mr.tigger
10+ year member
Senior VIP Member
it realy look nice we need more pic an video plz
mr.tigger
OP
528hz
10+ year member
Everything'sMiscellaneous
- Thread Starter
- #17
I know, I know...and as much hell as I've raised with others that do BP builds and not posting vids, I should be shot!
I'll get some vids up sometime this week. It doesn't move many objects especially since I've deadend my roof.
To be completely honest with everyone, and describe this the best I can, my car now sounds like I'm sitting in a home theater. No joke. The bass waves literally "wrap around" you. I honestly think that I could actually do well in a SQ comp with it now. That's just an analogy...
Thanks for the kind words, 528hz. I really wish I could come down to NM and hear it now. In response to the comments about the ported chamber being to small, it's actually pretty large for the subs in question. Before deciding if the vented portion is "too large" or "too small", it is best to consider first the drivers being used, second the design criteria, and third amount of power being fed to each sub.
These particular drivers have a relatively low Vas, less than .8 CF each. Using a vented chamber that is too large relative to Vas results in dangerous levels of gain, and sometimes even mechanical failure of the subs. So the low Vas was one limiting factor in sizing the vented chamber. In fact, Vas required such a small vented chamber that I had to reduce chamber height by .75" with a double top, partition off a section of the vented chamber, and still accept a higher level of gain than is generally considered safe. Even with a vented portion of only 1.75 CF (net), this box still models with a peak gain of about 4 dB.
The design criteria for this box were first that it get loud wile maintaining respectable SQ, second that it fit within 33" x 29" x 14", and third that it totally eliminate port noise if possible. #1 required that gain be kept at least partly in check, and that the roll-off slope be a good match for cabin gain. #2 required that I try about a dozen different "massing models", basically my way of breaking up a 3D shape into its respective parts. There really only were two, maybe three ways these subs could have been configured in the prescribed space without interfering with the other design criteria, and this one was the most buildable. #3 required that I fold the port in an aerodynamic way, and maximize port area to the extent possible.
The final reason I couldn't go much larger on the ported chamber is that that the subs will be fed in excess of 1000 watts RMS each. Too much gain and power handling would be seriously compromised.
There were about a dozen other variables that played into the final design, the above is just a summary. In this case, I used 1.75 CF ported and 1.375 CF sealed, with about 65 square inches of port area. Tuning of the vented chamber is about 50 Hz. This should by no means be considered a "rule of thumb", it is important to understand that a well-executed bandpass is A) vehicle specific or room specific, B) subwoofer/driver specific, and C) application specific. While 528hz described a balanced, enveloping bass that is very linear, using the same box with XYZ subwoofers could result in a one-note wonder, or using it with ABC subwoofers could result in a total loss of output. Using the same box in my '89 Sentra, if it fit, would result in a bloated sound, but using it in a 2010 Suburban would result in a total lack of bottom-end output.
528hz, one thing I haven't mentioned yet about this enclosure is that I did design in a bit of flexibility. The access panel lid is two layers thick, and the inside layer is held on with 4 torx screws. By removing the inside layer, you will gain about 0.08 CF in the vented chamber, and gain will go up about 0.5 dB. There is also a panel which could be modified for another 0.08 CF and 0.5 dB gain beyond that. So you could probably get an extra 1 dB of gain if you don't think you're already torturing the subs enough. However, I will note that you risk excess "boomyness" if you push the bandpass gain much higher than it already is.
I hope that answered some people's questions about the build.
These particular drivers have a relatively low Vas, less than .8 CF each. Using a vented chamber that is too large relative to Vas results in dangerous levels of gain, and sometimes even mechanical failure of the subs. So the low Vas was one limiting factor in sizing the vented chamber. In fact, Vas required such a small vented chamber that I had to reduce chamber height by .75" with a double top, partition off a section of the vented chamber, and still accept a higher level of gain than is generally considered safe. Even with a vented portion of only 1.75 CF (net), this box still models with a peak gain of about 4 dB.
The design criteria for this box were first that it get loud wile maintaining respectable SQ, second that it fit within 33" x 29" x 14", and third that it totally eliminate port noise if possible. #1 required that gain be kept at least partly in check, and that the roll-off slope be a good match for cabin gain. #2 required that I try about a dozen different "massing models", basically my way of breaking up a 3D shape into its respective parts. There really only were two, maybe three ways these subs could have been configured in the prescribed space without interfering with the other design criteria, and this one was the most buildable. #3 required that I fold the port in an aerodynamic way, and maximize port area to the extent possible.
The final reason I couldn't go much larger on the ported chamber is that that the subs will be fed in excess of 1000 watts RMS each. Too much gain and power handling would be seriously compromised.
There were about a dozen other variables that played into the final design, the above is just a summary. In this case, I used 1.75 CF ported and 1.375 CF sealed, with about 65 square inches of port area. Tuning of the vented chamber is about 50 Hz. This should by no means be considered a "rule of thumb", it is important to understand that a well-executed bandpass is A) vehicle specific or room specific, B) subwoofer/driver specific, and C) application specific. While 528hz described a balanced, enveloping bass that is very linear, using the same box with XYZ subwoofers could result in a one-note wonder, or using it with ABC subwoofers could result in a total loss of output. Using the same box in my '89 Sentra, if it fit, would result in a bloated sound, but using it in a 2010 Suburban would result in a total lack of bottom-end output.
528hz, one thing I haven't mentioned yet about this enclosure is that I did design in a bit of flexibility. The access panel lid is two layers thick, and the inside layer is held on with 4 torx screws. By removing the inside layer, you will gain about 0.08 CF in the vented chamber, and gain will go up about 0.5 dB. There is also a panel which could be modified for another 0.08 CF and 0.5 dB gain beyond that. So you could probably get an extra 1 dB of gain if you don't think you're already torturing the subs enough. However, I will note that you risk excess "boomyness" if you push the bandpass gain much higher than it already is.
I hope that answered some people's questions about the build.
DBfan187
5,000+ posts
Supa's mom was here!
do you have some dead space in there?
Yes, just a tiny bit.
OP
528hz
10+ year member
Everything'sMiscellaneous
- Thread Starter
- #21
HEY HEY! Nice to see you jumping in here, Tyler! I was hoping you would be the one to give the run down on this sine your are the "father."
I'll take into consideration adjustments, but the box really is perfect for what it does. Yes it's not quite as loud as my last setup, but the SQ is lightyears beyond. It would be loud enough most people, but for someone like me, I just need to get an SUV already and do 15s and 10K watts. Then have this car as it sits now.
It's hard for someone (especially like me) that tries to find "utopia" in a sub setup. God knows I've done enough sub stages in this car to know that it's almost impossible to find that perfect medium. And I do mean perfect.
I'll take into consideration adjustments, but the box really is perfect for what it does. Yes it's not quite as loud as my last setup, but the SQ is lightyears beyond. It would be loud enough most people, but for someone like me, I just need to get an SUV already and do 15s and 10K watts. Then have this car as it sits now.
It's hard for someone (especially like me) that tries to find "utopia" in a sub setup. God knows I've done enough sub stages in this car to know that it's almost impossible to find that perfect medium. And I do mean perfect.
tommyk90
5,000+ posts
THE WHOLE THING!!!
Thanks for the detailed explanation.
I didn't realize that the sealed chamber was as large as it was.
And yeah, that is a good amount of power per sub.
Did you run into any power compression issues with such a design? I was fiddling around with a series tuned 6th order bandpass for a single 10" and it would always fall flat on its face at about half the normal power I would give it in a normal ported box. Never got to fool with it much though since this was built for SPL competitions and the regular ported box was significantly louder at the time.
I didn't realize that the sealed chamber was as large as it was.
And yeah, that is a good amount of power per sub.
Did you run into any power compression issues with such a design? I was fiddling around with a series tuned 6th order bandpass for a single 10" and it would always fall flat on its face at about half the normal power I would give it in a normal ported box. Never got to fool with it much though since this was built for SPL competitions and the regular ported box was significantly louder at the time.
Compression may be a slight issue on this box, since it was not even possible to make the port as large as my math suggested. However, I made the port as large as possible within the design constraints, and went to great lengths to make sure it was aerodynamic to reduce this effect.
BTW, did you mean the vented chamber?
tommyk90
5,000+ posts
THE WHOLE THING!!!
Nope, I meant the sealed chamber.
In most of the 4th orders I've seen, the sealed chamber is very small relative to the subs (like 2 18's with a 2 cube sealed chamber).
i have 2 18s and my sealed chamber is 4 cubes total.
Just remember, there isn't an accurate rule of thumb. The chambers were both sized according to design criteria, and according to the practical consideration of what would fit.
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