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Old 9th December 2013, 11:05 PM   #501
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Quote:
Originally Posted by schmeet View Post
Thanks for letting me know. Can you see any pattern to when this happens?
This was brought up once but I thought I fixed it. I don't get it anymore...
It's only happened once since I updated to the latest version. So I can't determine a pattern from that but I thought you'd like to know that it did happen.


Quote:
I'm not sure what you mean by this? Exponential growth is f(t) = a.b^t
a is the starting point (i.e. Start Area). B is the growth factor (i.e. Taper Ratio) and t is how far along you are, i.e. position (x / L)
Exponential t = 1. (I believe that's true, I'm not really up to date on all the math and definitions.)

Then there's Salmon family Hyperbolic Exponential flares with adjustable t.
Vincent Salmon introduced the hyp-ex family of horns in US patent number 2338262.
Espacenet - Original document

I don't think anybody really uses a pure exponential t=1 flare at all for anything. Marshal Leach's math, which is the most widely used math used to design horns, produces hyp-ex flares and I think almost all the experts (like Edgar, etc) prefer to work with hyp-ex.

I can provide links to Leach's math, Edgar's math (which I believe uses Leach's math) etc (to show that all the experts prefer hyp-ex flares and not exponential flares) but I think all the math needed to describe hyp-ex flares is available in the patent link above.

If you have a copy of Hornresp, you can see that when the "System Design" tool is used, Leach's math is utilized to produce a hyp-ex flare. Also, you can design your own (without the help of the System Design tool) by selecting "Hyperbolic Exponential" for a segment flare type and then you can choose your desired t.

Last edited by just a guy; 9th December 2013 at 11:14 PM.
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Old 10th December 2013, 11:05 AM   #502
schmeet is offline schmeet  United Kingdom
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Yeah it's always useful know of errors. I'll keep an eye out for what could be causing it. If you could send me the error message next time it happens again (if it does happen again!), that'd be great.

Regarding the exponential. I have looked at the hyp-ex formulas and I can't get it to work for a fixed length and start/end areas. I thought it would help to look at how it works in HornResp, so I downloaded it and it seems you can only choose Parabolic, Exponential and Conical flares..

Could you go through how to use a Hyp-Ex flare? I've not used HornResp before and I'm struggling to get to grips with it...
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Old 10th December 2013, 12:09 PM   #503
schmeet is offline schmeet  United Kingdom
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Originally Posted by schmeet View Post
Yeah it's always useful know of errors. I'll keep an eye out for what could be causing it. If you could send me the error message next time it happens again (if it does happen again!), that'd be great.

Regarding the exponential. I have looked at the hyp-ex formulas and I can't get it to work for a fixed length and start/end areas. I thought it would help to look at how it works in HornResp, so I downloaded it and it seems you can only choose Parabolic, Exponential and Conical flares..

Could you go through how to use a Hyp-Ex flare? I've not used HornResp before and I'm struggling to get to grips with it...
Ok, I've figured out how to do it in HornResp, though I can't figure out how to rearrange the equations

I'll start a thread in main forum I think
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Old 10th December 2013, 12:15 PM   #504
schmeet is offline schmeet  United Kingdom
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If any is interested in offering a hand with it, or knows how it's done:

The formula is:

SL = So(cosh[L/xo] + Tsinh[L/xo])

L is the length of the element
So is the start area
SL is the end area
T is the exponential/hyperbolic form

We know all the above and need to find xo. I can't do it...
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Old 10th December 2013, 01:27 PM   #505
GM is offline GM  United States
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FWIW, I've had good luck using this math solver, but never tried this complex a formula: Solve Equation with Steps :: QuickMath.com - Automatic Math Solutions

GM
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Old 10th December 2013, 01:59 PM   #506
schmeet is offline schmeet  United Kingdom
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Ok, I've simplified it a little

SL = So(cosh[L/xo] + T.sinh[L/xo])

For now lets set L/xo to k (just for simplicity)

sinh(k) = [(e^k - e^-k)/2]
cosh(k) = [(e^k + e^-k)/2]

so...

SL = So([(e^k + e^-k)/2] + T.[(e^k - e^-k)/2])
SL = So([(e^k + e^-k)/2] + [(T.e^k - T.e^-k)/2])
SL = So((e^k + e^-k + T.e^k - T.e^-k)/2)
SL = (So/4).(e^k + e^-k + T.e^k - T.e^-k)
SL = (So/4).([1+T]e^k + [1-T]e^-k)
4.SL/So = ([1+T]e^k + [1-T]e^-k)
sqrt(4.SL/So) = [1+T]e^k + [1-T]e^-k
sqrt(4.SL/So) = [1+T]e^k + [1-T]e^-k

I can't get much further with it though...
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Old 10th December 2013, 02:10 PM   #507
schmeet is offline schmeet  United Kingdom
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Quote:
Originally Posted by GM View Post
FWIW, I've had good luck using this math solver, but never tried this complex a formula: Solve Equation with Steps :: QuickMath.com - Automatic Math Solutions

GM
Ah. That worked a treat! Thanks...
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Old 12th December 2013, 10:25 AM   #508
schmeet is offline schmeet  United Kingdom
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OK, I've pretty much got this working now with the t parameter.
I have a few other things I need to work on before I release it though.

Any other requests for the next update?
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Old 12th December 2013, 05:37 PM   #509
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in the patent x0 = speedOfSound / (2 * pi * f0) where f0 is the cut off frequency
this is a very simple newton's iteration to solve for x0

x0 = 0.001;
step = 1.0;
diff = 1.0;
n = 0;
while (diff > 1.0e-5)
n = n + 1;
sx = si * (cosh(x/x0) + T * sinh(x / x0))^2;
diff = sx - s;
if (diff < 0.0)
step = step / 2.0;
x0 = x0 - step;
else
x0 = x0 + step;
end
diff = abs(diff);
end
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Old 12th December 2013, 09:12 PM   #510
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Originally Posted by schmeet View Post
OK, I've pretty much got this working now with the t parameter.
I have a few other things I need to work on before I release it though.
Thanks for doing this.

Quote:
Any other requests for the next update?
Is there a way to use multiple drivers in a design? (Multiple identical drivers, not different drivers.) I couldn't find out how to do this, so if it's not already available, that would be a great feature. I use up to 12 drivers in a sim so it would be good to be able to specify the number of drivers in series/parallel groups.

Other than that it's starting to look pretty complete. There's a huge list of things that you could add (like impulse response, etc) but nothing really important.
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