Tercel-R Posted March 16, 2013 Author Report Posted March 16, 2013 That is also an interesting idea. Are you sure the 17" port length is correct though? I am using BassBox 6 Pro and it is giving me a port length of 21.5" for 3x 2" ports at 34Hz. Is the 7.07 sq.in for the 3" aeroport not adequate enough for an 8W7? For slot ports I believe 12sq in per 1cu ft, but the round ports are more efficient. Also, I am mainly going for sound quality so I'm not too concerned with port chuffing at high volumes.
Krakin Posted March 16, 2013 Report Posted March 16, 2013 Joe's box is an excellent design for your needs. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener.
Tercel-R Posted March 16, 2013 Author Report Posted March 16, 2013 That does look pretty bad ass. That is modeled at 21.5" port length. I do prefer being able to have the sub centered in the box...just looks nicer. What's the best way to secure a straight length of PVC pipe on the side...epoxy and silicone?
Krakin Posted March 16, 2013 Report Posted March 16, 2013 If you keep it at a 21.5" port you will lower the tuning bellow 31hz. Which seems pretty low if you going for a sq setup. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener.
Tercel-R Posted March 16, 2013 Author Report Posted March 16, 2013 Are you using the Torres calculator? I don't believe it is correct. BassBox Pro and the calculator on Precision Sound both give 21.5" for 34 Hz (both ends flared) I don't think I will have room for flares so the port length will be more like 21.125" http://www.psp-inc.com/tools.html
Krakin Posted March 16, 2013 Report Posted March 16, 2013 Torres yes. Even if 21.5 is too long then all you will have to do is cut it down. Krakin's Home Dipole Project http://www.stevemeadedesigns.com/board/topic/186153-krakins-dipole-project-new-reciever-in-rockford-science/#entry2772370 Krakin, are you some sort of mad scientist? I would have replied earlier, but I was measuring the output of my amp with a yardstick . . . What you hear is not the air pressure variation in itself but what has drawn your attention in the two streams of superimposed air pressure variations at your eardrums An acoustic event has dimensions of Time, Tone, Loudness and Space Everyone learns to render the 3-dimensional localization of sound based on the individual shape of their ears, thus no formula can achieve a definite effect for every listener.
Joe X Posted March 16, 2013 Report Posted March 16, 2013 That is also an interesting idea. Are you sure the 17" port length is correct though? I am using BassBox 6 Pro and it is giving me a port length of 21.5" for 3x 2" ports at 34Hz. Is the 7.07 sq.in for the 3" aeroport not adequate enough for an 8W7? For slot ports I believe 12sq in per 1cu ft, but the round ports are more efficient. Also, I am mainly going for sound quality so I'm not too concerned with port chuffing at high volumes. That sub can make good use of the extra port area but you be the judge, anyways I glad you picked up that Torres calc bug, I have pointed out that this issue many times and also to Torres, hopefully he will consider fixing it sometime in the future, in the meantime the PSP calc can be used: So without flares 20.5" since this would be using simple PVC pipe.
Tercel-R Posted March 16, 2013 Author Report Posted March 16, 2013 Awesome, thanks for the help. I'm going to proceed with "project triple port". Do you have to add enclosure material thickness to the port length? Like, is the "effective" port length only inside the enclosure? So add another 0.75 onto the 20.5"?
Sonic Posted March 16, 2013 Report Posted March 16, 2013 Port length remain 20.5", what decreases is the port volume that is taken up buy the 0.75'' wall thickness, but its very minimal so dont worry about it.
Tercel-R Posted March 16, 2013 Author Report Posted March 16, 2013 OK, thanks. This is the reason I asked, BBPro wanted to add the wall thickness to the length: I played around with the damping and that may be the reason for the discrepancy. If I add a little bit of damping material it will shorten the port length I'm looking forward to working on this puppy. I've never made a birch box and I'm hoping it works out because birch isn't exactly cheap haha
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