One Vented 15, or two 15s sealed?

[Slammer 10+ year member]

I am currently running a 15" Mojo in a 4.25cf net vented box. Sub is rated at 1500w rms and 3000w peak. I have it on a Sundwon SAE1200D amp. I like it, but would like to get louder. I have considered going to a pair of the 15" Memphis M3s, which are rated at 800w rms and 1600w peak. I know that I get some volume from the vent, but have to think that the cone area of the 2-15s is going to make the lower rated 15s louder than the one Mojo. Box volume for the sealed 15s would be approximately the same as the existing box. Gross volume of the sealed box is 5.42cf and the sealed 15s only need a net of 3.8cf to 4.0cf.

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[Ground_Pounder 10+ year member]

Two 15"s in a vented box.

 

[KickerL715 10+ year member]

why not just get a ported box for the 2 if you cant just keep the one 15 in ported box it matters trust me matters on the box size to if the box with the 1 15 is bigger and ported then you go to a liler box with 2 15s its not going to be better get a bigger amp 1500 rms 1 ohm stable

 

[Slammer 10+ year member]

Space is an issue with running a pair of 15s in a vented box. This is in an extended cab truck. The current box is 36"x17.5"x19". That is bigger than it sounds and weighs upwards of 100 lbs with the 40lb Mojo in it. Recommemded volume for a pair of the 15s in 6.00cf. I haven't drawn up a vented box yet, but that would have to be around 7.5cf to 8.0cf gross. The vent alone would be around 1.0cf, and then you have the two subs and the extensive bracing that would be required to support the weight and pressure that the 15s would cause. As for the amp, I have the Mojo on the Sundown 1200 now, but have a Memphis MC1100 on the way. I am told that these put out upwards of 1600-1700 watts rms @ 1 ohm. The Sundown is 1 ohm stable and should be getting me 1400-1500 now. I haven't had anyone put a clamp on it, but that seems to be the consensus. I would have to pull the box from time to time, and a 6.00cf box with a pair would be near impossible to get in and out.

 

[loud-n-low 10+ year member]

going to 2 15's sealed more than likely isnt going to give you the higher output you are looking for. maybe build a new box,change the tuning? im a fan of sealed boxes however,do you want to spend the money on a 2nd sub, larger amp etc for results that arent louder?

 

[tc3k101 5,000+ posts]

if you plan on going that big then why not a single 18" in a ported box depending on your budget with side firing aero ports loading off the side wall/glass? also if you are worried about weight why not use something like birch/trupan/mdf light? what are your max dimensions you can have?

 

[Kern417 10+ year member]

i like the single 18 idea

 

[Slammer 10+ year member]

I thought about the 18, but have heard that they produce poor SQ. As for the 15s, I would not be adding a 2nd Mojo. I would ditch the Mojo for a pair of the M3 15s. I have a single M3 15 in my girl's ride and it plays very loud and it is only on about 600w rms. I could go bigger with the box, but wold not be able to get it in and out. I have to pull the box a couple times a month and this would be a big problem. I do not want to go with a smaller vented box, tuned at a higher frequency. I like how low my 15 hits now. I have it tuned to around 28hz for that very reason. Vent is 15.5x3.5x30. Also, running the 18 would make the top of the box at least 20" wide, which would make it difficult to have the front seats back at all.

 

[Johnny Law.Lulz 5,000+ posts]

Single 18 would be nice. You could use Aeros also. Or 2 12"s ported.

 

[Johnny Law.Lulz 5,000+ posts]

I thought about the 18, but have heard that they produce poor SQ. As for the 15s, I would not be adding a 2nd Mojo. I would ditch the Mojo for a pair of the M3 15s. I have a single M3 15 in my girl's ride and it plays very loud and it is only on about 600w rms. I could go bigger with the box, but wold not be able to get it in and out. I have to pull the box a couple times a month and this would be a big problem. I do not want to go with a smaller vented box, tuned at a higher frequency. I like how low my 15 hits now. I have it tuned to around 28hz for that very reason. Vent is 15.5x3.5x30. Also, running the 18 would make the top of the box at least 20" wide, which would make it difficult to have the front seats back at all.

SQ from a driver depends on the install. Im sure there are 18"s that have better SQ than some 8"s when install is added. You gotta know what your doing.

 

[tc3k101 5,000+ posts]

I thought about the 18, but have heard that they produce poor SQ. As for the 15s, I would not be adding a 2nd Mojo. I would ditch the Mojo for a pair of the M3 15s. I have a single M3 15 in my girl's ride and it plays very loud and it is only on about 600w rms. I could go bigger with the box, but wold not be able to get it in and out. I have to pull the box a couple times a month and this would be a big problem. I do not want to go with a smaller vented box, tuned at a higher frequency. I like how low my 15 hits now. I have it tuned to around 28hz for that very reason. Vent is 15.5x3.5x30. Also, running the 18 would make the top of the box at least 20" wide, which would make it difficult to have the front seats back at all.

who ever said 18s have poor sq is a liar lol you can always just try a better sub than the mojo?

 

[NhustlaR 10+ year member]

More power, new box. Pick up a 2~k amp and build a new box. Tune higher too. 33-35 would be a lot better than 28hz. You should notice a difference with those two changes

 

[Slammer 10+ year member]

I have another box. It is 3.25cf and tuned to 33hz. I know that the higher frequencies play louder but really dig the low stuff. I was hoping to get louder with the extra sub, while staying near the same tuning. As for getting a better sub, I can't drop the cash for another Mojo (which I love by the way), but I can swap the Mojo at my local dealer for a pair of the M3s. Like I said, I have an M3 (2008 model) in another truck and it slams. Not to mention that the M Class 1100 would be perfect for powering a pair of 4ohm DVC M3s, at 1ohm at the amp. Looking for louder and don't mind the sub swap or building another box, but do not have the means to go with a true SPL sub or snag a 2k watt amp. I have thought about going with the HDC3A, but would have to sell my Mojo outright to make that happen.