ALK- What is an eliptical filter?

[Klewless]

Does anyone have a sample circuit showing an eliptical filter?

Did Klipsch ever use it and,if so, what crossover had it?

Are they good??? bad???

Thanks all.

[sfogg]

Look at the Extreme Slope networks on Al's home page. They are elliptic filters.

I think Klipsch used this type of filter on one of their tweeter circuits but Al would have the details on them.

Shawn

[Al Klappenberger]

Klewless,

Shawn is almost right! Elliptic function filters use notch sections to generate a very sharp slope with the minimum possible passband loss. The specific thing that makes them special is that the frequency of the notch sections are chosen such that the "arc" that comes up between each notch has equal height. Elliptics usually have what's called a single infinite zero of transmission and qute a few finite "zeros" of transmission. This is an odd order filter. Even orders have 2 extreme zeros. That's filter jargon and I suppose you might as well ignore it! But, the filters I use in my extreme-slope netwroks have only a single finite "zero" and several extreme zeros. This compromise gives a bit more loss than a full elliptic but keeps the "arc" to below 20 dB. They are actually called "pole placed" but in truth are "zero placed"!

Are they good? Yes, I believe they are. The tweeter filter in the "AK" and "AL" sereis networks broadly quaify as elliptic function filters.

Non-elliptic filters are normally called all-pole filters becasue they have lots of "poles" but no zeros (notches). Their response is also called "monotonic" becasue their attenuation goes straight down. Elliptic attenuation goes up and down but no lower than some specified amount.

Clear as mud, right? If there's any confusion, I'll post plots of the different types.

Al K.

[Klewless]

Thanks

That satisfies my curiosity about them. Had heard the term and wanted to know at least what they were.