Hello everyone -
(this is a duplicate of a post in Introductions I was instructed to make)
I'm going through the calculations of the late Ray Alden's excellent Speaker Building 201 book and I'm scratching my head about some of the formulae.
Specifically, in several sections on page 73 and 74, the numerator for some inductor calculations are shown as Rt, which is also used to describe the nominal resistance of the tweeter, but here the context seems like it should be Rw, for the woofer.
Of course, in cases where the woofer and tweeter are 8 ohm units, the point is moot, but if one is substituting real-world value, this could affect the resulting calculated values.
Am I missing something here?
(this is a duplicate of a post in Introductions I was instructed to make)
I'm going through the calculations of the late Ray Alden's excellent Speaker Building 201 book and I'm scratching my head about some of the formulae.
Specifically, in several sections on page 73 and 74, the numerator for some inductor calculations are shown as Rt, which is also used to describe the nominal resistance of the tweeter, but here the context seems like it should be Rw, for the woofer.
Of course, in cases where the woofer and tweeter are 8 ohm units, the point is moot, but if one is substituting real-world value, this could affect the resulting calculated values.
Am I missing something here?
And if some kind soul could try the last calculation for Lw near the bottom of the right-hand column on page 74 and report their results, I would appreciate it.
It's driving me nuts.
It's driving me nuts.
If you don't show what you are talking about you limit yourself to owners of that book, and the subset that know where they put it since they last used it ;-)
Jan
Jan
Formulae are saying this:
To find passive parts values for a given x/o point, use the appropriate driver rated impedance.
C=1/(2*pi*Fc*Rt); C=capacitor in Farads; Fc=x/o point in Hz; Rt=rated tweeter impedance in Ohms:
Assume tweeter specs:
Rt=6 ohms
Fc=2,500 Hz
pi=3.14
_______________________________
C=1/(2*3.14*2,500*6)=0.0000106517 F=10.6517 uF
Accordingly, you'd need a 10uF capacitor to form a 1st order tweeter high pass filter.
Use eqation for (L) if you wish to calculate first order midwoofer low pass filter.
Then Rw=rated woofer impedance.
A simulator (XSim for instance) can plot the results. It has a provision for esr of passive parts,
further refining it.
To find passive parts values for a given x/o point, use the appropriate driver rated impedance.
C=1/(2*pi*Fc*Rt); C=capacitor in Farads; Fc=x/o point in Hz; Rt=rated tweeter impedance in Ohms:
Assume tweeter specs:
Rt=6 ohms
Fc=2,500 Hz
pi=3.14
_______________________________
C=1/(2*3.14*2,500*6)=0.0000106517 F=10.6517 uF
Accordingly, you'd need a 10uF capacitor to form a 1st order tweeter high pass filter.
Use eqation for (L) if you wish to calculate first order midwoofer low pass filter.
Then Rw=rated woofer impedance.
A simulator (XSim for instance) can plot the results. It has a provision for esr of passive parts,
further refining it.
You can’t. You can’t copyright an idea. Only the expression of an idea. And the formulae concerned with crossovers are not original to this author. They arr prior art.
I don’t.
It is too bad you did not post a copy of those pages. With your description it only adds to the confusion. We don't see what the author gives for the formula for L, we don't see how the filter is composed.
For an R/L low pass filter:
Fc = R / (2*pi*L)
Since you probably have a woofer in series with your L, the R in this case is Rwoofer. The formula then becomes:
L = Rwoofer / (2*pi*Fc)
So I can only state what it should be.
For an R/L low pass filter:
Fc = R / (2*pi*L)
Since you probably have a woofer in series with your L, the R in this case is Rwoofer. The formula then becomes:
L = Rwoofer / (2*pi*Fc)
If I draw a circuit including the equations to calculate the values, and put my name on it, it is my copyright.
You are not allowed to copy that drawing or reproduce it without my consent.
It does not matter where the circuit comes from.
https://www.copyright.gov/what-is-copyright/
Of course, you can make your own drawing and put your name on it and call it your copyright, even if it essentially is the same circuit as mine.
Thrust me, I've been in the publishing business long enough to have been bitten by this more than once.
Jan
Jan, if you publish an equation, all I have to do is change the variable names and I have a different expression of the same idea. No copyright violation.
And there is nothing in this thread about reproducing an entire drawing.
And there is nothing copyright about C=1/(2*pi*Fc*Rt). The equation is about 150 years old.
And there is nothing in this thread about reproducing an entire drawing.
And there is nothing copyright about C=1/(2*pi*Fc*Rt). The equation is about 150 years old.
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You are perfectly right about the originality issue.
But that's not copyright!
If I write a book, and you scan it and put it up as PDF for free download, you violate my copyright. Even if what is in my book is trivial.
If you buy my book, read it and write your own using what you learned from my book, even re-drawing my figures to your own layout, you do not violate my copyright. The operating term here being 'copy'.
Edit: indeed, you cannot copyright C=1/(2*pi*Fc*Rt). For something to be copyrighted, there must be an element of new insight, something non-obvious about it. What the text in the link calls 'a flash of insight' or something like that.
Jan
But that's not copyright!
If I write a book, and you scan it and put it up as PDF for free download, you violate my copyright. Even if what is in my book is trivial.
If you buy my book, read it and write your own using what you learned from my book, even re-drawing my figures to your own layout, you do not violate my copyright. The operating term here being 'copy'.
Edit: indeed, you cannot copyright C=1/(2*pi*Fc*Rt). For something to be copyrighted, there must be an element of new insight, something non-obvious about it. What the text in the link calls 'a flash of insight' or something like that.
Jan
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