Talk:Zobel network

m-derived link
I just noticed that m-derived filters is a redirect to image impedance, and so the short sentence in italics that comes first is not very useful, in case anyone cares. Huw Powell (talk) 21:35, 28 April 2008 (UTC)


 * Yes, I care. It is a temporary link until the article in my userspace User:Spinningspark/m-derived filter is ready.  Sp in ni  ng  Spark  16:55, 1 May 2008 (UTC)

"Note that the circuit will work just as well if the capacitor and resistor are interchanged."

Uhhh.... This is normal for series components. Why does the article say this? —Preceding unsigned comment added by 71.167.66.237 (talk) 20:34, 12 March 2010 (UTC)


 * Because, as the article says, if you interchange them the circuit no longer fits the definition of a Zobel network and is making the point that describing these loudspeaker compensation circuits as Zobel networks, although traditional, is a bit of a misnomer.  Sp in ni ng  Spark  11:57, 2 April 2010 (UTC)

loudspeaker eq figure
In the figure labeled "Zobel network correcting loudspeaker impedance", the formula should read C' = R^2/L. Xref the "Derivation" section, under "input impedance" —Preceding unsigned comment added by 72.37.171.44 (talk) 15:57, 4 May 2011 (UTC)


 * Don't see how that can be right; R2/L is not in units of capacitance just to start off with.  Sp in ni ng  Spark  17:51, 4 May 2011 (UTC)
 * I produced the diagram, but I simply copied the formula from the previous version. The dimensions match $$\dfrac{L}{R^2} = \dfrac{\dfrac{V.t}{I}}{\left(\dfrac{V}{I}\right)^2} = \dfrac{I.t}{V} = C$$ and it agrees with independent sources such as http://www.trueaudio.com/st_zobel.htm (search for Henrys halfway through).  This is upside down compared to the balance condition $$Z'=\frac{Z_0^2}{Z}$$ because of the way capacitance is measured, with higher values passing current more readily than lower ones: it is more like conductance than resistance.  Certes (talk) 18:52, 4 May 2011 (UTC)
 * Just to make that clear, Certes is addressing the IP editor, not me. I agree with the above.  Sp in ni  ng  Spark  20:16, 4 May 2011 (UTC)

Rarely used nowadays?
This is a great article, but the article states that it is rarely used nowadays. May be rare in telecommunications nowadays, but I have seen it many times in modern schematics. Andries (talk) 15:47, 29 November 2015 (UTC)
 * In what context have you seen it? The article does not say it is rare, it says it is rare in traditional filter applications, ie, applications that ideally want a rectangular response.  That has always been the case and I would be flabbergasted if it was not still the case now. SpinningSpark 17:31, 29 November 2015 (UTC)
 * In audio amp if you ever want to build one specially for hifi or high-end, IT IS A MUST. Speakers impedances is so variable that you want to protect your power amp final stage unless you want to replace your output transistors. By the way, I searched for Zobel Network, Boucherot cell, and RC Snubber without finding them in Wikipedia.fr ???????? It's a shame I lost 2 hour on that 2001:18C0:9C4:3300:34ED:2421:9766:1EA3 (talk) 06:09, 18 April 2022 (UTC)
 * You are quite right on that, but this is the Boucherot cell application. Although this is often called a Zobel network, and as the article explains, it can be shown that the Boucherot cell can be derived from the general Zobel network, it is really quite a different application.  Zobel networks were all about equalising telecommunications lines for which a constant-resistance network is wanted.  The design criterion of the Boucherot cell was minimising reactive power.  There is nothing in Zobel's papers about this.  I would tend to treat them as separate beasts.  In any case, speaker impedance compensation is not filtering, so the article is still making a true statement.  Zobel networks are not used now, and never have been, for traditional frequency filtering. SpinningSpark 07:50, 18 April 2022 (UTC)

Draft:Lattice and bridged-T equalizers
We have this new comprehensive draft and I am wondering how much it duplicates existing material. Should we add this new article into the mix or should we try to use this new content to improve existing articles like this one, Bridged T delay equaliser, Electronic filter topology and Lattice network. ~Kvng (talk) 18:14, 19 February 2018 (UTC)


 * Our usual advice is to improve existing articles. However, in this case there is a large amount of new material and not a lot of duplication.  The scope is wider than any existing article, which makes it a new topic to my mind.  The style is a bit textbook/scholarly for an encyclopaedia article, and some thought is needed on integrating it into the encyclopaedia (incoming links) but I see no fundamental reason why it shouldn't be in mainspace. SpinningSpark 20:09, 19 February 2018 (UTC)

Are you sure?
Are these networks all due to Zobel? Some look rather similar to other inventors' efforts. They are all equalisers for sure, but Zobel,s?--213.205.242.154 (talk) 02:43, 20 December 2018 (UTC)

symbol usage
Why does this article use iwC instead of jwC. Electrical engineering has “always” used j as the symbol for the square-root of -1. Even Alexander and Sadiku, “Fundamentals of Electric Circuits”, sixth edition uses j. Really, it is just a question. — Preceding unsigned comment added by Rman2000 (talk • contribs) 19:03, 17 March 2019 (UTC)
 * Actually, more mathematically focused papers on electrical subjects commonly use $$i$$. Your claim that "electrical engineering has always used $$j$$" is  . Zobel certainly didn't in his papers and neither did any of his contemporaries as far as I recall.  Use of $$j$$ is probably much more recent.  In fact, I would go as far as to say that $$j$$ is only used in books aimed at a student audience. SpinningSpark 13:34, 18 March 2019 (UTC)