Originally Posted by Class A
Interesting. I used the chart w/my Threshold 90 watt modified Class A mono blocks on my 6's and got 100.8 db. Plenty loud for me in a small room. Also nice to see that Michael finally added the new 6T to his website. By the way the 6 is rated as a 6ohm speaker that will dip to 4ohms.
- was considering similar issues for our 6T's - namely should I look for a higher-power amp for more realistic dynamic range? Is it needed? Did some digging --
1) For typical, even loud, listening, the continuous power needed is very low - a few watts
2) Nothing is linear.
3) Dynamic range varies wildly - most modern music and movies have a limited dynamic range, no more than 10-15 dB. In fact a recent Metallica album had just 3dB (!) of range (see attached chart). Some classical can have 50 dB and a few 'audiophile' versions can reach 70 dB (from various tidbits on the web).
Example: Aerial 6T's
1) 90 dB efficient - 1 Watt of applied power creates 90 dB of sound pressure at 1 meter. (by the way, this is about 40 mW of sound power, so the speakers are about 4% efficient - electrical to sound. Fairly typical).
2) Room Ambient: 50 dB, fairly quiet - no fans, closed door, etc. Again from the web.
3) Desired dynamic range: 55 dB (a 1960's cassette tape range)
4) Seating 2.5 meters (8 ft)
5) calculation is per channel, assuming the loud burst of sound is localized to one speaker.
a) 50+55 dB = 105 dB; 15 dB (31X) over 90 dB, so 31 watts at 1 meter.
b) derate to 2.5 meters: (2.5^2 = 6.25), and 193 (peak) watts are needed. (100 dB requires just 60 watts).
A 100W amp with 3 dB of headroom would do it, but most amps seem to have about 1.5 dB of headroom.
105 dB is very loud, but we are talking about a transient sound.
Of course if you wanted 96 dB of a CD, add another 41 dB, and buy a 2.4 megawatt (peak) amplifier.
As Xiph.org points out this is the difference between a single mosquito somewhere in a (sound-proofed) room and a jack hammer 30 cm from your ear.