experience your Onkyo will provide more than enough power, especially if your room and speakers are set up properly. I think the height effect channels are safe to run from the Onkyo as well.

If you have the means, a dedicated 3-ch amp for the front stage would be an asset, especially if you want to get the most from your speakers. Plus, you can always add another amp for the surrounds if you feel you need to. Those Def Tech's look like they can handle a good deal of power, but at 92dB sensitivity they shouldn't be too difficult to drive to reasonable levels either. I'd take a look at maybe the Emotiva XPA-3 (200w x 3 for $699) or the XPA-5 (200w x 5 for $899). you could start with either amp, and then add the other if you feel you need it one day. I don't think you need to shoot for 300w, but I wouldn't discourage it if there's something you have in mind. More (clean) power is pretty much always better, as long as it is judiciously applied.

In short, maybe give it a try with just the Onkyo if you have a budget and the funds could be better used on a larger sub or room treatment. Add a 3 ch amp if the budget allows to get a little more oomph from the front stage. If you want to go all-out, add another amp to drive the rest of the surrounds and know that you will never run short on power.

_Edit: Oh, and yes, usually if an amp is rated X watts at 2-ch driven, it will be less than X watts with all channels driven, regardless of how many power supplies it has._


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## Sir Terrence (Jun 8, 2006)

There is no such thing as a 9.2 system. There is a 9.1 system with two subwoofers, but to the right of that dot should describe how many discrete channels are in the system, not how many subwoofers are producing a single channel. 

I know 9.2 sounds impressive, but it is also inaccurate.



> So is that to say if all four rear surrounds and two high fronts are driven at the same time, it would be way less then 145 watts each?


If this receiver operates like others, you can pretty much guarantee it will output less power when all channels are driven.


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## rf5000 (Mar 13, 2010)

Okay, 

So what do you recommend? Do you think putting a separate amplifier or two to these surrounds or front highs will make a huge noticable difference or not? Say I push 150 to 200 watts to each of these speakers instead of running them off the receiver, will it be hugely noticeable or just slight improvements?


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## Sir Terrence (Jun 8, 2006)

rf5000 said:


> Okay,
> 
> So what do you recommend? Do you think putting a separate amplifier or two to these surrounds or front highs will make a huge noticable difference or not? Say I push 150 to 200 watts to each of these speakers instead of running them off the receiver, will it be hugely noticeable or just slight improvements?


I am rather stiff necked about this, but I recommended using separate stereo amps for each of those channels. I am not sure it will produce an audible improvement, but it ensures that these channels won't run out of gas before the main channels do. I personally don't like using a receivers amps, and even when a receiver is doing the processing I always use outboard amplification.


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## Owen Bartley (Oct 18, 2006)

Sir Terrence is absolutely right, the best case scenario would be outboard amplification for all channels. I would say again that it is really a function of your budget. If the budget allows for 9 channels of amplification on top of the rest of the gear, you can't go wrong. However, if you have a certain amount to work with and need to be creative about it, I'd focus on the 3 main speakers at the front, and add amps for the rest of the channels later. Unless you plan to listen at very loud volumes I doubt you will hear a difference with more power to the surrounds in most material.

Sir Terrence, I'll defer here to your expertise, but I would guess that the front height channels really don't see much material for a few reasons. 1) there is no "front height" channel in the studio mix, and it is being derived from the receiver's processing, 2) if there was a lot of content coming from these speakers it would probably cause interference with the main front stage, and 3) a proper mix and a good setup should really be able to convey height without those extra speakers. In the spirit of full disclosure, I haven't experienced a 9.1 setup yet, although I do plan to build it into my next system just in case I do like it. They almost certainly won't have dedicated amplification, but that will be due to budget constraints.


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## Sir Terrence (Jun 8, 2006)

Owen Bartley said:


> Sir Terrence, I'll defer here to your expertise, but I would guess that the front height channels really don't see much material for a few reasons. 1) there is no "front height" channel in the studio mix, and it is being derived from the receiver's processing, 2) if there was a lot of content coming from these speakers it would probably cause interference with the main front stage, and 3) a proper mix and a good setup should really be able to convey height without those extra speakers. In the spirit of full disclosure, I haven't experienced a 9.1 setup yet, although I do plan to build it into my next system just in case I do like it. They almost certainly won't have dedicated amplification, but that will be due to budget constraints.


I REALLY agree with statement number three big time. 

I had two experiences with 9.1 and 10.2. I heard Tomlinson Holmann 10.2 system while in his class in college(he was a great professor by the way). The mix I heard was done especially for this system, and it was EXTREMELY effective. With the lights off, I felt like a train had just blown by me, and a plane flew over my head really low. 

I heard Dolby's PLz at Dolby labs, and I was not as impressed as I was with with the 10.2 system. I found the demonstration very inconsistent, with some effects coming off impressively, and others almost no effect at all. Mono material sounded echoey, and some spatial effects were not placed correctly. I brought my own mix of which I was very familiar with, so I had a good idea of what it sounds like. Multichannel music really threw a wrench in the works, and produced the most inconsistent results IMO. 

Personally(and not knocking somebody else's choices) I think both DSX and PLz are gimmicks. Having a DSP chip making decisions on where to point effects will produce unexpected results. It is more complicated to set up, and that along with the inconsistency makes it not worth it to me at least.

If we created mixes for that set up, I could recommended it easily based on my experience with the 10.2 system. But the idea of a 6 channel mix being blown up to 12 channels by a DSP chip is disturbing to me.:nono:


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## Andre (Feb 15, 2010)

I have always advocated experimention, this is a hobby. Plug in your reciever only and have a listen, borrow an amp (friend, store with return policy) and hook it up to the power 3, listen again, did it make a difference? If so, is the difference worth the money? 

I would also ask the question of the reciever is if I preamp out does it actually disable those amps giving the power supplies voltage to the others.


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## tonyvdb (Sep 5, 2007)

In the end it all comes down to what receiver your going to use as there are some mid to higher end receiver that do have plenty of good solid power and outboard amplification on all channels is unnecessary and over kill. But I always recommend going with at least a two channel amp on the front left and right channels. Its not the amps that run out of steam its the power supply in the receiver that cant deliver the juice to power the amps at the same time.
the Onkyo 5007 is one of those receivers that does have a great amplification section.


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## Owen Bartley (Oct 18, 2006)

Sir Terrence said:


> I had two experiences with 9.1 and 10.2. I heard Tomlinson Holmann 10.2 system while in his class in college(he was a great professor by the way). The mix I heard was done especially for this system, and it was EXTREMELY effective. With the lights off, I felt like a train had just blown by me, and a plane flew over my head really low.


That must have been amazing! You're a lucky guy, Sir T, to be able to work in the field, and to have had such great experiences with pioneers in the industry.


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## Tufelhundin (Jan 25, 2010)

Very interesting read thus far.

To the OP, here are my plans for a future setup...may be something you may want to consider as well....or not.

I am planning on setting up a 9.1 "height" system, at this time I am using a TX-NR1007 but I intend on getting at least a 5 channel external amp, I'm actually pining for a A-965, even though its not very powerful at 8 ohms which my speaker are at this time, I intend on getting SVS MTS speakers in the future and they are rated at 4 ohms and the A-965 from what I have heard is made for the lower ohm speakers....having the 2 extra channels is a bonus.

The reason I at least want to get a 5 channel amp is because if I am not happy with the height/wide setup I will have the amp for my 5.1 setup which consist of 4 x RS450 and Bigfoot....I like SACD and DVDA hence the reason for the setup.


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## Dwight Angus (Dec 17, 2007)

I also plan on setting up a 9.1 height system and will add a 5 channel external amp plus a 9.2 avr. I will drive the surrounds with the external 5 amp and use the avr to drive the height channels. When I added a 3 channel amp to drive my MTS mains plus MCS it made a huge improvement. Its like the LCR came alive . So that is why I will drive the side and back surrounds with an external amp. Perhaps overkill but for me a much better sound.


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