High Pass Filter for Subwoofer - Help Needed

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gp_freak

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Dear Members, There are actions put in place to build a subwoofer and since the plan is to tune it low, the subwoofer reaches it x max limits below 20 Hz in an astronomical manner. To save the sub, i would like put a high pass filter in Signal side to filter out the low frequency signals that might hurt the sub.

Please take a look at the Cone Excursion graph of the Subwoofer with a 4h Order butterworh high pass filter around 19 Hz . So question is, how should i tackle this ?

1. Put the filter before implication ( saves unnecessary amplification of these low signals, but sub needs to be dependent on this filter+ amp Combo.
2. Put the filter inside the sub ( Amplifier will work in amplifying these Signals too , but always with sub and help with matching to any amplifier )

In addition, i don have any Electrical or Electronic knowledge at all. So how to build a High pass filter tuned to a specific frequency. I searched online for boards, but most of the bass boards are low pass filter with Gain adjustments.

The amplifier may be a Class D based on INIC audio and their SMPS.
High pass filter.JPG
 

Otpidus

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What you need is known as "Sub sonic filter". Regarding circuit and exact component values, there are many types of implementations available for you on the Internet.
 

gp_freak

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What you need is known as "Sub sonic filter". Regarding circuit and exact component values, there are many types of implementations available for you on the Internet.
I know its a subsonic filter it is on the internet. What is not available on the internet ? :) No offence meant, but I am looking for Definite answers ! Like pre built boards or looking to have some schematics or advise from this forum. I am pretty sure some one here should have either built it or used it.
 

Otpidus

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Okay. Are you looking for an Active Filter or Passive?

Passive would be difficult (to procure parts during this time) because you would need about 60mH high current Inductor (with DC resistance of about 6 to 8 ohms) and it would cost a lot more (because this would be almost like winding a transformer) than an OpAmp based Active filter.

If you go for Active line level filter then it's quite straightforward. As I said in the previous post, here is one simple negative feedback design on the Internet using 741 OpAmp - Subsonic Blocker.

Hope this helps you get started.
 

gp_freak

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@Otpidus , Thank you. I have now decided to get help from Local PCB makers for audio to make me a board in dot Pcb. The other option i am thinking about is using mini DSP. How ever i will put that as a separate thread.
 
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