"Power hungry" speakers

El: My main system is actively crossed. No capacitors between amp and speakers other than the speaker cables themselves.

My Brother's system was previously quad-amped using passive networks a while back. He is now actively crossed and the passive networks came out of the system. The difference between active and passive was staggering to say the least. Bare in mind that the passive networks were VERY simple first order designs.

Sean125: The chart that you provided doesn't take into account the speaker going into compression and is also based on 1 meter spl's. Taking measurements at the seated listening position would alter those readings DRASTICALLY.

What others may find interesting and i find to be "coincidental" is that the mains in my HT system are rated at 87 dB's @ 1 w @ 1 meter. I was running these with two amps and passively biamping. I had 400+ wpc up top and 500+ wpc on the bottom end. When running these in two channel mode, even with this much power, i could drive the amps into saturation. Moving to a single amp that is rated at 1200 wpc and clips at slightly over 1450 wpc gave me the headroom that i needed. Not only does the system play louder, it does so in a cleaner fashion.

With that in mind, those interested in being able to sustain high spl's and / or obtain very dynamic peaks might want to print out and save the chart that you provided. They should also consider that they will be running two speakers when in stereo mode, so you effectively double the spl level for the same rated power output. As such, things are looking better in terms of trying to obtain clean dynamic output with lower power. Only problem is that most speakers WILL go into noticeable compression when you start throttling them.

The mains in my HT system are 4 ways with 5 drivers, limiting the power and bandwidth that any given driver has to deal with. If you want to "crank" the system and maintain linearity, you either have to use this type of approach ( multi-way with large surface area ) OR you can go with fewer crossover points, but use more total drivers i.e. two way line arrays, etc... Line arrays tend to maintain spl's better into the distance, so they are well suited to situations where you have a longer rooms and / or further listening positions.

Lots of variables in selecting speakers and there are quite a few different ways that "linearity" comes into play. Sean
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Well room etc ...all play a roll...I do not disagree with what you are saying but I think you know what I am getting at

Sean..So you have your capacitors in line level circuits instead of in the speaker circuit. Can you describe why these capacitors are OK, while others are fraught with problems?

I gather that you drive your tweeters directly from full range power amps (trusting the input signal to limit LF output). Isn't this a bit risky? It seems to me that the inductor based high pass filter would be ideal for tweeter protection.

In the past I have had many biamp (and multiamp) systems. When stereo was introduced I "canibalized" a biamp system to get the necessary two channels. I do believe that modern amplifiers have very much reduced the advantages of biamping, except for extreme situations like pro sound systems, and that biamping between a subwoofer and mains (which I still do) is where it is still worth the trouble.
When I say "in the past" I am talking of 10 watt amplifiers with 1 percent IM distortion. That's when biamping really helped!

Dazzdax, to get back to your question....Driver manufacturers have to balance efficiency, durability, linearity, smoothness, and frequency response, at least, to provide an excellent driver. Limiting factors is smaller two-ways are almost always the bass roll-off of the smallish woofer in its chosen bass alignment in a given volume (with or without vent, etc.). Usually the result is a rising frequency response unless crossover components are used to roll the mid/woofer off. Almost always tweeter sensitivity is higher than the mid/woofers used, so the tweeter must be "padded", usually with a resistor, to bring the response down to the desired spectral tilt. Lots of tweeters are left pretty "hot", resulting in that "tipped up" or "bright" response of some manufacturers' designs. This can also make it a bit easier to slightly inflate an efficiency spec, or at least provide a louder response with a given input signal. Other designers, seeking a warmer response, will pad the tweeters more, resulting in a fatter perceived bass, but resulting in lower overall efficiency, and the requirement of turningthe gain up to achieve a desired loudness.
Balancing bass response and extension with a chosen upper octave spectral tilt is the meat and potatoes of this, not power absorbed by simple crossovers, nor tweeter resistors, as they're operative above crossover frequency.
Indeed, adding MORE drivers, all other things equal, will increase efficiency nicely, just like using a bigger amp. ence the use of 3-way designs or multiple woofers. So in a simple way, you can see that a formula is to use as many woofers as necessary to match the sensitivity of the tweeter, for max efficiency using these drivers. Since lots of OE tweeters have sensitivities in the 89-93dB/w range (I'm guessing), it's pretty easy to design speakers with highish efficiencies if you use enough woofers and/or box volume to get equivalent efficiency in the bottom octaves. Dorealize that voice coils get REALLY hot...with consequent non-linear response, changes in resistance, blah blah. If a driver manufacturer uses too small a voice coil gap to increase motor efficiency they risk insufficient heat-sinking so the driver blows up...or even scrapes as it hangs off-center! Huge ss amps have allowed woofer manufacturers to design relatively inefficient drivers that are durable. Problem is you need to push 'em to get a lot of bass response, or again use a big box, or multiple drivers, pushing up costs dramatically.
I look to the Spendor SC3 center channel speaker I use, as a simple example. It uses two 5" mid/woofs and a 3/4" tweeter, and sports 88dB efficiency, exactly matching the 6.5" two-way S3/1P's that comprise my HT front trio. I could have bought the SINGLE-woofer S3 (old LS3/5) versions, but these have damped tweeters squashed down to match the much lower sensitivity of using only one woofer, and thus spec at 84dB or so (there are vent and box volume diffs too, the efficiency difference isn't exactly algebraic). You might have asked why the same-tweetered speakers have such a different rated efficiency (sensitivity). Now you know. Hope this helps.

El: active crossovers betweem preamp and amps, not passive. Sean
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