[kaigoss69]

Originally Posted by Technic

My installation is exactly like that and still I had the occasional "thump" of the magnet against the grille... so off they went.

Where is your high pass filter set at?

Also, how is your mid bass after the SWS-8 went in, any improvement? Do you know where the L7 system splits the low to mid frequencies? In other words, how high does the frequency output of the sub channel go?

[Technic]

Originally Posted by kaigoss69

Where is your high pass filter set at?

Also, how is your mid bass after the SWS-8 went in, any improvement? Do you know where the L7 system splits the low to mid frequencies? In other words, how high does the frequency output of the sub channel go?

I think that the L7 high pass frequency is around 250Hz.

The sub to mid crossovers are active -inside the amp. The mid to high crossovers are passive- inline between the mid and the tweeter in the L7 system.

My system is an Individual Audio with the SWS-8 and aftermarket amps and processors, so I lowered the front/rear high pass to 200Hz. I found that at that frequency the SWS-8 and the OEM 4" sound much better together than at 250Hz+. Less than 200Hz and some of the strong bass is lost, so this is a matter of personal preference.

[Random456]

It looks like I'm reviving an old thread, but here's the answer. The OEM underseat enclosure can probably be modeled as a leaky sealed enclosure. The plastic molded enclosure has a large opening that connects to the side skirts. The gap is sealed with a foam trim. The combined volume of the side skirt and the plastic enclosure is likely to represent the the "enclosure volume" that can be modeled. However, what I don't know is if the side skirts open up into the outside air anywhere. If they do, this would approximate an infinite baffle design. I'm thinking probably not. I'm assuming that the side skirts add to the sealed box volume. It make sense that the volume must be bigger than the OEM plastic box alone, based on plugging in T/S parameters of the SWS-8 and modeling the design.

R

[Technic]

Originally Posted by Random456

It looks like I'm reviving an old thread, but here's the answer. The OEM underseat enclosure can probably be modeled as a leaky sealed enclosure. The plastic molded enclosure has a large opening that connects to the side skirts. The gap is sealed with a foam trim. The combined volume of the side skirt and the plastic enclosure is likely to represent the the "enclosure volume" that can be modeled. However, what I don't know is if the side skirts open up into the outside air anywhere. If they do, this would approximate an infinite baffle design. I'm thinking probably not. I'm assuming that the side skirts add to the sealed box volume. It make sense that the volume must be bigger than the OEM plastic box alone, based on plugging in T/S parameters of the SWS-8 and modeling the design.

R

I use 0.6cuft. as the modeling volume of each underseat enclosure + door sill. So far the SWS-8 does very well in simulation compared with other shallow subs in the 8" to 10" size.

[kaigoss69]

Originally Posted by Technic

I use 0.6cuft. as the modeling volume of each underseat enclosure + door sill. So far the SWS-8 does very well in simulation compared with other shallow subs in the 8" to 10" size.

I have trouble seeing the enclosure as a "sealed" one. A sealed enclosure is "sealed" or "air-tight" meaning absolutely no air can escape during transients. Here you have foam seals and a door sill that is apparently part of the enclosure, no way that sill is going to be air tight... noooo way!

Sorry but this is not a sealed enclosure. It can only be (taking the words from a previous poster) "simulated IB". And if you think about how IB works, it makes perfect sense! The enclosure satisfactorily separates the front wave from the back wave, and through the "extended" volume of the door sill, provides a "free-air" air environment by preventing pressure build-up inside the enclosure.

Technic, if you agree, how about modeling this for free air and see how it comes out? I tried but failed due to inconsistent Thiele Small parameters I have for this driver (WinISD gave me errors).

[Random456]

Originally Posted by Technic

I use 0.6cuft. as the modeling volume of each underseat enclosure + door sill. So far the SWS-8 does very well in simulation compared with other shallow subs in the 8" to 10" size.

I ended up installing 6" Morel's (MW167), using a 0.5" thick MDF spacer, and lining the OEM enclosure with B-quiet (similar to Dynamat Extreme) - and it sounds TERRIBLE. I've tried low-passing it anywhere from 200 to 500Hz with 24-48dB slopes. Still sounds terrible. The side skirts rattle and the entire seat and floor carpet vibrates with one-note-itis. I had the same problem when I powered the stock subs from 200-300Hz down, before any enclosure mods. I wonder if it's either the few inches between the seat panel and the floor that sets up a nice standing wave and messes up the frequency response. I also wonder if it's the vibration from the car's chassis under the seat + side skirts. Oh well. I think I'll try sealing the enclosure and seeing if that helps.

R

[kaigoss69]

Originally Posted by Random456

I ended up installing 6" Morel's (MW167), using a 0.5" thick MDF spacer, and lining the OEM enclosure with B-quiet (similar to Dynamat Extreme) - and it sounds TERRIBLE. I've tried low-passing it anywhere from 200 to 500Hz with 24-48dB slopes. Still sounds terrible. The side skirts rattle and the entire seat and floor carpet vibrates with one-note-itis. I had the same problem when I powered the stock subs from 200-300Hz down, before any enclosure mods. I wonder if it's either the few inches between the seat panel and the floor that sets up a nice standing wave and messes up the frequency response. I also wonder if it's the vibration from the car's chassis under the seat + side skirts. Oh well. I think I'll try sealing the enclosure and seeing if that helps.

R

I think I remember the "rule" for IB application drivers to have at LEAST 0.5 QTS (better 0.6 or 0.7) and it seems the driver you used has a QTS of 0.35 .... so if this is indeed an IB application, you seem to be using absolutely the wrong drivers! The lower the QTS, the less damping the speaker itself provides and in an IB application, you have basically NO damping from the enclosure. For flat frequency response at the driver's resonance frequency, the QTC (damping of enclosure plus driver) should be .707. Anything below .707 should be considered "boomy" and anything above "tight".

This is what I remember without having to Google all this stuff all over again. Hope this helps.

Also, its seems the SWS-8 has a QTS of .69, which is just about ideal for IB.

[Random456]

Originally Posted by kaigoss69

I think I remember the "rule" for IB application drivers to have at LEAST 0.5 QTS (better 0.6 or 0.7) and it seems the driver you used has a QTS of 0.35 .... so if this is indeed an IB application, you seem to be using absolutely the wrong drivers! The lower the QTS, the less damping the speaker itself provides and in an IB application, you have basically NO damping from the enclosure. For flat frequency response at the driver's resonance frequency, the QTC (damping of enclosure plus driver) should be .707. Anything below .707 should be considered "boomy" and anything above "tight".

This is what I remember without having to Google all this stuff all over again. Hope this helps.

Also, its seems the SWS-8 has a QTS of .69, which is just about ideal for IB.

I don't think the OEM "enclosure" can be modeled as infinite baffle. I'm under the impression that it's the equivalent of a sealed enclosure with a volume equal to the size of the OEM box + the side skirt that it extends into. This was my assumption when I chose the driver (along with the shallow mounting depth requirement), and the calculated system Q is "close enough" to .707. I doubt a miscalculation is the cause of the excess vibration of the seat+floor. I've seen a couple of E90 installs with 6" drivers posted here. One was a Morel and the other was a JL. I think that both used custom-made sealed enclosures. So I think I'll try sealing the OEM box next. Hopefully I can squeeze some B-quiet sheets on the metal floor underneath as well.

I'm curious if anyone has achieved quality, detailed midbass using the OEM location.

R

[Random456]

Originally Posted by Technic

I think that the L7 high pass frequency is around 250Hz.

The sub to mid crossovers are active -inside the amp. The mid to high crossovers are passive- inline between the mid and the tweeter in the L7 system.

My system is an Individual Audio with the SWS-8 and aftermarket amps and processors, so I lowered the front/rear high pass to 200Hz. I found that at that frequency the SWS-8 and the OEM 4" sound much better together than at 250Hz+. Less than 200Hz and some of the strong bass is lost, so this is a matter of personal preference.

Say, how's the midbass with the SWS-8's crossed over at 200Hz?

R

[Technic]

Originally Posted by kaigoss69

I have trouble seeing the enclosure as a "sealed" one. A sealed enclosure is "sealed" or "air-tight" meaning absolutely no air can escape during transients. Here you have foam seals and a door sill that is apparently part of the enclosure, no way that sill is going to be air tight... noooo way!

Sorry but this is not a sealed enclosure. It can only be (taking the words from a previous poster) "simulated IB". And if you think about how IB works, it makes perfect sense! The enclosure satisfactorily separates the front wave from the back wave, and through the "extended" volume of the door sill, provides a "free-air" air environment by preventing pressure build-up inside the enclosure.

Technic, if you agree, how about modeling this for free air and see how it comes out? I tried but failed due to inconsistent Thiele Small parameters I have for this driver (WinISD gave me errors).

I did model the SWS-8 in free air as well as ported and it also came out pretty good compared to the current Pioneer shallow subs and the Morel Elate 9 and 10; I'm using WinISD as well but no errors.

Those Morel Elate 9 and 10 look to me like solid mid-bass drivers than sub-woofers based on the simulations (sealed, ported, free air), though. They "die" at around 40Hz...

[Technic]

Originally Posted by Random456

Say, how's the midbass with the SWS-8's crossed over at 200Hz?

R

I tried 250Hz, 200Hz and 150Hz in my set up, and so far 150Hz sounds about where it should be in my system (Individual Audio). Mid-bass is tight, with some subtle sub-bass down to 32Hz. I think that my DQXS helps a lot in tuning these SWS-8 to match the OEM enclosures size and configuration, as I can move that crossover point back and forth in real time while I can raise or lower the attenuation of specific frequencies within those points.

I also think that a pair of 10" shallow drivers with a better response below 40Hz would be a much better underseat setup, so no trunk sub would be needed. Pioneer is coming sometime next month with their new line of shallow subs that are supposed to be much better than the current line, and they show a 10" and even a 12" that could fit under the seats in a custom enclosure but there are no parameters published yet to simulate how they will perform compared with the SWS-8.

[Technic]

Originally Posted by Random456

I don't think the OEM "enclosure" can be modeled as infinite baffle. I'm under the impression that it's the equivalent of a sealed enclosure with a volume equal to the size of the OEM box + the side skirt that it extends into. This was my assumption when I chose the driver (along with the shallow mounting depth requirement), and the calculated system Q is "close enough" to .707. I doubt a miscalculation is the cause of the excess vibration of the seat+floor. I've seen a couple of E90 installs with 6" drivers posted here. One was a Morel and the other was a JL. I think that both used custom-made sealed enclosures. So I think I'll try sealing the OEM box next. Hopefully I can squeeze some B-quiet sheets on the metal floor underneath as well.

I'm curious if anyone has achieved quality, detailed midbass using the OEM location.

R

I calculated that the box volume is around .13cuft and the sill volume is around .45cuft, thus I use .6cuft as the max volume.

[Random456]

Originally Posted by Technic

I tried 250Hz, 200Hz and 150Hz in my set up, and so far 150Hz sounds about where it should be in my system (Individual Audio). Mid-bass is tight, with some subtle sub-bass down to 32Hz. I think that my DQXS helps a lot in tuning these SWS-8 to match the OEM enclosures size and configuration, as I can move that crossover point back and forth in real time while I can raise or lower the attenuation of specific frequencies within those points.

Interesting that you're crossing over at 150Hz (4th order on your DQXS). Someone here RTA'd the stock sub and found that the underseat bass rolls off at around 100Hz, with what looks like a 2nd order slope. I wonder if trying to play up to 200Hz+ is causing the bad vibrations and/or otherwise poor midbass. When I get a chance, I'm going to try a lower crossover point. I'm using a Behringer DCX2496, which has continuously variable crossover frequency and slope.

I also think that a pair of 10" shallow drivers with a better response below 40Hz would be a much better underseat setup, so no trunk sub would be needed. Pioneer is coming sometime next month with their new line of shallow subs that are supposed to be much better than the current line, and they show a 10" and even a 12" that could fit under the seats in a custom enclosure but there are no parameters published yet to simulate how they will perform compared with the SWS-8.

My plan is a 6" depth enclosure at the passenger footwell to enclose an IDQ10v2. I think that should be enough. I had dual JL W6v2's in the trunk, but the cabin is so well sealed (I don't have the ski-rack opening) that the bass just wasn't that great. So all I need is something to cover me from 80Hz up to 300Hz (ideally), but I guess I can settle for a dip around 150-300Hz or so. We'll see how it RTA's out in my car.

I'm also open to ideas/suggestion.

R