Rille skrev:Hur mycket effekt som går åt i ett register beror på vad registret ska återge. Ett stycke med cymbaler kräver väldigt lite av basen men mycket av diskanten. Frågan är således omöjlig att besvara.
Håller med dig. Men frågan är hur mycket energiinnehåll vid olika frekvenser musiken innehåller i praktiskt bruk.
Musik har som bekant väldigt lite gemensamt med sinustoner. Och folk lyssnar sällan på en cymbalkrasch på maxvolym.
Elliot har en väldigt intressant artikel här :
http://sound-au.com/bi-amp2.htm”The amplifiers for a triamped system may have an effect on the final sound quality. This is especially true of the tweeter amp, which will generally not require a lot of power (depending on crossover frequency). If we assume that the power drops off at 3dB/octave above 1kHz for 'typical' music signals, we can do a quick calculation - this is not difficult (nor is it terribly accurate), but will give an idea of how much power will be needed for the tweeters. Note that this formula errs on the side of safety (i.e. the tweeter amp will have more power than is really needed), and this provides a good margin - a tweeter driver amplifier which is clipping is not likely to enhance the sound quality!
We might quickly re-examine the power of the low and mid amps first, assuming that we have selected the 'equal power' low/mid frequency of about 300Hz. For a typical system for home use, 50 Watts for each will generally be enough - especially when you remember that biamping can give up to the approximate equivalent of double the actual power of the amps - i.e. 200 Watts.
So, for this example, given that we have arrived at using a 50 Watt amp for mid+high, we are now going to triamp, with a crossover frequency of (say) 3kHz. This is approximately 1.7 octaves above 1kHz (it's a little more, but it is not worth worrying about).
At 3dB/octave, and 1.7 octaves, this results in a power requirement for the tweeters of -3 x 1.7 = -5.1dB relative to the midrange amplifier. Reversing the dB (power) formula, it can be seen that the high frequency amp will need 0.31 of the midrange amp's power.
0.31 x 50 Watts = 15.5 Watts. I suggest that a 20-25 Watt amp will be appropriate, and will have more than enough headroom. This hypothesis has been proven in practice - my own system uses 70W midrange amps and a 20W tweeter amp. I doubt that it has ever clipped since the system was first set up.”
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Elliots mätningar och konstaterande stämmer bra in på mina egna mätningar hur energiinnehållet ser ut vid olika frekvenser- vid typiskt material. Det stämmer även bra med de effekter Adam och ATC använder i sina monitorer, som är delade hel-aktivt.