hispls Posted August 26, 2015 Report Posted August 26, 2015 What subs are you using, how much power are you going to run, what are you tuning the front chamber to? What are your goals for this system, what kind of bandwidth are you hoping to get out of the box? What vehicle is this going in? There are no generic designs for bandpass boxes. They need to be designed for the specific application they are going to be used for. Forget everything you have ever read about bandpass box ratios, they are a design shortcut for people that don't understand bandpass boxes and often times do more harm than good. This is exactly what is happening to you. 18 cu ft is a ridiculously large front chamber size for two 12"s. Correct me if I'm wrong, but it kinda sounds like you just picked a number out of the air for your rear chamber volume and then multiplied it by three to get your front chamber volume. That's kinda like walking into a shoe store without knowing what size shoe you wear and just picking a number, buying a shoe that size, and hoping it fits well. i misread the enclosure recommendations and accidently read the ones for the 15" in ported. but im going to be running 2 soundqubed hd200 12's on 1200 watts. i was looking into maybe 2 cu ft sealed and 6 ft ported. the port will be tuned to 35 hz, and i want more of an spl setup than a high range of frequencies. but thanks alot for pointing all of this out for me because it definetly makes the process faster when someone with experience can help. AFAIK the SPL bandpass boxes use a tiny sealed section and huge ported section You'll need a ton of port area to tune high (around your car's peak). I'd agree that you're just pissing into the wind here and preparing to waste a lot of wood if you don't get the TS parameters and throw them into some modeling software to see for yourself.
Jake Pichola Posted August 26, 2015 Author Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. ok cool, so with 4th order you want to tune the port higher than with just a ported box? because right now i have two sa15s tuned around 29-30 hertz and i like being able to go real low.(btw this project is for a stereo im building for my apartment)
Jake Pichola Posted August 26, 2015 Author Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. ok cool, so with 4th order you want to tune the port higher than with just a ported box? because right now i have two sa15s tuned around 29-30 hertz and i like being able to go real low.(btw this project is for a stereo im building for my apartment)
Triticum Agricolam Posted August 26, 2015 Report Posted August 26, 2015 Your are building this bandpass box for your apartment? If so, that changes everything. "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:
Jake Pichola Posted August 26, 2015 Author Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. Is port tuning for 4th order the same as port tuning for a normal ported enclosure? Or is it completely different?
Triticum Agricolam Posted August 26, 2015 Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. Is port tuning for 4th order the same as port tuning for a normal ported enclosure? Or is it completely different? How you calculate the tuning is the same, but the frequency you are going to want to tune to is completely different. So is this box for a car or your apartment? "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:
Jake Pichola Posted August 26, 2015 Author Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. Is port tuning for 4th order the same as port tuning for a normal ported enclosure? Or is it completely different? How you calculate the tuning is the same, but the frequency you are going to want to tune to is completely different. So is this box for a car or your apartment? Its for my apartment. I listen to mostly rap so thats why i like to tune so low.
Jake Pichola Posted August 26, 2015 Author Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. Is port tuning for 4th order the same as port tuning for a normal ported enclosure? Or is it completely different? How you calculate the tuning is the same, but the frequency you are going to want to tune to is completely different. So is this box for a car or your apartment? Its for my apartment. I listen to mostly rap so thats why i like to tune so low. i made this up in sketchup. dimensions are: Sealed= 28x14x18 Ported= 28x14x27 Port:Height= 6 Width= 16 Length= 19 does this seem good to you?
Jake Pichola Posted August 26, 2015 Author Report Posted August 26, 2015 No prob. A 2 cube rear chamber, and 6 cube front chamber is a lot more reasonable numbers for those subs. For a rear chamber I would recommend increasing it a bit to 4 cubes, this will lower the QTC below .7 (which is good) and bring the sealed resonant frequency down below 50 Hz (also good). It will help you get better low frequency output. 35 Hz is way too low of a tuning for the front chamber. Most people tune their front chambers to between 40-50 hz, with 45 hz being a good compromise. If you know what frequency your vehicle peaks at you could tune to there (as long as its around 40-50 hz). Keep in mind that with a bandpass box output drops off pretty quickly above and below the tuning frequency. Its a very good idea to make the port removable or otherwise adjustable so you can tweak the tuning frequency after you play test the box. For front chamber size, it depends on how peaky of output you want. The larger it is, the more output you will get, but only right around the tuning frequency. I think your plan of 6 cubes is a pretty reasonable starting point. Is port tuning for 4th order the same as port tuning for a normal ported enclosure? Or is it completely different? How you calculate the tuning is the same, but the frequency you are going to want to tune to is completely different. So is this box for a car or your apartment? Its for my apartment. I listen to mostly rap so thats why i like to tune so low. i made this up in sketchup. dimensions are: Sealed= 28x14x18 Ported= 28x14x27 Port:Height= 6 Width= 16 Length= 19 does this seem good to you? just noticed port might be too far back for motor so ill just change the port dimensions for the same freq, but besides that...
Triticum Agricolam Posted August 26, 2015 Report Posted August 26, 2015 Since this is for home audio use I would VERY strongly encourage you to NOT use a band pass box. For your application they offer almost no advantages and have many drawbacks. You will be MUCH better served by a properly designed ported box. What amp are you going to use to power this anyway? "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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