# db numbers for b14



## superfro86 (May 15, 2002)

anybody got db numbers for a b14? i got 137.8 on Audiocontrol mic with a IDMAX,hifonics brutus1000d,2.4 cube to 33-35hz (along with a 25 dollar noise violation ticket and my shit wasn't even up that much louder than what a stock stereo with nice bass could do at the time)hopefully i could obtain my goal of 140's on audiocontrol with more sounddampining, better eqing (like a pussy i still had my deh860mp sub level on -5 during the test and i was scared to trun on superbass or turn up the bass boost on the amp) also doesn anyone know the resonant freq of a b14sentra? i know the basic formula for finding this but i would like to know the exact. i'm thinking of building a comp box, 3.0 cube resonant freq for my IDMAX 12. but enough about my setup what have you guys hit in a sentra? please list amplifacation,sub set-up, box placement, box tuning, the mic used ect.


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## sr20dem0n (Mar 19, 2003)

nice score, I hope to test my new setup once I get it all going. Brahma 15 in 3-4cf 45hz (just for testing, not for daily) on a Cadence ZRS-8, hoping for mid 140's but I really don't know

Anyway...awesome sub, nice score, and good luck in future testing 


note: we need a thumbs up smiley here


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## wickedsr20 (Aug 8, 2002)

superfro86 said:


> hopefully i could obtain my goal of 140's on audiocontrol with more sounddampining, better eqing (like a pussy i still had my deh860mp sub level on -5 during the test and i was scared to trun on superbass or turn up the bass boost on the amp)


There are a lot of factors that could be changed that may not need to be, but the biggest things you could do to impress the mic is to change the tuning frequency on your port and (if you can) find a subsonic filter that will cut off frequencies JUST BELOW your vehicle's resonant frequency. This would allow you to really push your sub @ the desired frequency without having to worry about non-linear excursion from the lower frequencies limiting your output. If competition is now in your blood, I'd highly suggest to you to use TWO sets of ports for your box. One set for the street/everyday listening, and the other tuned for competition (I used 55 hz) use only. This worked very well for me.



superfro86 said:


> also doesn anyone know the resonant freq of a b14sentra? i know the basic formula for finding this but i would like to know the exact.


I think it's in the range of 50-55 hz. This worked very well for me using test tones from the first "Bass Mekanik" CD.



superfro86 said:


> i'm thinking of building a comp box, 3.0 cube resonant freq for my IDMAX 12. but enough about my setup what have you guys hit in a sentra? please list amplifacation,sub set-up, box placement, box tuning, the mic used ect.


You may not have to go larger on your box size for competition. Double check what port dimensions you'd need to raise your port tuning freq. My highest SPL in my personal car during competition was 142.2 db. This was a few years back. Pretty sure it was an AudioControl mic, US Amps US 200 (good for about 600w bridged @ 2 ohms), (2) 12" MTX Thunder 7000's in a ported enclosure facing to the rear of the trunk. Tuning frequency=50 hz. I also used an MTX LSB-1 used to high pass my subs @ about 45-50 hz (no exact actual markings on the control, just tuned by ear) also. Adding this allowed me to max the gain on my amp and gain a solid 2-3 db over not using it. I could have used more power also because the subs weren't even close to full excursion @ 50 hz either. Would have been nice to see it with a lot more behind it. 

I think with what you have, 140+ is achievable. Keep at it.


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## superfro86 (May 15, 2002)

my caculations were 56hz so that should be good. i'm trying to ask tech support at ID on what they think would be a good box size if i do decide to build a comp box. I know i could have gotten at least 189 that day if i didn't attenuate the sublevel, held down on the trunklid (vibrates like crazy.)unfolded both rear seats ect. I do wounder if a Audiocontrol epicenter would really raise my score more than just tweaking the 13 band on my cd player and the bass boost on the amp. I'm also playing with the idea of facing the box forward and sealing the trunk from the cabin. I think it should theoredically increase spl since it would reduce the amount of airspace that needs to be pressurized in the cabin since the volume of air in the trunk would be eliminated and there would be nothing blocking the air from the cabin but i wounder if that thing of the bass "magnifying" when it bounces of the back of the trunklid is true or is the reason why a box is louder when its turned to the back is because cancellation of waves is reduced. oh yeah i pretty much just did a 0hz and up sweep of the BM disc (v5.0 i think)


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## superfro86 (May 15, 2002)

my caculations were 56hz so that should be good. i'm trying to ask tech support at ID on what they think would be a good box size if i do decide to build a comp box. I know i could have gotten at least 189 that day if i didn't attenuate the sublevel, held down on the trunklid (vibrates like crazy.)unfolded both rear seats ect. I do wounder if a Audiocontrol epicenter would really raise my score more than just tweaking the 13 band on my cd player and the bass boost on the amp. I'm also playing with the idea of facing the box forward and sealing the trunk from the cabin. I think it should theoredically increase spl since it would reduce the amount of airspace that needs to be pressurized in the cabin since the volume of air in the trunk would be eliminated and there would be nothing blocking the air from the cabin but i wounder if that thing of the bass "magnifying" when it bounces of the back of the trunklid is true or is the reason why a box is louder when its turned to the back is because cancellation of waves is reduced. oh yeah i pretty much just did a 0hz and up sweep of the BM disc (v5.0 i think)

i would like to do the dual tune thing but i'm not quite sure how to execute it. would i build 4 sets of ports(2 tuned to "street"fq, 2 to resonant freq) and plug off the 2 i don't need at the time or what. that would seem alot easier than switching boxes.


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## superfro86 (May 15, 2002)

sorry for double post and i ment 139 not 189, i would be the man if i hit 189 with one idmax,1000watts and a street-tuned box.


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## sr20dem0n (Mar 19, 2003)

superfro86 said:


> i would like to do the dual tune thing but i'm not quite sure how to execute it. would i build 4 sets of ports(2 tuned to "street"fq, 2 to resonant freq) and plug off the 2 i don't need at the time or what. that would seem alot easier than switching boxes.


there are a bunch of ways to do it...I think one of the simplest is to give yourself a certain amount of port area, and say for 56hz it needs to be 10" long and for 30hz it needs to be 15" long (just pulling numbers out of my ass). You can make a 10" port inside the box, and then have a 5" continuation that you can attach to the outside of the box that adds 5" to the port and keeps the same port area. Another thing you can do is build a little insert that attaches inside the port, which reduces the port area and will lower the tuning frequency. You could also do what you thought, and have 2 separate ports and just plug one or the other depending on whether you want comp or daily tuning.


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## superfro86 (May 15, 2002)

I talked to ID. they said that with the power i'm giving it i need ports bigger than the 2 3" pvc pipes and that the ports are unloading. also suggest that i put it in a 2.8 cube tuned to something (i forgot what fq. he said) I'll probally build the largest rec enclosure they gave me for a street box since my taillight started to leak again and got my box wet (the mdf is all lumpy where it got wet at)


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