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Build the Perfect WO (Read 12893 times)
Circlomanen
Ex Member



Re: Build the Perfect WO
Reply #15 - 08/12/05 at 22:00:42
 
I think the ultimate WO would be double the height and four drivers, two on each side. Then add bent panels as in my "small WO with lotsa bass" thread.
The reason for this is that a slot or very rectangular horn mouth is a suboptimum shape as a horn. A horn should be round or as close as posible to that shape, to work as intended. If you make the height 24 inch the mouth will be bigger and will be more optimum shaped for a horn.
After feeling the extrem pressures in the WO box I want to make it as stable and heavy as possible. I would love making it out of concrete! Three inches thick!!!
Furthermore I want high efficiency. Light cones and lots of voicecoil in the magnetic gap. Realy strong magnets.
It doesnt matter if the woofers only can take 25 watts each as long as their efficiency is realy high. 103 dB/W/m or more. Four of those in a WO should give a total efficiency of 112 dB/W/m. 100 watt and 112 dB/W/m will give you 132 dBs of soundpressure!!!
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j_rock777
Ex Member



Re: Build the Perfect WO
Reply #16 - 08/13/05 at 14:13:12
 
What I am looking for is things that have worked in the past, like Circloman's curved flare.  And then combine them into one ultimate WO.  I really think I may be onto something with the slanted top for higher compression at the horn throat, so I might just build one quick.
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gexter
Ex Member



Re: Build the Perfect WO
Reply #17 - 08/18/05 at 12:12:53
 
I take it that you are trying to gather enough information to increase the probabilities of success with your modded design?
You have two good ideas to combine.
Is it not possible if you try to include too many mods that it will depart to far from the design to work well?
Your holding off in order to have a more successful attempt. Why not make it so you can dissassemble it easier until you get it right. Even with some air leaks it will give you an idea of where you need to go.
I have gutted my Little WO a number of times and it looks like crap but it gives me a chance to play with a single box without starting completely over.
using damping and making the sealed volume as big as you can so you can reduce it if needed is a thought. I think the volume of the chamber after the sealed one is more flexible in size than the sealed, just a guess though.
the type of path and size is the challange. I think Steves design is simple and uncluttered creating a simple and effective build right off.
Only us " modders" are willing to tweak and have failures and learn and move on. The design may be able to be adjusted with success but result in being more complicated.

As far as Ideas "build it and they will come"
Power to the Modders Smiley
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DirtDawg
Ex Member



Re: Build the Perfect WO
Reply #18 - 08/18/05 at 14:42:58
 
[quote author=gexter  link=1121529118/15#19 date=1124363573]Is it not possible if you try to include too many mods that it will depart to far from the design to work well?...............................................

.........................................As far as Ideas "build it and they will come"
Power to the Modders Smiley [/quote]


Very possible gexter, but the worst thing that happens when you change more than one thing at a time is that you don't know how much any one thing may have helped or hindered your design. Suppose you have a great idea and a bad idea incorporated at the same time and it improves performance because the great idea was so helpful. But, if you had left out the bad idea the design would have been great. Now compound your error by giving credit for the improvement to the bad idea and your next design includes more of the bad idea.....and you don't know why it doesn't work. Whoops! So, you're right, it doesn't work as well to alter too many things at once.

When I built my first 2 WOs I stayed as close to the design as possible. Then after a few tests I altered the port area mainly because it was either flexing under load or too sharp of a turn and adding harmonics to a pure sine wave. At first I temporarally added a corner filler and got an improvement but I still had some resonance, so I reshaped the port area and doubled it. Then most of the ugliness was gone, but I had a different harmonic become more noticeable. (That's when it feels like your hair is turning gray or falling out in my case.)
After much further goofing around (can't really call it testing this time) I discovered that the 2 sides of the pressure wave were actually out of phase to the point it was audible, usually meaning the horn flares too rapidly in some area. At that point I got out a microphone and some headphones and put the mic inside from the mouth at different positions to try and determine how to fix it. 2 or 4 mics and an o'scope would have helped, but I no longer enjoy such luxuries. After moving a 12" board around the second turn for a while I found the spot that was losing velocity and blocked it up. ......VOILA! No more harmonics in the signal!

I'm not prepared to say that I have improved the design, but I will say my WOs sound much better than before I tweaked them. I will also point out that my next pair will be built as close as possible to the original design, but I have a few tricks up my sleeve in case I need them.

"If you build it they (ideas and friends) will come" It's getting them to GO that's the trick.
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DirtDawg
Ex Member



Re: Build the Perfect WO
Reply #19 - 08/18/05 at 14:50:07
 
[quote author=j_rock777  link=1121529118/15#15 date=1123628354]any thoughts people? [/quote]


Build it!
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gexter
Ex Member



Re: Build the Perfect WO
Reply #20 - 08/18/05 at 16:49:01
 
Dirtdawg  "If you build it they (ideas and friends) will come" It's getting them to GO that's the trick.

So true
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Circlomanen
Ex Member



Re: Build the Perfect WO
Reply #21 - 08/18/05 at 19:58:26
 
Quote:
Power to the Modders
Smiley


Gexter, you wrote: Quote:
I think the volume of the chamber after the sealed one is more flexible in size than the sealed, just a guess though.

And even though you state "just a guess though." I would like to ask why ?? Why do you think the sealed chamber is more inportant??  i do think something similar but I have no real reason, no "why". Its an important piece of info.


Dirtdawg wrote Quote:
When I built my first 2 WOs I stayed as close to the design as possible. Then after a few tests I altered the port area mainly because it was either flexing under load or too sharp of a turn and adding harmonics to a pure sine wave. At first I temporarally added a corner filler and got an improvement but I still had some resonance, so I reshaped the port area and doubled it. Then most of the ugliness was gone, but I had a different harmonic become more noticeable. (That's when it feels like your hair is turning gray or falling out in my case.)  
After much further goofing around (can't really call it testing this time) I discovered that the 2 sides of the pressure wave were actually out of phase to the point it was audible, usually meaning the horn flares too rapidly in some area. At that point I got out a microphone and some headphones and put the mic inside from the mouth at different positions to try and determine how to fix it. 2 or 4 mics and an o'scope would have helped, but I no longer enjoy such luxuries. After moving a 12" board around the second turn for a while I found the spot that was losing velocity and blocked it up. ......VOILA! No more harmonics in the signal!


And that is very intresting since I have a lot of distortion and harmonics in my large WO.
Do you have a picture inside your box or a drawing pointing out exactly what and where??!?!?  
I would be Żberhappy for some answers!

Cheers Johannes. Smiley
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gexter
Ex Member



Re: Build the Perfect WO
Reply #22 - 08/18/05 at 22:21:55
 
It's a kind of one way thought Johannes and no concrete reason.

I feel that the sealed volume has to be at least big enough or maybe a little bigger, in order to get maximum output from the driver. I also think that sealed volume specs are the absolute minimum. ( this refers to a sub )
So a little smaller= bad a little bigger = not as bad.
When I have too little volume it makes a big differance in low end. I feel that I can manage the volume that may be too big in a full range or sub with the XO method. Plus with a basic box I have been able to shave it.
I can stuff a whole lot of dacron in the chamber in mine and it sounds better just less output.
But I have no specific reason and have not done enough testing to be absolutley sure.

Dirtdwag wrote:
"After much further goofing around (can't really call it testing this time) I discovered that the 2 sides of the pressure wave were actually out of phase to the point it was audible,"

I was not going to worry about a Cm or two while I construct my moddified horn. But now I am going to make sure it is as close as I can get it.
I am using the basic box that I built and adding a smooth horn in the very start of the horn and narrowing it. the spaces left between the new narrower horn and the old will be filled with expanding foam to resist flexing. I think this is better than nothing at all but an empty space.

Hair falling out Dirtdawg? you still have some? you have knowledge and hair? I am jealous

Honestly I am learning the science from you guys more each day  and learn why things may or may not work. I have learned so much over the last couple months I am at the point I can really make really big problems for myself.  :-* Wink
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« Last Edit: 08/18/05 at 22:24:52 by gexter »  
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DirtDawg
Ex Member



Re: Build the Perfect WO
Reply #23 - 08/18/05 at 22:38:04
 
This is horrible, but it's the best I can do with Paint

http://img246.imageshack.us/img246/6802/whplan22sg.png


There are actually 4 pieces that are different

1. The panel that makes the port is now 2 panels together with the sides rounded, but .75" is flat like the plan.

2. A small 30/60/90 triangle is added at the actual corner as a filler. it's also double thick, but most of it was cut away leaving 1" on the short side.

3. The big triangle extends from it's normal point at the top to 6" from center instead of 4".

4. An additional small piece (don't remember the angles) is added to the junction between the back of the box and the big triangle. It was 3.5" on the long side.

That's about as clear as I can get. Hope it helps.
Just remember that your box is different from mine and has different drivers, so my fix won't be exact for yours. The idea is to maintain an even expansion in the turns, where there is already a (pressure)phase shift, caused from folding/bending the horn. The air along the inner wall of a turn travels a shorter distance than the air along the outer wall. That's why "W" folded horns usually sound better than scoops.
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J_Rock
Ex Member



Re: Build the Perfect WO
Reply #24 - 08/18/05 at 23:13:18
 
I like everything except #3.  Wouldn't the waves then rebound somewhat after hitting the wall on the other side, instead of being guided down its length.
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DirtDawg
Ex Member



Re: Build the Perfect WO
Reply #25 - 08/18/05 at 23:50:47
 
John,

It's really not that big of a change. All you need to do is to maintain velocity/pressure/expansion. Take the top off and look at one with a couple of short sticks in that area and you'll see the change is not huge. The difference in sound however, is almost like tuning your instrument or not tuning. Most of the harmonic stuff is gone.

I was using a sine wave generator between 20 and 40Hz to help find the problem areas. Forget trying to use music to tune a box. It's too easy for your mind to listen to the music and forgive what's not music.
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« Last Edit: 08/18/05 at 23:54:59 by DirtDawg »  
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J_Rock
Ex Member



Re: Build the Perfect WO
Reply #26 - 08/19/05 at 00:15:00
 
first, whos John? hehe I am Jerick....

Next, it isn't that big of a change but you get a lip of expansion right at that point, I would rather sacrifice the decrease in expansion rate at that point and not have a point jutting into the wave path.

Perhaps incresing the height of the second triangle you added next to the bottom original triangle would alter the angles enough to keep the same rate of expansion around that turn?

The main question I have is wether or not it is better to have many small angled bends or one smooth curve like Circloman's WO?  I believe the curve would be better, but that is based on the designs of high frequency horns and the like.  Nobody really has designed a well raved about folded horn such as Steve's.  

I still think that for a 12 inch version, tilting the top so that the corner where the waves are inititally compressed is the same area as a ten inch version would prove to be a significant increase in output.  I may try using the wasted 10 inch version I have sitting in my garage and tilting it down to fit some 6 inchers....
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J_Rock
Ex Member



Re: Build the Perfect WO
Reply #27 - 08/19/05 at 01:33:26
 
It only makes sense that smoother would help the flow of air, but sound also should definetly travel better.

I also believe strongly in smmothing the surface of a horn is very important, which is why I often paint and/or clear coat the horn path.  Otherwise, you will get a slower flow of the air at the edgeds, because it is in contact with a higher level of friction.  so you get an overall slow-down of the air that does move.  Wether or not this is detremental or helpful in bass-horns is still beyond me, or wether it even occours...

Either way I like to smooth as much as possible to take out another variable many simulators cannot deal with....
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Circlomanen
Ex Member



Re: Build the Perfect WO
Reply #28 - 08/19/05 at 09:48:58
 
Quote:
I think smooth is always better when you are tallking about moving air, or anything for that matter. I've heard for years that bass horns don't have to be all that smooth, because they don't actually flow that much air. After building 28 (and counting) W bins I always get better sound after smoothing hard turns as much as possible. Just as important as air flow is the fact that the inner side of a curve is shorter than the outer. So slowing the inner curve with a hard corner and smoothing the outer curve is the best answer. Of course with a "W" layout the flow turns twice so the concerns are lessened. WO on the other hand is a gradual curve so I think the smoother the better.

This makes a whole lot of sense to me.
My small WO did sound very clean and had very little higher harmonics, but my large WO that is very much like the original WO but with a little longer horn extending all the way out to the sides has a lot of higher harmonics and distortion.

I beginning to think that those curved parts are a lot  more important than I realised from the beginning.

My freind built a scaled down WO with two 6,5 inch drivers and even if it could play realy loud, it dident sound as good as my small one.

Its time for some serious thinking about how to build one with perfectly rounded and smoothe expansion of the horn. No sharp bends at all. The port should be fireing straight down into a slowly turning bend. It should not start with a 90 degree sharp bend.

One more thing I strongly belive in, is making the mouth as large as possible. Efficiency and dynamics are all about radiating surface. A WO with four 10 inch woofers and 24 inch internal height wil probably have something like 9 db higher efficiency than a normal WO, mostly due to a larger radiating surface and higher acoustic radiating impedance, loading the drivers a lot better thereby lowering the travel and the distortion for any given spl. And increasing the powerhandling a lot.

Quote:
This is horrible, but it's the best I can do with Paint

http://img246.imageshack.us/img246/6802/whplan22sg.png


There are actually 4 pieces that are different

1. The panel that makes the port is now 2 panels together with the sides rounded, but .75" is flat like the plan.

2. A small 30/60/90 triangle is added at the actual corner as a filler. it's also double thick, but most of it was cut away leaving 1" on the short side.

3. The big triangle extends from it's normal point at the top to 6" from center instead of 4".

4. An additional small piece (don't remember the angles) is added to the junction between the back of the box and the big triangle. It was 3.5" on the long side.

That's about as clear as I can get. Hope it helps.
Just remember that your box is different from mine and has different drivers, so my fix won't be exact for yours. The idea is to maintain an even expansion in the turns, where there is already a (pressure)phase shift, caused from folding/bending the horn. The air along the inner wall of a turn travels a shorter distance than the air along the outer wall. That's why "W" folded horns usually sound better than scoops.


Thanks Dirtdawg!!!  Thats clear to me now. Very intresting and usefull.
Now I have to redesigne my WO once again.......... Cry Cry Cry

Smiley Happy Johannes with a lot of new tricks up his sleeve! Smiley
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Circlomanen
Ex Member



Re: Build the Perfect WO
Reply #29 - 08/19/05 at 09:51:15
 
Quote:
Honestly I am learning the science from you guys more each day  and learn why things may or may not work. I have learned so much over the last couple months I am at the point I can really make really big problems for myself.


Me too! Thanks all you guys out there. You are doing a great job!

Smiley Johannes Smiley
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