Bandpass boxes
10-15-2003, 11:54 AM
#1
2000 Watt CAFz'r
Thread Starter
Join Date: Jan 2001
Posts: 2,026
I am currently considering building a monster home sub enclosure. I am thinking about doing a 6th order bandpass with an MTX T6124A. Has anyone had experience with 6th Order bandpass? I've run it through WinISD, is there anything I should be aware of that the program will not catch?
Thanks
Thanks
10-15-2003, 01:27 PM
#2
Guest
Posts: n/a
Woo-hoo, have fun man!
Some really basic crude rules of thumb:
Large side should be ~1.5-2x the size of the small side. I've seen and built them the same though.
Small side tuning should be 80-110% that of the large side. I've built them closer though.
Large side is usually only about 2/3 to 3/4 the size that it would be if a standard vented box. ie if a regular box for a 12 is 3cuft then in a 'vented bandpass' the large side is 2-2.25cuft. Again - rough rule made to be broken.
Vented Bandpass boxes are tough dude. You have to juggle volume, tuning, bandwidth...
Good luck man.
Some really basic crude rules of thumb:
Large side should be ~1.5-2x the size of the small side. I've seen and built them the same though.
Small side tuning should be 80-110% that of the large side. I've built them closer though.
Large side is usually only about 2/3 to 3/4 the size that it would be if a standard vented box. ie if a regular box for a 12 is 3cuft then in a 'vented bandpass' the large side is 2-2.25cuft. Again - rough rule made to be broken.
Vented Bandpass boxes are tough dude. You have to juggle volume, tuning, bandwidth...
Good luck man.
10-15-2003, 06:30 PM
#3
2000 Watt CAFz'r
Thread Starter
Join Date: Jan 2001
Posts: 2,026
Okay Dukk,
This goes back to something you mentioned in my other post about the MTX 6124. Can I trust WinISD. Here is what I have worked out:
Front Chamber
Volume: 5990 cu"
Tuned to: 37 Hz
Ports: 2 x 3"ID x 5.67"L
Rear Chamber
Volume: 20879 cu"
Tuned to: 20.1 Hz
Ports 2 x 3"ID x 5.46"L
From what I have seen on WinISD, the frequency response rolls up around 40hz, and drops out again at 20hz.
I want to try this because of the SPL gain that I get from this set-up and because the bandpass set up acts as a second cross-over.
If you have the desire to figure out something better for me here are the MTX specs:
FS: 29.9hz
Vas: 77.2L
Qts: 0.66
Qes: 0.73
Qms: 6.46
Re: 3.24
Xmax: 9.4mm
RMS: 250
SPL: 87.2
Le: 1.8 mH
BL: 11.44Tm
The set-up I am looking for is getting the most flat frequency response, and the lowest frequency response. And if I can make it loud on top of that It'll be an extra bonus.
This goes back to something you mentioned in my other post about the MTX 6124. Can I trust WinISD. Here is what I have worked out:
Front Chamber
Volume: 5990 cu"
Tuned to: 37 Hz
Ports: 2 x 3"ID x 5.67"L
Rear Chamber
Volume: 20879 cu"
Tuned to: 20.1 Hz
Ports 2 x 3"ID x 5.46"L
From what I have seen on WinISD, the frequency response rolls up around 40hz, and drops out again at 20hz.
I want to try this because of the SPL gain that I get from this set-up and because the bandpass set up acts as a second cross-over.
If you have the desire to figure out something better for me here are the MTX specs:
FS: 29.9hz
Vas: 77.2L
Qts: 0.66
Qes: 0.73
Qms: 6.46
Re: 3.24
Xmax: 9.4mm
RMS: 250
SPL: 87.2
Le: 1.8 mH
BL: 11.44Tm
The set-up I am looking for is getting the most flat frequency response, and the lowest frequency response. And if I can make it loud on top of that It'll be an extra bonus.
10-16-2003, 06:41 PM
#5
2000 Watt CAFz'r
Thread Starter
Join Date: Jan 2001
Posts: 2,026
Alright alright . . .
SO maybe I'm asking too much from this woofer - its not an infinity perfect so I can't expect it to drive that low smoothly.
Forget about the top end roll-off. I have a 40-160hz variable crossover that I can customize for that. What set-up would you recommend to get nice solid freight-train/thunderstorm/rushing water rumble? The amp is 150WRMS so I won't be feeding it too much. I will be working with 3" PVC pipe for ports.
After reading your posts about box-building programs, I have suddenly become afraid of designing anything on my own power now. I don't what to over-drive me woofer and shorten its life span. But the deeper the bass, the happier I am.
I want my cake and eat it too. What is the best compromise between woofer longevity and home theatre rumble?
SO maybe I'm asking too much from this woofer - its not an infinity perfect so I can't expect it to drive that low smoothly.
Forget about the top end roll-off. I have a 40-160hz variable crossover that I can customize for that. What set-up would you recommend to get nice solid freight-train/thunderstorm/rushing water rumble? The amp is 150WRMS so I won't be feeding it too much. I will be working with 3" PVC pipe for ports.
After reading your posts about box-building programs, I have suddenly become afraid of designing anything on my own power now. I don't what to over-drive me woofer and shorten its life span. But the deeper the bass, the happier I am.
I want my cake and eat it too. What is the best compromise between woofer longevity and home theatre rumble?
10-22-2003, 09:28 PM
#8
0 Watt CAFz'r
Join Date: Oct 2003
Posts: 23
For what its worth I have never got the bass I was hopeing to with 6th order bandpass. I once was comparing notes with a friend who is a guru in the speaker world and he also had the same experience. He had tried a lot but eventually gave up on them. Theoretically they should work but the bass never has that live tonal quality you get from ported or sealed enclosers. Also you don't see any high end stuff using this technique -if that matters. On the other hand if your just intersted in learning about them or just want loud bass, a suggestion is that some drivers work better in them than others. Unfortunately I could only could determine that after I had plugged the numbers into my computer.
It had nothing to do with price of the driver either. Try and get your hands on some software that predicts box responses and has the 6th order bandpass option on it. You will see what I mean.
good luck
It had nothing to do with price of the driver either. Try and get your hands on some software that predicts box responses and has the 6th order bandpass option on it. You will see what I mean.
good luck
