18" sealed vs 12" ported

@symon_say I am working on 2 of the cheap jbl cs1214 end table designs that might work for you? They are about that size (3.5 ft3) vented and go down to 20hz. That is a pretty big room but I think dual 12s could pressurize it but others with more experience will have to jump in and comment.

Here is what I am building (2 of them) and got the design/idea from zarkoff500 - 3.5 cft CS1214 build. I did a cube version downfiring tuned to ~20 hz. I have not heard any audible port noises even with heavy bass scenes in Fury Road or BR 2049. A larger box would have had a more even response though. I'm using a single 4" Precision Port down firing along with the CS1214. It is powered by an older Dayton SA240 plate amp.


Here is a response from a big diy sub guy (LTD02) about building a single sub. He helped zarkoff500 with his build design - something around 5 c.f. tuned to around 20hz or so would be a good choice. that size cab will allow for a port that is large enough to not have chuffing. best would be to build a few if possible. one 12" in that large area may be a little underwhelming.


good luck!

For that room size I honestly think you'll need something like this to get any reasonable bass output.


Two of them in fact. Four would be even better if you want to reach towards 20hz (the more you have of these the deeper you can reach in frequency, front loaded horns are great that way). They can be placed upright or along the floor as part of TV stand and seating benches, room dividers, etc.
You can pick some cheap 18" PA woofers to start with, something with 94db+ 1w/m sensitivity, 500w power handling and 5mm-ish xmax (these are barely a hundred bucks each). Any cheap amp like EP4000 or Inuke amps etc will run two-four easily. Then later you can upgrade to something like faital pro 18XL2000 woofers with three times the xmax and four times the power handling, and one or two sanway amplifier depending on if you have two or four of these enclosures. You can even upgrade to the faital pro woofers without upgrading amp and just turn the highpass filter down to like 15-20hz because your cheapo amp won't be able to make the faital pros bottom out.

PS: if you note, there is un-used room in these enclosures so you can fit a set of normal front speakers in them and place them upright in each corner on the front wall. Cover in white acoustically transparent fabric (speaker grill fabric) (or whatever color you want, you can even manually dye the white fabric for a really cool custom look). Then your speakers and subwoofers are effectively hidden from view, and yet you'll have the sound level and quality of a full orchestra at your disposal.

PPS: Do not under-estimate the importance of front speaker midbass in terms of instrument realism, without good midbass from the front speakers realism is just lost instantly. And if you place your front speakers in these subwoofers then the midbass from the horns will mask any midbass shortcomings your front speakers may have because the midbass from these horns comes from the same place as the front speakers. Midbass is more directional than sub-bass you see.

PPPS: If you want anything less than this in physical enclosure volume, you'll have to place the subwoofers near-field (near the listener). And you'll still need proper midbass from the front speakers. And just because you get to the NOC point (nails of chalkboard point) doesn't mean you have a loud enough stereo, it just means your enclosures and room reflections produce so much noise that it no longer sounds right. A great PA sound system at home will use like 50 watts between the LCR speakers, and it'll play 110db cleanly without you hitting the NOC point (5db above reference). It should be noted 110-115db peaks is what you'd expect from an actual orchestra at front row.

eriksells916 said: here is a response from a big diy sub guy (LTD02) about building a single sub. He helped zarkoff500 with his build design - something around 5 c.f. tuned to around 20hz or so would be a good choice. that size cab will allow for a port that is large enough to not have chuffing. best would be to build a few if possible. one 12" in that large area may be a little underwhelming.


good luck!

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Glad to here these turned out! A quick update on my build as I have since swapped the JBL for the closeout HSU 12" from PE. It is quite a bit more than the JBL at $80 (but still cheap) but has more output and a flatter frequency response. Either make great subs for the price. Pictures for reference.

Another idea....

OR....




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18" sealed vs 12" ported

symon_say said:

Those are really nice ideas, I might be able to do something like that, I've always been afraid of those design and decoration on then, aren't they knock with subs vibration??

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Do they vibrate, yes a bit. Is it really noticeable no. They are braced well and very heavy. You can feel the vibration by putting your hand on the cabinets but it’s hard to see otherwise.

On the tall sub the light jiggles a little bit at really loud subsonic frequencies but so do the dishes and pictures in other rooms sooo.....

On the skinny long one the table above it doesn’t move at all. My wife puts her soda and wine glasses on it and never complain about it moving lol...

That said these are NOT drivers with MASSIVE excursion like the UM18 but I had one of those in a 4 CF box and when braced right the box barely vibrated even at crazy levels.


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