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Old 5th June 2005, 12:27 PM   #11
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Default Re: TL and Horn Comparison for FE-206E

Quote:
Originally posted by Onur
Why don't you have a look at my TL and Horn comparison for Fostex FE-206Es. It may ease thing up fo you. You can reach them from the link below and then clicking Fostex FE-206E link.

http://www.yildiz.edu.tr/~ilkorur/

/Onur

I confess I like the horn design... some interesting things there, good stuff!
Best
Scott
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Old 5th June 2005, 12:39 PM   #12
Onur is offline Onur  Belgium
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Default Why not look at the interior ...

I have realized that I haven't put the picture showing the interior of the Horn enclosure, and now, I have updated it.

/Onur
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Old 5th June 2005, 12:45 PM   #13
tonitze is offline tonitze  Singapore
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I'm looking forward for the enclosure dimension. Thanks Onur.

Toni
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Old 5th June 2005, 11:10 PM   #14
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One thing that has made me shy away from the fostex recommended horns is the squared horn contour with each segment being straight. I've seen reports from a couple of people who went to all the trouble of trying round all those square corners and they were disappointed in the end result, however, those who stuck straight to the plans seem to always be happy with the results. Could it be that the straight segments and square corners are essential to the proper functioning of these horns? If so, can someone point me to some more info to help me understand more about this type of horn and why it works?

It seems to be in direct opposition to Ron's Dallas horn for the FE206 over at the full range driver forum, http://fullrangedriver.com/tiki-view....php?forumId=1 . His successive versions of the Dallas have become a smoother and smoother horn contour up to the current model Dallas II version F .
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Old 5th June 2005, 11:23 PM   #15
squalor is offline squalor  United States
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I want a pair of FE206E's so bad I can taste it. My spousal approval rating is almost high enough-they will be mine.
Of all the enclosure designs I've seen so far; the one I like the best is Ron Clarke's Dallas II . With my limited wood working skills and tools it looks like it might be easier to build. Almost all angles are 45* and the print seems understandable. The print is based on 3/4 Birch ply and expressed in inches for us stubborn amuricuns. The Big Fun is too big for my room and I fear the Solo 206 would not have enough low bass. The Nagaoka is too wide and boxy and the Jericho looks too hard to build. The Dallas seems to have some good design features too. The filter chamber is smaller and the surfaces seem to reflect away from the back of the cone. The throat is at the bottom front of the 206e. The baffle is narrow and may image better. The horn mouth flair is not as truncated. Fewer bends in the horn may mean fewer standing waves. Hollow areas behind the driver that can be sand filled.
Am I off base on any of these design assumptions ? I'm very new here and there is just so much I dont understand yet but I am an apt student and do 10 searches for every post I make.
Good luck on what ever you build Toni ! Bon musicom, ceil sur terre !
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Old 5th June 2005, 11:38 PM   #16
Onur is offline Onur  Belgium
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Default Dividing a horn into Segments, but how?

If you have examined my page you will see that there is a Finite Element Simulation of a Transmission Line enclosure. I have generated a pulse in the top line and I have simulated the pulse wave till it left from the opening of the line. When it passed through the elbow, some of the acoustic energy reflected backwards. This is the case with sudden area changes in horns or transmission line enclosures, where dramatical cross-section changes occur. When this happens, you realize the effects by means of blured highs, unpleasent midrange. This reflections will rise the distorsion level, causing all the unwanted chain of reactions.

As far as my trials are concerned, I have seen that making the horn cross-section as close to the mathematical function, which describes it, as possible, reduces this effect. I have generated my own set of rules to make it robust. I didn't dig into the maths but my numerical solution of hyperbolic wave equation on an unbounded domain gave me reasonable results which I could be able to decide between right and wrong by just observing the outcome. I am not critisizing which horn geometry has the lowest distorsion level, but I am talking about which application of the same geometry can have the lowest distorsion level.

I believe building the horn without smooth corners doesn't effect the sound in audiable levels, by keeping the area change ratio under a reasonable value, however, folding the horn do cause some back reflections, which is the case with all folded designs. There are ways to get around this though.
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Old 5th June 2005, 11:57 PM   #17
squalor is offline squalor  United States
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Quote:
There are ways to get around this though
Like these Fostex Sound Reflectors ?
Where in the line would be a good place to put them Onur ?
$50.00 seems a bit much; wonder if I could substitute the cut out bottom of 2 liter soda bottles ?
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Old 6th June 2005, 12:00 AM   #18
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Onur,

Thanks for the reply. You mention blurred highs and midrange problems resulting from combining straight segments of increasing area to form a horn. You also mention energy reflections of the 90 degree folds which causes problems.

My gut feel is that the squared layout the Fostex designs use functions as a low pass acoustic filter and the reflected energy is only in the higher frequencies which is purposefully dissipated within the walls of the horn folds. Does that make sense or is that just a lazy noob not wanting to get into the math and physics enough to really understand what is happening ?
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Old 6th June 2005, 12:10 AM   #19
Onur is offline Onur  Belgium
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Default Fostex Sound Reflectors

I don't believe that they are the solution for what I have tried to say. At the first place, the dimension of those are smaller then the wavelength of any low frequency disturbance, which is causing the problem. I suspect those are on the market to reduce the unwanted reflections, which are caused by a small rear chamber, passing through the thin cone of the speaker unit.

I was trying to mention about horn or transmission line resonances, and unvanted reflections from elbows, bends and horn mouths or line terminus. You have to tame them before they move your cone backwards or forewards. Unwanted reflected energy may cause doppler distorsion besides distorsion in low frequency range.
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Old 6th June 2005, 12:31 AM   #20
Onur is offline Onur  Belgium
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Default what is really happening?

That is the question that I have been working on also. The math gets too complex when simulating these enclosures and you switch to finite element analysis or numerical solutions. I have generated my own code, which I will publish at the end of my PhD study, on my web page. This code simulates any geometry so that you can observe what is happening at a certain frequency. When you place a certain enclosure in the simulation field and generate some tones you can observe what is going on inside a horn or a TL. As for your question, I coudln't - yet - able to observe such a behaivour. When I examine Fostex designs, I see narrow labyrinths, sharp turns, which causes complex interferences in my simulation field. Psychologicaly speaking, my designs show a more relaxed and clean interior reflection as compared to those and I regard those results as close to the way how it supposed to be. It is a pity that my designs haven't been listened with many listeners therefore I do not know how they perform as compared to those ones.

I hope this could be an answer?
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