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Discussion Starter #1
I'd have a question about those amps/preamps/receivers stuff


basically what we have right now is a receiver that gets all the signals and sends them directly to the speakers. it has 130w for the fronts and 40w for rears and center.

now thats a pretty easy setup, right, ok



the speakers I am considering are those:

- 200w fronts (2x)

- 150w center (1x)

- 125w rears (2x)


looking at the amps they make nowadays most of them are 5.1, 7.1 with the SAME ammount of wattage per channel.


so I cannot get one with higher then 125w per channel as the rears will not be ok, but at the same time im only at the 5/8 potential of the fronts.


how doe those amps/preamps come into play here?

lets say you route from the receiver to the amp to the speakers

is the total power receiver+amp or amp or ???
 

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Don't worry about the speaker power "ratings" as they are pretty much meaningless other than the minimum power required, which is seldom a problem. Your speakers will only draw the current (power) they need at any given gime, and when things get hopping (loud) you are better off with more power, not less. Underpowered speakers can be damaged by clipping from the amp when it is asked to deliver more current than it can safely handle. What is important is your speaker's nominal impedance (typically 6-8 ohms) and sensitivity (typically 85-95 dB). The higher the impedance and sensitivity the easier the speakers are to drive. Most mass market speakers are rated at 8 ohms and about 88-92 dB sensitive, and that makes them easy for a 50-100 watt/ch receiver to drive, especially when the lower frequencies are cut-off to a subwoofer. If your speakers are rated at 4 ohms and less than 85 dB sensitive, you will want to get a higher priced receiver or a separate power amp, as most low to mid priced receivers do not like low impedance/low sensitivity speakers. Here are some articles about receivers and speakers:

http://www.ecoustics.com/Home/Home_A...iver_Articles/

http://www.ecoustics.com/Home/Home_A...aker_Articles/
 

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Discussion Starter #3
Thanks for the reply,


Those speakers have a nominal inpedence of 8ohms, minimum 4.

they's the mirage 260 / cc / fx


fronts: 93db

center: 90db

rears: 90db


so are you saying the wattage per channel doest really mather?

and I could take a 6 x 170 or something?
 

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First, an amplifer is just straight power... no volume knob, nothing - it's just a box. It needs a Pre-amp. That pre-amp has all the controls - bass and treble adjustments, volume knob, etc. But, both those units do not have a tuner for FM/AM so a separate tuner has to be purchased. A receiver is all three of those things in one box. Some people have a great two channel (stereo) receiver but want to add more speakers, so they'll let the receiver act as a pre-amp by taking two RCA cables out of the "Pre-Out" or "Tape Monitor" jacks on the receicer, into another amplifier that does either another pair of speakers or two. This is done so the receiver doesn't drain itself of too much power if you've got more than 2 pairs of speakers going at the same time - which is harmful to any receiver or amp. As for the wattage issue, it can be confusing. It doesn't make a difference if your speakers are only rated for 80 watts and your amp or receiver is 200. You won't hurt the speakers unless you're really pounding the sound and believe me, you can always tell when you're pumping too much power into a speaker because the sound distorts. It's how clean the power is in an amp/receiver that matters. I've heard an 18 watt per channel amp blow me out of the water with HUGE Tannoy Churchill speakers but that amp and pre-amp were about 30 grand. Most receivers will start distorting at about three-quarters up in volume so at that point, it doesn't matter if the speakers are rated at 1000 watts and the receiver/amp is only 75 watts. It's distortion that hurts speakers. Hope that helps!
 

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Quote:
Originally Posted by WojtekO
so are you saying the wattage per channel doest really mather?

and I could take a 6 x 170 or something?
It matters only in that your speakers should not be under-powered, which would cause the amps to clip at higher sound levels. Clipping not only sounds bad it can damage or even destroy your speakers. My main LR amp (Innersound ESL) is rated at 300w @ 8 ohms, 600w @ 4 ohms, and will output 1,000 watts at 2 ohms. The speakers they power are "rated" at 150 watts (although the manufacturer - Digital Phase, assures me they will handle 1,000 watts on a short term basis). The extra power provides the security of dynamic headroom when the soundtracks or music get explosive, and with this amp I never worry about clipping. Movie soundtracks can jump by 20 dB or more in sound pressure levels during such episodes, requiring more than a 100 fold increase in power. Read some of the articles in the links I posted and you will see what I am talking about.


Here is an article that will explain it better (I am not an EE):


http://hometheater.about.com/cs/topp.../aatphtiba.htm
 
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