"Power hungry" speakers

Ah Sean, I still love ya!

Actually, Sean, passive x-overs CAN be great:) Passive LINE-level x-overs yield excellent!
Goodbuy opamps (good thing, IMO), hello caps (not so good). Or, one could use coils (less losses than caps -- BUT who's got the patience & the workmanship to make them, to required specs...)

But that's still PRECEDING the amps; amps still driving voice-coils directly (an excellent thing IMO).

Overall, the story of our lives seems to be that good/v. good/ excellent amps drive less than stellar quality x-overs, rather than the speakers' drivers... Oh well

Op-amps can sound quite good when properly selected and implimented. Obviously, there are vast differences amongst Op-amps. Stereophile ran a very interesting article on the subject a few years back. Sean
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Sean, I'm not a techy. I just want to understand where your inverse equation (more efficient = less distortion) figures fit into my least efficient speaker's spectacular performance.

There must be some serious variables skewing the distortion versus efficiency equation. Take, for instance, the tweeter/mid ribbon array in my speakers. My speaker's 50' of naked aluminum ribbons, governing all signal above 700 hz, cost my speakers dearly in efficiency.

I have heard hundreds of vaunted systems at homes, and shows. I wouldn't trade my amp burners for any one of the speakers in those systems.

I honestly have never heard more true to life speakers.

Some distortions are not "additive" in nature i.e. they aren't creating / adding additional output on top of what the original signal had. This means that losing some ( any portion ) of the signal also equals to distortion. Since more power = more heat and more heat = thermal loss, you end up with more distortion from the speaker.

On top of that, lower sensitivity designs have to move more air to produce the same amount of air that a higher sensitivity design does. In order to do that, the driver has to make longer excursions. The longer the excursion that a driver takes, the more distortion that it will generate. Another side effect / drawback is that a longer excursion will also generate more reflected EMF ( electrical "back-pressure" ), making it harder for the amp to control & load into the speaker.

Besides those primary factors, the electrical characteristics of a speaker change as the power levels are raised. Depending on what power level / spl range a speaker was tuned or "voiced" at, one can end up running the speaker in a range where it is less accurate / running out of the linear pass-band of operation. Then again, the reverse is also true of a speaker that was tuned to operate at higher spl's being run at / not working as well at lower spl's.

As a side note, vented systems will suffer from what becomes a "roving resonance" depending on the transfer efficiency of the port itself. While ALL speakers end up raising their frequency of resonance as you drive them harder, "straight" ports or ports that are only flared on the exit side are much more sensitive to this phenomena than a double-flared port or passive radiator design. Passive radiators have their own problems though as they have the moving mass of the drone cone itself to overcome. This problem becomes more apparent / harder to deal with as spl's are raised. Since greater mass is harder to accelerate and / or stop rapidly, trying to do so with the longer excursions / more inertial momentum compounds the problem. This situation also occurs with sealed designs, but not as severely. That's because the pressure or "air spring" inside of a sealed box remains consistent regardless of the drive levels applied.

Other than that, most all of my speakers are sealed and of lower efficiency. This means that i need pretty sizable amounts of power to obtain good performance. On top of that, most are also low impedance designs, meaning that i need even more power to get them moving / keep them under control. Even with all of the above in mind and much like Muralman, the aforementioned trade-offs still aren't enough to make me want to get rid of them and move over to more efficient, but typically sloppier designs. The high efficiency designs that i do have ( 96 dB's and 104 dB's ) are both sealed. Since you can't get something for nothing and maintain linearity, the efficiency of the 104 dB design is achieved via horn loading. Due to the length and size of the horn used, low frequency extension is reduced. In order to obtain ultra high efficiency and maintain good extension, you have to go to a BIG horn like the ones that Mike aka Magnetar builds and uses. You can see what i'm talking about here on his "horny" website. The three subwoofer horns are the huge cabinets behind the mains ( they take up the WHOLE front wall ) and look like wood trim surrounding black centers. Yes, Mike is a "little" crazy, but he's a real nice guy. You just wouldn't want to live next door to him : )

The little 96 dB units that i have are horn loaded for the mids and tweeters, but not the woofers. As mentioned above though, you can't get something for nothing, so these too are also limited in terms of low frequency bandwidth.

By the way, the rear wave of a driver can be sealed or vented when using some type of front loaded horn. My larger horns are sealed and as far as i know, i think that Mike's MEGA horn's are too. Sean
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