# Help Calculate Amp power needed for setup



## phillihp23 (Mar 14, 2012)

Help me figure out how many watts I need per channel on a receiver. I plan on running 4 floor standing tower speakers and a center on the amp. The other 6 speakers will run off the receiver. 11.2 system.
I used this formula sheet as provided by another HTS member. Just don't know how to interpret it. 
Thanks in advance.




CALCULATE AMPLIFIER POWER FOR GIVEN LISTENING VOLUME 

Speaker sensitivity *89	dB *(1W RMS at 1m) 

Distance from seating to speakers *3.8	m* 
Volume reduction, for distance doubling *3	dB* 3dB for inside rooms, 6dB for open space / anechoic 
Additional volume required for distance *4.5	dB* 

Average listening volume * 65	dB * Dolby reference level is 85dB 
Difference of average & peak volumes *20	dB* Dolby standard allowance for headroom is 20dB 
Peak volume at listening position *85	dB* 

Number of speakers * 8* Enter 1, 2, 4 or 8 speakers 
Volume increase due to no. of speakers *6	dB* 

Peak volume at 1m from speaker *83.5	dB* 

Required amplifier power per channel *0.3	W RMS* To achieve no clipping at peak listening volume


----------



## phillihp23 (Mar 14, 2012)

Does this formula mean if I run 5 speakers I only require a total of 1.5 W (.3 W RMS x 5)???
How does that equate to how an amplifier is rated? A 200 watt per channel reciever?
I'm confused obviously? :help:


----------



## WooferHound (Dec 8, 2010)

65 db and 85 db is not very loud
with your first watt you are getting 89 db
You will get most of your volume with the first watt that your sound system produces
then everytime you double the power you will raise the volume by 3 db
so to get 101 db you would double the power 4 times and you would need 16 watts
RMS is an average power, the peaks in RMS power can be 10 times the RMS rating


----------



## chashint (Jan 12, 2011)

It means your 4520 is not going to have any problems.


----------



## DeltaDube (Jul 10, 2013)

chashint said:


> It means your 4520 is not going to have any problems.


imho head over to emotiva.. go separates.. buy all the power you can afford.. makes for better sound
quality.. you need head room for great dynamics..

cheers


----------



## hjones4841 (Jan 21, 2009)

I think something went awry in your calculation. There is no way that 0.3W will provide the volume you are seeking. Not all channels will be playing at the same time, so I don't think adding a contribution from all speakers is correct. Let's look at it on a channel by channel basis. We will use one speaker's rated sensitivity.

Speaker sensitivity: 89db/1m/1w
Reduction due to distance: 89-4.5=84.5
10x amp power = 10db, so at 10w we get 94.5db volume
Adding another 10db to get us to the 84.5db+20db= 100w amp power per channel.

So, 100w/ch is what you will need. Again, almost any AVR will do that as long as all channels are not driven at the same time, which is a valid assumption.


----------



## DeltaDube (Jul 10, 2013)

hjones4841 said:


> I think something went awry in your calculation. There is no way that 0.3W will provide the volume you are seeking. Not all channels will be playing at the same time, so I don't think adding a contribution from all speakers is correct. Let's look at it on a channel by channel basis. We will use one speaker's rated sensitivity.
> 
> Speaker sensitivity: 89db/1m/1w
> Reduction due to distance: 89-4.5=84.5
> ...


if you want great sound you need power and lots of it.. avr specs are way over stated and deceptive..
you should skip the text book approach and use your ears.. put atleast 250 wpc.. into 8 ohm and 500 into
4 ohm.. you will be very happy camper imho!!! 

cheers


----------



## chashint (Jan 12, 2011)

DeltaDube said:


> if you want great sound you need power and lots of it.. avr specs are way over stated and deceptive..
> you should skip the text book approach and use your ears.. put atleast 250 wpc.. into 8 ohm and 500 into
> 4 ohm.. you will be very happy camper imho!!!
> 
> cheers


Please list your equipment...speakers, pre/pro, amps


----------



## DeltaDube (Jul 10, 2013)

chashint said:


> Please list your equipment...speakers, pre/pro, amps


i thought i listed my equipment on the profile..

paradigm studio 100s

xsp 1 analog pre amp

xpa 1s x 2 mono blocks.. 

sweet.. sounds..

for the movies there is more...


----------



## tonyvdb (Sep 5, 2007)

The AVR4520, uses class D amps and will have no issues driving all your speakers to well above reference without issues. Dont get caught up in all the numbers, I would still look at getting a two channel amp to drive your mains and let the Denon run the rest. 500wats is well over anything you would ever need or use even if you were to run your mains full range.


----------



## DeltaDube (Jul 10, 2013)

tonyvdb said:


> The AVR4520, uses class D amps and will have no issues driving all your speakers to well above reference without issues. Dont get caught up in all the numbers, I would still look at getting a two channel amp to drive your mains and let the Denon run the rest. 500wats is well over anything you would ever need or use even if you were to run your mains full range.


man you got to love having 500 watts on your mains.. it really makes the speakers sing...

take your sq to another level..

cheers


----------



## tonyvdb (Sep 5, 2007)

DeltaDube said:


> man you got to love having 500 watts on your mains.. it really makes the speakers sing...
> 
> take your sq to another level..
> 
> cheers


:justdontknow:
Even your Paradigm studio 100s cant handle more then 350watts each. and at that level you would be pealing paint off the walls in your room. 
If you like to have the huge amount of headroom in your amps thats fine but its totally un-necessary. 

Sonnie who owns this forum has the same Denon 4520 and powers his Martin Logan Prodigys, probably one of the most difficult speakers to drive and he does not use any external amps anymore (he sold them as he heard no difference in the sound quality). That says alot.


----------



## DeltaDube (Jul 10, 2013)

tonyvdb said:


> :justdontknow:
> Even your Paradigm studio 100s cant handle more then 350watts each. and at that level you would be pealing paint off the walls in your room.
> If you like to have the huge amount of headroom in your amps thats fine but its totally un-necessary.
> 
> Sonnie who owns this forum has the same Denon 4520 and powers his Martin Logan Prodigys, probably one of the most difficult speakers to drive and he does not use any external amps anymore (he sold them as he heard no difference in the sound quality). That says alot.



wow really hard to believe imho and my experiences in audio.. I had a paradigm manager in my house
checking out my system just a month or so ago.. he said it sounded awesome.... you need da power
to bring out the dynamics of the music and lots of it.. 

studio 100s can handle a 1000s watt no problem for a few
seconds ... thats the dynamics in music.. thats why da power makes it sound better.. 

try some anthem equipement the M1 amp in particular...
wonder why paradigm anthems sister company makes the m1 amp and martin logan speakers...????
maybe to run the S8?? or the 100? im not a fan of class d amps tho.. give me a a/b amps.. some people say class d amps are cold sounding..



cheers


----------



## phillihp23 (Mar 14, 2012)

Decided on the XPA-5. I need at least a two channel amp to run 11 speakers as the denon only runs 9.
I chose the XPA-5 as it is only $100 more than the XPA-2. I feel this way I will take some load off the Denon. Besides I have towers for Front L/R and Front Wide L/R , will throw the center on the amp too. Should arrive tomorrow. Thanks for all the comments everyone.


----------



## DeltaDube (Jul 10, 2013)

phillihp23 said:


> Decided on the XPA-5. I need at least a two channel amp to run 11 speakers as the denon only runs 9.
> I chose the XPA-5 as it is only $100 more than the XPA-2. I feel this way I will take some load off the Denon. Besides I have towers for Front L/R and Front Wide L/R , will throw the center on the amp too. Should arrive tomorrow. Thanks for all the comments everyone.


You are going to really enjoy the xpa 5.. it will beat up your denon 4520 in a blink...

enjoy 

ps bet you go back for more good sound is addictive!!!! i know i did!


----------



## phillihp23 (Mar 14, 2012)

Check out my unboxing and review of the XPA-5 Gen 2

http://www.hometheatershack.com/forums/home-theater-receivers-processors-amps/68850-xpa-5-gen-2-unboxing-setup.html#post627260


----------

