Some good responses, but some that are clearly defenses of what people like in their own situations and use cases.
IME this is much more accurate for a system in a house, it shows 50 watts to be enough.
https://myhometheater.homestead.com/splcalculator.html
Agreed--this matches quite closely what I see when I analyze my room. Notice the room reinforcement resulting from reflective walls enclosing the space, which is greater for greater distances. As mentioned, the Crown guidance does not consider that effect, so for the same other parameters (speaker efficiency, distance, etc.), it will recommend vastly more power.
I have 91dB/2.83v rms @1m sensitive speakers (equivalent to 91dB/W that is cited here). I drive them using mono Benchmark AHB2s that deliver the equivalent of 360W/ch, also the bass units have 200W/ch class D amps and the two sub woofers are 400W/CH class D.
There are times when the clipping approaching indicators flash on the AHB2s.
That's the cost of being able to get down to 16Hz essentially flat and having high dynamic range music with 20dB crest factors- that means the average power is a few watts RMS, but the peak is 100x as much.
This is, to me, the most important point, said in several ways in this thread. The bigger amps simply never run out of headroom. An orchestra pianissimo might be 55 dB SPL from a given listening position, while a cymbal crash might have a 105 dB peak for a brief instant, even from the audience perspective. That's a 50 dB difference. If that violin pianissimo sounds great at 1 watt, the cymbal crash will need 80 watts. One of my use cases is playing orchestral music at the same SPL that I would experience when sitting on the back row of the orchestra, so I can play along on my tuba and not have to hold back. I have measured SPL peaks of 108 dB from fortissimo tympani strikes, from a distance of five feet. So, I want my system to be able to deliver 108 dB SPL for those kinds of peaks. I was using one pair of Advent Loudspeakers and a 125-watt amp--not enough in my current space. Two pairs of Advents driven by two 125-watt amps proved to be enough. The home theater calculator above, that considers room effects, suggested 180 watts (equivalent to two amps at 90 watts in my setup).
Those sharp peaks may occur when the average SPL is only 85 dB SPL, which is a solid, sustained orchestra forte at a listening position on the stage. That room calculator tells me that with my Advents, I only need a single watt.
What that means is that those Advents sound pretty great with a 35-WPC amp, and that's what I used for many years. When I bought it, the speakers were 3 feet from my head in a college dorm room. But that amp will compress the dynamics by clipping the sharpest peaks when I play it loudly sitting 10 feet away in a larger living room. Those peaks tended to be so brief and fleeting that the clipping wasn't noticed as clipping so much as a general lack of dynamic sparkle. I moved to a 125-watt amp in those days, and that was fine for general listening in a room that isn't too dead. That became my new sweet spot for a while, until I started wanting to play along. I moved to a 250-watt amp of mediocre quality, and what it lacked in sonic smoothness it made up for in dynamics. With my current two 125-watt amps, I'm at my latest 250 wpc sweet spot with smooth-sounding amps. But it wouldn't take much--truly dynamic jazz recordings with an exciting drummer, for example, to need 500 or 1000 watts to fully form those transient peaks at "in room" levels.
In the days of vinyl, recordings were compressed just enough to fit the material into the dynamic range of the medium. And I never play vinyl records that loud anyway--it seems to me a 108 dB transient will almost assuredly result in audible microphonics in a cartridge, even assuming the transient peak doesn't make the needle jump out of the groove.
For much pop music, the material simply doesn't have that kind of dynamic range, and the recordings are massively compressed as a result of the Loudness Wars. Playing that stuff at wife-complaining RMS average of 85 dB SPL (again, 1 watt) just won't demand those 108-dB SPL peaks.
Most of the time, of course, I listen at much lower volumes. But I think the low-wattage folks underestimate the sharpness of the peaks in dynamic music, and the power it takes to supply the necessary voltage (without running out of current). And before I get the lecture about hearing loss, let me remind you that a cymbal crash or tympani strike may attain that 108 dB from six feet away for only a few milliseconds. Average listening level will be far lower. But I still try to arrange seating when I play in my current groups (which are wind bands) so that I'm not right in front of the tympanist.
Neither one ...
Everyone talks about the db level of the music, but nobody talks about the qualities of the music ..
Acoustic Suspension speakers gain in dynamics and naturalness of reproduction with more power ....
Not sure what to call the qualities that improve separation between the instruments and definition of the notes ... just sounds more natural.
The music is more lively and the bass definition is tighter, quicker, little details come alive...
There is less of the constrained, un-natural sound that says "radio" .... not real music.
I would guess that it's related to available peak headroom ..
And I'm addicted to fast, tight well defined AS bass notes ..
It's easy to hear .. listen to an AS speaker with 20wpc and then upwards of 100wpc ..
It will sound like someone changed speakers on the system ..
This is another aspect of the same idea--acoustic suspension speakers, which are my favorites for the same reasons, damp cone motion using the sealed cabinet, and need big power to overcome that damping for the sharp peaks. In return for that big power, they don't create resonant boominess that I hear in ported speakers that ring at mid-bass frequencies. Porting makes a small driver sound big, but lots of funny stuff happens in the interaction between the driver and the port. Any ported speakers I can afford sound boomy compared to acoustic suspension designs, and they make me grumble if I'm playing music where I really want mid-bass clarity.
Rick "for whom the sweet spot is 250 wpc (or two amps driving two pairs of speakers at 125 wpc each) to listen to orchestral music at realistic levels, in a large, open-concept living space" Denney
