being loyal to my box types, i have decided to give the good old bandpass another go...
current box is using the max dimensions of my car.. 36.5in wide, 19in high, 23in deep. 0.5cf sealed chambers (each sub firing to the sides), port is about 150sq in and about 13in deep. i think it's tuned to about 65hz, didn't really calculate it til after it was built as i was a little excited. just went to the comp yesterday, and my car, even though the box was tuned to about 65, hit at 49hz LOL
anyway, i droped about 4db from my previous box to 148.6db. how do i tune this box lower? those bassbox programs are confusing as hell...
Full Version: 4th order bandpass help
Use basshead's trick and cram some phone books into it . Or bricks, they work just as good.
that would tune it higher
I have no idea and have never attempted one of these boxes (although I would like to).
I gather you have to adjust the tuning of the rear chamber and front chamber to your note by adjusting the rear chamber volume and adjusting the front chamber port length, just like a normal ported longer = lower tuning and bigger rear chamber means lower tuning also.
from what I can tell WinISD models the rear-chamber tuning just like a sealed chamber and as we all know soon as u shove that in a car its tuning varies coz of the pressure on the front of it or something, and I can imagine this effect would be even bigger on a box with another box mounted on the front of it causing even greater pressure further lowering the tuning I guess.
But I dunno i've never attempted one of these boxes, haven't read to much about them i'm just taking a guess
I gather you have to adjust the tuning of the rear chamber and front chamber to your note by adjusting the rear chamber volume and adjusting the front chamber port length, just like a normal ported longer = lower tuning and bigger rear chamber means lower tuning also.
from what I can tell WinISD models the rear-chamber tuning just like a sealed chamber and as we all know soon as u shove that in a car its tuning varies coz of the pressure on the front of it or something, and I can imagine this effect would be even bigger on a box with another box mounted on the front of it causing even greater pressure further lowering the tuning I guess.
But I dunno i've never attempted one of these boxes, haven't read to much about them i'm just taking a guess
I'd also like to take a guess in saying just like a normal ported box below the ports tuning frequency the port offers little to no accoustic suspension meaning that if its tuned to high your basically just playing with a sealed box... with your sound coming through the port... not being produced by the port
Can we have some pics?
WinISD says your rear chambers are tuned to ~75hz.
WinISD says your rear chambers are tuned to ~75hz.
i think when i was stuffing around in my last run i played a 71hz (or maybe it was 81hz) tone... it hit about 144db so yeh, tuned to 75 you think... oh well, must have missed the band as my car hits at like 50hz
pics for andu
pics for andu
The sealed chambers seem way too small for 12s.
How did you arrive at that figure?
Phil
How did you arrive at that figure?
Phil
QUOTE
Originally posted by rippedskin:
i think when i was stuffing around in my last run i played a 71hz (or maybe it was 81hz) tone... it hit about 144db so yeh, tuned to 75 you think... oh well, must have missed the band as my car hits at like 50hz
pics for andu
very nice!!! thats what WinISD says the rear chambers are tuned to. you have to tune both the port and the rear chamber remember... the box simply doesn't just have 1 tuning variable hehei think when i was stuffing around in my last run i played a 71hz (or maybe it was 81hz) tone... it hit about 144db so yeh, tuned to 75 you think... oh well, must have missed the band as my car hits at like 50hz
pics for andu
tell us the volume of the front chamber and the dimensions of the port and we can work out whats the tuning of the front chamber according to WinISD.
I don't know what tuning would be best for a band-pass for spl but i'm guessing just tune both front and back right on your note hehe
[ April 06, 2003, 18:15: Message edited by: Andu ]
phil: guessed it. i was concerned with the subs not having enough room for the port, so i made the sealed small.
the middle chamber, taking into account port and subs is roughly 4.5cf after displacement.
there was not much calculation involved in this box, i just basically screwed some bits of wood together and put the subs in and hooked her up. sounds like a.ss though. sounds better with only the front stage running full range
the middle chamber, taking into account port and subs is roughly 4.5cf after displacement.
there was not much calculation involved in this box, i just basically screwed some bits of wood together and put the subs in and hooked her up. sounds like a.ss though. sounds better with only the front stage running full range
there's a little more science in it than that i guess if u want it to really thump/boom. but yer, i know what it's like when u get a bit anxious. it's good to see people willing to try other stuff apart from sealed single chamber boxes. the things u'll learn from it (and the others here whom u've bounced ideas off too) will change the way u see things in designing u'r future systems. me built a huuuuuuuuuge 4th order bp for a single 12" e'quake cpds many years ago. we got a bit keen ( me and mates first expierience wif 12's) so we built the big mOfO, and shoved it on the back seat of his ea falcon and took it to a sound-off. they told us to f_ck off (safety reasons........skirts) , but we unofficially tested it at local soundshop and got 144 (i think?) @59 hz. no one believed me when i told them that it only had a single 12" min it. stoopid hicks.
Just playing with WinISD and well the peak output of a closed box isn't right on tuning anyways its a bit above
nothing wrong with guessing random box designs are the best, you never know what will happen
lol damn you john... everytime I come into spl discussion and read this thread then 4th order box is all I can think about for the next half hour.... I so have to build one next week
[ April 08, 2003, 16:37: Message edited by: Andu ]
[ April 08, 2003, 16:37: Message edited by: Andu ]
i have figured out why my 4th order didn't pull the big numbers. the subs aren't suited to small sealed boxes! i order to get a 4th order to work in a street car (limited space), the woofer(s) must be able to hack small sealed boxes, therefore giving enough space for the middle (ported chamber)... plus a car resonanting at about 70hz helps as well
andu, be different and go the 6th order
andu, be different and go the 6th order
QUOTE
Originally posted by rippedskin:
i have figured out why my 4th order didn't pull the big numbers. the subs aren't suited to small sealed boxes! i order to get a 4th order to work in a street car (limited space), the woofer(s) must be able to hack small sealed boxes, therefore giving enough space for the middle (ported chamber)... plus a car resonanting at about 70hz helps as well
andu, be different and go the 6th order
yeh it helps if you can peak your car at 79-80hz coz can get away with a smaller front chamber. But the question remains what to tune the rear chambers too... who can we ask?i have figured out why my 4th order didn't pull the big numbers. the subs aren't suited to small sealed boxes! i order to get a 4th order to work in a street car (limited space), the woofer(s) must be able to hack small sealed boxes, therefore giving enough space for the middle (ported chamber)... plus a car resonanting at about 70hz helps as well
andu, be different and go the 6th order
typical... its always the subs fault, not the box's fault
you have to match the subs to the box to the car
Well did a little bit of searching and everywhere seems to stress the point that the tuning of the rear-chamber must be the same as the tuning of the front chamber for best results.
i've worked out the design for my 4th order box but I don't i'm gonna get enough gain with the amount of box volume I have for the front chamber damn trunk status bites again.
[ April 10, 2003, 19:17: Message edited by: Andu ]
i've worked out the design for my 4th order box but I don't i'm gonna get enough gain with the amount of box volume I have for the front chamber damn trunk status bites again.
[ April 10, 2003, 19:17: Message edited by: Andu ]
look down sealed 10's
QUOTE
Originally posted by bassmekanik:
look down sealed 10's
what does this have to do with bandpass look down sealed 10's
andu: yeh, mine didn't look to flash when i hooked her up to the graphs, not at 50hz anyway at about 76hz it rocked
Not even yer girlies Festiva would hit that high .
Hrmm, I guess could you could try cramming the sealed section full of dacron and crossing your fingers that it works. Maybe glue some foam into the vented section and again, praying it works .
Altho whenever I tried that with the Magma's they'd tear it off the enclosures wall and blow it onto the port. Happened once at LiveWire and I'm sure Andu remembers at GLO when I made Macca bend his arm up in a compromising way to fetch out the foam. Gained a solid dB .
IMO forget being clever and go with whacha know.. rebuild the BAS 2k2 enclosure and run with it. Or sell me those Shocker's .
Hrmm, I guess could you could try cramming the sealed section full of dacron and crossing your fingers that it works. Maybe glue some foam into the vented section and again, praying it works .
Altho whenever I tried that with the Magma's they'd tear it off the enclosures wall and blow it onto the port. Happened once at LiveWire and I'm sure Andu remembers at GLO when I made Macca bend his arm up in a compromising way to fetch out the foam. Gained a solid dB .
IMO forget being clever and go with whacha know.. rebuild the BAS 2k2 enclosure and run with it. Or sell me those Shocker's .
i'm rebuilding a new box.. ya gotta keep trying new things... don't worry, i'll strike gold soon, it's only a matter of time now
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