Subwoofer speed is in the room, not the box

If you put the mains through a capacitor that was not previously there, what does that do to the overall phasing of the drivers, including the mid and high that now have an additional capacitor in their circuit?

What influence would this have on soundstage and imaging?

I run my speakers at 2.5 ways using an 18", a 9.5", and a Heil. I’ve put the cap on the 9.5" (run as three ways) and it is a loosing proposition as I lose a lot of the low end volume near the crossover frequency. I’d never considered it with respect to soundstage and imaging.

Also, different types and makes of caps have slightly different sounds. It seems that putting a cap on the mains will then create some degree of coloration that would not otherwise be there.

In another vein, yes a small sub is "faster" than a larger sub at the same volume level.

Ultimately the volume is directly related to the volume of air moved. Because a smaller cone must move further to displace the same volume of air as the larger cone, and it must make its displacement in the same amount of time (Hz), it travels a further distance in the same amount of time. Speed is defined as distance over time and a faster speed means that a further distance is moved over the same time frame.

So, then, the smaller cone is ligher making it easier to move, possibly reducing "flop/flutter".

But again, the cone travels faster and force is defined as mass times velocity squared. So while mass is a linear function, speed has more impact on the force required to make the cone change direction because it is based on the square of the speed and these forces must be overcome at each cycle of the cone.

@mijostyn wrote:

I have no experience with horn subwoofer. For most of us they are impractical do to size constraints. For sure distortion will be lower for any given size driver due to efficiency. They problem is low bass will rattle and resonate almost anything. IMHO is is much easier to make a small enclosure resonance free with clever design and balanced force construction. It will not come remotely close to the efficiency of a horn but is way more practical from a size perspective.

"Practicality" mostly comes down to convenience, aesthetics and making a decision about something, not what's strictly and barely possible to physically and acoustically integrate in one's home surroundings. You are right about the majority of audiophiles balking at grand size, to which manufacturers certainly cater, but who cares about the majority of opinion when all that matters is meeting a performance envelope in a dedicated listening space, from a DIY-approach and defined by oneself? I don't care about practicality or what's at first easy, as long as the damn things can get through the doors and be properly located in the listening room. Done. Henceforth (or for a while) they're no longer impractical and are well out of way in their respective corners - even at 20 cubic feet per cab. It's really about the will of things and what one sets his mind on.

And you don't think 8x12" sealed cab woofers crawling below 20Hz can make things rattle at elevated SPL's? My TH's will bend the windows at war volume, but there's no reason to go there. It's about how they sound at listening levels we're usually exposed to, and that there's an abundance in reserve even at our max. desired SPL's. Ease of reproduction is paramount. 

Please keep us updated on your quad cab subs development. They look great even with raw surfaces, and I'm sure the sonic outcome will turn out to be quite awesome. 

You are doing exactly as I suggested for crossover and slope. The game is keeping the sub out of the midrange or you will have mud. You are running 85 Hz @ 36 dB/oct. If you move up to 100 Hz you will have to steepen the slope.

We'll see what comes of it. If we're able to sufficiently clean up the upper band of the TH's I feel rather confident maintaining 36dB/octave slopes will do fine. 

I can change crossover points and slopes on the fly which is very helpful for AB comparisons. 

As can I. 

@phusis Thanx!

I think it is more a matter of, you have this idea in your head and dam the torpedoes you are going to do it regardless. I certainly am that way. Each enclosure has 84 individual pieces. I have a total of 4 coats of polyester lacquer to spray, wet sanding between coats and the last coat has to be sanded 4 times to 2000 grit then polished two times. I am putting together a pictorial diary of their construction in case someone wants to give it a go. I am not making any more for any reason ever. 

I have a much different situation than you. My main speakers are line sources all the way down to 1 Hz. The subwoofers, in order to match the volume at increasing distance have to act like line sources. I achieve that by spacing the drivers at the right interval right into both side walls so that they are acting acoustically as one driver, a bass line source array. No matter how large and powerful you make a horn it is still point source unless you space one every four feet from wall to wall. Instead of one very efficient driver in each channel I use four 12" drivers in each channel and 2500 watts per woofer. The over all distortion at any given volume below 100 dB (already too loud) is probably about the same. You do not see horns at big concerts any more. They hang two 40 foot curved line arrays and  A LOT of WATTS. Who cares about electricity bills? 

@100Hz and 36 dB/oct you will only be 20 dB down at 200 Hz. Imagine a phono stage with a signal to noise ratio of 20 dB. using 48 dB per octave you will be 60 dB down at 200 Hz which is low enough to be masked by louder signals. Other drivers are better at doing midrange than big woofers, that's just life. With ESLs there is a stark difference. If the subs run into the midrange you will easily be able to localize them which to me is very annoying. The subs are integrated correctly when the low bass is there, more felt than heard and you would swear there wasn't a sub in the room. 

BTW, I really am straying into solutions.  I am not saying you can't get good without a high pass filter, but rather, I find it a lot easier to get there.

In this sense, I'm 100% with Richard Vandersteen. :)