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Discussion Starter #1
Just a general question. Say a 2 channel amp and a 5/7 channel amp made by the same company. Both amps are rated 200w/channel. If I'm only interested in 2 channel music, would the 2 channel amp sound better and play louder with less strain than the 5/7 channel one?


The reason I ask is because I see 200w 2 channel amp around 1000 dollars and then I see 200w 5 channel amp made by same company costing less than 2k. If 2 channel music is more important but I also want the system to be able to play 5.1/7.1 movies, is it better to buy three stereo channel amps over one 5/7channel amp? I'm thinking 3 stereo channel amps probably sound better than 1 5/7 channel amp, but does it justify the difference in cost?
 

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Quote:
Originally Posted by miky702 /forum/post/12940966


Just a general question. Say a 2 channel amp and a 5/7 channel amp made by the same company. Both amps are rated 200w/channel. If I'm only interested in 2 channel music, would the 2 channel amp sound better and play louder with less strain than the 5/7 channel one?


The reason I ask is because I see 200w 2 channel amp around 1000 dollars and then I see 200w 5 channel amp made by same company costing less than 2k. If 2 channel music is more important but I also want the system to be able to play 5.1/7.1 movies, is it better to buy three stereo channel amps over one 5/7channel amp? I'm thinking 3 stereo channel amps probably sound better than 1 5/7 channel amp, but does it justify the difference in cost?


200 wpc is a lot. More than any typical sound system in a typical home needs. My home theater, as an example, would be happy with 20 wpc. I doubt you would hear any difference in the sound between the two. A two channel amp may be designed to drive lower impedance loads or have other advantages but sound quality wouldn't likely be one of them. Modern amplifiers are transparent. They should be and, for the most part, they are.
 

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Discussion Starter #3
Ok I see. Maybe 200watt amp comparison is a bad example. What about a three 150watt stereo amp vs one 150watt 5/7 channel amp? What I'm concerned the most is whether I can hear improvement with a dedicated stereo amp for 2 channel listening.
 

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From what I have experienced with some speakers is that more wattage doesn't really help them, but more current. My Epos ELS-3 for example really open up when you feed them with a high current amplifier. I have found that a lot of 4 ohm speakers really prefer high current amps to get the full potential out of them. While you really won't notice the difference between a high current and normal amp at high volumes, the difference becomes clear when hearing at low volumes.


I really became aware of this when hearing the B&W CM1 with two different sources. At 84dB they are not sensitive at all so when I heard them with a mid grade Yamaha receiver at moderate to low volumes they just sounded pretty crappy. Soundstage was tiny with so so imaging. Then I heard them with a Rotel RB-1070 high current amp and the difference was just staggering. So your speakers might be needing more current instead of more power.
 

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The design of audio amplifiers is a hugely complex subject. This guide is intended to help you sort out some of the more obvious and important differences among audio power amplifiers, because every different design has it's own set of compromises along with it's own set of advantages. Because of the nature of an eBay Guide, I must be brief, and I will leave out many details.


There are many different ways to build a power amplifier, and then there are many different ways to package the electronics into a metalwork "box". The most important differences are: the number of channels inside the box, and the choices the designer makes to provide a balance among energy usage (from the wall socket), power output to the speakers, and overall cost, all while maximizing sound quality. And quite a balancing act it is!


Number of channels of amplification

At it's core, an audio "amplifier" is a single channel device. (It is monophonic.) A single channel of amplification in it's own box is a "monoblock" amplifier. There are stereophonic amplifiers (stereo, or two channel audio with a "left" and "right" channel) but that's just two individual amplifiers sharing a single housing. Now, with the popularity of multichannel home theater, and multichannel audio via SACD and DVD-Audio, what's sold as an "amplifier" may have many individual channels (generally, 3-, 4-, 5-, or 7-channels) of amplification built into a single box.


Monoblock Amplifer Advantages:


* Having only one channel of amplification in a chassis is regarded as the best--but most costly--solution; it is intended to provide the utmost sound quality, all other considerations are secondary. Since everything in the box is devoted to a single channel, a monoblock amp is generally (not always!) more powerful than a stereo or multichanel amp. There is no electrical connection between the channels except at the wall socket, and so signal seperation is maximized.

* The amplifier can be placed close to the speaker (as in, within inches) minimizing the amount of speaker cable needed.


Monoblock Amplifier Disadvantages:


* Cost: You buy a seperate amp for each channel in your system. It's not uncommon for a single monoblock to cost the same as a stereo amp.

* There are those who argue that it's better to have short interconnect cables than to have short speaker cables. One thing is guaranteed: short cables do less damage to the signal than long cables, whether we're talking speaker cables or interconnect cables.

* Some speakers (Polk SDA series, for example) are designed to work with amplifier channels that share a ground path for the two channels. (These speakers are not common.) Seperate amplifiers don't have that common ground connection.

* You need to be able to "plug in" each amplifier seperately. Your home wiring needs to have outlets near where each amp is located. You may need to hire an electrician to "beef up" the wiring in your house so that the monoblocks have a source of enough electrical power.


Stereo Amplifier Advanatages


* Two-channel amps are more common than monoblocks or multichanel amps, because high performance audio was all about "stereo" for thirty years.

* Cost: Compared to monoblock amps, you're buying half the amount of chassis metalwork. One "box" instead of two. Make no mistake: The metal box that houses the electronics is a huge part of the total cost of an amplifier.

* "Dual Mono" is a variation of stereo, in that while both are two-channels of amplification in one box, a Dual Mono amp is designed in such a way that it has nearly the electrical seperation as a pair of mono amps. The two channels of a dual-mono amp share a chassis, (and usually a chassis ground,) a power cord and power switch, and--perhaps--the primary winding in a shared transformer. Some dual-mono designs use totally seperate transformers, and some (generally the lower-powered or less-expensive) use a transformer with three windings--a shared primary winding, and a secondary winding for each channel.


Stereo Amplifier Disadvantages


* They are the compromise between monoblocks and multi-channel. So, you're buying less metalwork (chassis) than if you bought a pair of monoblocks, but if you buy several stereo amps, you're buying more metalwork than if you bought a single multichannel amp.


Multi-Channel Advantages


* If you actually need several channels of amplification for a multichannel music or home theater application, you'll generally spend less money if you buy all the amplifiers built into one box.

* Some multi-channel amps are designed so that pairs of channels can be combined into a single channel but with higher output power. As an example: You may buy a 100-watt per channel, 4-channel amplifier (100 X 4) that allows you to combine a pair of channels so that instead of 100 X 4, you could have 100 X 2, plus a third channel of 200+ watts; or even combine the second pair so that you end up with 200+ watts X 2 channels. Not all multichannel amplifiers have this capability--be sure to check before you buy!


Multi-Channel Disadvantages


* Since size and weight becomes a concern, and because all those channels of amplification are drawing electrical power from one power cord off of a single wall socket, maximum amplifier output power can be compromised. There are "clever" designs that can reduce the price, size and weight of a multichannel amp, and still provide tremendous "rated" output. The problem is, those "clever" designs often compromise the sound quality in the process of providing a more consumer-friendly package.
 

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Quote:
Both amps are rated 200w/channel.

For how many channels? Multichannel amps tend to have more than one power rating--or should, anyway. It might be 200w into 1 channel, but 80w/ch into 5 channels, for example.


There's no way to answer your question based on the information you supplied.
 

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It depends on how the multichannel amp is made. If it can double into half the impedance and also doesn't run too hot, then it should be fine. I doubt you will hear any difference unless the multichannel amp cannot handle as high current as the stereo amp (and you have speakers that dip into very low impedances). If the amp overheats, you can get some distortion products as well, perhaps audible.
 

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Discussion Starter #8
Ok. For example rotel RB1080 stereo amp vs. rotel RMB1095 multichannel. Or nad c272 stereo vs. nad t973 multichannel. How would they compare in stereo music?


Quote:
Originally Posted by mcnarus /forum/post/12943406


For how many channels? Multichannel amps tend to have more than one power rating--or should, anyway. It might be 200w into 1 channel, but 80w/ch into 5 channels, for example.


There's no way to answer your question based on the information you supplied.
 

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Over audioholics the Behringer EUROPOWER EP2500 is said to be very good and a steal for what it offers. Some used two of those to drive front speakers and center channel while the receiver drove the surrounds.


It was recommended to exchange a fan in the unit with a more silent one.


With two of those I would for sure blow my fuse
 

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Just remember that the power supply in the amp must handle all the channels of an amplifier. If the power supply is being divided among 5 or 7 channels, it has to be up to the task. The same power supply, unless y conservatively rated, will perform better with two channels at "x" watts than with 7 channels at "x" watts. Bass transients demand large amounts of current on many speakers, and this is probably where the limitations of any choice can be evident. Of course, by redirecting all low bass to a subwoofer with its own internal amplifier, this problem can be alleviated.


Lee
 

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Quote:
Just a general question. Say a 2 channel amp and a 5/7 channel amp made by the same company. Both amps are rated 200w/channel. If I'm only interested in 2 channel music, would the 2 channel amp sound better and play louder with less strain than the 5/7 channel one?

OK, looking at the two Rotels you mentioned, I would say the answer to your original question is no. If anything, the multichannel will have more power than the advertised 200w when driving only 2 channels. It certainly won't be worse.


All this with the proviso that I'm looking only at the limited information on the spec sheets. More detailed measurements might be more revealing (or just more of the same).


The other point is that 200w is a huge amount of power for a home listening situation. What speakers are you trying to drive, and how big is the room you're in?
 

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Discussion Starter #12
I have NHT M6 with 86db sensitivity and 250watt rating. The room is about 3500 cubic feet and have an opening to downstairs. I was thinking about getting a 2x200w stereo amp but I also have a few subs that each of them needs 200watt to drive. That's why I'm wondering if it's better to just buy a 5/7x200w amp.
 
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