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Discussion Starter · #1 ·
Is there some simple formula for figuring out how much power you need for a given set of speakers.


I saw a few posts talking about how no reciever is going to push a Polk LSi 15s and that you would need an external amp, but this speaker is rated 20-250


I was personally looking at a set of RTi10s and I want to make sure im not putting my self in a position wher eI need to spean 4k to get enough power to drive them.

I was thinking about a Denon 2808,
 

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No real formula. Some people insist you need to match or exceed your speakers' max to get the most out of them, and that's true.


In your case, the Denon 2808 should be ok to power RTi10's, but it also has pre-outs for all channels, too, so if you ever decide to add an external amp (and no, you don't have to spend $4k) you can.
 

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Quote:
Originally Posted by zaniix /forum/post/12893944


Is there some simple formula for figuring out how much power you need for a given set of speakers.


I saw a few posts talking about how no reciever is going to push a Polk LSi 15s and that you would need an external amp, but this speaker is rated 20-250


I was personally looking at a set of RTi10s and I want to make sure im not putting my self in a position wher eI need to spean 4k to get enough power to drive them.

I was thinking about a Denon 2808,

There is no simple formula, unfortunately. My dealers sometimes nag me about Triad not having a power calculator on the website, but it would be meaningless. There are too many variables.


If you listen to chamber music, traditional jazz, and soft rock in a small room, your seating position is 7' away, and you listen at conversational levels, you will likely never use more than 5 watts continuous with 25 watt peaks. If you listen to loud music with great dynamics in a large room and you sit 20' back, you may need (different speakers, for sure) and 500 watts per channel...or more for peaks.


The louder you listen, the more power you'll need. The farther away you sit, the more power you'll need. The bigger the room, the more power you'll need. The deader the room, the more power you'll need. The less sensitive your speakers are, the more power you'll need...and then you may encounter power handling issues.


Maybe if you describe your room and listening habits, one of the geniuses here can offer an informed opinion. BTW, those are nice speakers for the money.
 

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The RTi10 speakers have a sensitivity of 89dB. This means that it takes 1 watt of power for a volume of 89 dB at 1 meter. For every 3dB of an increase in volume, it takes a doubling of power. For example, to play at 92 dB requires 2 watts and 95dB requires 4 watts. The watts become more important at higher decibels. At 107 dB, you would need 64 watts, but to increase to 113 dB you would need 256 watts (64 watts doubled to 128 and then doubled again to 256). 116 dB would require 512 watts.


Since the sensitivity is measured at 1 meter, your room can greatly change the sensitivity when measured at the listening position. As Paul mentioned, there are a lot of variables that effect the power requirements.
 

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Discussion Starter · #5 ·
The room is a rectangle with the TV on the long wall which is about 22 feet and the short wall is 14 feet. The couch is on the wall opposite the TV.


I am going to run a 5.1 Polk RTi setup, I may not use a Polk sub since many complain that others subs are better for the price.


I am not apposed to using a preout/amp setup like Emotiva has, but I was hoping the Denon 2808 or the 3808 if I decide to spend more would be enough to push it.


I listen to music at loud levels, but I like it to be clear and crisp. Mostly I want movies to sound amazing.
 

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I would not go to 3808 for just the extra 20W (the difference you cannot hear, btw) unless you need other features of it.


For the 2808 to 3808 price difference you can already buy a decent 2-ch power amp for your fronts should you find the 2808 does not have enough juice for your volume preference. It is very common to use an external amp for the front 2 or 3 speakers and let the receiver power the rest.
 

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Do the sound characteristics change with increased power? In other words, beyond clipping and an overall lower volume...what are you losing with decreased power? I am guessing the woofer is the most hungry for increased watts or does it really not work that way?
 

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You'll be listening to your moderately-sensitive speakers from around 12' away, most likely. Make sure you run the fronts "small" with a powered sub, and that will give both the receiver and the speakers more headroom.
 

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Listened to the RTi10's just a couple days ago. Tried them with an Onkyo 505, 75 watts, and compared it to the 805, 140 watts 4 ohm rated. The 505 had no problem driving them. When the 805 was switched over, it did add a bit of fullness and clarity to them. Personally, I would not hesitate buying them and driving them with something like the 505.


Also, regarding mid range receivers, you cant go wrong with Club Onkyo, Onkyo refurbs with a 1 yr warranty. Got the 505 for ~$130 total. Has HDMI, an EQ, 7.1... Do a search on them and you will find nothing but posotive comments.
 
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