[kaigoss69]

Originally Posted by 808MGuy

I have never heard of this and seen many installs with the magnet outside the box and the cone firing into the box. The woofer moves the same amount of air no matter which way it faces because the wavelength of the frequencies being played by the woofer are much longer than the enclosure. They are actually longer than the car. The main difference is that it will result in a phase shift. Yes you might have to reverse polarity to account for the phase shift but that's install dependent as sometimes people reverse polarity on a standard mounted sub anyway. Its not much to worry about since reversing polarity is as simple as switching + and - wires.

A friend of mine many years ago did this and it sounded like doodoo. Yes he reversed polarity. Yes you could hear noises from the motor structure. Yes you could hear the air rushing through the pole vent. He turned it around again and it sounded normal.

People mount subs inverted to either show off or because the box isn't deep enough. From an SQ standpoint, you want it playing the way it was designed to.

[Lee Rambler]

it's driver dependent. Some driver's make noise from the spider, some don't (I'd like to at least think most don't). The area of the pole vent (assuming there is one) will decide whether there is noise from it (much like the port area of a vented box dictating whether there is port chuffing noise). As far as cone area, it will depend on the driver - some will have considerably more cone are on the frontside than others (large voice coils vs smaller, soft dustcap vs hard or integral, etc). In his SWR's case, you are correct about larger cone area on the front side. The pole vent on that driver is not huge either, though I've never used one inverted to know if noise is an issue or not. Depending how much output he's looking for, it may not be an issue anyhow (though my guess is he's probobly looking for pretty good output).

but if seeing the motor structure of the driver is important to him, it may still make him happier that way in the end anyhow...

[fdriller9]

Originally Posted by Lee Rambler

it's driver dependent. Some driver's make noise from the spider, some don't (I'd like to at least think most don't). The area of the pole vent (assuming there is one) will decide whether there is noise from it (much like the port area of a vented box dictating whether there is port chuffing noise). As far as cone area, it will depend on the driver - some will have considerably more cone are on the frontside than others (large voice coils vs smaller, soft dustcap vs hard or integral, etc). In his SWR's case, you are correct about larger cone area on the front side. The pole vent on that driver is not huge either, though I've never used one inverted to know if noise is an issue or not. Depending how much output he's looking for, it may not be an issue anyhow (though my guess is he's probobly looking for pretty good output).

but if seeing the motor structure of the driver is important to him, it may still make him happier that way in the end anyhow...

I'm more concerned with how the sub sounds. I've been told it doesn't matter which way the sub faces as long as the enclosure is built right. This is why I wanted to have the magnet visable through the ski pass but if performance is really affected that much that forget it. Mdf is pretty cheap so if the way I make my enclosure doesn't provide a good response from the sub then I'll try different volumes and mounting techniques.

[CIGARGUY]

Honestly, it really won't make an audible difference. If you're looking at specs on paper, yes, there is a difference. However, from the info we've shared in this thread, I don't think you plan to create a mobile studio type sound system. Reverse mounting the sub will not effect the sound enough to make much difference.

[kaigoss69]

Originally Posted by e90David

http://www.e90post.com/forums/showthread.php?t=336905

That will only work if the sub is designed for "free air" which is very difficult to find nowadays. For that type of application, you need to seal off the front baffle (the board the woofer is mounted to) against the ski pass / back seat. So the waves coming from the front of the woofer are "directed" through the ski pass into the cabin. When I say "sealed" I mean sealed, with silicone, weatherstripping and shit. Air tight.

It should also be noted that a free air set-up does not have a very high power handling and the sound tends to be "loose" and "sloppy" if not done correctly or with the wrong sub. I would personally prefer to have an enclosure behind the sub, I think it would sound a lot better.

[fdriller9]

Originally Posted by kaigoss69

That will only work if the sub is designed for "free air" which is very difficult to find nowadays. For that type of application, you need to seal off the front baffle (the board the woofer is mounted to) against the ski pass / back seat. So the waves coming from the front of the woofer are "directed" through the ski pass into the cabin. When I say "sealed" I mean sealed, with silicone, weatherstripping and shit. Air tight.

It should also be noted that a free air set-up does not have a very high power handling and the sound tends to be "loose" and "sloppy" if not done correctly or with the wrong sub. I would personally prefer to have an enclosure behind the sub, I think it would sound a lot better.

Yea the free air design sounds too complicated. I'm going to be making a .75 cu ft enclosure out of 3/4 mdf and mount the sub inverted with the polarity reversed. I'll see how this sounds and if I don't like it then I'll make another enclosure. Probably a regular mounted one.

[Lee Rambler]

that sub needs far more than .75ft3 - try doubling that...

[fdriller9]

Originally Posted by Lee Rambler

that sub needs far more than .75ft3 - try doubling that...

Reverse mounted though? The recommend size for a regular sealed enclosure is 0.7 - 1.0 cu ft. I took out a little to account for the space the sub would have taken up inside the enclosure.

[kaigoss69]

.75ft3 should be a good size for that sub.

[CIGARGUY]

Originally Posted by *********

Yea the free air design sounds too complicated. I'm going to be making a .75 cu ft enclosure out of 3/4 mdf and mount the sub inverted with the polarity reversed. I'll see how this sounds and if I don't like it then I'll make another enclosure. Probably a regular mounted one.

I would agree that you won't be very happy with a .75 enclosure. I'd try a minimum of 1.0 or closer to 1.5 to get what you're looking for.

[fdriller9]

Haha well it looks like we're 50/50 here....I'm going to try the 0.75 cu ft enclosure and see how it sounds. This makes sense to me because the recommended size is between 0.7 - 1.0 cu ft for a regular mount, sealed enclosure. If it doesn't sound good I can always make another 1.5 cu ft enclosure. Can one of you maybe explain why it should be around 1.5 cu ft? Maybe then I'll have the same mentality as you two? Thanks.

[Lee Rambler]

for good low end response, in a car, you want a q of around .8-.85 (.71 is ideal in anechoic, but need to account for cabin gain). generally speaking, this is at the top end of most manufacturers box recomendations.... I tried to find the t/s specs for it to model it for you, but can't find them online anywhere - so I can't say for sure on the ideal size, though when that sub first came out and was super popular they sounded pretty good in 1.5-1.75ft3 sealed and absolutely hammered in ~2.25ft3 ported with a tune frequency of 38hz.

[Gavin@MMW]

I wouldnt reverse mount the sub, it wouldnt sound as clean with a typeR because they arent free air subs.

you should do something like me an e90David did (check his thread)

and here is mine:





2 subs offset, firing direct to the cabin through what used to be the skipass.

1800w Kenwood amp

Custom box done by my boy Vod @ SS Motorsports.

[kaigoss69]

Why are you guys going against the manufacturer's recommendations? Do you have a feeling that .75ft3 won't give the OP the response he is looking for? It clearly states in the owner's manual that the recommended enclosure size is 0.7 - 1.0 ft3. At around 0.8 - 0.9 ft3 the Qtc of the box is 0.7. Do you think the OP wants boomy bass from an oversized box? Is this what he asked for?

[kaigoss69]

Craven, is that box sealed off against the back seat?

[Gavin@MMW]

Originally Posted by kaigoss69

Craven, is that box sealed off against the back seat?

Yes it is, fiberglassed double baffle box. No port.

[kaigoss69]

Originally Posted by Craven 328

Yes it is, fiberglassed double baffle box. No port.

What do you mean with double baffle?

[fdriller9]

You guys are losing me here...haha this is going beyond my audio knowledge now. I kinda see where everyone is coming from though. I'm kinda leaning towards mounting it regularly now because I don't know what a good volume is for a sealed reverse mount sub would be. The 0.75 cu ft was just my estimate from what I knew and what I was given from the manufacturer. Maybe this will help...these are the specs from Alpine:

Mounting Depth: 7.7"
Mounting Diameter: 10.9"
Displacement: 0.071 cu ft
Added Volume - Reverse Mount (Magnet out): 0.085 cu ft

Sealed Box Volume Range: 0.7 - 1.0 cu ft
External Box Dimensions: 13"x13"x12.5"
Gross Internal Volume: 0.85 cu ft
Net Internal Volume: 0.78 cu ft
F3, Qtc: 49Hz, 0.7

Vented Box Volume Range (Gross): 0.75-1.75 cu ft
External Box Dimensions: 18"x13.5"x16.5"
Gross Internal Volume: 1.7 cu ft
Vent Area (Dimensions): 15 in sq (12"x1.25")
Vent Length: 22.75 in
Vent Displacement: 0.305 cu ft
Net Internal Volume (Vb): 1.3 cu ft
F3, Ripple,Fb: 33Hz, 2.5Db, 36Hz

[Gavin@MMW]

Originally Posted by kaigoss69

What do you mean with double baffle?

basically if bounces sound off the front chamber and the inside chamber of the box, and is stronger then a normal box so it can hold heavier subs and take more power without the box flexing out

[Gavin@MMW]

Do a sealed box, with volume of .9 (box volume, dont take into account the space taken up by the magnet and stuff)

seal it up against the rear seat (take out the felt and build the box to the fiberglass) and have it fire into the cabin. You wont regret it.

I wish you were local so you could hear my car

Originally Posted by *********

You guys are losing me here...haha this is going beyond my audio knowledge now. I kinda see where everyone is coming from though. I'm kinda leaning towards mounting it regularly now because I don't know what a good volume is for a sealed reverse mount sub would be. The 0.75 cu ft was just my estimate from what I knew and what I was given from the manufacturer. Maybe this will help...these are the specs from Alpine:

Mounting Depth: 7.7"
Mounting Diameter: 10.9"
Displacement: 0.071 cu ft
Added Volume - Reverse Mount (Magnet out): 0.085 cu ft

Sealed Box Volume Range: 0.7 - 1.0 cu ft
External Box Dimensions: 13"x13"x12.5"
Gross Internal Volume: 0.85 cu ft
Net Internal Volume: 0.78 cu ft
F3, Qtc: 49Hz, 0.7

Vented Box Volume Range (Gross): 0.75-1.75 cu ft
External Box Dimensions: 18"x13.5"x16.5"
Gross Internal Volume: 1.7 cu ft
Vent Area (Dimensions): 15 in sq (12"x1.25")
Vent Length: 22.75 in
Vent Displacement: 0.305 cu ft
Net Internal Volume (Vb): 1.3 cu ft
F3, Ripple,Fb: 33Hz, 2.5Db, 36Hz

[fdriller9]

Originally Posted by kaigoss69

What do you mean with double baffle?

I think that means double thickness...3/4" mdf on the sides top and bottom and 1.5" mdf for the front (sub mounting panel). Or maybe he doubled it all around. I might be wrong though...that's my understanding.

[fdriller9]

Originally Posted by Craven 328

basically if bounces sound off the front chamber and the inside chamber of the box

Wow, I was way off...