Active filter/EQ examples and calculators

FullThrottleRic · 28th November 2006, 04:05 PM

Hi everyone,

I wasn't sure if this should go in Electronics or this forum, but it seems more relevant here

Does anyone know of a website/book where I can get examples of, and calculators for active filters? It's specifically notch and shelving filters I'd like to be able to design but for the life of me can't find any theory or utilities for designing them

I bought 'The Active Filter Cookbook' from Wilmslow audio thinking it would all be in there but it isn't. It basically explains what each type of filter is, how it works and it's intended use but doesn't give any useful info for designing them.
I really want something along the lines of this but for an active version.

Thanks again

ch83575 · 28th November 2006, 04:23 PM

This is probably the best description of the different configurations you can use to acomplish each of the necessary filters for a loudspeaker. There are formulas, but it always takes me a few minutes with pencil and paper to figure out his examples before i can jump right in and make the calculations for my own speaker. All in all it is very comprehensive (much like the rest of Mr. Linkwitz's site) but keep in mind that all of the filters presented could be acomplished in any number of other ways than the way he does it... they dont even need to use op-amps, they all can be done with descrete components as well.

Hope this is what you were looking for... Good luck

Chad

jackinnj · 28th November 2006, 05:03 PM

FilterPro from Texas instruments is "freeware" and quite effective -- they also have free simulation software -- TINA on their site. LTSpice from Linear Technology is free as well.

Davey · 28th November 2006, 08:17 PM

Some of the speaker-design programs will do this.

Try the demo version of LspCAD. It allows you to design active filters of various types. The demo version has limitations but it will still accomplish what you want.

http://www.ijdata.com/LspCAD_demo.html

Notch filtering with active circuits can take a bit of iteration and sometimes verifying with a prototype to make sure you got it right.

Cheers,

Davey.

FullThrottleRic · 28th November 2006, 10:45 PM

Thanks very much!

28th November 2006, 04:05 PM	#1
FullThrottleRic diyAudio Member Join Date: Apr 2001 Location: Leeds, UK	Active filter/EQ examples and calculators Hi everyone, I wasn't sure if this should go in Electronics or this forum, but it seems more relevant here Does anyone know of a website/book where I can get examples of, and calculators for active filters? It's specifically notch and shelving filters I'd like to be able to design but for the life of me can't find any theory or utilities for designing them I bought 'The Active Filter Cookbook' from Wilmslow audio thinking it would all be in there but it isn't. It basically explains what each type of filter is, how it works and it's intended use but doesn't give any useful info for designing them. I really want something along the lines of this but for an active version. Thanks again

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28th November 2006, 04:23 PM	#2
ch83575 diyAudio Member Join Date: Jan 2005 Location: Michigan	This is probably the best description of the different configurations you can use to acomplish each of the necessary filters for a loudspeaker. There are formulas, but it always takes me a few minutes with pencil and paper to figure out his examples before i can jump right in and make the calculations for my own speaker. All in all it is very comprehensive (much like the rest of Mr. Linkwitz's site) but keep in mind that all of the filters presented could be acomplished in any number of other ways than the way he does it... they dont even need to use op-amps, they all can be done with descrete components as well. Hope this is what you were looking for... Good luck Chad

28th November 2006, 05:03 PM	#3
jackinnj diyAudio Member Join Date: Apr 2002 Location: Llanddewi Brefi, NJ	FilterPro from Texas instruments is "freeware" and quite effective -- they also have free simulation software -- TINA on their site. LTSpice from Linear Technology is free as well.

28th November 2006, 08:17 PM	#4
Davey diyAudio Member Join Date: Dec 2001 Location: Bremerton, WA.	Some of the speaker-design programs will do this. Try the demo version of LspCAD. It allows you to design active filters of various types. The demo version has limitations but it will still accomplish what you want. http://www.ijdata.com/LspCAD_demo.html Notch filtering with active circuits can take a bit of iteration and sometimes verifying with a prototype to make sure you got it right. Cheers, Davey.

28th November 2006, 10:45 PM	#5
FullThrottleRic diyAudio Member Join Date: Apr 2001 Location: Leeds, UK	Thanks very much!

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