Low freq. from small drivers? Is it possible

The current trend towards 6" drivers (or smaller) has been going on for quite some time...and i do think it is a good trade in relation to the large 10" drivers and cabinets of yesteryear...the gain in transparency and involvement of small two-ways at the expense of deep bass is a fair trade in my estimation...small speakers are capable of very good bass extension...especially in small rooms...

Karls...Stop pontificating!

Of course LF energy flows through the inductor to the woofer. That's why it doesn't flow through the tweeter, so that the tweeter tweets and doesn't woof.

Suppose that you change the inductor value: make it smaller. The frequency at which its impedance equals that of the tweeter goes down, which means that the tweeter carries energy at lower frequency. Its crossover frequency has been changed. Now, has the woofer been affected? I don't think so, except for possible second order effects. Some current that formerly flowed through the inductor now flows through the tweeter, but a full range signal arrives at the woofer. Same as before. Now the capacitor across the woofer provides the low impedance path for HF and keeps it out of the woofer.

This whole silly discussion is about how to name the inductor. I claim that it should be called the "tweeter" inductor because it determines the tweeter crossover frequency. You like to call it the "woofer" inductor because it carries the spectrum of signal that is routed through the woofer (by the capacitor I might add).

Let's change the subject. Why do you think that a series crossover is superior to a parallel one, assuming that both are properly designed and optimized for the driver characteristics? I know of no reason why one should be better than the other, and I suspect that the recent flurry of series designs may be a marketing ploy.

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