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Pass band? (Read 3780 times)
Hellion
Ex Member



Pass band?
12/29/05 at 20:20:10
 
Okay I am thinking of building a wiked one box.  I have a great ammount of curiosity and love trying new things.  I would like to know if it would be a good idea to try introducing a vent in the sealed volume.  Suppose I were to vent the box as if it were a 6th order bandpass with a pass band around 40 hz on one side, and a pass band of about 60 hz on the other.  This is assuming that the volume in front of the driver before the opening into the horn acts like the front volume of a bandpass enclosure.  (Please correct me if I'm wrong I do not understand how this box works at all.)  I have had good results with a 6th order bandpass, though choosing the right cutoff frequency is crucial to powerhandling characteristics and overall efficiency. (Not a good idea for ultra low frequency high volume boxes.)  Just adding a bit of lining goes a long way with this kind of box, and I was curious if a bit of lining wouldn't hurt.  It always seems to clean up the 6th order boxes and get rid of noise outside the pass band.    

Perhaps the transient performance of 6th order band pass systems is worse than sealed?  If so, Please advize! I do not want to make a sub standard WO my first time around. Grin
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jj420
Ex Member



Re: Pass band?
Reply #1 - 12/29/05 at 21:19:47
 
somebody here did port a WO, with interesting results.  Im not certain excactly, but the final report was that while SPL went up, SQ went down in a big way, so i guess it depends on what you are trying to make.
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Adrian D.
Ex Member



Re: Pass band?
Reply #2 - 12/31/05 at 15:57:57
 
as far as i know, the wo is said to be a fast design.
i'd say don't port it. people say it's loud enough the way it is.
i don't know about lining the inside. i guess a VERY small amount won't hurt. you'll find the answer to some of your questions here
imo, the wo is a bp4 which fires in a folded horn (please correct me too if i'm wrong, i'm here to learn). i'm also very curious, but i haven't got any space inside for a wo Sad. maybe i'll do a garden sub
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bnew63
Ex Member



Re: Pass band?
Reply #3 - 12/31/05 at 17:47:12
 
As said many times by many people on this site,Build a stock one first its easy enough to scale up or down.You,ll love it as it is.Then if you get the hankering to modify,go crazy.I think you should experience what Steve intented this design to sound like.I've built four of them over the past two years all of different sizes and after a few tweeks they all performed beyond my expectation.
Just my two cents
              Brian
     
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gexter
Ex Member



Re: Pass band?
Reply #4 - 01/01/06 at 05:41:33
 
[quote author=bnew63  link=1135891210/0#3 date=1136051232]As said many times by many people on this site,Build a stock one first its easy enough to scale up or down.You,ll love it as it is.Then if you get the hankering to modify,go crazy.I think you should experience what Steve intented this design to sound like.I've built four of them over the past two years all of different sizes and after a few tweeks they all performed beyond my expectation.
Just my two cents


  Brian

    [/quote]

I second that, while stating that the only reason you may see hacks for me is only because of lack of funds and a wonderful supply of used junk.

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Jet-Lee
Ex Member



Re: Pass band?
Reply #5 - 01/03/06 at 14:31:43
 
[quote author=gexter  link=1135891210/0#4 date=1136094093]

I second that, while stating that the only reason you may see hacks for me is only because of lack of funds and a wonderful supply of used junk.

[/quote]
haha, me and gex are on the same page.

Build the original first.

Disregard what I build. It's just a bunch of junk I throw together for the simple joy of building, and lack of funds.
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vivio
Ex Member



Re: Pass band?
Reply #6 - 01/08/06 at 10:10:18
 
I.am  right now  modifing the wo to 6th  :)
just build  a 1/2 wo : and trying to get it loud  for spl.
trying to make it a One note wonder . @ 65 hz  
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Jet-Lee
Ex Member



Re: Pass band?
Reply #7 - 01/09/06 at 14:35:23
 
65hz? Isn't that kind of high for SPL comp?

Most systems I've heard play best around 40-50hz. What's the resonant frequency of your car? (I'm assuming this is for a car, since it's being made for SPL).
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Hellion
Ex Member



Re: Pass band?
Reply #8 - 01/11/06 at 07:23:00
 
uhh how do I know what my car's RF is?

Sorry, but I haven't posted here because I am making the origional wo like some people suggested, though I am wondering about making one that would be an eighth order triple reflex bandpass.  Which definately would NOT be a one note wonder!  He he try that one on for size!
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« Last Edit: 01/11/06 at 07:30:07 by Hellion »  
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Jet-Lee
Ex Member



Re: Pass band?
Reply #9 - 01/11/06 at 21:25:22
 
Isn't the general rule of thumb that the higher the order the less the range? So an 8th order is more of a one note wonder than a 6th?
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Hellion
Ex Member



Re: Pass band?
Reply #10 - 01/12/06 at 03:34:28
 
To be honest, I don't know.  I do not know for sure if the origional wo is a bandpass.  If it is then I would be making an 8th order triple bandpass. if not then it would be a sixth order dual reflex.  You can tune one side of a sixth order dual reflex to one frequency, and the other side to another by changing the volume of the chambers, and the length of the ports. definately not a one note wonder.  

I don't really understand the wo anyway.
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Hellion
Ex Member



Re: Pass band?
Reply #11 - 01/12/06 at 03:36:05
 
oh by the way check this out...
http://www.the12volt.com/caraudio/boxes6.asp
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J_Rock
Ex Member



Re: Pass band?
Reply #12 - 01/12/06 at 04:21:06
 
The WO isn't a kind of box.  The closest you get to it as far as design is a 4th order BP with exponential ports, yet still it doesn't work out so well.

If you port the sealed chamber you could call it a 6th order and many would believe it.

If you port the sealed chamber twice, once out to the trunk the other into the compression chamber, it would become an 8th order.  

I have no idea how you could hope to model the Box since there really is no way to model the horn type port thing(Rubber throat or Impedance Transformer).

Building a spec'd out 8th order is going to be easier, but not easy.

Its all pretty much guess and check above 4th order, although winISD pro calculates 6th order.

If you are looking for serious bass with no musicality Higher order BPs are definetly your ticket, they are just a pain in the ass.
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J_Rock
Ex Member



Re: Pass band?
Reply #13 - 01/12/06 at 04:26:06
 
Also like to add that the higher you go in order of BP the smaller frequency response that the box can handle.

And on 12 volt the guy talks about unloading the woofer.  That can happen below the box's ported frequency, but not above it.  Above the tuning frequency the port no longer resonates acting like a sealed enclosure.  Thats why ported enclosure can still go up in frequency fine, but they need a XO below the tuning frequency.

Also, when tuning ports in an enclosure they must be off of each other's frequencies or else you get serious cancelation.  I.E. one port must be 60 hz, the other 65hz.
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DirtDawg
Ex Member



Re: Pass band?
Reply #14 - 01/12/06 at 04:56:02
 
Even if you try to deal with the narrow passband by building more boxes, like 1 well tuned "one-note box" for each note, you will still have poor transient response. Without good transients your system won't be very musical. Cry
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