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Heya guys. I have 2 rockford fosgate p2 d4-15's running about 1000 rms at 1 ohm. ( i know its a little over rated for these subs but ive lowered the gain to compensate.)

the box is as follows:Screenshot_20190620-233211.thumb.png.55455f0407a956e7b8f7551c3fe2e10c.png

The box is sitting in the boot of a seat altea. Its an mpv. Subs facing window screen, ports firing up to roof. Box is

34" wide x 20"tall x 17.5" deep.

 

Any advice to make this box better would be much appreciated. If you need more info let me know guys.

I tried modeling it in WINisd and it came out with a peak at 50hz.

However running frequencies in the car shows a peak more between 36hz and 45hz.

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So win WInISD is saying:

3.113db at 38.6 hz

7.021db at 49.98hz

And if i try to auto calculate a sealed box it comes out at 50ft3 🤣

Dont know where im going wrong.

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What exactly are you hoping to learn from WinISD?

I'm happy to model your box for you, but I need to know what kind of information you are after.  


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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Sooooo been hoping some one would answer 🤣 thanks dude.

Would like to know where im at roughly with tuning.

Specs ive built the box too say 31.4hz

however in the car im getting roughly 38-43 ( going off my ears running frequencies on a tone generator)

Wondering if i messed up the box and port tuning or if its due to cabin gain.

Would like my loudest notes in the low 30s.

 

Hope this makes sense.

Edited by Joshy 94
Damn spelling

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Still not able to get winisd to work with those subs.

However. I have come to the conclusion that those subs are not suitable for the application I am after. ( loud, low bass ) they do hit pretty well dont get me wrong. Great for bump on a budget.

I modelled another sub i have in mind on winisd ( one of the edge 15's, they are a european brand and im for england hence the choice. Its those or vibe really.) And it worked out great the parameters all went in great and the spl was well within expected raanges of what i had in mind.

But a few questions spring to mind.

How much can you realistically over size a ported sub box ? ( i feel 5.5 ft3 is a little small for 2 15's on 1000rms trying to hit 31hz)

Would a bigger box help get louder lower ? ( like a 6ft3 box or 6.5ft3)

This is kind of what i was trying to use winisd for.( dont know why it screws up on those rockford fosgates)

All help is greatly appreciated and sorry for the long ass post.

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7 hours ago, Joshy 94 said:

Still not able to get winisd to work with those subs.

However. I have come to the conclusion that those subs are not suitable for the application I am after. ( loud, low bass ) they do hit pretty well dont get me wrong. Great for bump on a budget.

I modelled another sub i have in mind on winisd ( one of the edge 15's, they are a european brand and im for england hence the choice. Its those or vibe really.) And it worked out great the parameters all went in great and the spl was well within expected raanges of what i had in mind.

But a few questions spring to mind.

How much can you realistically over size a ported sub box ? ( i feel 5.5 ft3 is a little small for 2 15's on 1000rms trying to hit 31hz) - Increasing box size will increase cone excursion, just how far you can go depends on how much power you are running.  Those RF subs would probably benefit from a little bigger box.  

Would a bigger box help get louder lower ? ( like a 6ft3 box or 6.5ft3) - Yes, it would, as long as the increase in box volume was reasonable.  The bigger the box, the more output you get around the tuning frequency.

This is kind of what i was trying to use winisd for.( dont know why it screws up on those rockford fosgates) - WinISD works fine for those RF subs, its not screwing up.  You just have to learn how to interpret the results.  

All help is greatly appreciated and sorry for the long ass post.

My answers are above in blue. 


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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9 hours ago, Joshy 94 said:

Sooooo been hoping some one would answer 🤣 thanks dude.

Would like to know where im at roughly with tuning.

Specs ive built the box too say 31.4hz

however in the car im getting roughly 38-43 ( going off my ears running frequencies on a tone generator)

Wondering if i messed up the box and port tuning or if its due to cabin gain.

Would like my loudest notes in the low 30s.

 

Hope this makes sense.

Your tuning may be ~31 Hz, enclosures don't always have peak output at the tuning frequency.  
 

The biggest issue you are dealing with is those particular RF subs are really meant more for a sealed box.  This is why the output rolls off below 50 Hz and why you saw such a difference when you modeled a different sub in WinISD.


"Nothing prevents people from knowing the truth more than the belief they already know it."
"Making bass is easy, making music is the hard part."

Builds:

U7qkMTL.jpg  LgPgE9w.jpg  Od2G3u1.jpg  xMyLoO1.jpg  9pAlXUK.jpg

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