8ten8 Posted May 30, 2017 Author Report Share Posted May 30, 2017 27 minutes ago, Joe X said: The easiest way would to do that mod would be making the chamber on the right a little wider and adjusting the port on that chamber to the new tuning and the increased airspace. Hmm, seems the easiest way won't work as my max width is 42" shoehorned. I do have room to go deeper thoe. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted May 30, 2017 Report Share Posted May 30, 2017 2 minutes ago, 8ten8 said: Hmm, seems the easiest way won't work as my max width is 42" shoehorned. I do have room to go deeper thoe. I can modify my original design to reflect Joe X's suggestion. I won't be able to get to it until tomorrow though. "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: Link to comment Share on other sites More sharing options...
8ten8 Posted May 30, 2017 Author Report Share Posted May 30, 2017 2 minutes ago, Triticum Agricolam said: I can modify my original design to reflect Joe X's suggestion. I won't be able to get to it until tomorrow though. That's very kind of you, thank you sir. Zzzz Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted May 30, 2017 Report Share Posted May 30, 2017 7 hours ago, 8ten8 said: That's very kind of you, thank you sir. Zzzz Here you go: The new outside box depth is 22 5/16". There is one issue I ran into. The larger front chamber and higher tuning shortened the port to the point that I'm not confident in my port length formulas. Depending on the end correction value I use I get a length between 8" and 2.75" long. The best thing to do would be to cut it long, assemble the box and measure the tuning, and then adjust the length down to raise the tuning where you want it to be. Unfortunately measuring the tuning requires either a way to measure the impedance or a calibrated mic. You could just make the front chamber port about 7.5" in total length and worse case scenario you will be tuning a little lower than 55 hz. "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: Link to comment Share on other sites More sharing options...
8ten8 Posted May 30, 2017 Author Report Share Posted May 30, 2017 54 minutes ago, Triticum Agricolam said: Here you go: The new outside box depth is 22 5/16". There is one issue I ran into. The larger front chamber and higher tuning shortened the port to the point that I'm not confident in my port length formulas. Depending on the end correction value I use I get a length between 8" and 2.75" long. The best thing to do would be to cut it long, assemble the box and measure the tuning, and then adjust the length down to raise the tuning where you want it to be. Unfortunately measuring the tuning requires either a way to measure the impedance or a calibrated mic. You could just make the front chamber port about 7.5" in total length and worse case scenario you will be tuning a little lower than 55 hz. Wow, this is all very exciting. I'll go with your suggestion starting at 8 and working my way down. One more reason to acquire the SMD IM-SG. I can't thank you enough for going the extra mile. I'll post updates when I get her done Link to comment Share on other sites More sharing options...
Joe X Posted May 30, 2017 Report Share Posted May 30, 2017 Port lengths are shown as follows for port areas of 41 1/4" square inches (16.5 x 2.5): Rear chamber: 40.85 in Front chamber 8.85 in After taking out the end correction of 1 1/4" Rear chamber: 39.6 in Front chamber 7.6 in The displacement plot is as follows: Clearly shows ports loading at about 25 and 55Hz respectively. Link to comment Share on other sites More sharing options...
Triticum Agricolam Posted May 30, 2017 Report Share Posted May 30, 2017 1 hour ago, 8ten8 said: Wow, this is all very exciting. I'll go with your suggestion starting at 8 and working my way down. One more reason to acquire the SMD IM-SG. I can't thank you enough for going the extra mile. I'll post updates when I get her done Sounds good. An IM-SG is exactly what you need. I look forward to seeing some pics as you get it built!! "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: Link to comment Share on other sites More sharing options...
8ten8 Posted May 31, 2017 Author Report Share Posted May 31, 2017 6 hours ago, Joe X said: Port lengths are shown as follows for port areas of 41 1/4" square inches (16.5 x 2.5): Rear chamber: 40.85 in Front chamber 8.85 in After taking out the end correction of 1 1/4" Rear chamber: 39.6 in Front chamber 7.6 in The displacement plot is as follows: Clearly shows ports loading at about 25 and 55Hz respectively. I didn't understand that last part. How long do you recommend the two rear port pieces to be and the one front port piece to be Link to comment Share on other sites More sharing options...
Joe X Posted May 31, 2017 Report Share Posted May 31, 2017 The numbers I posted regard to center line port lengths, you can see them below: The last post was aimed to compare calculation results from different softwares, it will be intereting to see your results from IM-SG measurements. The rear chamber in the original layout is tuned higher than the stated 25Hz to 26.5Hz according to my calculations, it's a very small difference so it can be left as is, the front chamber port should be shorter than the original 10" to tune to 55Hz, the 7 5/8" shown should get you closer. Link to comment Share on other sites More sharing options...
8ten8 Posted May 31, 2017 Author Report Share Posted May 31, 2017 Gotcha. Much much thanks JoeX for taking time out and breaking it down. Looks like I'm heading to the lumber yard after work today ? Link to comment Share on other sites More sharing options...
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