Low freq. from small drivers? Is it possible

Eldartford,

I'm not pontificating at all. It's just that things aren't as cut-and-dried as you would like to assume. The crossover point in a series crossover is a function of both the inductor and capacitor. If you want, you can change them both, and yet still keep the crossover point the same. If you don't believe me, look it up. It's not that hard to find.

In order to carry this conversation further, you are going to have to dedicate some effort to learning the actual math behind the problem, starting with the concept of transfer functions. It is in most college junior-level electrical circuits classes.

The advantages of series crossovers are real, but again require some mathematical background to understand. The two that in my mind are the most beneficial are:

1. It guarantees a constant-voltage transfer function. This is theoretically possible, but by no means guaranteed, by the parallel.

2. It is essentially insensitive to tolerance variations in both the drivers and reactive elements, thus giving a much better chance of good performance in the real world compared to the parallel.

To this can be added the additional benefit, stated in one of my earlier posts, that the series topology forces you to do everything exactly right. While this is also theoretically possible in the parallel, for all practical purposes it NEVER happens in the real world. Almost every speaker you look at with a parallel network has grossly obvious and serious flaws, simply because the designer didn't want to spend the effort necessary to make it perfect. Thus it is a final "test" of the design, ensuring that there is no "fudging" going on and compromising the end result.

What I'm saying is that if a parallel is done exactly right, there is no reason, at least theoretically, it can't be as good as a series. But in the REAL world, it never is.

Karl Schuemann
AudioMachina

Karls, nice of you to condescend to explain to us filter theory! Math is nice, but understanding English is even more important. Semantics do mean something. (tongue in cheek, of course).
Listen to Eldartford's explanation and perhaps you will grasp what he is saying. I thing that he used at least grade 12 English.

inpepinnovations:

That, unfortunately, is not a useful contribution to this discussion. Of course semantics mean something, but when it comes to filter design, math rules, whether you like it or not. If you were to put a hundred filter design experts, none of whom spoke the same language, into a room with a chalkboard, they would still be able to communicate perfectly well on the subject of filter theory. But ask a hundred English majors who know nothing of filter theory to design you a crossover, and see how far you get.

I understand Eldartford's explanation perfectly, but what you haven't figured out is that my way of thinking is a very useful intuitive approach to figuring out any electrical circuit, not just crossovers. As such, it was my hope that Eldartford would grasp it and come to see that series and parallel are two sides of the same coin, to mix a metaphor.
It is not just an issue of semantics; it is an important equivalence rooted in (gasp! horror!) mathematics.

Karl Schuemann
AudioMachina

And to Eldartford:

I was too quick to jump on you in my last post, got my hackles up I suppose. I don't like to think of myself as a pontificator, but I do sometimes get a bit hardheaded when it comes to trying to get people to see what I'm saying. My apologies, and I agree with your assessment that we are only differing in how we name the elements. I think of the series and parallel forms as being equivalent, since the equations are the same, but I must admit that my calling it a "woofer" inductor could raise some eyebrows.

Peace,
Karl

It's more than 40 years since EE101, and although, as an aerospace systems engineer (not an EE) I worked with a lot of fancy circuits since then I never actually designed a crossover network except at home for audio. I went to the only reference that I have handy at home to read up on series networks, Dickason's Cookbook, but I drew a blank. He says that the parallel configuration is "definitely preferable" and therefore does not discuss series further.

I have always been a "contrarian", so if everyone else is using parallel configuration I would probably look at series, as you have done. However, when you take the contrarian path you must be prepared to strike out a lot. But the grand slam HR makes it worth while. Your bases are loaded.

Peace
Ed