Box tuning freq and slot length help

[mystamo 10+ year member]

hey guys. making a new box for my kicker CVR 12"

My box's internal dimensions are 21.75" by 12" by 12" I have cut a 2" slot on on side of the box where I plan on extending a piece of 3/4 mdf to acquire my target freq of 40hz maybe slightly lower if someone recommends this.

My question. How long do I need to make the slot port length to get to this frequency. Also please note that the box wont have any bends in the slot port since the port goes parallel to the longest length of the box.

Any help would be awesome!

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[subzero 5,000+ posts]

RE Enclosure Calculator

 

[mystamo 10+ year member]

Been there kinda done that.. Here is my problem with that calculator. In and around 2008 I remember reading that the calc does not do a good job at calculating the right frequencies. Also.. is the re calc setting the internal dimensions or external. My box is already made and I've stated the internal volumes. I'm not really too sure how the RE calc is aligning the box walls. I think my port needs to be around 20" just need an exact number from someone more experienced them me! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[UMWDawg92 10+ year member]

I assume tuning to 40hz your going for SPL? otherwise I'd advise lowering it to ~35hz

 

[mystamo 10+ year member]

I've been making a lot of 30hz boxes for my previous subs like Kicker L7 15" and Re MX 12" but I want to try 40hz for a change besides I'm just going with kickers own recommendations on this sub except i had to tweak the dimensions a little hence my confusion

 

[UMWDawg92 10+ year member]

did you not like your 30hz tuned boxes? or do you just want more output?

 

[RAM_Designs 5,000+ posts]

CVR's like big boxes...your box is very small.

 

[mystamo 10+ year member]

Yeah I like my boxes tuned low to mid single subs running 2000+watts rms .

It's for my GF and got very limited space in her car, I've only got an old amp kicking around 100w rms so I'm trying to squeeze out some extra output.

I ended up getting an equation out of a website and calculated that after port displacement I needed a 17" Slot length and had to trim back my slot size a bit to lower the freq and I was sitting at about 38.. Sounds like a dream. My gf really likes it and it seems to be working with most of the shit she listens to anyways.

Thanks guys

 

[RAM_Designs 5,000+ posts]

Just to clarify: bigger box = louder on same amount of power.