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):-)

Boy, you've opened a potentially big can-o-worms. I have no idea who is right, but there are those who maintain that it is far easier to damage a speaker with a low powered amp that clips than with a high-powered amp. I believe the theory is that when an amp clips, it outputs something akin to a square wave. A square wave is a sine wave with a series of harmonics. In other words, a clipped wave has more energy in the upper frequencies than the original waveform, and therefore, more energy is sent to the tweeter which burns the tweeter out.

I have no idea if this is true. I don't understand how anyone can run speakers so loud that they can be damaged. Long before damaging levels are reached, the woofer bottoms or the amp clips and makes a horrible sound, and any sane person backs the power down.

As far as sonic concerns (i.e., aside from the damage issue) I am not in the more power is better camp. With tube amps, I don't know of any pentode amps that match the sound quality of triode amps or SETs, assuming the speaker is efficient enough to work with the lower powered amps. With solid state, I like the sound of lower-powered amps, particularly those running hot (generally class A) over a really big amp that is loafing along at a fraction of its output. Solid state amps with huge banks of multiple output devices often sound flat and uninvolving to me. Maybe they really kick ass at high volume, but I never want to go there anyway.

Before anyone wanders off on a tangent...It isn't my intention to run any amp at clipping for any length of time beyond the time it takes to turn the volume down..and not to go to clipping on any regular basis. SL's point was only that the amp will bottom out before the driver does.

I know that clipping is harder on drivers than than clean power...my interest here is the time frame....is the extra power only needed to fill out the millisecond peaks. I don't think anyone would choose to power a driver into submission..not much point to that.

Eldartford...planar speakers are a whole nuther topic.

The clipping of a low wattage amplifier frying tweeters is a myth. A square wave is the sum of a sine wave plus all of its harmonics with amplitude 1/n. The third harmonic has barely 1/10th the power of the fundamental. Real world numbers are even better. Music has a disproportionate amount of power in the bass range so those notes clip first. With a low tweeter cross-over like 1440Hz as used in the Orion the tweeter won't see anything from a clipped 200Hz tone until the 7th harmonic which is 17dB down from the fundamental. More typical cross-over points will result in even less energy reaching the tweeter.

When you're clipping bass notes increasing the volume setting can't make them any louder. Unfortunately this does increase the high frequency energy to far beyond what you have with music. Speakers designed with some level of power handling for music can handle a lot less when all of the energy is at high frequencies. You won't have problems if you don't act like a drunken teen ager who insists on turning up the volume on a distorting system.

The SPL from a speaker is a simple function of the air it displaces, which is a function of excursion, which is proportional to the drive voltage. When you increase sensitivity you move more air with less voltage. When you're limited by excursion more power isn't going to get you any more peak output.

I built and own a pair of Orions.

Since they're active speakers and don't need to pad down higher sensitivity frequency ranges to match the least sensitive, sensitivity can vary with frequency.

The variation is radical as a consequence of driver count differences (two low frequency drivers get you a 6dB sensitivity increase), radiation space changes (there's a full to half space transition from 200 - 100Hz which gets you another 6dB at 100Hz and below), dipole roll-off at 6dB/octave, and the extremely low Q woofers (about .2 before equalization, loosing 14dB at their resonance arround 20Hz). Dipoles also don't need baffle step compensation which can cost a conventional monopole designed for free space placement 5dB in sensitivity.

At 80Hz woofer sensitivity is about 97dB/2.83V/1 meter. If you drive them with amps producing 60W into 8 ohms on the verge of clipping you'll get 114dB out of them. A 150W amp would get you to 118dB, although midrange excursion/power is going to limit how loud you can play without loosing hi-fi distortion characteristics.

Things would be different on paper with most passive speakers. At a not atypical 87dB/2.83V/1 meter you'd need 600W for the same bass output and a more sensitive 90dB/2.83V/1 meter would take 300W. But you don't need the same volume - a 60W amp would still get you 105 and 108dB from such speakers. Solid state amplifiers give you enough wattage that power isn't a problem in most domestic situations.

Orion sensitivity and maximum output are low in the last octave although that doesn't matter because there's little musical content and the the equalization is 6dB down at 20Hz.