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5 channel amp or 2 channel + 3 channel

post #1 of 28
6/24/09 at 3:54pm
Thread Starter 
I'm looking to put together a multi-channel system to add surround-sound to movies / TV via cable box and DVDs. But I've run into a dilemma and need a little help deciding what the best amp configuration would be for my system.

Presently I only have a two channel system for movies and TV but I also enjoy listening to two-channel CD and FM stereo on a regular basis. I currently have a Parasound amp and preamp (preamp has a HT bypass). So when I decide to add a multichannel pre/pro and a multi-channel amp, I was wondering if it might be better to set up my system with two separate amps (2 + 3 channel) rather than a single 5-channel amp. The reason being is with two amps, I could have it configured to where my two channel amp triggers on when I power on either my FM tuner or CD player, but have both amps trigger on when I power on my cable box or DVD player.

Does that sound like it makes sense or doesn't it really matter? Does it make any difference if I'm listening to FM radio or listening to a CD through a 5-channel amp vs a 2-channel amp? The other 3 channels aren't receiving a signal so they won't be sending out any power, correct? In other words, is there any real benefit in setting up my system with a two-channel and three-channel amp vs a single 5-channel amp?
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post #2 of 28
6/24/09 at 4:19pm
A good multi channel preamp pro will let you listen in 2.0 or 5.1 channel - the amp could care less - it simply plays what the preamp pro tells it to play.

A good 1 amp solution would be the Emotiva XPA-5. Or just add an XPA-3 to your current 2 channel amp for 5 channels.

The UMC-1 - soon to be released by Emotiva - might be something to look at for a multi channel preamp. I'm considering one - currently I have the Onkyo SC885 which I find quite adequate.
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post #3 of 28
6/24/09 at 4:56pm
Thread Starter 
Thanks for the reply. I should have mentioned that the 2-channel amp I'm using at the moment is not going to be used in my multi-channel setup. I already have a use for it in another application. So please don't consider it when replying my original post/questions.

You say that "the amp could care less." So I take it then that a 5-channel amp would not be utilizing the other three channels at all when receiving a two-channel signal, and in reality, is merely a two channel amp when receiving two-channel signal. In other words, the three channels not receiving a signal are idle and thus not being used at all with no components from those idle channels being unnecessarily powered during 2.0 channel usage, correct?
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post #4 of 28
6/24/09 at 5:15pm
Quote:
Originally Posted by RetRoe View Post

I could have it configured to where my two channel amp triggers on when I power on either my FM tuner or CD player, but have both amps trigger on when I power on my cable box or DVD player.

This is exactly what I do currently. The trigger for multichannel also triggers on the amps for my subs and tactile effects. One 5 channel amp will cost less than a similar spec'd 2 + 3. However I went with the 2 + 3. Actually I went with 2 + 3 + 2 + 2 + 2 + 1 + 1. The first 7 channels are for the the seven in 7.1. The next two 2 channels are for four passive subs. The last two 1's are Buttkicker amps.

- if I wanted to upgrade 2 channels for say more power, I could do so without changing the whole amp
- similar to above, I could buy the same amp as my L & R and bridge the two amps for more power, experiment with biamping (active!) etc
-I like to have any equipment not being used for 2 ch listening turned off to lower the noise floor every so slightly.
- the power amps for the subs have the ability to be daisy chained in stereo mode or parallel mode. Very flexible for experimenting (stereo .1, mono .1 combination of etc).
- I have more placement options with two amps
- generally I can run more power with the two amps. There is only so much a 15A 120V outlet can supply for 5 channels unless the 5 ch amp has a 20A connection and you have 20A outlets.
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post #5 of 28
6/24/09 at 5:31pm
Quote:
Originally Posted by RetRoe View Post

You say that "the amp could care less." So I take it then that a 5-channel amp would not be utilizing the other three channels at all when receiving a two-channel signal, and in reality, is merely a two channel amp when receiving two-channel signal. In other words, the three channels not receiving a signal are idle and thus not being used at all with no components from those idle channels being unnecessarily powered during 2.0 channel usage, correct?

Yes is the answer to your question. I have a 7 channel in action and only use 3. The balance (4) are not being used. Knucklehead is correct in his comment about the amp will only do what your processor/receiver/line stage tells it to do with the signal after connected to X amount of channels.
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post #6 of 28
6/24/09 at 5:32pm
Quote:
Originally Posted by RetRoe View Post


You say that "the amp could care less." So I take it then that a 5-channel amp would not be utilizing the other three channels at all when receiving a two-channel signal, and in reality, is merely a two channel amp when receiving two-channel signal. In other words, the three channels not receiving a signal are idle and thus not being used at all with no components from those idle channels being unnecessarily powered during 2.0 channel usage, correct?

If your preamp processor is playing 2 channel music - and most can do this reasonably well - you will only get 2 channels of input to the amp - hence my "the amp could care less" remark.

Or is that couldn't care less?

Anyway with 3 channels being idle you get 2 channels of music - and usually - depending on the amp - more power for the music.

I have an Emotiva UPA-7 - 7 channel amp which is rated for 125wpc 7 channels driven. With 4 ohm speakers and 2 channels driven it is rated for 180wpc into 7 channels - but I get 280wpc into my main speakers in 2 channel mode. The power not being used for the other 5 channels is available to the 2 active channels. Not all of it, but enough to make a big difference, 100wpc in fact.

Good enough for my 2 channel listening pleasure.
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post #7 of 28
6/24/09 at 6:56pm
Thread Starter 
Quote:
Originally Posted by Mozvz View Post

Yes is the answer to your question. I have a 7 channel in action and only use 3. The balance (4) are not being used. Knucklehead is correct in his comment about the amp will only do what your processor/receiver/line stage tells it to do with the signal after connected to X amount of channels.

That's exactly what I was after. EC certainly has a lot of flexibility with his system. But if I'm going to get pretty much the same performance from equally powered separate 2-channel and 3-channel amps as I am a 5-channel, then it makes sense to me to save money by going with a single 5-channel unit. I would ideally like separate amps, but like most of you, I'm on a budget and just want a nice sounding system, i.e., it doesn't need to be reference quality; just decent quality and enjoyable listening is what I'm after.

By the way, I aint really looking to add a sub at first but what's the deal with these passive subs and a separate amps? Since I've described what I'm going after (sound-wise) would a powered sub be sufficient when I'm ready to add one or is it a quite noticeable difference going with a passive sub and a dedicated amp, such as EC has?
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post #8 of 28
6/24/09 at 7:15pm
Quote:
Originally Posted by RetRoe View Post

That's exactly what I was after. EC certainly has a lot of flexibility with his system. But if I'm going to get pretty much the same performance from equally powered separate 2-channel and 3-channel amps as I am a 5-channel, then it makes sense to me to save money by going with a single 5-channel unit. I would ideally like separate amps, but like most of you, I'm on a budget and just want a nice sounding system, i.e., it doesn't need to be reference quality; just decent quality and enjoyable listening is what I'm after.

By the way, I aint really looking to add a sub at first but what's the deal with these passive subs and a separate amps? Since I've described what I'm going after (sound-wise) would a powered sub be sufficient when I'm ready to add one or is it a quite noticeable difference going with a passive sub and a dedicated amp, such as EC has?

One mans opinion: I've found that a two channel amp tends to provide better 2 channel music playback then a multi channel amp. I've used 5 channel amps (Sherbourn and Parasound) and a numerous 7 channel amps (Sim Titan/Sherbourn/Gemstone Blue Diamond) in the past and somewhat recently added a 2 channel amp (Pass) and found the 2 channel playback is improved. However, with that in mind, I feel it's something you need to prove to yourself by either testing on your own, or soliciting others opinions. The nice item about a multi channel amp is it's an all in one package that takes less rack or floor space and does an excellent job if system synergy matches. The easiest solution is implement a multi channel and you will probably be a happy camper whatever manufacturer you choose.

As far as the sub, I've never used a passive sub with external amplification. It would seem after being involved on audio forums for quite some time, most people use the one box solution of sub and amp enclosed into one container. Again, it's a simplistic and easy answer to add LFE and bass enhancement (reads like a Viagra commercial) without the potential inconvenience of separate amp and sub woofer. To each his own in each aforementioned situation.
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post #9 of 28
6/24/09 at 7:57pm
Quote:
Originally Posted by RetRoe View Post

By the way, I aint really looking to add a sub at first but what's the deal with these passive subs and a separate amps? Since I've described what I'm going after (sound-wise) would a powered sub be sufficient when I'm ready to add one or is it a quite noticeable difference going with a passive sub and a dedicated amp, such as EC has?

Generally speaking, passive subs are the exception not the rule unless you are a DIYer. When I bought my subs (SVS Ultras) they did not have an active version. Even if they did, I would still go with the passives given the choice for various reasons:

- placement ease (don't need an outlet nearby)
- I can use balanced inputs (at the time, only the upper echelon subs had balanced input connectors)
- I have a choice of amps: in my case I use two Crown K1's. In addition to the flexibility I mentioned in my first post. These amps are beasts at driving difficult loads at high volumes.
- I use external EQ (SMS-1) and so adjustments are easier. If your passive subs are ported, you want an electronic low pass cut off before the amp if one is not built in the amp.

For the record, I do use a powered sub (Velodyne HGS-12x) with an outboard active crossover (Bryston 10B) for 2 ch for listening. For me, I value flexibility and don't mind paying a "small" premium for it. If budget is a concern then for sure a 5 ch amp with a traditional powered sub is the way to go. There are many good powered subs out there at various price points.
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post #10 of 28
6/24/09 at 8:13pm
Quote:


Mozvz;
One mans opinion: I've found that a two channel amp tends to provide better 2 channel music playback then a multi channel amp.

Are you saying that by simply having more channels in one box that it affects the rest of the amp?
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post #11 of 28
6/24/09 at 8:31pm
Thread Starter 
Hi EC, your system (from what you've described) sounds amazing. I also viewed your HT pics and you look to have an awesome setup (looks like you should charge admission). I only wish someday to have something as cool, but for now I'm kind of just sticking my toe into the water.

I currently have a pretty nice TV (Samsung HL67A750 67" LED DLP) and want to add a decent surround-sound system to it while still being able to play stereo music via CD or FM radio. My universal disc player is a Lexicon RT-20 so I'm looking to add a nice pre-pro and a 5-channel amp. Just wasn't sure if I should split up the amps (2 + 3) or a single 5-channel amp.

Everything you've said makes a lot of sense to me and the flexibility would be a nice advantage. But I'm no where near your level yet and from what others have stated and your comments, I think it might be simpler for me to go with a 5-channel. I really liked the idea of a dedicated 2-channel amp for stereo. But if I'm not going to notice much difference and a 5-channel amp is going to act (for all intensive purposes) as a 2-channel when playing CDs or FM listening then it serves my needs very well.

Now my only choice is whether to go with a new Emotiva XPA-5 or something used from off eBay or Audiogon like a B&K Reference 200.5 or a used Rotel RB-1095. Then I'm wondering if 125 wpc amps would be all I need. Too bad Emotiva doesn't make a 125 wpc version of their XPA-5 the same way Rotel and B&K do with their RB and Reference series, respectively. Decisions, decisions.
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post #12 of 28
6/24/09 at 8:41pm
Quote:
Originally Posted by RetRoe View Post

Hi EC, your system (from what you've described) sounds amazing. I also viewed your HT pics and you look to have an awesome setup (looks like you should charge admission). I only wish someday to have something as cool, but for now I'm kind of just sticking my toe into the water.

I currently have a pretty nice TV (Samsung HL67A750 67" LED DLP) and want to add a decent surround-sound system to it while still being able to play stereo music via CD or FM radio. My universal disc player is a Lexicon RT-20 so I'm looking to add a nice pre-pro and a 5-channel amp. Just wasn't sure if I should split up the amps (2 + 3) or a single 5-channel amp.

Everything you've said makes a lot of sense to me and the flexibility would be a nice advantage. But I'm no where near your level yet and from what others have stated and your comments, I think it might be simpler for me to go with a 5-channel. I really liked the idea of a dedicated 2-channel amp for stereo. But if I'm not going to notice much difference and a 5-channel amp is going to act (for all intensive purposes) as a 2-channel when playing CDs or FM listening then it serves my needs very well.

Now my only choice is whether to go with a new Emotiva XPA-5 or something used from off eBay or Audiogon like a B&K Reference 200.5 or a used Rotel RB-1095. Then I'm wondering if 125 wpc amps would be all I need. Too bad Emotiva doesn't make a 125 wpc version of their XPA-5 the same way Rotel and B&K do with their RB and Reference series, respectively. Decisions, decisions.

What speakers are you using and how loud do you usually like to listen?
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post #13 of 28
6/24/09 at 9:12pm
Thread Starter 
Quote:
Originally Posted by Planescape View Post

What speakers are you using and how loud do you usually like to listen?

My fronts are a pair of Paradigm Export Monitors which are rather large bookshelf style speakers. No longer in production and difficult to find info on so I emailed Paradigm and the sent me the following specs for my speakers:

Design: 2 driver, 2-way bass reflex, Quasi-3rd order resistive port

Crossover: 4th order electro/acoustic at 1.6kHz

Driver Complement: one 25mm(1") Q25/XPT high-frequency driver, one 210mm(8") Q210/XPT bass/midrange driver

Performance: Low Frequency Extension 28Hz(DIN)

Frequency Response:
On Axis 0 degrees +/-2dB from 45Hz-20kHz
Off Axis 30 degrees +/-2dB from 45Hz-15kHz

Sensitivity-Room/Anechoic: 89dB/86dB

Suitable Amplifier Power Range: 15-150 watts

Maximum Input Power: 100 watts

Nominal/Minimum Impedance: 8 ohms/4 ohms

-----------------------------------------------------------

I don't have a center channel speaker yet but am leaning towards a Paradigm CC-590 as Paradigm said that their studio series centers would match my Export Monitors quite nicely. For satellites I only have a pair of Polk RT25 bookshelf speakers I plan to use. As I've stated I don't plan on implementing a sub right away.

As far as listening levels go for music (CD, FM radio) I tend to play it at moderate levels with occasionally cranking favorite tunes. Movies and TV are moderate levels as well. I currently have a Parasound Zamp v.3 amp running my sound and its only 45 wpc and does a pretty fine job with movies but its limitations are clearly defined when wanting to turn up the volume while listening to music.
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post #14 of 28
6/24/09 at 9:44pm
Quote:
Originally Posted by RetRoe View Post

Too bad Emotiva doesn't make a 125 wpc version of their XPA-5 the same way Rotel and B&K do with their RB and Reference series, respectively. Decisions, decisions.

Emo does have the UPA-7, it's 125 watt x 7. It's not a lot less than the XPA-5 ($700 vs $800), but would give you somewhat more than that if you were only using 5 channels and flexibility to go to 7 channel in the future.
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post #15 of 28
6/24/09 at 9:58pm
Thread Starter 
It's my understanding that the XPA is in a different league compared to their UPA series amps. Plus I don't really see a 7-channel system anytime soon but correct me if I'm wrong; won't 7-channel source material sound just fine on a 5.1 system with the four surround channels being down-mixed into two?
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post #16 of 28
6/25/09 at 6:14am
Quote:
Originally Posted by RetRoe View Post

It's my understanding that the XPA is in a different league compared to their UPA series amps. Plus I don't really see a 7-channel system anytime soon but correct me if I'm wrong; won't 7-channel source material sound just fine on a 5.1 system with the four surround channels being down-mixed into two?

Look. I'm one of "those people" who think the only real difference between a 125 wpc amp and a 200 wpc amp, is 75 wpc.

There's nobody I can recall seeing in the 120+ pages of the Emo thread who had an UPA vs XPA that thought one "sounded" better than the other. Knucklehead90 has always spoken very highly of his UPA-7.

The people who say things like "they're in a different league" IME are the people who believe that if your amp doesn't have the magic pixie fairy dust that triples or quadruples the price of the amp, then it can't sound as good as their amp.

Typically they are also not people who have actually done a REAL Double Blind Test comparison, if they've even heard both units.

First AFAIK there is very little material that is a true 7 channel surround mix. 95% of what's out there is really just a 5 channel mix. I think there's a thread on this in the Blu ray software forum (WARNING : Most of the people in there would not be happy with the image quality of a pristine 70 mm print being run on George Lucas's personal theater setup).

In any case, I'm quite certain that you are loosing far more from not having a center channel than you would be from the additional 2 surrounds.
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post #17 of 28
6/25/09 at 8:02am
Thread Starter 
Quote:
Originally Posted by TPnBobcats View Post

Look. I'm one of "those people" who think the only real difference between a 125 wpc amp and a 200 wpc amp, is 75 wpc.

The people who say things like "they're in a different league" IME are the people who believe that if your amp doesn't have the magic pixie fairy dust that triples or quadruples the price of the amp, then it can't sound as good as their amp.

Well look, I friggin want and need that "magic pixie fairy dust" that triples or quadruples the price and places the amp in a different league.

Seriously, I get your point and I was just reiterating what I've read in the past (please don't ask for sources as its been a while and I have totally forgotten where I seen it stated but my guess is I read it on Emo's own forum). I've also read in these forums of people who look down on with disdain at Emo gear and call Rotel the "poorman's separates". It's overwhelming sometimes all the conflicting opinions.

Quote:
Originally Posted by TPnBobcats View Post

In any case, I'm quite certain that you are loosing far more from not having a center channel than you would be from the additional 2 surrounds.

I totally am planning on adding a center channel speaker (leaning towards a Paradigm CC-590) to my system once i finally get a multi-channel amp and pre-pro. I've been watching for a sale on the Emo amps but I think I'm going to wait awhile on the new UMC-1 until I see that it has any potential bugs worked out. That said I've been looking at older pre-pro units on the used market, namely the B&K Reference 50 S2 or, if I can find a good deal, a Lexicon unit.
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post #18 of 28
6/25/09 at 8:20am
Quote:
Originally Posted by RetRoe View Post

Seriously, I get your point and I was just reiterating what I've read in the past (please don't ask for sources as its been a while and I have totally forgotten where I seen it stated but my guess is I read it on Emo's own forum). I've also read in these forums of people who look down on with disdain at Emo gear and call Rotel the "poorman's separates". It's overwhelming sometimes all the conflicting opinions.

You will receive many different opinions on the vast majority of audio gear here, from speakers, to amps, etc. What you read is always someone elses experience and the best way to figure this out is read and sort out the muck. At the same time, the only way you can make a decision is either buy the equipment and test it for yourself, or find a poster/s who you respect and follow their advise. Best case scenario is test for yourself because in the end, you have to live with your equipment decisions.
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post #19 of 28
6/25/09 at 8:53am
I agree with Mozvz. The final decision will be up to you. The experiences forum posters have can have an influence on that choice - as it did with my buying decision when I was looking for an AVR to replace my outdated HK AVR 520 last year.

What I was looking for - and what I ended up with - are very different and I can't imagine going back to a single AVR solution. I now have an Onkyo SC885 preamp processor feeding signals to an Emotiva UPA-7 in a 5.1 setup. The 2 channel music is fantastic - and I can mix it into 5.1 stereo or Dolby Digital with the Onkyo if I wish to. Its very flexible. I've owned many 2 channel setups over the years and this sounds better than any of them ever did.

My main speakers are 4 ohms and the UPA-7 delivers 280wpc in 2 channel. I don't think a 2 channel amp delivering the same wattage would sound any better. How could it? After all, amps pretty much all sound the same - unless one colors the music - and I wouldn't own one that did. And 5 idle channels can't affect the music in any appreciable way.
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post #20 of 28
6/25/09 at 9:18am
Quote:
Originally Posted by RetRoe View Post

I've been watching for a sale on the Emo amps but I think I'm going to wait awhile on the new UMC-1 until I see that it has any potential bugs worked out. That said I've been looking at older pre-pro units on the used market, namely the B&K Reference 50 S2 or, if I can find a good deal, a Lexicon unit.

They seem to run their best sales around christmas time (surprise, surprise). I got my XPA-5 for $700 with free shipping. That deal was just too good to resist. I wouldn't be too surprised to see some sort of a bundle with the UMC-1 and an amp around then as well.

I'm on the pre-order list for the UMC-1 and I know there's several others who post in the Emo thread who are. So just keep an eye out there for updates.

Still no new info from Emo yet though...
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post #21 of 28
6/25/09 at 10:43am
Quote:
Originally Posted by TPnBobcats View Post

Still no new info from Emo yet though...

I bought my UPA-7 in Dec. $599 and free shipping. Great price and a great amp too.

Looks like the "late June" limited release for the UMC-1 ain't gonna happen, eh?
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post #22 of 28
6/25/09 at 10:52am
Quote:
Originally Posted by Knucklehead90 View Post

Looks like the "late June" limited release for the UMC-1 ain't gonna happen, eh?

There's still almost a week left.
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post #23 of 28
6/27/09 at 2:18pm
Quote:
Originally Posted by RetRoe View Post

Suitable Amplifier Power Range: 15-150 watts

Maximum Input Power: 100 watts

Nominal/Minimum Impedance: 8 ohms/4 ohms

That is what you then have to look at, if you have a SPL meter I would see how loud you like to listen but a 125 watt amp will be plenty of power.
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post #24 of 28
6/27/09 at 10:07pm
Thread Starter 
Quote:
Originally Posted by Planescape View Post

That is what you then have to look at, if you have a SPL meter I would see how loud you like to listen but a 125 watt amp will be plenty of power.

I was looking at possibly getting a Rotel RMB-1085, which is a Class-D, 5-channel amp, rated at 100 watts per channel, all channels driven @ 8 ohms. Are these decent amps?

I like the fact that they lightweight and read some good reviews that they're very good sounding clean power-amps. Just not sure if the RMB-1085 is something I should buy in today's market and wondering if new developments in technology have been implemented for Class-D amps. If anyone can offer some advice concerning the RMB-1085, I'd really appreciate it.
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post #25 of 28
6/28/09 at 3:37am
Half price...

http://www.audiogon.com/cgi-bin/cls....-channel-amp--
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post #26 of 28
6/28/09 at 6:39am
Quote:
Originally Posted by RetRoe View Post

I was looking at possibly getting a Rotel RMB-1085, which is a Class-D, 5-channel amp, rated at 100 watts per channel, all channels driven @ 8 ohms. Are these decent amps?

I like the fact that they lightweight and read some good reviews that they're very good sounding clean power-amps. Just not sure if the RMB-1085 is something I should buy in today's market and wondering if new developments in technology have been implemented for Class-D amps. If anyone can offer some advice concerning the RMB-1085, I'd really appreciate it.

Yes. Rotel makes a fine product. Just ignore the people who look down their noses at them.

Keep in mind that anytime you hear someone claiming "Product Y suck (because it costs less than). Product X is vastly superior (because I paid a LOT more money for it)." is basically 99% BS to justify to themselves, having spent large sums of money (You know unless it's something I bought! ).

There have been no dramatic new breakthroughs in Class-D/H/whatever amps in recent years. So you aren't "loosing out on" anything wonderful by buying a used amp.
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post #27 of 28
6/28/09 at 9:36am
Quote:
Originally Posted by RetRoe View Post

I was looking at possibly getting a Rotel RMB-1085, which is a Class-D, 5-channel amp, rated at 100 watts per channel, all channels driven @ 8 ohms. Are these decent amps?

I like the fact that they lightweight and read some good reviews that they're very good sounding clean power-amps. Just not sure if the RMB-1085 is something I should buy in today's market and wondering if new developments in technology have been implemented for Class-D amps. If anyone can offer some advice concerning the RMB-1085, I'd really appreciate it.

It will be fine but as stated before the only down side is price.
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post #28 of 28
6/29/09 at 8:27am
Thread Starter 
Well, thanks to MLKstudios' post, the price was right. I bought the amp he linked to on Audiogon. Offered the seller a little less (-$50) than his asking price and he accepted my offer. I've since spoken with him and he's a really nice guy. He's even sending me the original receipt in case I need warranty service. He states he has two of those amps and the one I bought from him is brand new and still factory sealed!

Thank MLK, that's a great deal on the exact amp I asked about. Much appreciated.
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