Triticum Agricolam Posted April 14, 2016 Report Posted April 14, 2016 BTW he graph im seeing on you other post confirms my theory. the dual 3" ports peaked harder and fell off faster.. do 3 4" ports against the 2 3"s ports that's 37.7in^2 now double that( right around half the SD) and let me know.. if i'm wrong ill stand corrected my testing showed what i'm telling you. i'm in no way a speaker master just a curious cat.. lol and thank you for handling the subject like a man instead of a kid.. like i said i have a prototype coming in very soon and plan of getting it tweaked for production and i will preform and test anyone here wishes me to do.. its what i like to do! I'm sorry, but I think you are misunderstanding my graphs in the other thread. They are not comparing the different size ports to each other. Each graph is showing the performance of one port at different input power levels to show the difference port compression makes. The smaller port shows a larger change in performance as power is increased since port velocity is higher, and thus port compression is more severe. The only graph that compared the performance of one port to the other is the one I posted earlier in this thread and it showed the two ports performance to be identical, which runs contrary to what you are saying. If you would like I can make a port for my test box using two 5" round ports, which should provide about 40 sq in of port area. If I measure that port and its performance is identical to what a single 4" port does, would you accept that as evidence that changing port area does not affect the frequency response of a non-compressed port? "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:
bassfreak85 Posted April 14, 2016 Report Posted April 14, 2016 BTW he graph im seeing on you other post confirms my theory. the dual 3" ports peaked harder and fell off faster.. do 3 4" ports against the 2 3"s ports that's 37.7in^2 now double that( right around half the SD) and let me know.. if i'm wrong ill stand corrected my testing showed what i'm telling you. i'm in no way a speaker master just a curious cat.. lol and thank you for handling the subject like a man instead of a kid.. like i said i have a prototype coming in very soon and plan of getting it tweaked for production and i will preform and test anyone here wishes me to do.. its what i like to do! I'm sorry, but I think you are misunderstanding my graphs in the other thread. They are not comparing the different size ports to each other. Each graph is showing the performance of one port at different input power levels to show the difference port compression makes. The smaller port shows a larger change in performance as power is increased since port velocity is higher, and thus port compression is more severe. The only graph that compared the performance of one port to the other is the one I posted earlier in this thread and it showed the two ports performance to be identical, which runs contrary to what you are saying. If you would like I can make a port for my test box using two 5" round ports, which should provide about 40 sq in of port area. If I measure that port and its performance is identical to what a single 4" port does, would you accept that as evidence that changing port area does not affect the frequency response of a non-compressed port? i would be inclined to agree as long as the box size and tune does not change..
Triticum Agricolam Posted April 18, 2016 Report Posted April 18, 2016 i would be inclined to agree as long as the box size and tune does not change.. I was able to get the double 5" port made up and do some testing today, you can see my full results on my other thread here: http://www.stevemeadedesigns.com/board/topic/204068-port-compression-and-optimization/?p=3100647 The short version is that there was virtually no difference in frequency response between the single 4" port and the dual 5" ports when tuned the same. Here's the graph: The red line is the 4" port and the green line is the dual 5" ports. No smoothing was applied, that's raw output. "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:
bassfreak85 Posted April 18, 2016 Report Posted April 18, 2016 i would be inclined to agree as long as the box size and tune does not change.. I was able to get the double 5" port made up and do some testing today, you can see my full results on my other thread here: http://www.stevemeadedesigns.com/board/topic/204068-port-compression-and-optimization/?p=3100647 The short version is that there was virtually no difference in frequency response between the single 4" port and the dual 5" ports when tuned the same. Here's the graph: The red line is the 4" port and the green line is the dual 5" ports. No smoothing was applied, that's raw output. dual 5" ports are still only about 27in^2 i would be inclined to agree as long as the box size and tune does not change.. I was able to get the double 5" port made up and do some testing today, you can see my full results on my other thread here: http://www.stevemeadedesigns.com/board/topic/204068-port-compression-and-optimization/?p=3100647 The short version is that there was virtually no difference in frequency response between the single 4" port and the dual 5" ports when tuned the same. Here's the graph: The red line is the 4" port and the green line is the dual 5" ports. No smoothing was applied, that's raw output. has some slight changes nothing to really point out but your still way lower than what is used typically for a 15. the number people are going by is 16in^2 per cube. so n 4 cubes that's 64in^2 are just about half the SD of your typical 15.. ill take it for what it is but like i said your still seeing a-little resistance. if you keep stepping it up you will se changes. ill take you testing for it, and soon ill do my own testing and share the results. thanks for your time and effort! im interested to see how it manages in car as well
Triticum Agricolam Posted April 18, 2016 Report Posted April 18, 2016 dual 5" ports are still only about 27in^2 has some slight changes nothing to really point out but your still way lower than what is used typically for a 15. the number people are going by is 16in^2 per cube. so n 4 cubes that's 64in^2 are just about half the SD of your typical 15.. ill take it for what it is but like i said your still seeing a-little resistance. if you keep stepping it up you will se changes. ill take you testing for it, and soon ill do my own testing and share the results. thanks for your time and effort! im interested to see how it manages in car as well You need to check your math on how much port area two 5" ports is. Its just under 40 sq in, not 27. While the port area per cube may be on the low side for what is usually used its still 1/3 higher than the 7.7 sq in per cube Alpine recommends for this sub. Honestly I kind of feel like no matter how much port area I would have used you would have said "well if you would have used more you would see a difference". The fact remains that I increased port area over 3x what it was with the single 4" port and there was virtually no measurable difference in frequency response. "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:
bassfreak85 Posted April 19, 2016 Report Posted April 19, 2016 misprint 2.5^2*3.145*2 39.31. right below the 10in^2 per cube. http://cholla.mmto.org/speakers/theory/vented-2.pdf keep going. why ya think SPL guys use HUGE ports?
Jessica Posted April 19, 2016 Report Posted April 19, 2016 Is anyone building any of this or just modeling this in software? Rest in peace, walled 87 accord build log 03' Corolla build with AA Mayhem inside. My super random youtube channel and terrible camera work. Wiring comparison by CaptainzPlanetz Wire and fuse guide by Guest SyKo13
Triticum Agricolam Posted April 19, 2016 Report Posted April 19, 2016 Is anyone building any of this or just modeling this in software? Built and tested: "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:
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