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whoooaaaaaa.....I just got a thought. (Read 11228 times)
Jet-Lee
Ex Member



whoooaaaaaa.....I just got a thought.
05/15/06 at 19:21:13
 
Now I need to draw it out and think about it some more.

Picture a Wicked One, not hard I know.

Now, figuring out what the vented(front) chamber is tuned to, port the rear chamber to the same except 180º out of phase, and channel the port around the outside of the box, opening up at the throat of the horn.

Just a quick, completely not-thought-about idea that popped in my head.

EDIT-I guess doing such would essentialy give you a one-note-wonder-fart type of box, eh?
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« Last Edit: 05/15/06 at 19:22:23 by Jet-Lee »  
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phd5000
Ex Member



Re: whoooaaaaaa.....I just got a thought.
Reply #1 - 05/15/06 at 20:49:15
 
i was kinda thinking a slap might do good ( not in the horn ) but on the left & right side of the sealed part
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« Last Edit: 05/15/06 at 20:51:21 by phd5000 »  
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J_Rock
Ex Member



Re: whoooaaaaaa.....I just got a thought.
Reply #2 - 05/16/06 at 18:19:54
 
The key then would be to find the loudest frequency of your WO.  say its 40 Hz.  Then tune the rear chamber to 40Hz, but have the port duct in a way that the delay from the front is enough to totally sum the front and rear waves at the horn and port exits.

Very one noteish, but could be converted back to normal WO simply by capping the port up.
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jj420
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Re: whoooaaaaaa.....I just got a thought.
Reply #3 - 05/16/06 at 19:35:09
 
sounds like a lot of work for a quiet BP6, and a lot of space  (even) for a TL.  MIND YOU...  If you were to build a very large common port for the sealed chmbers to fire into, say starting on the back, and going full width, all the way down to the bottom, and then becoming a new bottom for the WO. In That case, firing the port forwards would be ok since the output from that port would be very low and phasing wouldnt really matter.

This would be a good solution for HT/music hybrid as well, come to think of it.  Hooked into the 2ch XO network it would use the WO portion to make good music, and hooked to the LFE channel for movies, that large port would be well loaded with the WO portion behind the woofers.

The only issue I see potentially causing problems would be in the power handling of the system, likely it would drop, but hey, its all compromise in this game.

Intersting thoughts Jet, try the big slot port idea and let us all know please!.
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djman37
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Re: whoooaaaaaa.....I just got a thought.
Reply #4 - 05/17/06 at 19:09:30
 
[quote author=J_Rock  link=1147720873/0#2 date=1147799994]The key then would be to find the loudest frequency of your WO.  say its 40 Hz.  Then tune the rear chamber to 40Hz, but have the port duct in a way that the delay from the front is enough to totally sum the front and rear waves at the horn and port exits.

Very one noteish, but could be converted back to normal WO simply by capping the port up. [/quote]

dbdon did it years ago.  won canadian nationals 'with 600 watts' I believe the quote went.  It's a one noter all right.  i've got the mod plans somewhere.  There's a pic on decware.com that shows the 'slot' too.
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Jet-Lee
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Re: whoooaaaaaa.....I just got a thought.
Reply #5 - 05/17/06 at 19:56:30
 
hmm......horn load the front and rear of the driver. Like a dual-horn-loaded 6th order bandpass!

ok...Lee....calm down
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djman37
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Re: whoooaaaaaa.....I just got a thought.
Reply #6 - 05/17/06 at 20:40:19
 
[quote author=Jet-Lee  link=1147720873/0#5 date=1147892190]hmm......horn load the front and rear of the driver. Like a dual-horn-loaded 6th order bandpass!

ok...Lee....calm down [/quote]

I'd like to see a certain 'square' driver used as well.
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Jet-Lee
Ex Member



Re: whoooaaaaaa.....I just got a thought.
Reply #7 - 05/17/06 at 21:08:00
 
Although the space required for that 'certain' driver is quite large. Would a WO be large enough?? Maybe using an 8" square driver??
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bassboy
Ex Member



Re: whoooaaaaaa.....I just got a thought.
Reply #8 - 05/17/06 at 22:46:32
 
Guys, I'm not sure you are fully understanding Jet's idea, either that or I'm not.

I am not picturing an open port on the front.  He mentioned taking the rear chamber wave and porting it not to the outside, but rather around the outside of the box, then back into the box at the beginning of the throat to sum the front and back chamber waves together AT THE BEGINNING OF THE HORN, meaning both the front and back waves from the speaker would go through the horn.

There's got to be an prettier way to run the port than around the outside of the box, but that's design phase and this is still planning.

I've never heard of anything like this and it may be as big a breakthrough as Steve's SO.  The problem is that it is impossible to model, as far as I know, and would be an incredible pain in the butt to try to optomize.

I have had thoughts in the past of a single driver with separate horns on both front and back of the driver to exact the same sensitivity advantage.  Jet's idea is kind of the same but half the size and probably a much better idea.

I have since given up this idea as it is too risky and let's face it, the WO is fine the way it is.  But Jet, if you can make it work it would be twice as loud, I'm guessing.  It's probably worth the effort if you have spare wood and spare time but it's way to risky to get onto my project list.

EDIT - if I am understanding JJ correctly, he is actually talking about the single driver dual horn idea but closer to horn loaded on driver front, BR/TL concept for the driver back.  Maybe not, I'm not sure.  I have a feeling I might be way off on this but without pictures maybe I'm misunderstanding everybody.
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« Last Edit: 05/17/06 at 22:52:48 by bassboy »  
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Jet-Lee
Ex Member



Re: whoooaaaaaa.....I just got a thought.
Reply #9 - 05/18/06 at 00:50:50
 
bassboy nailed the original idea on the head.

You can see how it would be a one-noter, then.

I've put some thought/work into it, but not much, as I've been super busy lately between work, court(for a friend), and moving.

Will do some more work on it tomorrow, draw out a sketch of the idea and what not.
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« Last Edit: 05/18/06 at 00:51:21 by Jet-Lee »  
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bassboy
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Re: whoooaaaaaa.....I just got a thought.
Reply #10 - 05/18/06 at 01:58:37
 
Ok so I get the original idea but I would have no understanding of how to make sure the back wave is in phase with the front wave at the point that they meet at the throat.

You gotta be a lot smarter than me to figure out how to make them exactly in phase to be additive.  Anything else would actually hurt the performance because technically the front and back chambers are joined by the port in this design.  

Like I said, the risk is extreme and I wouldn't even know where to start.  I don't know how skilled you are with math and phase relations but good luck man, you will probably need it.  Unless you want to tweak for days with no real idea of the design's potential.
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« Last Edit: 05/18/06 at 02:05:41 by bassboy »  
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J_Rock
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Re: whoooaaaaaa.....I just got a thought.
Reply #11 - 05/18/06 at 04:56:36
 
Well, You would first have to select the frequency you want to do this all at.  COnviently this would be the resonant frequency of your car and the loudest frequency of the box.  Whichever you choose or maybe both are the same.

Then simply port the rear chamber with a port that is long enough to delay the rear wave 1/2 a wavelength.  

Lets pretend the frequency you choose is 45 Hz.

A 45Hz wavelength is 7.64 m long.  In order to make the rear wave sum with the front wave, you would need to delay the rear wave 1/2 wavelength, or 3.82 m.  

Now figure out a port that will have a length of 3.82 and tune the rear chamber to 45Hz.

Duct the port into the compression chamber and whamo bamo.


Only problem is, will the driver be controlled throughout this motion?  If so, the driver will be doing the work of two drivers.  Each forward and back stroke does double duty.  The forward stroke sums with the rear stroke one way, and then the other way.  Which should double the amplitude of the wave...
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Jet-Lee
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Re: whoooaaaaaa.....I just got a thought.
Reply #12 - 05/18/06 at 13:57:17
 
Here's a thought. My current design sums the waves together, in a sense. Having the drivers in the last part of the mouth of the horn, with the rear wave passing between. I notice almost no cancellation (that I can tell) from 100hz-30hz. I've got the center of the cones exactly 26.5 inches from the beginning of the port. I forgot what math I used for it, something about speed of sound(static) and distance offset.

Maybe that 26.5 inches is the key?
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djman37
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Re: whoooaaaaaa.....I just got a thought.
Reply #13 - 05/18/06 at 16:44:37
 
pics 3 & 4 were the ones that interested ME.
http://www.decware.com/whorn1.htm
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bassboy
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Re: whoooaaaaaa.....I just got a thought.
Reply #14 - 05/18/06 at 16:47:23
 
Should I say risky a couple more times, just to be clear?

Apparently you don't care, and I guess that's why you are successful as you are with your designs.

Sounds like J is onto the theory of it all, but that is one heck of a long port.

The reason I don't play with unproven theory is that if it goes wrong you don't know why and if it is right you don't know if it is as good as it can be.

By the way, stuffing the port with fibreglass could save you a bit of length at the cost of sensitivity.  And J has a very good point about cone control.  It has the potential to work kind of like a 6th order bandpass in that both sides radiate usable output, but like a 6th order bandpass I imagine the design is very intolerant of mathematical mistakes in design.
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« Last Edit: 05/18/06 at 16:51:02 by bassboy »  
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