16hz HPF - Home Theater Forum and Systems - HomeTheaterShack.com

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post #1 of 23 Old 10-30-13, 07:36 AM Thread Starter
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16hz HPF

Hello people.

I have finally got my sub, amp and power supply but I have an issue that I need to limit my sub for anything less than 16hz because the drivers are going beyond excursion

Any idea how I would start to make one or better yet one I can buy off the shelf, ideally an adjustable HPF?

Thanks

Craig
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post #2 of 23 Old 10-30-13, 08:07 AM
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Re: 16hz HPF

An unbalanced miniDSP or a Reckhorn B-2 would do the trick. The miniDSP would have many more options, but is a bit more expensive. I have both and would get the miniDSP 10:1 if you like to tinker.
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post #3 of 23 Old 10-30-13, 08:46 AM
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What's the input impedance on the amplifier? (And is the amp just for the sub?)

Could easily put a capacitor on the input.
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post #4 of 23 Old 10-30-13, 10:01 AM
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Re: 16hz HPF

Quote:
Paulcet wrote: View Post
What's the input impedance on the amplifier? (And is the amp just for the sub?)

Could easily put a capacitor on the input.
+1. I have done this before with accurate results.

If a 1st-order filter is all you need, this is by far the simplest and cheapest solution.


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post #5 of 23 Old 10-30-13, 10:51 AM
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Quote:
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+1. I have done this before with accurate results.

If a 1st-order filter is all you need, this is by far the simplest and cheapest solution.
This is interesting. I'm also looking for getting a minidsp, but this could be a short term solution. looking forward for more details
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post #6 of 23 Old 10-30-13, 12:17 PM
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Re: 16hz HPF

Using the formula for HPF and a spreadsheet you get the following results for a 16 Hz cutoff and assuming your amp's input impedance is 47 kΩ or greater, then the combined impedance of R1 and R_amp (R2) is 8.25kΩ
Then using the info from here: http://www.t-linespeakers.org/tech/f...ssiveHLxo.html you get R1 as 10 kΩ and C1 as 1.2 micro Farad

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DIY completed:

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post #7 of 23 Old 10-30-13, 06:43 PM Thread Starter
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Re: 16hz HPF

Thanks guys, I am not mega clued up on the elctronic side of things so I am unsure of input impedance, is there an easy way to find out?

The amp is dedicated only to the subwoofer.

As above if a 1.2Micro farad will do, how would I connect it, across the lines or in series?

Thanks for the help

Craig
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post #8 of 23 Old 10-31-13, 01:21 PM
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Re: 16hz HPF

Most modern amps will have an input impedance of at least 47 kΩ so you can ignore it.

The setup would be: Sub Output from receiver goes into the capacitor with the resistor after it connected to earth. (As per the picture, the sub out is on the left and the power amp input is on the right.)

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post #9 of 23 Old 11-01-13, 07:36 AM Thread Starter
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Re: 16hz HPF

Please excuse the very poor MSpaint drawing, is this how I would physically connect it up?



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post #10 of 23 Old 11-01-13, 08:17 AM
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Re: 16hz HPF

Yes, if you go with a single component filter. Which is what I would do probably. And Fusseli too. You would need a .211 uF capacitor. (Someone please check my math and correct me if I'm wrong!)
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