Forums
http://www.decware.com/cgi-bin/yabb22/YaBB.pl
SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> Wicked One Support Forum >> whoooaaaaaa.....I just got a thought.
http://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1147720873

Message started by Jet-Lee on 05/15/06 at 19:21:13

Title: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 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?

Title: Re: whoooaaaaaa.....I just got a thought.
Post by phd5000 on 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

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 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.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by jj420 on 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!.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by djman37 on 05/17/06 at 19:09:30


J_Rock wrote on 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.


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.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 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

Title: Re: whoooaaaaaa.....I just got a thought.
Post by djman37 on 05/17/06 at 20:40:19


Jet-Lee wrote on 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


I'd like to see a certain 'square' driver used as well.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 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??

Title: Re: whoooaaaaaa.....I just got a thought.
Post by bassboy on 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.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 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.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by bassboy on 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.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 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...

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 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?

Title: Re: whoooaaaaaa.....I just got a thought.
Post by djman37 on 05/18/06 at 16:44:37

pics 3 & 4 were the ones that interested ME.
http://www.decware.com/whorn1.htm

Title: Re: whoooaaaaaa.....I just got a thought.
Post by bassboy on 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.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 05/18/06 at 17:11:04

I wouldn't say I don't care, because I do or I wouldn't be experimenting. I'd say, I'm not afraid of failure. I've made many things that flopped, I just learned to not try that again or figure out why and fix it. We can sit here and theorize all we want, but that's all it is. I can draw and draw and draw and theorize and calculate till I die, but how do I know if any of it was right or accurate until I actually DO it?

That is a long port.....not sure how it would be implemented, and what it would do to the overall outer dimensions of the box.

I picture it simply as a 6th order bandpass, sensitivity to intolerances and all.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by bassboy on 05/18/06 at 17:29:38

A port that long might start taking on tl characteristics and change the tuning even further.  There are just so many things to consider.  I hope it works out for you.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Jet-Lee on 05/18/06 at 18:16:52

That's my concern.  ???

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Michael E on 07/02/06 at 12:34:40

A 'port' that long IS a tline. Note that a port tunes a certain volume box to a certain area/length port.


Title: Re: whoooaaaaaa.....I just got a thought.
Post by Circlomanen on 07/03/06 at 20:01:09

http://www.danleysoundlabs.com/pdf/danley_tapped.pdf

Here is a lot of info of using both sides of a driver to feed a horn.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by bassboy on 07/04/06 at 03:25:47

But it doesn't tell you how to do it.  You can try it if you want (but probably not commercially) but there's no way to model what will happen and if you don't do it right it could be worse than traditional loading.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Hellion on 09/07/06 at 10:12:03

I know how to do what you want to do.  Essentially, you build another wo without a top. Reverse the direction of the horn.  Port the rear chamber into the horn and use pieces of wood to bind the two together. on the outside.

Get it?

Title: Re: whoooaaaaaa.....I just got a thought.
Post by AudioNirvana on 09/10/06 at 18:03:05

But you would want to reduce the volume of the chamber in the WO you are porting into surely? Or is that assumed all along?

Title: Re: whoooaaaaaa.....I just got a thought.
Post by jj420 on 09/11/06 at 01:24:57

No Way, tuning the port into the second WO would take up enough of that chamber anyways, and likely the lower tuning of the passive WO would drop considerably, eliminating a lot of cancellation issues that would come up in the double WO from the SPL thread.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by Lee in Arkansas on 09/11/06 at 14:22:59

Wow, that lost me.  :-[

Pic?

Title: Re: whoooaaaaaa.....I just got a thought.
Post by mrezstreet on 10/02/06 at 14:57:57


jj420 wrote on 09/11/06 at 01:24:57:
No Way, tuning the port into the second WO would take up enough of that chamber anyways, and likely the lower tuning of the passive WO would drop considerably, eliminating a lot of cancellation issues that would come up in the double WO from the SPL thread.


so if i understand what you are sayin...( kind of new to all this) this would be like a 6th oreder bp w horn ports that would have low cancellation issues ? sorry i have been kicking this around in my head......and then read this post...lol :D
i have a singel 12 that would be a good test sub....cuz if it dies...its for a good movement.....

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 10/02/06 at 18:34:07

Your best bet is to tune the rear chamber 5-10hz off the WO's normal tuning- supposedly 45 hz.

hence a rear chamber tuned to 35-40 or 50-55.  That will put a huge spike in response right in the middle of the tuning frequencies.  Probably the easiest way to get loud with the WO.  Would destroy any resemblence of an SQ box and would only be SPL.

I personaly suggest the 10 inch version with rear chamber tuned to 40 hz.  It models a result of 20+db increase at 42.4 hz.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by mrezstreet on 10/02/06 at 20:39:49


J_Rock wrote on 10/02/06 at 18:34:07:
Your best bet is to tune the rear chamber 5-10hz off the WO's normal tuning- supposedly 45 hz.

hence a rear chamber tuned to 35-40 or 50-55.  That will put a huge spike in response right in the middle of the tuning frequencies.  Probably the easiest way to get loud with the WO.  Would destroy any resemblence of an SQ box and would only be SPL.

I personaly suggest the 10 inch version with rear chamber tuned to 40 hz.  It models a result of 20+db increase at 42.4 hz.



+20 db.....i will make a wo to specs....then well go mod just so i know 4 my self.....my table saw likes killin mdf anyhowz

Title: Re: whoooaaaaaa.....I just got a thought.
Post by musgofasa on 10/02/06 at 22:34:03

I wonder how the thing would sound with the rear chamber port tuned like that? When we ported for SPL boxes we went with 55-60hz trying to get higher resonance numbers. Very one-notish results like that though.
Have you modeled one tuned that high to see what sort of spike it gives J?

Thanks for taking the time right now, I am just swamped with work and moving and mortgages and and and lol

See ya later guys!

Robert

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 10/02/06 at 23:49:51

That places a larger spike (+23 db) at 51hz.  But yes-absolutely this box would be SPL only.  No where near SQ useable response. lol  It looks like a pyramid.

I might make this SPL monster.  All I would have to do is cut port holes into the chamber and add ports for a testing phase.  If I want to go back to SQ- just plug the holes lol.

Also- I am not exactly sure what the front chamber is tuned to with the flared port/horn.  I used Steve's comment about it being close to 45hz tuning frequency.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by fordpwnzchevy on 10/03/06 at 19:11:38

A flat piston driver such as the older ed's, earthquake magmas maybe, and a couple others wouldnt have these phase issues.  Obviously, since both sides of the cone share the exact same shape, the front a back wave will be in phase.  I bet if you used a flat coned woofer this would work out awesomely and be more than just a 1 note wonder.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by musgofasa on 10/03/06 at 19:29:05

I have been in this a long time and I have never heard that the shape of the cone would affect the phase of the sound wave???????
I am not usually a smart alek and I will try not to sound like one here, but how would the shape of the cone affect the fact that the wave created by the direction of movement is opposite?
If this is true, it throws a whole lot of the theories I use out the window in one fell swoop.

Like I said, not trying to be smart, but I would like to hear this explanation. I used a bunch of the old PPI woofers back in the day with the flat pistons. I didn't notice that they were any different personally.

clarification??

Thanks,
Robert

Title: Re: whoooaaaaaa.....I just got a thought.
Post by fordpwnzchevy on 10/03/06 at 19:36:09

To tell you the truth i have no justification except pictures in my mind and what alot of people have told me about flat piston woofers.  Not to sound ignorant (although it thoroughly does haha), but the people that i've heard this from i've usually taken their word as law for audio purposes and never thought otherwise.  Hopefully someone else can come along and prove it right or wrong.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by musgofasa on 10/03/06 at 20:23:27

OK
so the way I see phase is pretty simple:
Driver moves one direction sound moves away from driver in that direction.
Driver moves other direction, sound moves in the other direction
IE out of phase to first direction by 180 degrees.

There are other types of phase shift and lags that are common to frequency shift and other electronic factors, but mechanically speaking that should be about it.
Case in point. Take two speakers (left and right) play music through them. Run balance to one side and then the other. If the speakers produce more bass when both are playing, they are in phase. If the bass goes away when both are playing, then one is firing in the opposite direction to the other and needs to be reversed.

Now if we can apply that simple philosophy to the length of time it takes the sound from the back side of the driver to reach the same point that it is leaving the front side, we could increase efficiency at the frequency that it happens. Unfortunately it would have the nasty result of throwing all other frequencies out of phase (correct me if I am wrong) 180 degrees per octave?

That is what causes most SPL cars to have that classic "Wet fart" sound
(Sorry EZ, couldn't resist)

Robert

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 10/03/06 at 21:15:27

No matter the shape of the cone, the rear wave is always 180 out of phase from the front wave.  Which is why a woofer sitting on the floor will have little if any of the output it will have in an enclosure.  

Just picture a sine wave.  A perfect up and down wave.  This picture represents the position of the speaker at any given time. No matter what the cone looks like, everypoint on the cone moves like that.

As a matter of fact, thats the whole original point of enclosures, to contain the rear wave of the speaker.  Then they were adapted to turn the rear wave into useful output and control the movement of the driver better.



Title: Re: whoooaaaaaa.....I just got a thought.
Post by fordpwnzchevy on 10/04/06 at 01:42:05

Glad thats cleared up haha, thnx. :'(

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 10/04/06 at 01:50:28

Sorry if I sounded condescending, its these major theorys that need to be correct for you to do your own thing in audio.  I just wanted to make sure you knew- because that is a pretty big mistake to make and would hinder you from now on when attempting to go big and loud.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by fordpwnzchevy on 10/11/06 at 08:05:42

One thing just came to mind.  I dont know if it is right or wrong.  The Adire Parthenon.  It uses a flat piece of mdf as the cone surface and is for use in free air, no enclosure, from what i understand.  I dont mean to bring up dead threads, or questions that've been answered.  And dont want to seem pestering or anything.  But i seem to have a slightly questioning nature.  I was wondering if someone could explain this driver to me.  Also, sorry for threadjacking.

Title: Re: whoooaaaaaa.....I just got a thought.
Post by fordpwnzchevy on 10/11/06 at 09:30:22

One other thing i was thinking about was the sine wave thing you mentioned.  It would seem to me the only way the negative part of the wave would cancel out the positive is if they were playing at the same time.  Ex.  2 subs wired 180 degrees out of phase.  One sub plays the positively and the other plays negatively, both at the same time.  Equal but opposite.  I cant describe the full thought i have at the moment which more than likely means i'm ignorant (not being able to explain something means you yourself dont understand it hahaha).  But i think you would at least understand why i had the incorrect idea in my head about phase cancellation.

*edit*- srry for ranting and threadjacking again, i'm really interested in this topic.:(

Title: Re: whoooaaaaaa.....I just got a thought.
Post by J_Rock on 10/11/06 at 13:27:27

Well, its a matter of partial vs full cancelation.  A driver playing free air with no baffle will make noise- this is because some of the sound energy is canceled out, but some is not.  

Even playing two subs out of phase next to each other would result in some output.  Simply because- yes the wave are out of phase, but the distance seperating the source causes a lag so the waves may sum in in different places.

The Parthenon was made with a square cone simply because it was a structural solution.  It was tested without an enclosure and I bet was used without one.  This is probably due to the size of the baffle allow it to be used OB- open baffle.  Theres a huge thread in the speakers builder forum on this site that goes into OB.  

Title: Re: whoooaaaaaa.....I just got a thought.
Post by ST33M on 06/08/07 at 19:56:51

What if you were to port the sealed section into the front next to the sub before the horn, only one octave over ?

Say you know your peak is 40hz and port it to 80hz. Would this in turn help in spl or would this hurt ? Just throwing something out there to ponder on.

Forums » Powered by YaBB 2.2.2!
YaBB © 2000-2008. All Rights Reserved.