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Discussion Starter · #1 ·
On the back of my receiver there are pre-amp outputs (I think thats what they are, im at work now so doing this off of memory), what are those for? also if my receiver puts out 120 watts or so per channel why use amps?
 

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I'm not really an expert either, but I'll try and answer to the best of my ability.


Those pre-outs hook up to your amplifier. There's separate RCA hookups for each channel.


I can think of a few reason's to use a separate amplifier. The biggest one is more power. Many receivers that advertise a certain power rating can't actually sustain that power continuously over all channels. It's more like peak power through one channel.


Another reason is future-proofing. You could go nuts and spend a ton of money on a powerful AVR, but when it comes time to replace that unit, either for new features or because it broke, you're going to have to pay that same cost again. Amps, on the other hand, rarely change, and good ones are generally very reliable. This means that when you need a new processor, you don't have to take power into account, and save a little money by opting for cheaper, less powerful models. You also open up the option of buying stand-alone pre processors, though, surprisinglyh, these cost more than receivers.


Also, if you're driving inefficient, low impedance speakers, you've got to worry about the excess current cooking your receiver. A good amp will handle them without any problems.


Lastly, amps maintain their value, as the technology behind them doesn't change very much.
 

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Discussion Starter · #3 ·
Now isn't there processors n pre-processors? I'm guessing the processor would be like the receiver without the amp inside? Then what's a pre? I've always just done a standard receiver n speakers but now that I've bought a home and am half way done with installing my home theater Im wondering what else is out there to advance my movie watching at home. This site needs a freaking glossary
 

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I doubt that there will be any money saved by going with the preamp/amp route as these setups tend to be expensive. If one wants good performance at a reasonable cost then one capitalizes on the economy of scale and buys a moderately priced "all in one" AVR. I seriously doubt that anyone really needs a separate amplifier just to watch a movie in their living room.


DelJ



Quote:
Originally Posted by cytokinesis /forum/post/19592470


...You could go nuts and spend a ton of money on a powerful AVR, but when it comes time to replace that unit, either for new features or because it broke, you're going to have to pay that same cost again. Amps, on the other hand, rarely change, and good ones are generally very reliable. This means that when you need a new processor, you don't have to take power into account, and save a little money by opting for cheaper, less powerful models. You also open up the option of buying stand-alone pre processors, though, surprisinglyh, these cost more than receivers. ...
 

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Quote:
Originally Posted by stegen /forum/post/19592375


On the back of my receiver there are pre-amp outputs (I think thats what they are, im at work now so doing this off of memory), what are those for? also if my receiver puts out 120 watts or so per channel why use amps?

Most likely your receiver is not even putting up 60 watts or less with all channels driven. This is fine if you are using typical slim towers or bookshelves/satellite speakers with low power handling crossed over to subs. You might not need an amp in this regard.


However if you are using large towers or pro speakers then a receiver's power is a joke at best and will not allow you to utilitize these types of speakers to their full capabilities.
 

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Large towers may be more efficient than small speakers, so I don't think that's a reliable way to think about the problem.


google 'amp power calculator' and punch some numbers in to get an idea of how much power is needed. You will need to know your approximate listening distance from your speakers and speaker sensitivity.


I can play music on my system very loudly while measuring an average (RMS) voltage of 5 volts. At this level it's louder than I would normally listen to it. If the peak to average ratio of the song was 15 dB, I figure I need 5 times the voltage peak, or 25 volts. That would be 78 watt into 8 ohms.
 

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Quote:
Originally Posted by MichaelJHuman
Large towers may be more efficient than small speakers, so I don't think that's a reliable way to think about the problem.


google 'amp power calculator' and punch some numbers in to get an idea of how much power is needed. You will need to know your approximate listening distance from your speakers and speaker sensitivity.


I can play music on my system very loudly while measuring an average (RMS) voltage of 5 volts. At this level it's louder than I would normally listen to it. If the peak to average ratio of the song was 15 dB, I figure I need 5 times the voltage peak, or 25 volts. That would be 78 watt into 8 ohms.
It's a little late for me to start number crunching how much power large towers need. My point is that it's different giving large speakers just enough power to fulfill their duties rather than giving them plenty of power to perform at their finest without breaking a sweat.


Also every low power amp or receiver I've tried using with Large speakers either clipped or exhibited horrible distortion before going into standby. Now if someone wants to take a large pair of highly efficient pro speakers let say and pair it with a rinky dinky 100 watt per channel amp or even weaker receiver then I'm sure they might be able to get by with it.


But in my personal experience it was a big suprise when giving large drivers higher power reserves rather than just enough. To each his own though. We will just have to agree to disagree on this one.
 

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I was thinking from an efficiency standpoint. If you look at a lot of bookshelf speakers, they seem to run in the high 80s to maybe 90 dB.


Many floorstanders do better than that. I am no speaker expert, but as I recall small enclosures tend to be less efficient, which would explain this trend.


So in some ways, in my experience, and based on specs listed, bookshelf speakers may on average be less efficient than floorstanders.


Just my thoughts...I don't pretend to be an expert, and am certainly willing to hear contrary points of view.
 
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