Axiom Home Page Forums General Discussion Technical Questions More on Amp power

Exactly.

One point. If your meter peaked at 90 db, then that number includes the required headroom and you are using even less than that whopping 23 watts.

Edit: But then again, maybe you want to transport youself from the cheap seats to the front row when you are at home.

Wow. I thought all this "Applied Physics" stuff was just good for jokes on "The Big Bang Theory". Who knew it could actually save you real money!

Not sure but I think you might be double-dipping on the room gain.
The M22s are 89dB anechoic and 93dB in room.
Also I suspect that the calculator is looking for anechoic sensitivity as it is more of a standardized measurement while “in room” would be dependent on room size used.

All of these calculations are for 1 channel. What is the resulting decibel level of having, say, 3 channels all producing 90dB?

The same I would think. The calculator gives the power required to generate that volume whether you use one speaker or 5.

Johnk will be along sometime this evening to correct me if I am wrong.

Assuming you are right, let's re-run the numbers:
Distance: Still 3m (10Ft)
Desired volume: 90dB
Sensitivity: 93
Headroom: 12db

New Tally Please..... 71 Watts. That gives me up to 90db average sound with peaks up to 102db correct?

Scamp, as I've mentioned several times, I'm unenthusiastic about the Crown calculator. The main reason is that if it was used as shown on the calculator page the result would be far too high. Only in their discussion page do they point out that the result pertains only to anechoic or out-of-doors conditions and suggest using a 6dB correction factor to account for a typical room contribution. Of course, 6dB means that the result would then be 1/4th of the calculator result.

What my analysis would be is that the M22 has a sensitivity of 89dB(anechoic)and the studies of Dr. Toole and others indicate that sound level in home listening rooms(counting both direct sound and room reflections)drops off about 3dB per doubling of distance. At 3 meters(also about what my listening distance is)the level would be a bit over 4dB lower than at the 1 meter measurement distance. For about 85dB at 3 meters the M22 would use 1 watt. For the 90dB peak you measured during Also Sprach Zarathustra a bit less than 4 watts would be used.

Incidentally, I've also taken my SPL meter to concerts a couple times. As compared to what I could afford when I was a student, I now sit a lot more up front and the peak measurement on the Max setting was 106dB(during the Shostakovich 5th Symphony). I also had to explain what the meter was to some rather apprehensive patrons. They were satisfied that it wasn't a bomb and likely felt that although I was a nut, I wasn't a dangerous one. To duplicate that 106dB at home(I certainly almost never listen that loud)requires about 100 watts used by an M22.

You have it right now Scamp. I understand John's concern about the calculator not having something specific for room gain, but if you understand how the formula works, you can add it in where appropriate. Axiom just adds it to their sensitivity number.

I can't say I have ever listened to something at an average level of 90 db in my livingroom. I usually listen between 75 and 85 db depending on my mood. 90 just hurts (I did try it with spl meter in hand).

John. I'm trying to picture you with an spl meter in hand at a concert. Quite funny!

Damn. The kids really will be able to do some damage with these... Hopefully they won't figure out how to re-set the volume limiter.


The concert, Movies, outdoor events, me and my spl meter are inseparable. I may need a "weird but not dangerous" T-Shirt.

Are you suggesting that 2 speakers producing 90dB each aren't louder than one or that the amplifier power required, per the calculator, can be divided by the number of channels or both?