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JBL GT150 15 " subs (Read 13165 times)
db_audio
Ex Member



Re: JBL GT150 15 " subs
Reply #60 - 01/30/06 at 04:01:53
 
sponsorship...team jbl
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J_Rock
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Re: JBL GT150 15 " subs
Reply #61 - 01/30/06 at 04:47:52
 
thats all we get? no pics?

Well, at least you are back on the forums!
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db_audio
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Re: JBL GT150 15 " subs
Reply #62 - 03/01/06 at 13:13:45
 
Wow! what a long few months...no play time - just work all the time.
UPDATE: Good news...I have a wo about 90% complete for 2 JBL GTi 10's. I wanted to see how the 36" model sounded so i can compare the larger ones for the 15's. i will post pics as soon as i get a new cable for the camera. -dan-
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J_Rock
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Re: JBL GT150 15 " subs
Reply #63 - 03/01/06 at 20:49:30
 
I was just thinking about how I was gonna have to track you down and force you to finish. lol.
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bassboy
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Re: JBL GT150 15 " subs
Reply #64 - 03/03/06 at 02:34:27
 
Hi J, I saw some of your posts in the other forum and some people seemed more intent on  questioning the original design of the WO than answering the question you asked.  People that should know better, but they have their own stuff to sell, I guess.

I did a google search on exponential port and surprise, surprise, I didn't find much.  Maybe people know about them and are calling them something else, but there's not too much info on that particular search.  These are my observations based on listening to a WO and conventional horn theory.  Let me begin by saying I may be completely wrong and welcome comments and critisism.

The WO is NOT a horn by definition, at least not when used as a subwoofer.  Then gentleman in the other forum was right, by definition, this thing should not be able to go any lower than about 70, and that's if you stick it in the corner.  If you stick it in the middle of the room as a coffee table, it shouldn't be able to go lower than a few hundred hertz.  That would mean that when we cross it over at 80, we should be theoretically listening to absolutely nothing.  Is that the case?  Of course not.  I'm just guessing here, but I think most WO's are flat down to at least driver fs, regardless of room position.

So what is going on?  I have read at least 3 times in different articles about bass horns that until they get about 5 feet long they are not working as horns at all.  Not once did they mention what was going at at this length, the general consensus is just that it needs to be bigger.  This is why I believe Steve only scales in one dimenstion.  To elongate the horn (flared port, exponential port) too much would make it act like a horn, effectively making it useless as a subwoofer.  I can't prove that and I certainly am not going to build one to prove it won't work.

The flare contour or expansion rate does not seem to matter nearly as much as a real horn.  For example, Steve's corner horn is also much too short to theoretically do what it does, so it must also be a flared port, although it increases dramatically faster and ends with a much larger mouth.

So what is important?  In my opinion, based on absolutely nothing, it appears that a flared port should begin with a throat roughly the same as a corresponding real horn would have.  It should increase in surface area and length, to a length of not more than 4-5 feet and a mouth of no less than 5x throat area and I don't know about mouth maximum area but using the cornerhorns as a reference it should be able to get pretty big.

As far as porting this box, I do not think the gain will be worth the consequences.  I believe that raising the low frequency of a subwoofer is a crime tantamount to murder.  Just my opinion.

So please bring your critisms, as I would like to better understand this type of box.  I know my theory doesn't make a lot of sense but remember that by traditional theory this box used as a subwoofer coffee table in the middle of the room should have close to 0db output.
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J_Rock
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Re: JBL GT150 15 " subs
Reply #65 - 03/03/06 at 03:34:15
 
Basically the main thing I think we need to realize, is that we don't know exactly how the WO works so well.

I am with you in the fact that it most certainly is not a simple 4th order, and it is defineatly not a simple horn at the frequencies it is being used.


I think you should start a different thread also, because I am sure this thread doesn't need this discussion, but the forum as a whole does need the discussion.
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bassboy
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Re: JBL GT150 15 " subs
Reply #66 - 03/03/06 at 03:42:36
 
The reason I posted here and not a new thread is because this guy is considering building 3 upscaled models with ports.

My first point was that I don't think upscaling is a good idea.  The second is that I don't think ports are a good idea.

That's all I was trying to get across.
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J_Rock
Ex Member



Re: JBL GT150 15 " subs
Reply #67 - 03/03/06 at 03:58:02
 
Well, actually in the end here he decides to build 3 simply scaled to fit the driver.

And he decided against porting I believe.

I thought you were just trying to strike up a good conversation about design other boxes similar to the WO or unraveling the "Mystery" of why the WO works.

My bad!

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db_audio
Ex Member



Re: JBL GT150 15 " subs
Reply #68 - 03/03/06 at 13:17:23
 
Final versions will be up-scaled to fit the 15" driver...NO ports...and the only reason I wanted more than one WO is first is I have more than enough drives to do this with! second reason is I was thinking that I could achieve a decent amount of coupling. These are for a expedition - not a house sound room. I have a heck of alot of experience in box building and design but I wanted to experiment with something a little different...thanks -dan-
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J_Rock
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Re: JBL GT150 15 " subs
Reply #69 - 03/03/06 at 15:46:45
 
Just drop us a line as soon as you have pictures or if you are going to be at any car audio shows!
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db_audio
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Re: JBL GT150 15 " subs
Reply #70 - 03/03/06 at 22:23:44
 
ok. as much as i am working, i really dont know if ill be able to get to Daytona (SBN) this year...darn-it! im upset about it but i guess you have to work so you can still play a little. i promise that i will keep everyone updated! -dan-
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