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E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.


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Old Thu, Apr-05-2018, 06:35:51 PM   #41
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

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Originally Posted by bigjae1976 View Post
You’re sub will be about 8ft from you vs the front mid which is a 2 ft away?

That’s about a 6dB loss from your trunk sub or your front speaker will be 6dB louder.

That equates to about 180 watts of power to your trunk sub to achieve the same volume level. That doesn’t factor in the sound suffocating BMW trunk. You’re probably looking at needing 300 watts at a minimum.

Again, you’re adding a sub and amplification to achieve the same or a similar result you’d get from only running a set of front speakers.

Just a thought...


Sent from my iPhone using Tapatalk


I wish it was that optimistic. If you look at the equal loudness curves you will se that you need to add like 15db on a top of that if you want to boost 50hz compared to 100hz. So much more power there. Taking into account that 8” woofer in a smallish sealed cab will be falling like -6db or more at 50hz... that’s how we come to all those gigawatts for subs. On a bright side in the car you will have cabin modes at around 70hz, so no reason going much lower.

What type of music you like to listen Obioban? For most music better reproduced 60-70hz is better than boomy 40 . So if you find 5-6” woofer with lowish Fs and Qts~0.7 door drivers might be what you need.
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Old Thu, Apr-05-2018, 07:10:23 PM   #42
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

ITT a bunch of audiophiles talking past a lightweight addict
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Old Thu, Apr-05-2018, 07:50:49 PM   #43
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

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Originally Posted by mcfreid View Post
ITT a bunch of audiophiles talking past a lightweight addict
This is why I don’t understand why he’s trying to make another box in an already existing box. It makes no sense.
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Old Thu, Apr-05-2018, 07:55:39 PM   #44
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

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This is why I don’t understand why he’s trying to make another box in an already existing box. It makes no sense.
The battery box is far from a sealed enclosure, so I assume it wouldn't be very effective to just drill a hole in the lid and mount a sub.

My understanding, and I am far from an audiophile of any sort, is that an enclosed box makes a sub of a given size/power more effective. So, my thought was that I could make a 2-3 lb sealed enclosure that will fit in an available area while not detracting from functional trunk space, and boost the output of a small/low power sub.

If I don't use it for a sub, I'll put in part #7 below... which doesn't seem that useful, and does seem like it would collect a bunch of debris :P.

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Old Thu, Apr-05-2018, 08:05:50 PM   #45
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

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Originally Posted by mcfreid View Post
ITT a bunch of audiophiles talking past a lightweight addict
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Old Thu, Apr-05-2018, 08:31:10 PM   #46
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

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Originally Posted by rbg View Post
I wish it was that optimistic. If you look at the equal loudness curves you will se that you need to add like 15db on a top of that if you want to boost 50hz compared to 100hz. So much more power there. Taking into account that 8” woofer in a smallish sealed cab will be falling like -6db or more at 50hz... that’s how we come to all those gigawatts for subs. On a bright side in the car you will have cabin modes at around 70hz, so no reason going much lower.

What type of music you like to listen Obioban? For most music better reproduced 60-70hz is better than boomy 40 . So if you find 5-6” woofer with lowish Fs and Qts~0.7 door drivers might be what you need.
Exactly


You will get better sound with less weight by simply mounting the MM6501 drivers (162.5mm x 67mm) solidly to the metal (which does mean cutting a hole that no one will ever see), and adding power to them (they are rated for 125wRMS/250wPeak).

You can find plenty of light weight options in Marine and Motorcycle offerings; like the 3lb Rockford Fosgate TM400X4ad that would provide 2 x 200w.

I'm sure you are thinking "I already said I don't want it to go thumping", but the additional power is needed to get full range of motion (aka x-max) from the driver and "move air" for the low frequency response.
Add to that, you want low distortion when reproducing peaks (i.e. a kick drum punch). Both require more power.

P.S. Sealed box subs are less efficient (aka not as loud and need more power), but when sized correctly they typically provide a flatter response curve. Infinite baffle will get you more output with less power and less weight...just not with a flat response. But if that flat response is at the cost of lower output from 40Hz to 80Hz, don't bother.
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Old Thu, Apr-05-2018, 09:20:32 PM   #47
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

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Originally Posted by Obioban View Post
I don't care that much about sound quality, so much as having it be light weight

Easy non-audiophile option: Kicker Hideaway

Comes with everything to install. Weighs ~10lb. Removable in seconds.

I put one in my wagon between the space saver and luggage compartment. You wouldn't know it's there. Made a world of a difference on my non-HK base audio setup.
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Old Thu, Apr-05-2018, 09:59:46 PM   #48
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

^I have one of those in my truck under the rear bench, took the stereo from zero bottom end to nice full sound, and yep probably 10lbs with the wiring.

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Old Thu, Apr-05-2018, 11:43:14 PM   #49
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

Quote:
Originally Posted by ultimatemj View Post
Exactly


You will get better sound with less weight by simply mounting the MM6501 drivers (162.5mm x 67mm) solidly to the metal (which does mean cutting a hole that no one will ever see), and adding power to them (they are rated for 125wRMS/250wPeak).

You can find plenty of light weight options in Marine and Motorcycle offerings; like the 3lb Rockford Fosgate TM400X4ad that would provide 2 x 200w.

I'm sure you are thinking "I already said I don't want it to go thumping", but the additional power is needed to get full range of motion (aka x-max) from the driver and "move air" for the low frequency response.
Add to that, you want low distortion when reproducing peaks (i.e. a kick drum punch). Both require more power.

P.S. Sealed box subs are less efficient (aka not as loud and need more power), but when sized correctly they typically provide a flatter response curve. Infinite baffle will get you more output with less power and less weight...just not with a flat response. But if that flat response is at the cost of lower output from 40Hz to 80Hz, don't bother.
Interesting

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Old Fri, Apr-06-2018, 02:53:15 AM   #50
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Default Re: I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls

Quote:
Originally Posted by Obioban View Post
The battery box is far from a sealed enclosure, so I assume it wouldn't be very effective to just drill a hole in the lid and mount a sub.

My understanding, and I am far from an audiophile of any sort, is that an enclosed box makes a sub of a given size/power more effective. So, my thought was that I could make a 2-3 lb sealed enclosure that will fit in an available area while not detracting from functional trunk space, and boost the output of a small/low power sub.

If I don't use it for a sub, I'll put in part #7 below... which doesn't seem that useful, and does seem like it would collect a bunch of debris :P.

If you don't care how it sounds, you can literally tape up the gaps in the battery box and get good enough. It doesn't need *that* much integrity when it's a lightweight and small driver. If you want to feel like you've done a good job closing it up, put a couple sheets of fiberglass over the holes you've taped up. Easy, requires essentially no skill, super light.

So, do you want maximum lightness, or best sound in a limited weight budget?

And yes, as the other poster noted, sealed boxes are the LEAST EFFICIENT way to get bass, although they are frequently (but not always) the best sounding.

The best way to get bass on a limited weight and power budget would be to mount something IB in the ski pass, IMO. No box, no resistance to driver excursion. (I'd burn the weight you save from no box on something larger than an 8" driver as 8" doesn't really do that much.) 300W is more than enough to drive a decent sized driver.

Next best is something IB on the rear deck. (Mostly, this is next best because you may have to do weight adding work to keep the rear deck from rattling.) Do it in place of the rear deck speakers if you haven't already removed them to offset some of the weight.
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1989 M3 Alpinweiß/Black - S62B50 in progress...

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Discussing I'm 3D printing a sub woofer enclosure using tough PLA.How thick should the walls be? in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 Forum.com (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)