Amplifier : how much power do you need

[patate91]

For those who are interested, here's a quick way to estimate your amplifier's power needs, based on your average SPL listening level :

1- You need the crest factor of your music track, usually between 10-20db :

http://www.richardbrice.net/leq.htm#:~:text=Symphonic, orchestral music can have,of only 8dB; see below.&text=It's interesting to note a,9dB greater than hip-hop.

2- Calculate the power needed :

10xLog(Amplifier's RMS) + 3 db. Then substract the track's crest factor.

https://www.prosoundweb.com/understanding-the-nuances-of-crest-factor/2/

and convert dbW to W :

https://www.rapidtables.com/electric/dBW.html

3- Use this caculator, with your speaker sensitivity to see what max SPL average level is allowed with your setup :

http://myhometheater.homestead.com/splcalculator.html

If there's something incorrect let me know.

*EDIT*

Or use this link :

https://www.kvalsvoll.com/Articles/AudioCalculatorspl.htm

 

[pjug]

I would use at at least 20db for crest factor. There are plenty of tracks with higher than this. I would use 25db to give a worst case estimate.

If your amp has some headroom above the continuous power rating, use the dynamic power spec.

I have little feel for peak SPL. Just speaking for myself. I think a listening method is better. Either using a scope or using the Pano method.

 

[patate91]

I would use at at least 20db for crest factor. There are plenty of tracks with higher than this. I would use 25db to give a worst case estimate.

If your amp has some headroom above the continuous power rating, use the dynamic power spec.

I have little feel for peak SPL. Just speaking for myself. I think a listening method is better. Either using a scope or using the Pano method.

I agree : a 20 to 25 db crest factor will give a worst case scenario estimate.

 

[patate91]

I would use at at least 20db for crest factor. There are plenty of tracks with higher than this. I would use 25db to give a worst case estimate.

Do you have some exemple of 20db crest factor songs??

 

[pjug]

Do you have some exemple of 20db crest factor songs??

I am traveling right now but not too long ago I used Rickie Lee Jones: Ghetto Of My Mind which has more than 20db crest factor.
Edit: sorry for the horrible thumb typing or autocorrect. Trying to clean it up. Also I think the 2L sample tracks are ballpark 20dB crest factor.

 

[Kvalsvoll]

For those who are interested, here's a quick way to estimate your amplifier's power needs, based on your average SPL listening level :

1- You need the crest factor of your music track, usually between 10-20db :

http://www.richardbrice.net/leq.htm#:~:text=Symphonic, orchestral music can have,of only 8dB; see below.&text=It's interesting to note a,9dB greater than hip-hop.

2- Calculate the power needed :

10xLog(Amplifier's RMS) + 3 db. Then substract the track's crest factor.

https://www.prosoundweb.com/understanding-the-nuances-of-crest-factor/2/

and convert dbW to W :

https://www.rapidtables.com/electric/dBW.html

3- Use this caculator, with your speaker sensitivity to see what max SPL average level is allowed with your setup :

http://myhometheater.homestead.com/splcalculator.html

If there's something incorrect let me know.

There is ONE calculator on the net that can calculate this easy and correct and simple, it is on my web page, and if you find it, it is free to use, it does not require any registration or log-in, it does not collect ANY information about you as a user - it does not even log the data you enter.

So, why did you not use it? Because you never heard of it.

Sometimes, I really wonder what is the point in what I am doing. This is one of those times. No, it is not your fault, but seeing questions like this and knowing I have had the answer on my pages for years, makes me wonder if the world will ever evolve.

 

[patate91]

There is ONE calculator on the net that can calculate this easy and correct and simple, it is on my web page, and if you find it, it is free to use, it does not require any registration or log-in, it does not collect ANY information about you as a user - it does not even log the data you enter.

So, why did you not use it? Because you never heard of it.

Sometimes, I really wonder what is the point in what I am doing. This is one of those times. No, it is not your fault, but seeing questions like this and knowing I have had the answer on my pages for years, makes me wonder if the world will ever evolve.

Just add the link here

 

[Kvalsvoll]

Just add the link here

Oh no, you find it yourself. It is not exactly on the front page, but if you can't find it with reasonable effort, that can be part of the explanation.

On the blog-section there is an article about this subject "How much power..", a discussion around the subject, and how you can arrive at some useful answer.

 

[TankTop]

Oh no, you find it yourself. It is not exactly on the front page, but if you can't find it with reasonable effort, that can be part of the explanation.

On the blog-section there is an article about this subject "How much power..", a discussion around the subject, and how you can arrive at some useful answer.

Click bait!!! You don’t even list your webpage.

 

[Kvalsvoll]

But, here is the link to the article:
https://www.kvalsvoll.com/blog/2018/12/02/how-much-power-do-i-need/

As you can see, when you start to look into the details, answers become more complex.

 

[Kvalsvoll]

Click bait!!! You don’t even list your webpage.

The web page is listed in the signature.

 

[escape2]

Just add the link here

I'm guessing it's this one:
https://www.kvalsvoll.com/Articles/AudioCalculatorspl.htm

 

[patate91]

Oh no, you find it yourself. It is not exactly on the front page, but if you can't find it with reasonable effort, that can be part of the explanation.

On the blog-section there is an article about this subject "How much power..", a discussion around the subject, and how you can arrive at some useful answer.

Maybe Google is not referencing you very much. And if I don't know who you are it's pretty hard to find your profil. And add the fact that cellphone browsing sometime removes informations such as signature. Anyway I'm glad I've found your web site, this is usefull information and tool

 

[frogmeat69]

 

[Kvalsvoll]

I'm guessing it's this one:
https://www.kvalsvoll.com/Articles/AudioCalculatorspl.htm

Yes, there it is. 6 years old! And the other one https://www.kvalsvoll.com/Articles/AudioCalculators.htm# is for multichannel movie systems.

The first (your link) is easier to use, the algorithms behind are the same. It does not calculate required power, but you enter say 100W, and see what you get. The other page calculates required power.

 

[Kvalsvoll]

Anyway I'm glad I've found your web site, this is usefull information and tool

Thank you, then at least it made sense to tell you about this calculator.

 

[Head_Unit]

with your speaker sensitivity

Good thread!
- Sensitivity is often exaggerated...OK, LIED about, the higher the more a lie, so be conservative.
- Amp power is fine but look at the 4 ohm power for 8 ohm speakers or 2 ohm power for 4 ohm. Because speakers are NOT resistors.

 

[Toslink]

There's also this tool on the Crown Audio site.

https://www.crownaudio.com/en-US/tools/calculators#amp_power_required

 

[RayDunzl]

There's also this tool on the Crown Audio site.

Ok, let's try a Pro setup... for "peak" power

I wasn't so far off, maybe...



Crown: How Much Amplifier Power Do I Need?

"Although a rock concert in an arena could be powered by 15,000 watts (allowing only 6 dB of headroom for peaks,) you'll often see large touring sound companies using 80,000 to 400,000 watts total. That much power is needed to handle 20-to-24 dB peaks without any clipping, and to power extra speakers for even coverage of a large area."

https://www.crownaudio.com/how-much-amplifier-power#:~:text=Although a rock concert in,80,000 to 400,000 watts total.

 

[Toslink]

This tool gives you a very good look at why speaker sensitivity is important when it comes to amplifier power. That is, your power requirements go up quickly when running low-sensitivity speakers. The calculator, however, assumes a 6dB drop in SPL as distance doubles, equivalent to free space use. According to Harman's Todd Welti, who conducted a course in room acoustics I attended a few years back at the CEDIA trade show, the sound level drop off in "small rooms" was closer to 3dB for each doubling of distance due to wall reflections.