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Presenting the WO SPL Thread (Read 10321 times)
J_Rock
Ex Member



Presenting the WO SPL Thread
10/04/06 at 02:24:50
 
Seems lately we have been having alot of discussions on making the WO a pure SPL.  In a quest to consolidate and explain, I present what I believe is a suitable solution to turn the WO into an SPL monster.  

First off- how do I model the WO?  It has been read here many times by forum members, and on the decware webpage that you can model a 4th order bandpass box to get an idea of what to expect.

Here is the model of a 36 x 36 WO with 2 10" Dayton Reference Series High Fidelity Subs.  I choose to model these because I own a pair.  

http://img.photobucket.com/albums/v652/J_rock777/WOresponse.jpg

You will notice that there are 3 graphs in this picture.  The blue line is a normal WO for these drivers, the purple and green the SPL WOs I will am going to describe.

My personal recomendation to create an SPL WO is to simply port the rear chamber 5-10 hz off of the Horn's normal- 45Hz.

As you can see, the green line is ported to 40hz, while the purple is tuned to 50hz.  

The Higher tuning, 50, results in a modeled increase of 15dB over the normal WO, at its max SPL, 47.5Hz.  

The Green line, tuned to 40hz, has a 12dB increase over the normal WO.  

Note the normal WO is a pretty badly modeled box- definately not something I would build normally.  Yet it has a max 8dB increase over the ideal sealed or ported enclosure.

Feel free to add, contradict, comment in any way.  Ideally I would like this thread to turn into a design and test it thread- but I am not sure when I will be building anything next.


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colinreynolds
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Re: Presenting the WO SPL Thread
Reply #1 - 10/04/06 at 05:59:06
 
Very nice post.  I haven't built a standard WO yet, but I want to.  After reading all of the posts here lately for SPL WOs, I have been really wanting to build one  and test it for SPL.  I have some 8"s that I am not even using.  If I could build a box that made those crazy loud.... then what would a WO for good 10s or 12s do?  I have been tossing around the idea of putting a wall in my van when I build it again.  I think 3 SPL WO's stacked on top of one another with highly efficient 12"s would be great fun!
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rock4016
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Re: Presenting the WO SPL Thread
Reply #2 - 10/04/06 at 13:42:32
 
Something to consider when looking at the WO model, is that the cabin gain of any vehicle would make that box model almost flat from 50hz down.

I'd like to see an RTA graph of a WO in someones car.
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musgofasa
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Re: Presenting the WO SPL Thread
Reply #3 - 10/04/06 at 14:22:51
 
There I go again!!!
I had the RTA readouts from an 8"wo in a 240sx and the readouts from the original 10" version in a blazer and in an explorer.
You are very close to correct. The response was flat from 55 or 60 hz down to about 35. There was a fairly sharp drop from 30 hz down in car response though.
This was playing pink noise and white noise. With frequency sweeps it was a little flatter probably down to 25hz or so.
Seems like in car was about 6db down at 22hz and 12 or so at 15hz.
It has been years since I had those graphs though.
As far as higher SPL, the models are exactly what one would expect I think. Beyond what can be seen, the only suggestion I can make is to measure the resonant frequency or highest SPL frequency in the car and try to tune the box (within 10hz or so of the normal 45 hz model) closest to the cars "happy" frequency.
I have thought about making the port external on the outside wall from the horn mouth and making it expanding so to take advantage of the "inherent" tuning frequency. I haven't thought of a way to model this or found many vehicles that it would fit in at 46-48 inches wide though. At least not and have enough output to justify considering the size of the vehicle in question. Perhaps I will think on this again to see if it can be set up and built. Now all i need are guinea pigs with MDF, saws and cars they want to play with lol.

Thanks for the thread J. I think we have been through this so many time, yet there has never been a comprehensive thread to assemble the info. I may see if I can get Don to post his results from his testing too. If I can find any of my graphs I will post those. Maybe he still has some of them.

Later

Robert
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mrezstreet
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Re: Presenting the WO SPL Thread
Reply #4 - 10/05/06 at 13:20:42
 
^^^^^^^^X2 Cheesy Cheesy Cheesy
[quote author=musgofasa  link=1159928690/0#3 date=1159968171]There I go again!!!

I have thought about making the port external on the outside wall from the horn mouth and making it expanding so to take advantage of the "inherent" tuning frequency. I haven't thought of a way to model this or found many vehicles that it would fit in at 46-48 inches wide though. At least not and have enough output to justify considering the size of the vehicle in question. Perhaps I will think on this again to see if it can be set up and built. Now all i need are guinea pigs with MDF, saws and cars they want to play with lol.



Later

Robert [/quote]



me have mdf...lol....big van.......and 4 15" subs with only 2k power to play with....only a week left in the 16-18 hour days...so soon the van is ganna get jiggy!
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« Last Edit: 10/05/06 at 13:21:51 by mrezstreet »  
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musgofasa
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Re: Presenting the WO SPL Thread
Reply #5 - 10/05/06 at 13:36:43
 
Mr EZ,
How much height do you have in the van?
I just had a thought lol.
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djman37
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Re: Presenting the WO SPL Thread
Reply #6 - 10/05/06 at 15:10:12
 
good lord, look at that graph!
G/L fellas!  I'll be checking in regularly on this one.

Right now I'm running either RE MT 15's (dual .7) or DD 9515e (dual 1) and a IA 40.1 and would be interested in seeing the SPL results.
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colinreynolds
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Re: Presenting the WO SPL Thread
Reply #7 - 10/06/06 at 06:13:57
 
Yeah.... an Astro Van has 51" between the wheel wells.  I know.  I would think that other GM vehicles would be very close to that.
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J_Rock
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Re: Presenting the WO SPL Thread
Reply #8 - 10/06/06 at 15:18:19
 
I am going to try to get into contact with someone who is set up to get a frequency response in car.  I don't have a mic or software to do it.

After I find someone, I plan on cutting the holes in my WO.  Then test it sealed, get frequency response, then drop the ports in and get frequency response.  Hopefully I can do it at 1w/1m, but I will for sure do same power for both tests.
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djman37
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Re: Presenting the WO SPL Thread
Reply #9 - 10/06/06 at 17:16:56
 
nvm, i have a TL but live in Texas.
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« Last Edit: 10/06/06 at 17:18:03 by djman37 »  
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mrezstreet
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Re: Presenting the WO SPL Thread
Reply #10 - 10/10/06 at 17:47:12
 
next week the 36x36 wo box for 10's will have 4 ed 6.5" subs 2 on each side and 2k to run em got a show the 28th of oct....just 45 min from home Cheesy...robert....we ganna get jiggy with the cargo...side job is giving jo$h some play money ???
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dbjunkies
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Re: Presenting the WO SPL Thread
Reply #11 - 10/11/06 at 02:50:18
 
total noob to this, but what mods would have to be made to make this work for 15's?

also, does it matter which direction the subs are facing?
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« Last Edit: 10/11/06 at 03:20:44 by dbjunkies »  
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J_Rock
Ex Member



Re: Presenting the WO SPL Thread
Reply #12 - 10/11/06 at 03:47:59
 
Well the construction of a box for dual 15s is up in the air since its not really recommended by Steve.  But if you make the box larger- via scaling I would assume.  You would need to first calculate the center tuning frequency of the horn (I would assume again) then tune the rear sealed chamber to +/- 5-10 hz away.

Should result in a nice big peak like above.

Thats how I would do it, but I don't know how to actually go about doing it.

The subs facing direction can help control the High frequency resonse of the design for 10s or 12s- not sure for 15s, but probably the same. Having the magnet in the sealed chamber results in a better HF response, while placing the magnets in the compression chamber results in lower HF reproduction.

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« Last Edit: 10/11/06 at 03:51:33 by j_rock777 »  
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dbjunkies
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Re: Presenting the WO SPL Thread
Reply #13 - 10/11/06 at 15:06:01
 
hey, thanks for the help--I think we'll try a 10" version first to get familiar with it and go from there! Cheesy
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mrezstreet
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Re: Presenting the WO SPL Thread
Reply #14 - 10/12/06 at 19:40:14
 
update: the other 2 6.5" ed eu700d's are in.......soon the box will be built Smiley
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