How do I figure resonant frequency using a cars interior dememnsions?
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Gold Member Username: InsearchofbassPost Number: 3075 Registered: Jun-04 | Ok before you say it I know your going to tell me to take the box out of the in an open area and measure with an spl meter but I already know that way. Im curious how you would claculate it with these interior demensions in a 99 Toyota Corolla 56.75" Across the center width wise, and 99" front-to-back? |
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Gold Member Username: InsearchofbassPost Number: 3077 Registered: Jun-04 | found it  |
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Silver Member Username: GeekbikePost Number: 235 Registered: Dec-04 | That would have been the link I would have suggested. What're you planning? |
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Gold Member Username: InsearchofbassPost Number: 3084 Registered: Jun-04 | just gathering knowledge lol. |
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Silver Member Username: GeekbikePost Number: 236 Registered: Dec-04 |  Now that I look at it, it's a transmission line (1/2 wavelength) tuned to resonant frequency. |
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Gold Member Username: InsearchofbassPost Number: 3085 Registered: Jun-04 | i found this website http://www.teamgates.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=14;t=000077 and wanted to understand how the guy would calculate the application. |
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Gold Member Username: InsearchofbassPost Number: 3086 Registered: Jun-04 | no it isnt he calculating wave form which tells me you resonant frequency can be manipulated. Which is why I asked the question partially. copy and paste that link above in another window and it will work. |
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Gold Member Username: InsearchofbassPost Number: 3087 Registered: Jun-04 | im sure if you think about it you can see what Im driving at. |
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Gold Member Username: InsearchofbassPost Number: 3088 Registered: Jun-04 | its front wave measure distance to point of refererence and rear wave three times the distance to the front wave |
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Gold Member Username: InsearchofbassPost Number: 3089 Registered: Jun-04 | ps...there are more ways than one to manipulate a wave length to fit your desired range |
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Silver Member Username: GeekbikePost Number: 240 Registered: Dec-04 | Well, if a transmission line was tuned to the resonant frequency of the vehicle, and used 1/2 wavelength of that, the wave would move another quarter to the reference point. This would give you a 3/4 wavelength from the rear of the woofer to the reference point. But also, youhave to remember that the wave starts out at 180deg or 1/2 wavelength. This would have the entire wave at 1 and 1/4 wavelength at the reference point. The two waves would be matched up, giving the highest possible SPL with the room available (a horn would give higher spl, but it would be impossible to fit in anything but an 18wheeler). I haven't modelled a TL, so I cannot comment on the gain they produce. It would be much more complicated figuring out the waves inside a ported enclosure, but it may yield higher results. Resonant frequency can be manipulated simply by changing the amount of space. And the guy with the Corolla, having 4 12" subwoofers, a TL wouldn't be possible in the space he has. A ported probably wouldn't even be possible in the space he has. Possibly if he wanted to wall it up, but he made no mention of it. By your last comment there, are you referring to using other parts of the wavelength? |
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Gold Member Username: InsearchofbassPost Number: 3100 Registered: Jun-04 | "Well, if a transmission line was tuned to the resonant frequency of the vehicle, and used 1/2 wavelength of that, the wave would move another quarter to the reference point. This would give you a 3/4 wavelength from the rear of the woofer to the reference point. But also, youhave to remember that the wave starts out at 180deg or 1/2 wavelength. This would have the entire wave at 1 and 1/4 wavelength at the reference point. The two waves would be matched up, giving the highest possible SPL with the room available" reply...I follow your thing there and I agree. "Resonant frequency can be manipulated simply by changing the amount of space." reply...I follow you again because the front to rear measurements would change affecting the calculated waveform giving numerous possibilities but that requires more space being used up (a negative). "By your last comment there, are you referring to using other parts of the wavelength?" reply... at that point I was thinking of reflection to guide a wave just like how your folded transmission line worked (if you think about it) I have other ideas to go along with all this but ill stick to the points of our conversation. |
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Silver Member Username: GeekbikePost Number: 250 Registered: Dec-04 | Now something like this:  or:  would probably produce HUGE bass. The waves would be coupled (assuming the TL was tuned to 1/2 wavelength) before being further increased by the port or horn. With the horn, tune it to 1/4 wavelength, giving huge gain on the wave and having it placed 1/2 wavelength away from the reference point. Everything would peak at the absolute highest possible point. Doing this will large woofers is not practical for testing purposes, as it would take huge room and materials to construct. I hope to try and model this with some small drivers later on. Maybe a project for your Tangbands? |
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Gold Member Username: InsearchofbassPost Number: 3105 Registered: Jun-04 | your using the same concept i had there knacko except yours is an internal chamber. My idea used an external chamber around the subwoofer corner loaded making the front and rear wave in phase. I assume your example one is rear wave 3 times the front wave distance. |
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Gold Member Username: InsearchofbassPost Number: 3109 Registered: Jun-04 | ps.. i have other ideas to shrink the box size so dont worry about that |
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Gold Member Username: InsearchofbassPost Number: 3114 Registered: Jun-04 | also im going to put the dont go below a speakers fs to the test with one of my designs i do i believe its possible to go much lower in the right box....how bout 25 hz for a 6.5 inch sub???? |
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