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Half-Scale WO (Read 9350 times)
Blotch
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Half-Scale WO
07/04/07 at 23:26:21
 
Since I had some time and free materials laying about I thought I'd try my hand at building a WO with my Brother's help. Here are some Pics of the Build (sorry for the image size - had camera set wrong Sad )

The Drivers:

http://www.geocities.com/mickymouse00031/WOPics/Drivers.jpg

Layout sheet I drew at work:

http://www.geocities.com/mickymouse00031/WOPics/LayoutSheet.jpg

Layout Board:

http://www.geocities.com/mickymouse00031/WOPics/LayoutBoard.jpg

Various Build Pics:

http://www.geocities.com/mickymouse00031/WOPics/UnderConstruction4.jpg

http://www.geocities.com/mickymouse00031/WOPics/UnderConstruction3.jpg

http://www.geocities.com/mickymouse00031/WOPics/UnderConstruction2.jpg

http://www.geocities.com/mickymouse00031/WOPics/UnderConstruction1.jpg

http://www.geocities.com/mickymouse00031/WOPics/34View.jpg

http://www.geocities.com/mickymouse00031/WOPics/LookinDown.jpg

And heres the finished product:

http://www.geocities.com/mickymouse00031/WOPics/Alldone1.jpg

http://www.geocities.com/mickymouse00031/WOPics/AllDone2.jpg

In order to see how it performs I built optimum sealed and ported enclosures for the two drivers. We measured the frequency response at 2.83V/1m. All settings on the source unit and amplifier were the same during the testing. Tones were produced with a cd I made several years ago and SPL was measured with a digital Radio Shack SPL meter.

The Resulting graph:

http://www.geocities.com/mickymouse00031/WOPics/Graph.jpg

As you can see the WO does increase the output of these tiny drivers by quite a bit. Unfortunately I can't see much use for a speaker with a high output between 65 and 80 hz - LOL. We are most likely going to build a 24x36 WO to place in my Brother's car. Should be fun.

On a side note...if anyone decides to build a WO, I would suggest making the little wedge in the center FIRST. The angle was quite extreme and was very difficult to cut on my tablesaw as it doesn't lay over that far. Have plenty of scraps laying around to get those angles right. Ours weren't dead on the money but it worked out anyways Smiley


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Adrian
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Re: Half-Scale WO
Reply #1 - 07/08/07 at 22:13:29
 
Sweet effort. seems it could be useful as a mid-bass speaker. maybe even mid-range if you open up the throat..
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Too much bass never hurts, or does it ?
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60_and_up
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Re: Half-Scale WO
Reply #2 - 07/09/07 at 02:42:47
 
the overall shape of it looks wrong? (too narrow) did you scale it accurately or just throw some wood together?
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« Last Edit: 07/09/07 at 02:43:33 by 60_and_up »  

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Blotch
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Re: Half-Scale WO
Reply #3 - 07/09/07 at 13:39:50
 
it is an exact half scale of a 36x36 10" driver WO. To be honest it sounds horrible, about all it's good for is to irritate the neighbors - lol. someday i'll actually build a 24x36 or 36x36 since my bro has a couple 10" drivers laying around Smiley.
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60_and_up
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Re: Half-Scale WO
Reply #4 - 07/09/07 at 15:50:50
 
so it measures 18"x18" ?

it looks longer and thinner. 22"x16" ?
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Blotch
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Re: Half-Scale WO
Reply #5 - 07/10/07 at 22:44:26
 
18 x 18. Think your eyes are playin tricks on you LOL. Yes - it's exactly half size. I haven't drawn out a 36 x 36 yet so i can't measure the throat and mouth to give you a comparison. I had the plans laying around for a long time prolly just a optical illusion on your monitor ^^
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Matthew
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Re: Half-Scale WO
Reply #6 - 07/11/07 at 00:56:41
 
I think you forgot to scale the material you made the box with.  The original .75" should now be likened to .375" or what... 3/8"?  Your resulting internal volume is now smaller than it was suppose to be, messing up the sealed enclosure as well as the throat of the horn.
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Blotch
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Re: Half-Scale WO
Reply #7 - 07/11/07 at 05:11:16
 
When you build/scale a WO the material sits outside the lines made for the throat of the horn, therefore, the horn volume isn't effected by material thickness. The only thing effected is the sealed and compression chamber volumes which, in the case of my itty-bitty 4" drivers, is about the same as an optimum sealed enclosure. If i was using different drivers requiring more volume then yes, I used the wrong thickness material. Unfortunately I don't own a thickness planer and didn't have a bunch of 3/8" material laying around. This was mostly a test to see if my tools would give satisfactory results for the angles and I had stuff laying around to try it out. Either way as you can see on the graphs, A WO will increase the output of a narrow band quite dramatically over a sealed or ported enclosure. I seriously doubt scaling a WO below an 8" driver would give satisfactory results especially if you are planning on using it as a subwoofer UNLESS you plan on extending the length of the horn by either adding some sort of extension for the mouth or corner loading it. Someday I'll make a full size WO Smiley
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Gexter
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Re: Half-Scale WO
Reply #8 - 07/11/07 at 12:36:10
 
blotch
take the drivers and move them as far as you can to the vented end, even if you have to have them at an angle. then loosely stuff the sealed area.
Open up the vent slightly and round off the edges on the vent.
It may make is usable with a low crossover. The biggest drawback to your design is the lack of volume  in the sealed area. Second is the distance from the vent on the first bend.

before you throw it away try that out. throw it on its face about 1-2 inches from the floor in the corner of a room and give a whirl. It all fun and games and self education!
It never hurts to try something out just for fun if you have the time to waste Smiley

I run WO's and WO32's full size  just shorter to accomadate the smaller subs with much better luck. I have build some downsized ones that would not be to bad as long as they were in a trunk. IMHO they do not sound as good as the full size at all and require too much attention to get to a decent point ( even in a trunk)
thats what I think.
I did make  a downsized 5 1/4 that sucked pretty bad and I spent a lot of time modifiy it. by the time I was done it was much better, but it was crossed over really low and and had very little output.
When It was first built and crossed at 100 and it was "loud" but not in a good way.

have fun
Gex

EDIT
those are shielded speakers are they not? maybe with a cloth soft dome tweeter  you could use them as a center channel.
A ported enclosure may work better in this case with those puppies.
or full range ported with poly tweets.

the cheapest thing is to just mod it the way I said, to try it out and then throw it out instead of wasting more time.
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« Last Edit: 07/11/07 at 12:45:23 by gexter »  
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Blotch
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Re: Half-Scale WO
Reply #9 - 07/11/07 at 13:12:49
 
interesting concept. i may try that before i add it to the "test box" pile in the corner of my garage Smiley. I tested these drivers to get the specs before i started. Optimum sealed is .25 cu ft each and ported is 1 cuft each tuned to 45hz. I have 6 of these drivers (got screaming deal on case of pc "subwoofers") just trying to find a use for them - hehe. I was surprised at how well they sounded in a proper ported box though i still wouldn't consider them subwoofers. IMHO a subwoofer plays well ito the teens and 20's. guess i could use em with some low effeciency tweeters and make some 2-ways. Hmmmmm........
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60_and_up
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Re: Half-Scale WO
Reply #10 - 07/11/07 at 15:10:42
 
clamshell 4 of those drivers in the front of your baffle (not the rear where they are now). and maybe open your compression/throat/bandpass corner thing a little?

it looks tight Smiley
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Blotch
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Re: Half-Scale WO
Reply #11 - 07/11/07 at 22:22:13
 
hmmm......i didn't think of that till now.....another thing to try - lol.
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Matthew
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Re: Half-Scale WO
Reply #12 - 07/12/07 at 22:45:37
 
I'm not trying to be a nag, but I fail to see the logic here... if you don't scale down the thickness of the material in the entire enclosure, the distance between any given panel inside the enclosure will never be to scale.  By retaining the .75" material in a downscaled enclosure (essentially only lowering the internal volume within the circumference of the enclosure) the throat cannot possibly be as large as it it supposed to be.  Even if you still have the same distance between the absolute corner of the enclosure and the tip of the panel making up the throat, the distance between the sides of that panel and the outer panels of the enclosure will not be to scale, effectively making the throat smaller.  Am I figuring this right?  I'm not trying to be irritating, it's just that no matter how many times I try to run this scenario through my head it doesn't work without downscaling the material.   Undecided
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chickenkofta   IP Logged
Blotch
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Re: Half-Scale WO
Reply #13 - 07/13/07 at 13:35:28
 
Get a piece of paper, Draw out a WO on it following the original plans. Now, when you lay out the boards they go OUTSIDE of the throat lines. The dimensions of the throat and mouth are NOT effected by material thickness, except for a small distance change from the rear panel to the front of the mouth which in this case is a mere 3/8". The main thing that is changed due to panel thickness is the size of the sealed chamber and the compression chamber. One must remember that this is basically a front loaded horn and when it is scaled up/down the effective operating frequencies will go up/down also IE a 36x36 is about the same as a 45hz horn whereas my itty bitty one turned out to be a 75hz horn. I'll draw out a 36x36 and measure the dimensions as well as measuring the dimension off my 18x18 plan sheet and post them - this should make the explanation more clear.
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Matthew
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Re: Half-Scale WO
Reply #14 - 07/13/07 at 18:27:46
 
All I'm doing is imagining the wavlength that can travel within the horn which IIRC affects low frequency output.  The black lines are the hugantic panels you used (hehe) and the red is representative of what should have happened.

hay guys am i doing it right
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