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Car Audio Help
Enclosure Design & Construction
EXPERTS ONLY PLEASE Building the perfect transmission line box, many questions
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<blockquote data-quote="1995Tercel" data-source="post: 8660797" data-attributes="member: 643428"><p>Vehicle : 2000 Honda Insight</p><p></p><p>Location in the vehicle: Terminus output behind driver seat, subwoofer facing rear of the car, under the package shelf</p><p></p><p>Space available (Length x Width x Height): Depends on what design I end up with, I'm going to try and fit the box we come up with.</p><p></p><p>Subwoofer make and model: Sundown Audio SA-8 V3</p><p></p><p>Subwoofer Size: 8inch</p><p></p><p>Number of Subwoofers: one</p><p></p><p>Amplifier make and model: Sundown Audio SAE-600D</p><p></p><p>Type of Port (Kerfed, Slot, Aero, etc.): circular</p><p></p><p>What type of music do you like?: all</p><p></p><p>Is your goal SPL or Everyday Music?: Goal is maximum extension (minimal Db taper past 20Hz), zero resonance, perfect bass. How loud the system gets is not a concern for me. Complete focus on quality.</p><p></p><p>Tuning Freq (Hz): I'm not sure, but the FS Hz for the subwoofer is 38.29</p><p></p><p>Volume : Also not sure</p><p></p><p>Questions: So, I'm attempting to make a straight tline box, but I just don't know where to begin. It is difficult to find practical information on this style box, as almost every single box i see, is done incorrectly. I also cant rely on calculations for those boxes, for the same reason. Many boxes I see have a parallel wall opposite the subwoofer (on top of zero sound deadening, with all parallel walls) which is all very poor design.</p><p></p><p>Just so people helping me are on the same page, Tline boxes exist to reduce or eliminate resonant frequencies, should be tapered wall, terminus output port 1/3 to 1/4 the area of the subwoofer radiating surface area, the first half of the transmission line lined with TL (not sure what this acronym stands for) second half filled with BAF Wadding. (If I'm wrong on this, please correct) I will also attempt to fit the box without compromising the design, so no internal turns or baffles, just straight.</p><p></p><p>1a. I think I need a bass chamber, that is 1/5th the wavelength distance, but I'm not sure what bass chamber means, what wavelength I need to use, or how to calculate volume of the box. Do I use the 38.29Hz of the subwoofer FS value? (Using that value I get a 1/5th wavelength distance of 69.40in at the calculated yearly average temperature of 50 degrees f where I live.)</p><p></p><p>1b. What is a bass chamber in a Tline box? Is "bass chamber"just referring to the overall structure of the box?</p><p></p><p>1c. I have read that I need to add a small distance to the overall length of the sub box to accommodate "end correction." How do I calculate this distance? This is another critical aspect, as the proper amount greatly increases low end extension.</p><p></p><p>1d. How do I cancel out the 3rd fundamental harmonic? the 5th one is done with the proper calculation of 1a.</p><p></p><p>2. What is the radiating surface area of my sub? I contacted Sundown audio, they just told me its 50.24 square inches, which is simply using a full 8 inch radius. I am very skeptical of this, as I've read this can be significantly different actual area among different subs. I need the exact area, because the port on the opposite end of the box needs to be between 1/3 and1/4th the area.</p><p></p><p>3a. How do I know what volume to use for the entire box?</p><p></p><p>3b. How do I calculate this volume?</p><p></p><p>3c. Are there separate volumes I need to calculate? Or is does this box simply taper from the subwoofer to the port?</p><p></p><p>Thank you for your assistance and expertise.</p></blockquote><p></p>
[QUOTE="1995Tercel, post: 8660797, member: 643428"] Vehicle : 2000 Honda Insight Location in the vehicle: Terminus output behind driver seat, subwoofer facing rear of the car, under the package shelf Space available (Length x Width x Height): Depends on what design I end up with, I'm going to try and fit the box we come up with. Subwoofer make and model: Sundown Audio SA-8 V3 Subwoofer Size: 8inch Number of Subwoofers: one Amplifier make and model: Sundown Audio SAE-600D Type of Port (Kerfed, Slot, Aero, etc.): circular What type of music do you like?: all Is your goal SPL or Everyday Music?: Goal is maximum extension (minimal Db taper past 20Hz), zero resonance, perfect bass. How loud the system gets is not a concern for me. Complete focus on quality. Tuning Freq (Hz): I'm not sure, but the FS Hz for the subwoofer is 38.29 Volume : Also not sure Questions: So, I'm attempting to make a straight tline box, but I just don't know where to begin. It is difficult to find practical information on this style box, as almost every single box i see, is done incorrectly. I also cant rely on calculations for those boxes, for the same reason. Many boxes I see have a parallel wall opposite the subwoofer (on top of zero sound deadening, with all parallel walls) which is all very poor design. Just so people helping me are on the same page, Tline boxes exist to reduce or eliminate resonant frequencies, should be tapered wall, terminus output port 1/3 to 1/4 the area of the subwoofer radiating surface area, the first half of the transmission line lined with TL (not sure what this acronym stands for) second half filled with BAF Wadding. (If I'm wrong on this, please correct) I will also attempt to fit the box without compromising the design, so no internal turns or baffles, just straight. 1a. I think I need a bass chamber, that is 1/5th the wavelength distance, but I'm not sure what bass chamber means, what wavelength I need to use, or how to calculate volume of the box. Do I use the 38.29Hz of the subwoofer FS value? (Using that value I get a 1/5th wavelength distance of 69.40in at the calculated yearly average temperature of 50 degrees f where I live.) 1b. What is a bass chamber in a Tline box? Is "bass chamber"just referring to the overall structure of the box? 1c. I have read that I need to add a small distance to the overall length of the sub box to accommodate "end correction." How do I calculate this distance? This is another critical aspect, as the proper amount greatly increases low end extension. 1d. How do I cancel out the 3rd fundamental harmonic? the 5th one is done with the proper calculation of 1a. 2. What is the radiating surface area of my sub? I contacted Sundown audio, they just told me its 50.24 square inches, which is simply using a full 8 inch radius. I am very skeptical of this, as I've read this can be significantly different actual area among different subs. I need the exact area, because the port on the opposite end of the box needs to be between 1/3 and1/4th the area. 3a. How do I know what volume to use for the entire box? 3b. How do I calculate this volume? 3c. Are there separate volumes I need to calculate? Or is does this box simply taper from the subwoofer to the port? Thank you for your assistance and expertise. [/QUOTE]
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EXPERTS ONLY PLEASE Building the perfect transmission line box, many questions
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