# Box size for a RF 18



## dougelam (Apr 24, 2009)

I have an old school Rockford Fosgate SPPR 184 that I hade re-coned and never used. Now my son is raiding my closet and wants it in his Montero. All I can find is some of the T.S. parameters and not sure what size/type of box is recommended. Space is not a problem and he also took my US-200 to run it. I have been out of car audio for 12 years and It seems all the old school rules don’t apply anymore-When did physics change???
Any thoughts would be appreciated.


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## emak212 (Apr 13, 2010)

A good friend of mine helped me build a box for my civic a couple years ago. He did most of the carpentry so I don't remember all of the details, but I believe he used MDF (medium density fiberboard). MDF is pretty heavy and will provide a more rigid frame for improved acoustics. We also used an enclosure calculator online to determine the dimensions for the box. I don't remember the specific website, you can probably find a reputable one online somewhere. I was taking a look at one the other day that I would like to link to you, but the forums won't let me post links for some reason. Good luck!


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## SPLmonster13 (Jul 5, 2010)

what kindve bass is he looking for? Cause i mean with a driver that size you can port it, tune it low. and it will rock. Its definatly made for the lower end of the bass spectrum but you can seal it and it will produce some different tones. If it was my 18 and my montero it would be in a huge box with a huge L vent.


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## dougelam (Apr 24, 2009)

Very low as just as you thought. What kind of L vent were you thinking of?
Here is what we have so far,

www.doug.elam.com/montero


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## el_chupo_ (May 27, 2007)

Check this out:

WinISD Tutorial


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## The Dude (Mar 24, 2007)

If it is the SPP184 then the full specs are here: http://www.rockfordfosgate.com/library/datasheets/spp-184_188-ts.pdf

Not sure about box sizes, sorry. The WinIsd link above should help. Good luck.

*** Just found this: http://www.rdrop.com/~billmc/enclosures There are some recommended enclosure sizes for that sub on the list, if you follow it down. I had a look at the numbers, he has bigger box volume requirements for the 15" Fosgate subs over the 18" ones. Not sure how accurate the list is, or if he mixed up his numbers a bit on the list......


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## The Dude (Mar 24, 2007)

Not sure if this helps also, may or may not be the same sub: Rockford Fosgate Discussion Forum - rockford series1-184

In a pinch you could contact Rockford directly also...


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## SPLmonster13 (Jul 5, 2010)

I think you finish what you have off by sending a nice vent done the onside right side of the box, run it to the back and continue you italing the back wall of the enclosure about 4". As large as that sub is it will be sure to produce very nice low notes ad move impressive amounts of air


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## dougelam (Apr 24, 2009)

Thank you spl monster, but I cannot understand some of your terminology?
Are you recommending framing a vent with wood on one side venting out in the same direction as the speaker is facing?


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## Cruzer (Jul 16, 2010)

According to Winisd for best SQ, u would want a 4 cubic foot box tuned to 27.


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## dougelam (Apr 24, 2009)

I did download the Winisd program but could not make heads or tails of it. Your picture shows more tabs than mine. I am going to use a 4" port and try to tune it after completion. Any other thoughts??

Thank you for the info
Doug


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## Cruzer (Jul 16, 2010)

i have winisd pro. not sure the difference, im still very new to it as well.

with the 4" port do u know how long it must be to tune it to 27 or 30-32 at least?

there is a website that has a good calculator for that if u dont know how long it should be. if u need the site ill try and find it


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## dougelam (Apr 24, 2009)

I am mobile today so I do not have the site name, it stated a 4" vent @ .5" long in a 6cft box. I think the smaller the box the longer the vent. I will post it Later though. I am planning a wedge style enclosure, I want to place a divider inside the box to direct the air flow around an down the tube then out to reduce port noise-what do think, I will post a drawing before I build it.


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## dougelam (Apr 24, 2009)

I updated my site,
Doug
with better pictures and what this calculator,
Speaker Enclosure Volume Calculator
determined is the proper length of my port using 4cft as the baseline. With internal bracing and the speaker is self it will be pretty close to 4cft.


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## Cruzer (Jul 16, 2010)

ive never done aero port so im not much help with it. but if 12 volt says its good, its should be fine.

does it have enough port area? like each size sub supposedly requires so much port area so no noise is heard.

ive only built 1 ported box, i made it so it had the right port area for a 15 and it sounds good, no noise.


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## RyanM923 (May 12, 2007)

Do ~5ft tuned in the 28-30hz area. A single 4" port is way too small for what you're wanting to build. I'd personally stick with a single slot port...sub firing up, port firing to the rear.


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## dougelam (Apr 24, 2009)

I really do not like to have the speaker face upwards, they tend to fail quicker from debris and they can also be seen easer and then taken. PA speakers have slots for ports but they run full range don't they?


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## RyanM923 (May 12, 2007)

dougelam said:


> I really do not like to have the speaker face upwards, they tend to fail quicker from debris and they can also be seen easer and then taken. PA speakers have slots for ports but they run full range don't they?


You can do sub and port facing to the rear also.

I'm uncertain what your question about the full range speakers and slot ports is really asking. It sounds like you're worried about using a slot port?


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## Cruzer (Jul 16, 2010)

subs are meant to play no more than 200hz, and most use either 80, 100, or 120 and under on the sub stage.

i also dont see how a sub facing up is going to fail faster but heh im just a noob


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## dougelam (Apr 24, 2009)

As I stated they get destroyed from things falling on to them or dirt and stuff getting on them. Facing in any other direction lets my 25yr old son put things in the back with out worry. Also facing down puts the ft closer to what is in T/S parameters.


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## RyanM923 (May 12, 2007)

dougelam said:


> As I stated they get destroyed from things falling on to them or dirt and stuff getting on them. Facing in any other direction lets my 25yr old son put things in the back with out worry. *Also facing down puts the ft closer to what is in T/S parameters*.


I lost you here.


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## dougelam (Apr 24, 2009)

The distance from the driver to the hearing location. In an open cabin like my sons Montero if you place the driver facing up there is effectively 5 feet from the cone to the point where your head is. Just by facing it to the back can add 4ft off distance. I always felt that sub bass should be felt not heard, that is for the drivers up front. Similar to surround sound in the house, the sub usually faces down and the sound pressure is spread out in a 360° pattern. Keep in mind that the material absorbs a lot (carpet/headliner) that is where I use a hard floor under the sub box to let the sound pressure bounce off from it and spread out as even as possible.


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## Cruzer (Jul 16, 2010)

I've never seen a downfiring ht sub.

If what u say is true u would want it in the middle of the room.

If u put it in a corner the sound doesn't go out 360 because its against the wall so it will just bounce out the front which is not a 360 sound.

My gf has my old 12" subs and amp. They were redic loud facing forward and up in 2 of my vehicles. In her car the only way it fits is facing the trunk. 

Its much much more quieter. If the sub facing up or forward is too loud or too in your face u can def turn it away and lose some of that.

I'm not gonna say your wrong, or tell u how to do it. I'm just saying what my experiences are.


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## RyanM923 (May 12, 2007)

dougelam said:


> The distance from the driver to the hearing location. In an open cabin like my sons Montero if you place the driver facing up there is effectively 5 feet from the cone to the point where your head is. Just by facing it to the back can add 4ft off distance. I always felt that sub bass should be felt not heard, that is for the drivers up front. Similar to surround sound in the house, the sub usually faces down and the sound pressure is spread out in a 360° pattern. Keep in mind that the material absorbs a lot (carpet/headliner) *that is where I use a hard floor under the sub box to let the sound pressure bounce off from it and spread out as even as possible.*


Good idea. Sounds like firing back or downfiring is your best bet, based on your preferences.



Cruzer said:


> I've never seen a downfiring ht sub.


There are lots.


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## Cruzer (Jul 16, 2010)

RyanM923 said:


> There are lots.


Did u even read my post? lmao

I said im only giving my experience. I have not personally seen a downfiring HT sub. Obviously its not far from believing, why u had to comment, is beyond my understanding.

but i do agree with the OP's needs. it would probably work great if whatever he points it as is nice and sound deadened to reflect the sound back the best.


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## RyanM923 (May 12, 2007)

Cruzer said:


> Did u even read my post? lmao
> 
> I said im only giving my experience. I have not personally seen a downfiring HT sub. Obviously its not far from believing, why u had to comment, is beyond my understanding.


You're reading too much into it.


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## dougelam (Apr 24, 2009)

It is completed. The sound is amazing and the staging is right up front and center just as I wanted.

Have not come up with a ring or cover for the speaker though.










Happy listening
Doug


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## RyanM923 (May 12, 2007)

Box specs? Having any issues with that small port?


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## dougelam (Apr 24, 2009)

The port is 4" at 4.5" long and no, no problems as of yet and no port noise that is audible. 

By the way, is there any way of seeing a list of members from my area? I would like to have one listen and post their opinion on the sound of this system here.

Grand Rapids Michigan


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