software for designing passive notch filters

Puggie · 24th June 2005, 12:17 PM

is there any good freeware out there for designing simple notch filters, I need someting at about 3.2kHz with a Q of about 4, and would like a nice bit of software that shows me what component values I need.

what are the pros and cons of series and parallel filters for this?

f4ier · 25th June 2005, 01:48 AM

I think, from memory, Jeff's PCDC spreadsheet calculates prototyping values for these things. You can find it at the FRD Group page.

Pros, well, they do what they're supposed to do. You just have to be mindful of the component values, at which frequency band it'll be operating and amplifier safety. You wouldn't want to use a series RLC circuit in parallel with the system if the addition of the circuit means dropping the impedance low enough to give your amplifier a hard time. Parallel RLC circuits in series can also lessen speaker damping. So try these circuits out and see if the pros/cons make a significant difference.

MarkMcK · 28th June 2005, 03:32 PM

The free application Speaker Workshop (http://www.audua.com/) includes a simple notch filter calculator. Once you have the center frequency you can use the measurement features of the application to optimize the resistor value for Q.

Just one small point. If you are trying to equalize frequency response (and not just imped), then unless your source imped is high, a series network in parallel will not impact driver response.

Best,

Mark

24th June 2005, 12:17 PM	#1
Puggie diyAudio Member Join Date: Oct 2004	software for designing passive notch filters is there any good freeware out there for designing simple notch filters, I need someting at about 3.2kHz with a Q of about 4, and would like a nice bit of software that shows me what component values I need. what are the pros and cons of series and parallel filters for this?

25th June 2005, 01:48 AM	#2
f4ier diyAudio Member Join Date: Sep 2001 Location: Sydney	I think, from memory, Jeff's PCDC spreadsheet calculates prototyping values for these things. You can find it at the FRD Group page. Pros, well, they do what they're supposed to do. You just have to be mindful of the component values, at which frequency band it'll be operating and amplifier safety. You wouldn't want to use a series RLC circuit in parallel with the system if the addition of the circuit means dropping the impedance low enough to give your amplifier a hard time. Parallel RLC circuits in series can also lessen speaker damping. So try these circuits out and see if the pros/cons make a significant difference. __________________ Crossover/Subwoofer Simulator

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28th June 2005, 03:32 PM	#3
MarkMcK diyAudio Member Join Date: Aug 2003 Location: Ohio	The free application Speaker Workshop (http://www.audua.com/) includes a simple notch filter calculator. Once you have the center frequency you can use the measurement features of the application to optimize the resistor value for Q. Just one small point. If you are trying to equalize frequency response (and not just imped), then unless your source imped is high, a series network in parallel will not impact driver response. Best, Mark

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