Too small enclosure but very powerful 21” sub

J0b006

CarAudio.com Newbie
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2
London
Hi, I have a dilemma.

Couple years ago I built a 4.5 cu ft ported enclosure for my 2000w 15” kicker, it slams…

Some time after building the box I figured out that I could fit a 21” Apocalypse SA521 NEO in the box!!

The NEO’s mounting diameter is 19.41” and my box is a few millimetres bigger than 20” on the inside coated with epoxy. It will fit!

Problem is… the manufacturer recommends 7.769 cu ft (220L)… 3.8 cu ft is really all I’ll have with the speaker displacement, so the actual internal volume will be more like 50% of the recommended volume. Ive done some research finding that smaller enclosures will compromise low end extension… all the way to it causing distortion!

But this is a neodymium motor and capable of 20,000 watts, with a 5” voice coil…. So I’m thinking the sub will be fine and still play well.

is this a waste of money?
 

Coolhand20th

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Sry that is not a 20,000 watt subwoofer. RMS is 5,000 watts and max is 10,000.

Contact a box designer and have him look into if it is even worth doing in the space you have. Otherwise you will just end up wasting money. If it needs that much space and you have half the amount I highly doubt it is worth doing. Better off finding another 15" then doing what you are thinking about. You have a box that a lot of 15" would slam in and would be a lot louder and nicer then that Kicker.

 

J0b006

CarAudio.com Newbie
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2
London
  • Thread Starter Thread Starter
  • #5
Sry that is not a 20,000 watt subwoofer. RMS is 5,000 watts and max is 10,000.

Contact a box designer and have him look into if it is even worth doing in the space you have. Otherwise you will just end up wasting money. If it needs that much space and you have half the amount I highly doubt it is worth doing. Better off finding another 15" then doing what you are thinking about. You have a box that a lot of 15" would slam in and would be a lot louder and nicer then that Kicker.

It’s 5000w rms at 1+1 ohm, so 2 ohms. 20k at 1 ohm

but that sound advice, ignore the pun
 

djdilliodon!

CarAudio.com Veteran
504
443
NY
It’s 5000w rms at 1+1 ohm, so 2 ohms. 20k at 1 ohm

but that sound advice, ignore the pun
sub is rated at 5000w rms total not per coil. In a box assuming it’s sealed and being half the size it should be, this will ruin the ability of the coil to cool itself, have poor low end output, and sound terrible as well. In too small of a ported enclosure it can also sound terrible but increase power handling but also have laughable low end extension. While big subs can get louder, the biggest benefit imo of all is the increased output in the low end. You are absolutely wasting your money if that box is your only option.
 

J0b006

CarAudio.com Newbie
4
2
London
  • Thread Starter Thread Starter
  • #7
sub is rated at 5000w rms total not per coil. In a box assuming it’s sealed and being half the size it should be, this will ruin the ability of the coil to cool itself, have poor low end output, and sound terrible as well. In too small of a ported enclosure it can also sound terrible but increase power handling but also have laughable low end extension. While big subs can get louder, the biggest benefit imo of all is the increased output in the low end. You are absolutely wasting your money if that box is your only option.
Sound. My greed for power is bigger than capacity to hold it. 21” sub sound nice in theory, but if I want it I’ll have to work on a bigger enclosure. I’ll work on it haha
 

akheathen

trianoacitol contraceptiv
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if you dont have enough volume for a real port, then you just dont. start stuffing the port with blocks, or block it completely and run sealed. i doubt you can get away with 10-8sq/cu for a port, but may be possible. compact sealed might just be your only option.
 

mat3833

CarAudio.com Elite
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This is roughly the size of a 14 cubic foot enclosure. I'm still doing the math for internal volume, but it should be somewhere at 15.4 cubic feet. This is for 2 18" drivers on 3k.

Internal dimensions are as follows:
20t
48w
20 deep on the bottom and 31 deep on the top.

20220521_131959.jpg


Putting a sub in HALF of its recommended volume is bad in many ways. I'm not going to get into specifics, but a horrible generalization is this: the smaller the box, the higher the resonant frequency is and the louder the sub will play at that specific frequency. You will end up with a very peaky sub playing 50hz and up. Yes, you can throw a ton of power at it, and add a bunch of EQ to make it play lower and more flat, but it's not worth it. Pick up a decent 15 or pair of 15's and be done.

If you are going to ask a question on a forum, listen to the responses and don't be a dick. Most of us have been doing this for 10+ years and actually know what we are talking about. You want to waste the money on the sub, go for it. Its not my money.

Matt
 

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