adding a 4th sub, do chamber specs need to match other 3 to sound good?

[sbarber82 10+ year member]

is your port even a port or just a slot on top of the box? It looks like by the pics its just a slot with no port walls going in to the box

 

[RSDXzec 10+ year member]

I can't really say how much it would increase. You would have to do some bracing but not much for 3 low power subwoofers. What are the current dimension on your box? Could you go any wider, taller, or deeper? Having a shared chamber will add some volume, so will having the port on the rear of the box because the port will have more common walls.

Any higher would block my rear view, wider wouldn't fit in the car, and deeper would make my back seats fall down... they already can't lock into place because of the size of the box. The external dimensions judging from the model I made of it are 22.7"high, 36"wide, 23.62" deep. The port does go along the rear wall already... I'm not sure how people here are visualising my port, the next pic I uploaded should help a bit more.

is your port even a port or just a slot on top of the box? It looks like by the pics its just a slot with no port walls going in to the box

hahahahahah is that a serious question? lol ofcourse it's a port

this might help you out

 

[Better-Action 10+ year member]

How deep is the top and how deep is the bottom? If you build the box inside the care could you go a little wider?

 

[cfox10 10+ year member]

Port area is WAY too small. You will get substantially louder with a larger port and shared chamber. Can you go any taller? To the roof?

I'd suggest trying to sell this box on craigslist to recoup and build a better one. Talk to someone like doubl07 to get a cut sheet or something with a larger port.

 

[RSDXzec 10+ year member]

How deep is the top and how deep is the bottom? If you build the box inside the care could you go a little wider?

I'm not sure what you mean by deep at the top and bottom... and no I couldn't go any wider, it would hit the wheel wells, when I designed this box I made sure it was as big as I could make it because I didnt plan on making a new box until I buy a new car.

Port area is WAY too small. You will get substantially louder with a larger port and shared chamber. Can you go any taller? To the roof?
I'd suggest trying to sell this box on craigslist to recoup and build a better one. Talk to someone like doubl07 to get a cut sheet or something with a larger port.

If I went taller to the roof I wouldn't have a rear view... which is illegal for me. Dunno if we have craigslist here in oz but even on ebay or something like that nobody would want this box, considering it's made for a 30 year old car and I'm in a small city so less people to come pick it up, and I get my sheets at my local store.

 

[Better-Action 10+ year member]

How deep is the bottom and the top of the box. You got your width and the height. But the top and bottom depth are different because of the angle. I'm just trying to get what your dimensions are so I can see if I can suggest a route to go with the space you got.

After seeing the pics where was the 4th sub gonna go? I think optimizing your space to get some more port for the 3 is your best bet. You've already given up crucial port area to fit the 3. Adding the 4th you'll have to sacrifice port AND internal volume. Its not worth it.

 

[RSDXzec 10+ year member]

How deep is the bottom and the top of the box. You got your width and the height. But the top and bottom depth are different because of the angle. I'm just trying to get what your dimensions are so I can see if I can suggest a route to go with the space you got.
After seeing the pics where was the 4th sub gonna go? I think optimizing your space to get some more port for the 3 is your best bet. You've already given up crucial port area to fit the 3. Adding the 4th you'll have to sacrifice port AND internal volume. Its not worth it.

I was planning to make the fourth sub go between the back seats, so it wouldn't be in the boot.

23.62" is the long depth, I'm not sure about the short depth, I'll have to check that when I get home in a few hours but i think it's around 18".

 

[RSDXzec 10+ year member]

actually the top depth was 10" lol, dunno where i got 18" from.

 

[Better-Action 10+ year member]

After checking your dimensions it really doesn't get better. The port are is so small honestly I think you will probably be louder with 2 in a killer box. For running 3 its about as good as it gets. With the space though and if your amp actually does rated then you have allot of options. With your power and space you could run a very nice 15" or two nice twelves and both would surely be louder if done right. If you could sell the 4 12s you would have a good head start on a good 15. I dunno how easy it would be to do that though being were you live.

Sorry I couldn't help ya further but space is your bottleneck and you've hit it. So the way to get louder at this point is efficiency with the power you got.

 

[RSDXzec 10+ year member]

After checking your dimensions it really doesn't get better. The port are is so small honestly I think you will probably be louder with 2 in a killer box. For running 3 its about as good as it gets. With the space though and if your amp actually does rated then you have allot of options. With your power and space you could run a very nice 15" or two nice twelves and both would surely be louder if done right. If you could sell the 4 12s you would have a good head start on a good 15. I dunno how easy it would be to do that though being were you live.
Sorry I couldn't help ya further but space is your bottleneck and you've hit it. So the way to get louder at this point is efficiency with the power you got.

thanks a lot for the help so far. For reference what port area would you recommend (per cube/per sub surface area)? Looking at most other boxes on youtube my port area doesn't seem ridiculously small... and it's definitely larger than prefab boxes. atm I only have 3 subs and I'm considering buying a 4th if I can find one second hand on ebay because they're really good for the money.

I'd like to know what would be a good amount of port area to see what I can do even though at this point it looks like not much.

 

[Better-Action 10+ year member]

I can't remember what yours came out to cuz I don't have.my computer right now but it was under 10" of port per cube. For reference I run a single 15 the port is 15" tall by 5" wide and about 50 inches long. Yours is like what? 10.5" tall by 1.5" wide and about 18 inches long per port?

For reference here is what mine will do with a little more power than yours, lots of port and a single 15.

Ext cab Sonoma American bass xfl flex - YouTube

 

[RSDXzec 10+ year member]

I can't remember what yours came out to cuz I don't have.my computer right now but it was under 10" of port per cube. For reference I run a single 15 the port is 15" tall by 5" wide and about 50 inches long. Yours is like what? 10.5" tall by 1.5" wide and about 18 inches long per port?
For reference here is what mine will do with a little more power than yours, lots of port and a single 15.

Ext cab Sonoma American bass xfl flex - YouTube

that looks pretty good for 2kw, tbh Im only running my system at 400wrms atm because I'll be upgrading to a new battery soon to use the full 1k so I don't have much of a point of comparison. But I'd like to ask if you think I'd be able to fit a single 18 using the 6 cubes total I have, I'm all for surface area so I'd like to keep the size large and that's just a little less surface area than my 3 12"s. The only problem for me is choosing a good sub, here in aus i'm limited to JL Audio, Soundstream, Kicker, JBL, Alpine, Boston, Polk, Fusion, Sony etc... nothing compared to what you have access to in the US, my only chance is Ebay but postage is a fair bit. So are there any nice subs I could get over ebay without it costing an arm and a leg? Looking to handle up to 1500wrms at 1 ohm.

 

[Better-Action 10+ year member]

I don't know much about 18's as far as which ones like small boxes. But with your space I'd say the most viable option is 2 12's or the single 15. My box is 4.5cf and over 2cf of port. So my box total is like 6.5-6.9cf can't remember exactly how much volume my port has but its in that area.

Cone area does play a big role, but with a good sub you can do allot wit not as much cone area. I've had 2 15 kicker cvrs on 1400 rms and the single 15 xfl is louder. On both volume and it destroys the lows when compared. If you sstill want as much cone area I'd say go with the 2 12's. For a simpler and slightly cheaper route I'd say go the 15". The 2 12's will most likely be slightly louder but the single 15 will probably be cheaper and simpler to build for.

 

[RSDXzec 10+ year member]

I don't know much about 18's as far as which ones like small boxes. But with your space I'd say the most viable option is 2 12's or the single 15. My box is 4.5cf and over 2cf of port. So my box total is like 6.5-6.9cf can't remember exactly how much volume my port has but its in that area.
Cone area does play a big role, but with a good sub you can do allot wit not as much cone area. I've had 2 15 kicker cvrs on 1400 rms and the single 15 xfl is louder. On both volume and it destroys the lows when compared. If you sstill want as much cone area I'd say go with the 2 12's. For a simpler and slightly cheaper route I'd say go the 15". The 2 12's will most likely be slightly louder but the single 15 will probably be cheaper and simpler to build for.

would you recommend that xfl 15 as a good 15 for 1kw? I saw your video but with such a small cabin I imagine it's much easier to get loud.

or what 12"s would be good in my situation? would i be able to use 2 of the 12"s I have now or should i get something better? I haven't had much experience with subs and I keep using winisd to compare specs, and with that comparison the single xfl 15 is around the same as my 3 12"s. I can get the XFL 15 on ebay from the US for $290 + $60 postage, the only other brand i can see on ebay is re audio and sundown audio, skar, not sure if there are others.

 

[Better-Action 10+ year member]

would you recommend that xfl 15 as a good 15 for 1kw? I saw your video but with such a small cabin I imagine it's much easier to get loud.or what 12"s would be good in my situation? would i be able to use 2 of the 12"s I have now or should i get something better? I haven't had much experience with subs and I keep using winisd to compare specs, and with that comparison the single xfl 15 is around the same as my 3 12"s. I can get the XFL 15 on ebay from the US for $290 + $60 postage, the only other brand i can see on ebay is re audio and sundown audio, skar, not sure if there are others.

I checked out eBay Australia and **** shits expensive over there. To get an xfl 15 in the states will cost ya 220 but 350 in Australia.

On my youtube channel I also have a video of a single 15 xfl I did in a Bonneville trunk. The truck is louder but not by much. So I'm sure it would be pretty nasty in your hatchback.

The xfl is rated at 1000 wrms so your amp would be totally fine for it. They can take 2k easily but 1k will still do you well. How much would it set ya back for 2 sundown sa-12's? For your power and plenty of space for 2 12's the sa's should get ya louder than the 1 15 xfl.