Amplifier Power Required?

[kinggimp82]

I found a calculator on this web site that tells you how much power you would need to reach a desired SPL at a certain distance with certain speaker sensitivity.

Here is the link to the calculator.
http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

I have a few questions about this calculator. Is it calculating how much power you need to reach this SPL with a single speaker? I would assume so. The amplifier headroom box always defaults to three DB. What exactly does that mean?

I am using the calculated to figure out how loud I can listen to my Sierras without causing damage. I don't listen at insane levels or anything but I do like listening loud. Main thing is they are such nice speakers I'm afraid to push them too much and cause damage. I'm using a 100 wpc onkyo receiver. So far the loudest I have gone with the receiver is -20 on the volume. To me it sounds pretty loud at that volume level but it feels to me like they could play louder.

I have also read somewhere that even though a receiver lists that they have 100 wpc that isn't necessarily the case. Like Either it's only so with one channel driven or that there are not 100 watts of clean power thus inducing high harmonic distortion the closer you get to 100 watts. This also makes me hesitant to play the Sierras too loudly.

So back to the calculator itself. My listening distance is 2 meters. The sensitivity of the Sierras is 87. After playing around with the calculator I came to the conclusion I can listen at an average of 94 decibels fairly easily. The required power is 40 watts. But if this calculator is for a single speaker does that mean running the Sierras in stereo will give me an extra 3 decibels of output. If so would that mean that I could safely listen to the Sierras at an average of 97
decibels with peaks at 100 decibels? Does this sound correct or am I looking at this the wrong way?

Any info or advice on this would be appreciated.

[Blutarsky]

http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

This calculator is very similar with the basic Headroom at 4dB. A little more conservative.

There is an old hot rodder aphorism...

"The only substitute for cubic inches, is rectangular dollars"

Looks the same for audio.

You aren't going to get loud without a big efficient speaker, or powerful amp.

[kinggimp82]

I understand you aren't going to get loud without a big efficient speaker, or powerful amp. I am more or less just wondering how loud I can play my Sierras (crossover at 60) safely with my current setup.

[Blutarsky]

Sorry, I just love the old aphorism.

Personally I would use 4 dB headroom in the calculator. I also heard that you get another 3 dB from using a pair of speakers.

There is also the issue of different gain between sources. I just learned this the hard way when my ROKU sent a burst of Pandora through my new Sierra-1's, blowing a woofer.

I will now try to be conservative. Maybe 94 dB for a pair of Sierras. If you could compute the headroom on your amp, you might push it closer.

I am considering a pair of Horizons for mains. Towers, if my Sig-O will go for it. Maybe stop listening to Rock and Reggae, and appreciate Chamber Music?

[davef]

I found a calculator on this web site that tells you how much power you would need to reach a desired SPL at a certain distance with certain speaker sensitivity.

Here is the link to the calculator.
http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

I have a few questions about this calculator. Is it calculating how much power you need to reach this SPL with a single speaker? I would assume so. The amplifier headroom box always defaults to three DB. What exactly does that mean?

I am using the calculated to figure out how loud I can listen to my Sierras without causing damage. I don't listen at insane levels or anything but I do like listening loud. Main thing is they are such nice speakers I'm afraid to push them too much and cause damage. I'm using a 100 wpc onkyo receiver. So far the loudest I have gone with the receiver is -20 on the volume. To me it sounds pretty loud at that volume level but it feels to me like they could play louder.

I have also read somewhere that even though a receiver lists that they have 100 wpc that isn't necessarily the case. Like Either it's only so with one channel driven or that there are not 100 watts of clean power thus inducing high harmonic distortion the closer you get to 100 watts. This also makes me hesitant to play the Sierras too loudly.

So back to the calculator itself. My listening distance is 2 meters. The sensitivity of the Sierras is 87. After playing around with the calculator I came to the conclusion I can listen at an average of 94 decibels fairly easily. The required power is 40 watts. But if this calculator is for a single speaker does that mean running the Sierras in stereo will give me an extra 3 decibels of output. If so would that mean that I could safely listen to the Sierras at an average of 97
decibels with peaks at 100 decibels? Does this sound correct or am I looking at this the wrong way?

Any info or advice on this would be appreciated.


I understand you aren't going to get loud without a big efficient speaker, or powerful amp. I am more or less just wondering how loud I can play my Sierras (crossover at 60) safely with my current setup.

Hi Andrew,

It is quite a bit more complex than using that calculator. Room gain and standing waves also play an important part -- as does the real available headroom in your amplifier.

As a rule of thumb, when listening to loud levels, if you hear distress simply turn the volume down as you might be reaching the limits of the speaker or your amplification.

With a 60Hz crossover, I would estimate that at only 2 meters back with 2 speakers, assuming +3dB for room gain (average) and allowing 10dB of headroom (more realistic) – you should be able to run at 98-99dB continuous without issue. Please note that this is extremely loud and I do not recommend listening at these levels.

[Blutarsky]

Thanks for putting the Calculator there for me. I learned a lot. In my stereo days, I used powerful High Current amps of 250 WPC or greater and didn't worry much about speaker efficiency.
It is hard to get high power out of HT receivers, without going to seperate amps. (The old rectangular dollar solution)

http://www.wyred4sound.com/webapps/category/74030/117839/18048
.......for instance.

Also a good argument for Ascend Towers, or the Horizons. with their higher efficiency.

The internet has sure improved my knowledge base, A good forum, with a lot of inquisitive members, Is a powerful tool.

Blutarsky

[kinggimp82]

Hi Andrew,

It is quite a bit more complex than using that calculator. Room gain and standing waves also play an important part -- as does the real available headroom in your amplifier.

As a rule of thumb, when listening to loud levels, if you hear distress simply turn the volume down as you might be reaching the limits of the speaker or your amplification.

With a 60Hz crossover, I would estimate that at only 2 meters back with 2 speakers, assuming +3dB for room gain (average) and allowing 10dB of headroom (more realistic) – you should be able to run at 98-99dB continuous without issue. Please note that this is extremely loud and I do not recommend listening at these levels.

Well I measured the highest volume level I listen to right now with some of my louder CDs during the louder parts. The average continuous spl is 91 decibels at 2 meters. I'm thinking 98 or 99 dbs will be too loud for my liking. 95 db continuous is the highest I would want the volume. So you think at 2 meters from the Sierras running them at 95 db continuous can be done without issue with my 100 wpc ontyo receiver?

[Gov]

^^^^Yes :D

[Blutarsky]

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

This tool includes room gain as a variable.


Blutarsky

[phlw]

I know this won't answer you question, but may help with future purchases. In my experience amplifier watts are not all created equal. A high quality, lower wattage amp will usually be fuller and smoother sounding than a less expensive higher-wattage amp. Therefore you will probably enjoy the high-quality more at reasonable levels. A high wattage less expensive amp will crank Eruption louder, but will not be as enjoyable overall. As far as tubes, I have no experience unfortunately.