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View Full Version : I have to rebuild box, I searched, RE SRx

way2sl0
06-01-2010, 01:34 PM
So right now im using a 15 RE SRx giving it double RMS.

My box is around 3.2 net cu ft, @ 30 hz or so, with a 3" PVC pipe port. Yes there is port noise and it sounds bad and not that tight when loud.

So what should I give it? RE web says 3cu ft. If I could go smaller but get slightly less volume (but more useable since it sounds cleaner) id rather do that.

aeroportspwn
06-01-2010, 02:55 PM
So right now im using a 15 RE SRx giving it double RMS.

My box is around 3.2 net cu ft, @ 30 hz or so, with a 3" PVC pipe port. Yes there is port noise and it sounds bad and not that tight when loud.

So what should I give it? RE web says 3cu ft. If I could go smaller but get slightly less volume (but more useable since it sounds cleaner) id rather do that.

I am the one that sent you the pm saying your old box port was way to small while no one else caught it lol. Just follow the specs I gave you, I can't remember exactly what they were.

way2sl0
06-01-2010, 05:17 PM
yes I thank you for your response. I know you said im probably running one 4 now, and I should be running two. Well im running one three, and I don't want as large a box either, since I have the sub gain down all the time anyways. I want the flattest response in the smallest enclosure possible. I don't have access or want to buy aero ports, so I am thinking ill just make a box with a square port. I still need a good box outline though.

way2sl0
06-01-2010, 05:37 PM
Ok well I am plugging the numbers and trying to make this myself. A little difficult. I am using these calcs; Subwoofer Enclosure Calculators, Fraction to Decimal, Parallel, Series, Port Length and Volume Calculators (http://www.the12volt.com/caraudio/boxcalcs.asp)

So I calculate the box, 36 x 17 x 10" = 2.63 cu ft internal (0.75" mdf)

So then I say in port calc, ill make it 3 inches opening, and 15.5" high (height - thickness of the two top pieces of wood)
It says my port needs to be 22.88"

So I am guessing my port would be two pieces. The first would be 4.25", which leaves me 3" diameter throughout it (8"-0.75=7.25") and my second piece would be 22.88-4.25= 18.55" - 0.75" from the 1st piece, so 17.8"

Ok but now here is where I am stuck. That is a big internal port, and I have lost more internal space, so wouldnt that alter the tuning freq all over again, not to mention considerably reduce the internal volume?

aeroportspwn
06-01-2010, 10:01 PM
Some people say the RE box calculator is not accurate but just use the re box calculator it is about 99.9% accurate. All you need to do is subtract the subwoofer displacement yourself after it gives you the box volume and you are good to go. At most after you do that the box tune will only change about .3-.4 higher or so..

RE Enclosure Calculator (http://www.reaudio.com/speaker_box/LPort_Box_Calc.html)

you can adjust the port width and everything yourself.

Make sure your box has enough depth for your sub when you have such a long slot port inside. You will need to make it deeper than 10".

way2sl0
06-02-2010, 09:16 AM
Is a 2" slot port enough? Or will there be noise

MONSONwarrior
06-02-2010, 09:24 AM
Noise. I can't exactly remember the saying but for a 2.5 cu. ft. box DD says I need 40 cu. in. of port and you have 31

way2sl0
06-02-2010, 09:29 AM
The internal volume is around 2.3-2.4

I am kind of worried because they say 3.0 @ 34 is optimal, but man that creates a peak and is not very flat in freq response. I am so torn between what I am doing....

MONSONwarrior
06-02-2010, 09:36 AM
The internal volume is around 2.3-2.4

I am kind of worried because they say 3.0 @ 34 is optimal, but man that creates a peak and is not very flat in freq response. I am so torn between what I am doing....

You're still a tad under then. I would just go by specs, that looks like it'll get loud, yet deep. My DD/AQ design is 2.5 for a 12 and at 38 hz, so 2.4 is pretty small for a 15 and 31 cu. in. of port is kinda narrow. What are your size constraints?

way2sl0
06-02-2010, 09:52 AM
Ill take some measurements and get back to this thread this afternoon, thanks for your help :-)

way2sl0
06-02-2010, 02:00 PM
Ok so I have...
33" wide, 16.1" high, and 12" deep of space. Thats it.

Its interesting because TBH like I said id rather use ALOT less then that...and its heavy...
How much output would I lose using 1/2 or 5'8ths MDF instead of 3/4?

aeroportspwn
06-02-2010, 03:29 PM
trust me stick with 3/4" mdf do not go smaller.

MONSONwarrior
06-02-2010, 06:02 PM
Ok so I have...
33" wide, 16.1" high, and 12" deep of space. Thats it.

Its interesting because TBH like I said id rather use ALOT less then that...and its heavy...
How much output would I lose using 1/2 or 5'8ths MDF instead of 3/4?

That's only 2.78 cubes so you're gonna be on the small side... Then you add port displacement and driver and you're in a tiny box... My driver, bracing, and port displacement was around .6 cubes so 2 is really low for your sub..

way2sl0
06-02-2010, 06:28 PM
Well hell then. Are you saying I should just keep it sealed? I mean the Q value of the sub is good for either according to most of the calculators I have used. I don't want to have to give away all my trunk space for a subwoofer setup that is always attenuated on my deck. I mean like I said I just want flat response. The only thing I am worried about I guess is losing alot of efficiency from not going ported. Right now it takes almost no power, even though im giving it double RMS, to get it moving. The voice coil config won't allow me to run my amp at 4 ohms so I can't run it at 400, it has to be 600. I even tried trading my 15 for 2 10's, but I think it would be noticeably quieter.

I guess bottom line you are saying is, I will be destroying any low end response I would be gaining by using a ported box, if I give it only 2-2.2 cubes? It isnt that far off from RE's 2.5 compact size recommendation.

MONSONwarrior
06-02-2010, 10:42 PM
Well hell then. Are you saying I should just keep it sealed? I mean the Q value of the sub is good for either according to most of the calculators I have used. I don't want to have to give away all my trunk space for a subwoofer setup that is always attenuated on my deck. I mean like I said I just want flat response. The only thing I am worried about I guess is losing alot of efficiency from not going ported. Right now it takes almost no power, even though im giving it double RMS, to get it moving. The voice coil config won't allow me to run my amp at 4 ohms so I can't run it at 400, it has to be 600. I even tried trading my 15 for 2 10's, but I think it would be noticeably quieter.

I guess bottom line you are saying is, I will be destroying any low end response I would be gaining by using a ported box, if I give it only 2-2.2 cubes? It isnt that far off from RE's 2.5 compact size recommendation.

Well I lost .6 to a smaller sub and smaller port so you'd be under 2 cubes roughly. I just say stick with what you got or try and go with a beefy 12.