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How much sound comes out from port and from sub?


akuma4u

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Hey just wanna know how much sound volume is produced by the slot port versus the face of the sub itself? Is it like 90% port or more like 50/50?

Reason im asking is i am attempting to build a enclosure in trunk with port aiming into cabin. I was excited because now i could have my backseat up all the time however the builder told me i would still need the back seats to be down or else i will not get any volume from the sub itself and it wouldnt sound right. Is this true? 

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I could be a little off here but most of the sound comes from the woofer itself, the port is more so for tuning features and only moves the air in the box that it is in.

And if you want sound then do not face it towards the cabin, you will get less then if you faced it towards the trunk lid so it can reverb which will give you more boom.

Yes I have personally tried both and found cabin Vs trunk lid is a big difference.

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11 minutes ago, AlpineNut said:

I could be a little off here but most of the sound comes from the woofer itself, the port is more so for tuning features and only moves the air in the box that it is in.

And if you want sound then do not face it towards the cabin, you will get less then if you faced it towards the trunk lid so it can reverb which will give you more boom.

Yes I have personally tried both and found cabin Vs trunk lid is a big difference.

I agree with you on facing the sub towards rear vs towards cabin. With a plain slot ported box i tested both ways and the rear facing sub and port was better in every way and louder. The only benefit i found from facing it forward was that it sounded cleaner and i could feel the air dispersment better on my arms and neck. But it failed on extension and spl. 

I was hoping that by having the port aimed into cabin up thru rear deck i would get all the bass into cabin and could bypass the trunk completely. But..if what you say is true then it doesnt really make a difference as the tuning would remain the same vs port in trunk vs external port firing up and aiming into cabin and the sub will always remain in trunk as well..

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Ya I did a SPL contest back in early 2k's tried the box both ways and there was a HUGE difference in SPL when I turned it around facing the cabin there was a loss of about 4 dB or so, turned towards the trunk I hit 142.2 db with just 2 12's

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11 minutes ago, AlpineNut said:

Ya I did a SPL contest back in early 2k's tried the box both ways and there was a HUGE difference in SPL when I turned it around facing the cabin there was a loss of about 4 dB or so, turned towards the trunk I hit 142.2 db with just 2 12's

I believe the key in facing it towards rear is that now a loading wall is created and soundwaves strengthen when they hit it and bounce back..  I do see so many guys facing subs and port forward but they also seal off everything as well..maybe that makes a big difference. I didnt seal off nothing when i did my test. Im assuming you also didnt. 

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Right at the tuning frequency almost 100% of the output comes out of the port.  As you move away from the tuning frequency output from the port drops off and output from the cone picks up. 

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majority of the range is played solely by the sub. the sub will start to roll off around the 50-60hz range, the slope will depend on the enclosure. if the port is tuned lower than the roll off point, the port will start to pick up till the tuning frequency than start rolling off after the tuning frequency. the old saying of +3db gain from a ported enclosure is based off of most boxes being tuned high where the sub and port combine playing frequencies. look at a tuning graph and the lower you tune the flatter the response. then when you tune higher you'll notice that the higher you tune the higher of a gain you'll get. it's because the sub and the port are both playing the frequencies. I believe it's Term-Pro that allows you to see the frequency response graph with the sub being in blue and the port being in red and the overlapping frequencies in purple.

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