Can somebody verify this is correct??

[Fuknmovin 10+ year member]

It seems like this is not right, but yet it says it is... I am trying out a simple ported box for my cheap MA 10's there will be three housed in two enclosures like this on in the attachment. Do the specs make sense? It is weird, it says the port is 27" long and yet the port wall is only like 17" or something,..is it because the port is in the corner? I have never built a box like this before, I have always just placed the port in the middle or something, never used a common wall like this. Let me know. Thanks!

-Bryan

Click to read more...

 

[justafifteen 10+ year member]

Could you post a bigger picture?

Port length continues past the common wall into the box at a 45 degree angle. Like this:

See the pink line?

 

[Fuknmovin 10+ year member]

OK I have tried, but it will not show up any friggin bigger, but I understand what you put there. Mine has a port wall of 17" with NO right angle on the port wall it just stops at 17" the box is 24" across and its on the side just like yours, but the RE calculator is showing 27" of port? What gives? And can I trust the Hz the RE calc is giving me? Its saying like 34Hz with this much port length and 57 SQ" of port area in a 3.865CUFT gross box.....Make sense?

 

[justafifteen 10+ year member]

OK I have tried, but it will not show up any friggin bigger, but I understand what you put there. Mine has a port wall of 17" with NO right angle on the port wall it just stops at 17" the box is 24" across and its on the side just like yours, but the RE calculator is showing 27" of port? What gives? And can I trust the Hz the RE calc is giving me? Its saying like 34Hz with this much port length and 57 SQ" of port area in a 3.865CUFT gross box.....Make sense?

I can't really help with the port issue without seeing the full-size pic. AFAIK, the RE calc is usually off by ~2hz, so not very noticable at all.

 

[Oneswtredhead 10+ year member]

2hz can make a huge difference depending on the sub.

re calc sux just use a port cal

the12volt.com has a very accurate 1

 

[Fuknmovin 10+ year member]

OK, so how do I accurately measure the port length then? does it stop at the end of the port wall or is there some other trick to it?

 

[spltuscon 10+ year member]

No, the "effective" port length of a slot port continues past the end of the port by 1/2 the width of the port. So for example if the port is 4"wide then the additional length the port "sees" is called end correction factor and it would be 2" for my example. The RE box calculator really sucks though. Use the one on 12volt as mentioned above. Don't forget to accurately account for the port displacement when figuring volume though. You have to include the port wall in your figures. Example: a port is 4" wide by 12"h and it is 8" long (the interior section would be 7.25)...the displacement would be 4.75x12x7.25=413.25in3 (.239ft3)

 

[Fuknmovin 10+ year member]

OK, THANKS! I think I get it now, wish me luck!

 

[spltuscon 10+ year member]

No problem, good luck!