Quote:
Originally Posted by

**kbarnes701**
EDIT: In my original post, quoted above, I mistakenly gave the sensitivity of my speakers as 89dB - on checking it turns out to be 90dB.

The THX PM3 approval for my monitors is for the nearfield distance of 1 meter. That's one area that the PM3 rating differs from the consumer ULTRA standard.

I also realized that for active monitors/speakers it's not just as simple as adding the separate amp wattage ratings together and using that as the number.You would have to enter each amp/driver combo of RMS wattage and driver sensitivity into that type of calculator separately.

So, with an exact distance entered of 1.86 meters/6.1 ft for the woofer section of one of my front 3 HR824's with what I believe is a 89db sensitivity driver plus the 150 watts RMS from the amp,I would only safety reach 102dB at the seating position. For the tweeter section it would be 100dB with the RMS amp output of 100 watts and if the tweeter had a sensitivity of 89dB. I can't seem to find the sensitivity ratings for the original HR824 now.

For the HR624's at the exact distance of 1.37 meters/4.5 ft for the woofer section with 100 watts RMS with a 89dB sensitivity driver,I would only reach 103dB at the seating position.For the tweeter section with a 91dB sensitivity and 40 watts RMS amp it would only be 101dB at the seating position.

Some of those amp output ratings from Mackie are also into 4 or 6 ohms depending on the driver and speaker model.Lot's of variables to take into account.

The Crown calculator also states:

*The calculations discussed here apply to anechoic or outdoor conditions. If the sound system is inside a venue, the room reverberation will increase the SPL typically by 6 dB. You can use this room gain as extra headroom.*
What about the Audyssey correction filters and how they boost or cut frequencies differently for each speaker? That would also affect how much headroom and clean output you could reach at the listening position for each speaker.