Active Crossover?

It seems that for our set-up, we will need some kind of an active crossover in our demo car: a 2001 Corvette. We have the following: Our company's Entertainment/Information System (PC) An Audigy 2 NX (external sound processor) Amplifiers: JL Audio 1000/1 JL Audio 500/1 JL Audio 300/2 Speakers: 2 - 12" JL Audio 12w6v2 subwoofers (in the back) 2 - 8" JL Audio 8w3v2 subwoofers (in the doors) 2 - (3-way Component Set) - JL Audio XR653-CS (for the doors/kickpods) The 1000/1 controls the subs, the 500/1 controls the 8" subs, and the 300/2 controls the 3-way set. My questions is: Is this system basically considered a 2-way, in terms of an active crossover set-up? We are looking at ordering an AudioControl 6XS, will this be adequate to run this set-up? Can we do this with a less-costly active crossover? Thank you for the feedback in advance!

Firstly, running 8s in the doors off a mono amp is BAD... the frequencies you will be running to 8s in the doors are high enough that you SHOULD be running a stereo amp. In answer to your question though, I personally believe this will be much closer to a three way system. You will have a crossover point between sub and 8s, and between 8's and components. Three driver complements - three way crossover. And finally, yes, the 6XS will do what you want, and a really nice piece of gear as well. Why would you even consider all the time and energy you are considering for this install, then cheap out on your signal processing? Spend the money... You may need to build your own crossover modules for it, though. It will most like NOT come from the factory crossed over the way you will need... Suggestions for crossover points (and these are the way *I* would do it - yours and others mileage may vary): Seeing as you have 8s in the doors, 50Hz and down for the subwoofer (so you can CALL it a subwoofer rather than a detached woofer) 50Hz to 200Hz for the 8s and 200Hz and up to the component sets...It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

Now ehhh... some of this equipment choice seems... well.. very poor. Like 'burning your money' poor. First off, the 500/1 , like heamph says, has no place in your system, remove it and use a 300/2. Now, the second thing really jumping out at me is the amplifier choice for your mains.. have you considered using the 450/4? The onboard xover on the 450/4 makes it natively useful to bi-wire a componet set, as the 150x2 channels on it have a built-in bandpass xover... I'd highly recommend you take a look over there and perhaps at a more conventional 2-way componet set.. like perhaps the ZR series.... seeing as you plan on using dedicated midbass... which... incidently, you are going about completely the wrong way. The 8w3 is not designed to be used 'infinite baffle' ... that is.. it is designed to be in an enclosure, not inside a door ... that isn't going to be an enclosure that will allow that speaker any sort fidelity.. let alone the fact that *is* designed as subwoofer driver, not extended midbass.. I'm not even sure if the driver has a rated response up at 200hz or so. For that matter, why you would even consider coloring such beautiful speakers like the 12w6 with the low-end, middling speaker that is the w3, is totally, and completely, beyond me. You really need to re-evaluate your entire install."I'm finished!" - Daniel Plainview

WOW... tough room! LOL A few more observations, based on sedate's reply.

sedate wrote: Now ehhh... some of this equipment choice seems... well.. very poor. Like 'burning your money' poor.

Not necessarily... I agree, there are certainly some choices that definitely need reevaluation, but "burning your money" sounds a little bit harsh...

sedate wrote: First off, the 500/1 , like heamph says, has no place in your system, remove it and use a 300/2. Now, the second thing really jumping out at me is the amplifier choice for your mains.. have you considered using the 450/4?

I don't know what amps JL offers, so I reserved suggestion...

sedate wrote: The onboard xover on the 450/4 makes it natively useful to bi-wire a componet set, as the 150x2 channels on it have a built-in bandpass xover... I'd highly recommend you take a look over there and perhaps at a more conventional 2-way componet set.. like perhaps the ZR series.... seeing as you plan on using dedicated midbass... which... incidently, you are going about completely the wrong way.

The three ways will do fine, and in MOST cases offer a better soundstage than the two way systems - IF they follow the manufacturers suggestions and recommendations, especially regarding mid-to-tweeter placement... This will be the MOST critical driver placement in the ENTIRE system! Their 4 inch center to center placement recommendation tells me that the crossover point from mid to tweeter is around 3500Hz. This will do fine, but I will admit that when I suggested a 200Hz crossover from 8 to components, I did NOT consider the crossover point between 6 and mid... probably close to that suggested 200Hz. Call JL, and get the crossover point for the 6 to mid... sedate recommended an ADDITIONAL active crossover point, and I am not disagreeing with him here. One additional active stage crossing the 6 to the mid could not hurt, but take the crossover point to around 350 to 400Hz. What you end up with in this case would be ("A" stands for active "P" stands for passive): 12 inch 50Hz and down (A) 8 inch 50Hz (A) to 200Hz (A) 6 inch 200Hz (A) to 400Hz (A) mid 400Hz (A) to 3500Hz (P) tweeter 3500Hz (P) and up Sounds complicated, but it isn't. All you will be doing is giving the 6 inch driver it's own amp channel, and NOT connecting it AT ALL to the supplied passive crossover.

sedate wrote: The 8w3 is not designed to be used 'infinite baffle' ... that is.. it is designed to be in an enclosure, not inside a door ... that isn't going to be an enclosure that will allow that speaker any sort fidelity.. let alone the fact that *is* designed as subwoofer driver, not extended midbass.. I'm not even sure if the driver has a rated response up at 200hz or so. For that matter, why you would even consider coloring such beautiful speakers like the 12w6 with the low-end, middling speaker that is the w3, is totally, and completely, beyond me.

In a SUBWOOFER application, yes, it'd beat itself to DEATH in a door. Since you are planning on using this as a WOOFER, and actively driving the woofer with a DEDICATED amplifier channel, your excursion should not be high enough to cause any problems. At 24dB/octave, supplied by the 6XS, anything below 50Hz will be cut off so fast... ANY woofer will go to 200Hz. I have taken 15's to 200Hz. They sounded like crap, to be sure, but it WILL do 200Hz. The issue is inductance in the voicecoil, and beaming. 200 is perfectly reproduceable by an 8 inch diaphragm. That is right at the point where beaming will start to occur. Since SQ of the drivers is a such a completely suggestive quality, so I'll not say anything at all regarding that. Especially considering that I an not familiar enough with it to form an opinion at all...

sedate wrote: You really need to re-evaluate your entire install.

Not the WHOLE system, just some aspects of it.It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

sheesh! I wasn't trying to be harsh .... I just had this mental image of an 8" woofer beating inside a Corvette door right... and the driver, sitting there at the stoplight, testing out the new system, sunglasses, laid out all back in the seat right .... has absolutely no idea the 1/8" plastic/fiberglass body panel on the door is distorting in and out 100 times a second utterly destroying what appears to be a * gorgeous* paint job... And I seriously don't think that is going to sound very good. Even JL recommends against using its SUBwoofer drivers as midrange or infinite baffle... indeed, before that awful redo of thier website I could've linked to a blurb about NOT using thier 6w0 as a midbass or as an Infinite baffle speaker, as either will produce poor results... certainly the 8w3 isn't going to be the first choice here either. I think there are probably about a bazillion better choices for an 8" woofer... most of which can prolly be had for $40 over at partsexpress. If he wants sumthin to show off for a woofer application.. I dunno he can get that Adire Extremis or whatever ppl here like so much. That 8w3 is just the wrong driver all the way around. BUT all that is just about the 8"... I still think that is going to produce seriously marginal results anyway... particularly next to a 3-way componet set. heamph, of course every single OBJECTIVE thing you said was correct.. but the most impressive statement was the *one* subjective thing you said:

heamphyst wrote: Sounds complicated, but it isn't.

AHAHAHA.... ur such a gearhead. What we did to *MY* front stage was complicated... *this* is ... IMO, a total mess. The mixture of passives and actives, particularly the passives up top, make proper adjustability really questionable to me. One thing I've begun to appreciate having all actives channels in my car, (and I only have 3) is the chokehold I can (and need to) exert over every speaker to reach sweet spot I'm aiming for.. The fact that the mid-range and tweeter are NOT going to be independently adjustable here I think is going to be a *severe* limitation to proper system tuning, particularly with all that garbage down below. To me, as I read your system-plan, I see something that isn't realistic, just technically feasible. I can think of a dozen variations on this system but regardless, I really think if we're seriously looking at dedicated midbass, there is *no* concievable gain (at least, far, far past diminishing-returns) in an actively crossed 3-way componet set up top... Here is what I would do... to simplify things, remove all (but one) passive xovers, and have a *damn* fine bi-amped system: Ditch the whole AudioControl box.. we do this more elegantly.. Amplifiers: 450/4 300/4 (We're using this as a 2-channel, but it costs the same as a 300/2 and has 2 more channels.. so I'm not really sure the point of the 300/2... ) 1000/1 Speakers: A high-quality 2-way componet set(but this would *not* be my choice..) A high-quality subwoofer.. And of course, our elusive high-quality midwoofer/midbass/woofer/whatever Now we have our equipment... First, we take the 450/4 (heamph you've never looked at this amp!? It gives me goosebumps!) and bi-wire it to our midranges and tweeters directly to the amplifier. heamphs xovers points are perfect and all selectable from the amp natively. Next our 300/4: Here we unfortunately need our single passive xover... this will be a simple custom job ... at least I'm guessing. I've never built my own xovers before, but I just spend 5 minutes reading this and playing with the calculator and it looks like a simplistic (as far as this nutty system goes) matter.. anywho.. the 24dB/slope is what I'd use this low in the spectrum... but I didn't see calculators for that so .. eh "3rd order high-pass" or whatever.. Anywho, low-pass the amp, which is bridged to our midwoofers, at 200hz or so, and passive it with a ... I dunno I really don't think you should go so low as 50hz.. But either way.. you guessed it.. the low, low xover point and midwoofers really gives me pause at the *pair* of 12's... perhaps something bigger would better handle such a LOW low-end... and, IMO, be as technically impressive.. Indeed, have you considered a pair of 300/4's, the ZR's (or XR for that matter) built in bi-ampable xovers? Then wiring one 300/4 to the componet set and other, as outlined above, to your midbasses?"I'm finished!" - Daniel Plainview

WOW.. I had no idea this would start such an in-depth topic here. I really appreciate you guys explaining the details of your answers. I will have to sit down and look over every option that you have presented more thoroughly, and apply it to the aspects of the system that will *have" to be used in this install. I just want to make something VERY clear about the doors: they are being sound deadened inside, both the far back panel (exterior) and the closer door panel, both have TWO (2) layers of B-Quiet Ultimate on them. The doors are being sealed as MUCH AS POSSIBLE so that there is VERY MINIMAL, if any cancellation going on. The three drivers that will be custom installed in the door will be air tight. For the doors, we are making a custom adapter (mounting bracket) out of fiberglass and resin, basically replacing the factory mounting bracket, only fit for our three (3) drivers. This adapter will be sealed well to the door, so that the back of the drivers (inside the door) will be completely sealed off from the outside of the door... creating a *sealed enclosure*. Of course, we cannot seal the part of the door where the window comes in and out of completely... but this will be as good as it's gonna get. Keep in mind: the doors have an OEM, from the factory bracket inside of them that is made for a very flat 8" subwoofer, and a 3.5" midrange/tweeter. Thus, we are basically using the same principle as the factory: -The Door -An Adapter -Door Cover (actual door panel) The 'Door Cover', or the visible door panel will NOT be sealed in any way... it is simply custom made out of fiberglass and *Suede* to be cosmetically pleasing to the eyes. Thus, the only important aspects of the door, adding to the actual funcionality of the door system will be the actual SEALED door and the adapter that will hold the two/three drivers. There are a few reasons why we have chosen to go with a system that has an 8" driver. The reality of it is that we ARE going to use the 8w3v2 because we have bought it, just like we have already bought the XR653-CS 3-way component set. We have NOT bought the 12" subs, Amps or Crossover. I do appreciate the suggestion to substitute the 8" subs, but we are trying to go with ALL JL AUDIO equipment in this car. This is how the speakers will be set-up, remember that I am open to suggestions: the 6.5"s will be in the door pods that are next to the legs, and pointed up into the CENTER of the vehicle. The 8" subs, will be in the door, and the 4" midrange will be on TOP of them. These will basically touch at one point, and will be angled so that the point where they touch will protrude outwards. Thus the 8" sub will be pointed slightly down, while the 4" midrange will be angled slightly upward (ideally angled at the center of the vehicle).Think of a 90 Degree angle... the two legs of the angle will be the drivers, and the hypotenuse is the actual door. The 1" TWEETER in each door, will be right next to the 4" midrange, pointed in pretty much the same direction as the midrange. I hope this gives you guys a much better picture of how the door drivers will be positioned. The 8" sub should not disrupt the 4" midrange, even though they're using the same airspace in each door. Any suggestions or problems that you guys can forsee with this set-up? Is there basically no need to use the two (2) Passive Crossovers that the components speakers will come with?? In other words, should we just have ALL the drivers run DIRECTLY off of the amps? *controlled by the Audiocontrol 6XS Active Crossover, of course* ANY additional suggestions and comments would be great! Thanks a lot so far guys.

<deep sigh> Oh boy okay.

blazinls1 wrote: The doors are being sealed as MUCH AS POSSIBLE so that there is VERY MINIMAL, if any cancellation going on.

Huh? Cancellation is an effect of multiple drivers playing the same frequency.. I'm not sure what the doors have to do with it..?

blazinls1 wrote: This adapter will be sealed well to the door, so that the back of the drivers (inside the door) will be completely sealed off from the outside of the door... creating a *sealed enclosure*. Of course, we cannot seal the part of the door where the window comes in and out of completely... but this will be as good as it's gonna get.

Oh boy this entire plan is probably the absolutly worst way to go about installing such nice equipment it seriously makes me almost crazy.. look, its not my Corvette, but if you *insist* on installing those 8"s, you are really, I'm telling, going to render your stereo completely retarded. You can kiss whatever fidelity you have in the car goodbye... as well as spend another $300 on the amp to do it. I know you want a car full of JL stuff but you bought something you can't use. I'm sorry. Not only do you NOT have a sensible range which to even run them, you do NOT have a proper way to install the thing.. custom adapater bracket/door panel or not. Dude I know this makes perfect sense in your head but it is NOT going to work... you have to have the *right* sized sealed enclosure... and it has to be sealed. Like airtight. Not only 'sealed' except for the part where the window is. SEALED. Not only is the woofer not going to play properly this way, you will probably hear a "pssst" escaping from your windows seals when your woofer plays. That should sound nice.

blazinls1 wrote: The 8" sub should not disrupt the 4" midrange, even though they're using the same airspace in each door.

WHAT?! What do you base this statement on? I'm sorry man, as you make it, this statment is *completely* incorrect. By virtue of the fact that they share the same airspace, and the 8" woofer will be BEATING THE BEJEZUS out of that airspace, you will be *constantly* changing the air pressure in your psuedo-sealed 'enclosure' ... and the 8" woofer will *constantly* color (read=destroy) the response of that little midrange. And the airspace of the 8" will be changing as it plays... which, again, colors the 8"'s output. Not going to work. Sorry man. Not a viable plan, at all. The ONLY way you can install those woofers to build completely sealed enclosures, of the proper airspace... minimally .5cft... we're talking custom fiberglass pods built onto an MDF frame here... not a fiberglass 'adapter'... what you are going to do is simply sonically unexceptable.. I mean.. I'd continue to address the rest of your system and help you make it sound amazing.. you certainly are willing to spend the money... but as long as you insist on using the 8"'s, ESPECIALLY with the plan you have for thier installation.. which is flat out incorrect and *WILL* destroy the fidelity and possibly mechanical reliablity of the remainder of the componet set.. there really isn't much else I can say. "I'm finished!" - Daniel Plainview

That's a weird looking subwoofer.

Dude, I'm really sorry if you feel attacked. I only mean to help you.. Look. The jumps in logic you making from the stock Bose system and the cabinet speakers bely a misunderstanding about the SPECIFIC drivers you are using and the way you explained your plan to install them. What you want to do will not work properly, I don't care about whoever said what in whatever thread. You didn't post any links so I'm not going to bother searching. So, once again, from the top:

blazinls1 wrote: Hmm... so how is it that the stock Bose system is fully capable of pushing two drivers in my door without any serious sound issues? It has a thin 8" woofer, with a 3.5" midrange on top of it. YES, they are both using the same airspace of the door. Keep in mind that the door is VERY POORLY SEALED. There were holes all over the place when we took the door panel off.

Again, this is WHY it works, not why it shouldn't... you are using, you yourself said, a THIN 8" woofer and a smallish midrange... in something that IS NOT sealed. Do you understand air pressure? This is exactly WHY it works in the case of the stock Bose system.. First and formost is the driver in the Bose system.. it is designed to be mounted in a door, and designed to be used Infinite Baffle... it doesn't have any real excursion to speak of and runs on probably less than 20watts/rms... Now, it is NOT SEALED. Which means that the air pressure inside the door, if increased, vents to whereever it is normal. Read up on Bernoulli's Law okay. So like you said, the stock Bose system sounds great. You are making an egregious jump in logic here, one that will cost you the life of your little XR midrange, and the fidelity of both speakers. Now the 8w3 is NOT an Infinite baffle speaker, so right off you are making a poor choice. I'm not sure if you think every 8" speaker is just like another, but this seems to be your implication. If you mount it like you want to in your door, you have to build a sealed enclosure for JUST the 8, and foam certainly won't do for a w3. There is a MASSIVE, MASSIVE difference between the little Bose woofer that came in your door and a freakin JLw3 getting a 150 JL Watts okay? ONE of those w3's will push more air than your ENTIRE stock system did before so stop trying to compare the two. Furthurmore, as you described, for some reason you plan on (almost) sealing them off, alone, with a little 3.5" midrange in a smallish airspace. This is precisely the OPPOSITE of what was originally done to your doors.

blazinls1 wrote: "Remember that huge tower speakers, or concert speakers have MULTIPLE drivers in each cabinet, ALL sharing the same airspace"

Again, this is a jump of logic that, as you describe your installation is NOT applicable. First off, cabinet speakers like this typically have multiples of cubic feet.. not the rat-hole space of a pseudo-sealed door okay? And AGAIN, these are DIFFERENT drivers, designed to be used together in these applications. Here, your XR midrange is certainly fine for this.. your JLw3 is NOT. This is what I keep trying to tell you. The 8w3 is not a driver to be applied this way.. there ARE a BAZILLION drivers that are... *including* the woofer that came with your XR componet set..

blazinls1 wrote: What cancellation is, is when you have a speaker playing at a frequency, and you have.. let's say another speaker pointed DIRECTLY at it, playing the SAME frequency, but 180 degrees OUT-OF-PHASE.... THAT is when you have cancellation.

This is correct, yet, unfortunately, misapplied:

blazinls1 wrote: That is why in a sealed enclosure, you have the front part of the speaker COMPLETELY sealed from the back part of it, or vice versa. The sound waves in front of the cone are moving 180 degrees out-of-phase from the BACK of the cone. If the Corvette's doors have holes in them, then that basically means it is not doing a good job of creating a sealed enclosure, thus causing cancellation.

Who told you this? Sheesh. A sealed enclosure isn't sealed because it needs to prevent cancellation or whatever, it is sealed because this provides the woofer cone with the most linear movement it can produce.... the air acts as a fixed spring for the cone... this is why a sealed box is 'sealed'... not only that, but the rear sound waves can add significant breadth to sound.. kinda the whole concept behind the ported box.. uhh.. anyway I'm getting kinda pressed for time but otherwise I'd run the numbers for you and show you that indeed, there is *no* cancellation going on in your Corvette... especially at those frequencies.. ..anywho.. "I'm finished!" - Daniel Plainview