speaker excursion..."mo power"..and bass..Sean

I don't know why, but I have found that every increase in power (up to 600 watts) for my MG1.6 speakers has improved the sound. I don't think it is the power per se, but some other characteristic that tends to go along with high power capability.

FAIR WARNING!!!!! If you follow Sean's example you will have multiKilowatt amps (and blown out speakers):-)

Fishboat...Mention of the MG1.6 is just to clarify what speakers I am making amp power observations about. I also have Dynaudio Gemini speakers, small (5" woofers) MTM boxes, and these also responded well to power increases up to 450 watts (4 ohms). I haven't tried them with the 600 watt amps.

Drew_eckhardt...I think that the concern about clipping relates to the amp doing bad things, like oscillation, which may occur at frequencies completely unrelated to the waveform that caused the clip. Let's see what Professor Sean says.

Sean...Of course I am a long time believer in biamping, but I do think that the original reason (and I am talking about 50 years ago) was to avoid intermodulation distortion. Power amps have improved so that this is no longer a significant issue. As you say there are power delivery advantages also, but in this regard amplifiers have also improved about tenfold. (Back then a "big" amp was about 25 watts, and now it would be 250 watts or more).

Which leaves us with the elimination of the passive crossover as the remaining advantage. I cannot understand how many people seem to think that driving two separate full range amps into the passive crossover is "biamping".
I have two comments here.

1...It is dangerous to run a tweeter directly from a power amp. Turnon and turnoff can be accompanied by "thumps" that the tweeter won't like, and a loose interconnect can be an instant disaster.

2...Passive crossovers do not absorb power to the degree that you suggest. The simple test for this is to consider how hot they would get if they did absorb a lot of power, particularly since they are usually mounted inside a closed box, and surrounded by insulation. To take the scientific approach: Capacitors (ideal) dissipate zero power. EE101. Real capacitors are near ideal in this regard. Inductors will dissipate power because they cannot be made with zero resistance. The externally mounted 3.5mH inductors of my MG1.6 are 10 AWG air core coils with dc resistance of 0.2 ohms, which is about the same as the original equipment iron core inductors. Since the driver is 4 ohms, 0.2/4 which is 5 percent of the power will end up as heat in the inductor. (But they never feel warm). Resistors are used in crossovers, but not in the signal path except for the tweeter, where some power loss is usually necessary to balance SPL. If the tweeter padding resistor needs to be a large value, the wrong model of tweeter has been used.

What is the basis of your suggestion that lost power will be 50 percent?

Cinematic_systems...In a passive crossover, power does indeed "go to ground", but it goes through the drivers, which is the whole point of the thing. The power "wasted" by notch filters is minimal, unless the drivers are truly aweful.

The 10 AWG air coil inductors in my MG1.6 have about the same resistance as the original iron core inductors. This is why most speakers use iron core inductors.

When estimating the broadband signal equivalent to two bandlimited signals, the usual approach is to do an RSS. For example...

100^2 + 60^2 = SIGNAL^2

SIGNAL = 117

If the two band limited signals are equal, the equivalent broadband signal is maximized at 1.41 times the band limited signal.

However this assumes that the two bandlimited signals are uncorrelated, and this is not typical of music, where loud low notes are often simultaneous with high frequency harmonics, not to mention cymbal clashes.

As to tweeters burning out...I guess that some may be huskier than others, but I just took out two SEAS Excel T25CF-002 Millenium tweeters with about a three second burst of noise due to an interconnect problem. And these tweeters were not driven directly from the amp, but rather through a passive crossover. However, replacement voice coils are available, and Madisound even installs them for free. This suggests to me that blown out voice coils must be quite common.

Cinematic_systems...Whoops! You are right that in a second order or higher passive crossover some power is "dumped to ground". For example, for the woofer, after the inductor rolls off the highs, a capacitor to ground rolls them off further. However, I don't believe that the "dumped" power amounts to much, as the "dumping" starts near zero at the X/O frequency and increases at 6 dB/oct, but working with an input that is already rolling off at 6 dB/octive. Perhaps there is an EE out there who still remembers how to calculate the "dumped" power in a second or third order crossover. Fourth order would involve a second "dump".

If Sean is right, and we all got rid of passive crossovers, perhaps the global warming problem would be solved.