Help with parallel notch filter

matevana · 21st June 2011, 03:14 PM

Getting some conflicting information from various online calculators. I have a simple peak I'm looking to tame at 630 Hz. It is 6dB strong, and about 3dB strong on either side at 500Hz and 800Hz respectively. Beyond that it is basically flat.

I'd love to come up with some consistant inductor, capacitor and resistor values as a starting point. Can anyone help?

Thanks

Jay · 21st June 2011, 03:26 PM

May be it is conflicting because it is not sure which one is parallel and which one is series?

Are you talking about the notch filter which is in parallel with the driver?

matevana · 21st June 2011, 03:31 PM

Quote:

Originally Posted by Jay

May be it is conflicting because it is not sure which one is parallel and which one is series?

Are you talking about the notch filter which is in parallel with the driver?

I believe it is called a parallel notch because the three components are connected in parallel. It is however in series with the driver. I think a series notch filter is typically used to tame a resonance around the drivers Fs point. The parallel notch can be designed to tame any peak in a drivers operating range.

Jay · 04:24 PM

Quote:

Originally Posted by matevana

I believe it is called a parallel notch because the three components are connected in parallel.

Okay, I understand. I have checked the internet, indeed one site has erroneous calculator. This one attached is okay (but it is theoretical). In practice it is a bit different

matevana · 21st June 2011, 05:50 PM

Thank you! I did see that calculator but was concerned that the formula may have been off. Is there a preference as to whether the notch filter go between the driver and crossover, or crossover and amp?

John Bsuch · 21st June 2011, 08:22 PM

http://www.mh-audio.nl/spk_calc.asp#newqts

Jay · 23rd June 2011, 01:28 AM

Quote:

Originally Posted by matevana

Is there a preference as to whether the notch filter go between the driver and crossover, or crossover and amp?

It depends on the real crossover: what drivers are affected at 630Hz? If this peak is on total response, and there are more than one driver producing this frequency signal, then you have to put between amp and xover if you expect a theoretical (symmetrical) notch.

In a 3-way, at 630Hz usually 2 drivers are in effect so you cannot put the filter on the woofer or midrange alone.

AllenB · 23rd June 2011, 02:16 AM

matevana, you cannot put the filter between the amp and crossover for your needs. The filter requires source impedance to work (something in series before it). Putting a notch filter before the crossover has another purpose and is useful for modifying the impedance to make the speaker easier for the amp to drive, but this is often not done.

matevana · 23rd June 2011, 01:26 PM

This is a simple 2 way design crossed at 2k Hz. Since the peak occurs at 630 Hz, I am assuming its all coming from the woofer rather than the system. I gather then the notch filter should go between the crossover and the woofer?

AllenB · 23rd June 2011, 01:47 PM

That should work.

I am wondering where this would be coming from. Have you investigated the possibility of floor bounce?

21st June 2011, 03:14 PM	#1
matevana diyAudio Member Join Date: Feb 2010	Help with parallel notch filter Getting some conflicting information from various online calculators. I have a simple peak I'm looking to tame at 630 Hz. It is 6dB strong, and about 3dB strong on either side at 500Hz and 800Hz respectively. Beyond that it is basically flat. I'd love to come up with some consistant inductor, capacitor and resistor values as a starting point. Can anyone help? Thanks

21st June 2011, 08:22 PM	#6
John Bsuch diyAudio Member Join Date: Oct 2007	Another great source http://www.mh-audio.nl/spk_calc.asp#newqts

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21st June 2011, 03:26 PM	#2
Jay diyAudio Member Join Date: Feb 2003 Location: Jakarta	May be it is conflicting because it is not sure which one is parallel and which one is series? Are you talking about the notch filter which is in parallel with the driver?

21st June 2011, 05:50 PM	#5
matevana diyAudio Member Join Date: Feb 2010	Thank you! I did see that calculator but was concerned that the formula may have been off. Is there a preference as to whether the notch filter go between the driver and crossover, or crossover and amp?

23rd June 2011, 02:16 AM	#8
AllenB diyAudio Member Join Date: Oct 2008	matevana, you cannot put the filter between the amp and crossover for your needs. The filter requires source impedance to work (something in series before it). Putting a notch filter before the crossover has another purpose and is useful for modifying the impedance to make the speaker easier for the amp to drive, but this is often not done.

23rd June 2011, 01:26 PM	#9
matevana diyAudio Member Join Date: Feb 2010	This is a simple 2 way design crossed at 2k Hz. Since the peak occurs at 630 Hz, I am assuming its all coming from the woofer rather than the system. I gather then the notch filter should go between the crossover and the woofer?

23rd June 2011, 01:47 PM	#10
AllenB diyAudio Member Join Date: Oct 2008	That should work. I am wondering where this would be coming from. Have you investigated the possibility of floor bounce?

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