Best 6.5" round speaker?

[BadKachina]

It depends on how they are designed but... basically... yes.
It's easier for a network filter to deliver different frequencies to different drivers. There are designs that allow signal frequencies above a certain point to flow more easily to one driver and signal frequencies below a certain point to more easily flow to another driver.
In this case, the crossover filter network will not have to dissipate as much signal as it would if there is an independent crossover filter for each driver.
In the case of putting a capacitor on a tweeter, bass energy the tweeter isn't receiving is being absorbed in the capacitor and radiated as heat. If you were to remove the capacitor, you would find your tweeter will get really hot. The power has to go somewhere.
The capacity of the components is not the only factor in determining a crossover network's ability to handle power. The value of the components has a lot to do with it too.
In a 6dB Butterworth crossover design, it's pretty straight forward. You have a crossover point and all frequencies above or below (depending on the configuration of low or high pass) are basically shorted out. That is to say, signal at those frequencies is provided an easier return path than through the speaker. In this case, the crossover has to dissipate all of that energy. Still, the crossover point will largely determine how much power the filter network has to dissipate.
With a 12dB crossover (2 step ladder), the amount of energy each component has to dissipate is different again. 18dB would be your 3 step and 24 dB would be your 4 step ladder. ..... at least in a Butterworth design.
In other words, the number of turns on the inductors, as well as the value of the capacitors has a huge impact on the amount of power the filter is required to dissipate.... the power rating of the components has an impact on the amount of power the filter can dissipate.
With an active crossover, the same principles apply but it's all done on such low power signal that energy dissipation is not much of a problem.
The benefit of an active crossover is that downstream of the active filter, the amplifier doesn't have to amplify a bunch of signal that is only going to be absorbed by the crossover filter. That means less work and energy required of the amp... and no need to short out a bunch of unused signal at line levels in front of the speaker. It's a far, far more efficient way to go. ... but brings with it other problems that can be relevant in some situations.
Nice post Tom. Lots of good info.
Here's another thought to ponder. On my Focal Utopias, I'm running bridged 4 channel Fosgate Power 800's. So bridged they are about 500 watts per channel at 4 ohms. That allows me to have enough power for each set of mids to keep the gains at a minimun level and keep the distortion to a minimum.
The bad part is that when I first built the system I was destroying my tweeter crossovers and blowing tweeters left and right. I'm still running the Focal tn 51 tweeters but I had to go to a third order crossover with some resistors because the tweeter couldn't handle the power. I also ran two sets so that the tweeters are 8 ohm, to help handle the load. So one amp has two sets on it and the other has no tweeters on it. This made a huge difference in reliability. As for building my crossovers I have some audiophile nerds that deal in home audio build them for me. I have no idea how they come up with the stuff they come up with.
On Infinity crossovers, I have a set of Kappa's in my truck, that were in a customers boat but kept throwing his amp into protection mode. I put them in my truck with a JL amp and wouldn't you know it, same thing. I switched the crossovers out for some old Focal crossovers I had stashed for a rainy day and no more problems.
Those Infinity's gave me fits, in the boat and in my truck. I guess the amps were seeing a short when they would get too hot or the volume level got too loud. What a pos they are (the crossovers). The speakers themselves actually sound pretty decent and look well made though.

[Dave C]

thanks
I've used XTC foam baffles in the past. They work OK.
I can't say how they would perform compared to a tupperware container.... no idea but I'll share a link, in case you find the idea interesting.
The foam is pretty soft. That will raise the Q of the driver, which isn't necessarily the best thing. .... but it's also quite porous which would reduce the amplitude of the rear wave, which is definitely a good thing.
Again.... I'm not recommending them specifically and I'm not recommending them over the plastic container idea (I've never tried it). I'm just saying I've used them and thought they were OK.
XTC foam baffles (http://www.partsexpress.com/pe/showd...number=260-788)

[Froggystyle]

That is an impressive DB gain. More than twice as loud! Do passive crossovers really absorb that much power from an amp?
The Infinity Perfects are rated for 100 watts RMS. The JBL C608GTi are rated for 150 watts. Comparing the crossovers supplied by the MFG look pretty similar but not sure if they really are the same.
It isn't actually twice as loud, that is a misconception. It is considerably louder, but on an "A" weighted scale 92 is not twice as loud as 87. It is noticiably louder though.
Up near 150db, a 5 db gain does amount to nearly double the volume, as the exponential scale goes nearly vertical there. At 120 however, which was what the boat was earlier, the 5 db gain to 125 is considerable enough to really be heard. More important was the clarity and drive gain.

[Froggystyle]

On the subject of the tupperware enclosure... That is an easy fix, that I guarantee will help your sound. There are better enclosure designs by a lot, but none easier. Take your speaker to the store and find a Tupperware/Rubbermaid bowl that has a lip at the same location as your mounting screws. When you through-bolt the speaker, sandwich the tupperware lid between the nut/washer and the back of the panel they are being mounted to. You may have to make a cut in the lip of the plastic to allow the lip to sit flat where you drill it.
I put some dynamat on the back side of the bucket to add a little density and to keep it from oil-canning under load. It is also vented on the bottom and top with about a 1" hole to allow condensation to escape and water to drain if humidity has its way with your boat. Nothing worse than creating a bucket for electronics to sit in unless it is truly totally sealed.

[rivercrazy]

It isn't actually twice as loud, that is a misconception. It is considerably louder, but on an "A" weighted scale 92 is not twice as loud as 87. It is noticiably louder though.
Up near 150db, a 5 db gain does amount to nearly double the volume, as the exponential scale goes nearly vertical there. At 120 however, which was what the boat was earlier, the 5 db gain to 125 is considerable enough to really be heard. More important was the clarity and drive gain.
The decibal scale is logarithmic.
A 10 decibal increase is 10X as intense. Increase the db's another 10db's and its 100 times as intense. Add another 10db's to the base number and its 1000 as intense. An example:
* 100db base number
110 db's is 10 times more intense than 100 db's
120 db's is 100 times more intense than 100 db's
130 db's is 1000 times more intense than 100 db's
An increase of 100 to 103 db's is 3 times as intense.
Applying this scale to humans is difficult due to significant differences from one set of ears to another and the fact that human ears amplify certain frequencies (typically 1000hz to 4000hz).
It takes twice as much power to equal a 3db gain. Those passive crossovers must absorb a butt load of power...........

[Tom Brown]

An increase of 100 to 103 db's is 3 times as intense.
I assume this is a typo.
It takes twice as much power to equal a 3db gain.
3 dB is a notation for doubling a value. 10 dB is 10x times, just as you have outlined.
Your post misrepresents the gains of sound pressure increases. Psycho acousticians have determined that human sound perception is approximately logarithmic in nature. That means, a 10 fold increase in sound pressure will be perceived as approximately a doubling by the people listening, exactly as Froggystyle indicated.

[rivercrazy]

I assume this is a typo.
3 dB is a notation for doubling a value. 10 dB is 10x times, just as you have outlined.
Your post misrepresents the gains of sound pressure increases. Psycho acousticians have determined that human sound perception is approximately logarithmic in nature. That means, a 10 fold increase in sound pressure will be perceived as approximately a doubling by the people listening, exactly as Froggystyle indicated.
Your right. I meant to say an increase of 3db's from 100 to 103 decibels is 3X as intense.
My post focuses on the science of sound "intensity" not SPL heard through the human ear.

[Beer-30]

Yeowch!
http://www.woofersetc.com/images/products/4312.jpg
Focal Kit N°7 - Focal Utopia Be 6.5" 3 Way Component System
3-way,6-1/2" (16,5cm) "W" woofer, 3" (8cm) "W" midrange, 1" (2,5cm) Beryllium tweeter
Frequency response (+/- 3 dB): 55 Hz - 40 kHz
Nom. power handling: 100 W
Sensitivity (2,83V/1 m): 89 dB
Nom. Impedance: 4 ohms
Voice Coil Diameter: 40 et 25 mm
Voice Coil Height: 17 et 8 mm
Xmax: 5,5 mm
This system is also available as N°7 Active version (without Crossblock filter)
Our Price: $4,165.99

[Tom Brown]

Your right. I meant to say an increase of 3db's from 100 to 103 decibels is 3X as intense.
In this case, you are incorrect.
Sound pressure doubles every 3 dB.

[rivercrazy]

In this case, you are incorrect.
Sound pressure doubles every 3 dB.
Not really. The definition of "intensity" as it pertains to measuring db's is different than "SPL" per the human ear.