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<blockquote data-quote="Below 30" data-source="post: 366261" data-attributes="member: 551745">Venting measurments/results. 15 cubic internal, 3/4&quot; mdf, dual 15&quot; drivers (Tumult). Rear board has a total of 17&quot; by 2.5&quot; vent. It is just a Vent, no tube/board into the box. Actual design of vent is; 10&quot; by 3&quot; in center of box, two 2&quot; holes on left side and two 2&quot; holes on right side.&nbsp; External box size is in earlier post, result for the design is, lowest useable frequency down to 14Hz. I believe that ported boxes may be less SQ relative to non-intrusion vented, because as the main rival mentioned, it may cause back pressure, since the air must be routed to the specific port opening. Another problem is the common front port design. The speaker pushes the air back naturally, then the air has to travel through the port and go foward, which would be the lag and extra pressure build.If people built 2 boxes, one with manufacterer style port specs, then one as I have done with just the cut-out at the back of box, there will be a big difference. I see now its because I was so use to my style of venting rear wave, I wasn&#039;t realizing industry standard porting will yield different (restrictive) results. Which is why I couldn&#039;t understand all this &quot;Ported is for SPL and not SQ&quot;.Anybody with time and extra board, should try the two air-escape methods and see if you don&#039;t notice a difference. The measurements I gave for my enclosure and total vent-escape area, probably has a mathematical equation you can use to figure the total vent-escape you can use, if your enclosure is smaller. Don&#039;t just talk about it, try it, get the real-world facts, then come back with the findings.</blockquote>

[QUOTE="Below 30, post: 366261, member: 551745"] [COLOR=blue]Venting measurments/results. 15 cubic internal, 3/4" mdf, dual 15" drivers (Tumult). Rear board has a total of 17" by 2.5" vent. It is just a Vent, no tube/board into the box. Actual design of vent is; 10" by 3" in center of box, two 2" holes on left side and two 2" holes on right side. [/COLOR] [COLOR=#0000ff]External box size is in earlier post, result for the design is, lowest useable frequency down to 14Hz. [/COLOR] [COLOR=#0000ff]I believe that ported boxes may be less SQ relative to non-intrusion vented, because as the main rival mentioned, it may cause back pressure, since the air must be routed to the specific port opening. Another problem is the common front port design. The speaker pushes the air back naturally, then the air has to travel through the port and go foward, which would be the lag and extra pressure build.[/COLOR] [COLOR=#0000ff]If people built 2 boxes, one with manufacterer style port specs, then one as I have done with just the cut-out at the back of box, there will be a big difference. I see now its because I was so use to my style of venting rear wave, I wasn't realizing industry standard porting will yield different (restrictive) results. Which is why I couldn't understand all this "Ported is for SPL and not SQ".[/COLOR] [COLOR=#0000ff]Anybody with time and extra board, should try the two air-escape methods and see if you don't notice a difference. The measurements I gave for my enclosure and total vent-escape area, probably has a mathematical equation you can use to figure the total vent-escape you can use, if your enclosure is smaller. [/COLOR] [COLOR=#0000ff]Don't just talk about it, try it, get the real-world facts, then come back with the findings.[/COLOR] [/QUOTE]

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