From this lesson, it appears that all you have to do is buy a really big power amplifier to create optimum clarity. But there is a limit as to how much pushing force (power) you can use with your speakers. There is a physical constraint as to their power-handling ability and adding more amplifier power can literally blow them up. So what is an audiophile to do? Let's focus on what musical peaks are first and then look at what can be done about them.
At the 1-Watt level, the speakers deliver 85dBa of sound pressure (at one meter) into the room and at this level the amplifier has a power reserve capable of producing a maximum SPL of 109dB. This means that the dynamic range is the difference between the loudest it will go and the level at which you listen, here 109-85 or 24dB. If you turn up the volume control for an average listening level of 91dB, your speakers are demanding 4 Watts of power from our amplifier and this translates into a dynamic range of 109-91 or 18dB. So here's the catch: people normally listening to music at loud levels require a system capable of handling and delivering a lot of power if you want to maintain a wide dynamic range (optimum clarity).
The amount of power demanded by your speaker doubles with every 3dB increase of sound pressure, so for a speaker with a 1-Watt sensitivity of 85dB, the power demands go approximately like this:
The Listening Position
Putting it another way, if your speakers have a maximum SPL of 109dB at one meter, at two meters it will be about 103dB (-6dB down), at three meters about 99.5dB (-9.5dB down), and four meters about 97dB (-12dB down). The maximum SPL you can hear from your system at your listening position is lower the further from the speakers you listen.
If your listening position is four meters from your speakers, the loudest you can hear them go is a function of the [Manufacturer's Rated Maximum SPL] minus 12dB.
For example, if your speakers have a sensitivity of 92dB/W/m with a power handling capacity of 150 Watts, and your listening position is four meters from the speakers, then the following is true:
- Maximum SPL @ 1 meter = 107dB
- Maximum SPL @ 4 meters = 95dB
How to Resolve this Dilemma
As mentioned earlier, you could buy a bigger amplifier and hope that you do not toast your speakers one day in a breathtaking but brief experience. I would not recommend doing this. Despite your best intentions, someone will one day twist the volume knob on your preamp all the way up after which you will be searching for replacements.
Another way to do this is to bi-amplify your speakers. Now the sound pressure will not change but the clarity will improve giving you the impression that your system can go louder. What's happening is much like several people carrying a heavy chair instead of one person struggling with it alone: it makes carrying the chair easier when two people do it and so does multiple amplifiers attached to your speakers. It's the same chair (same weight) but you've added twice the people (more power) so the load is distributed making it is easier to carry.
So there you have it. Another mystery explained and debunked. Stay tuned for more along this line of additions in the infinite search for high-end audio perfection.