Need help with 2nd Order LPF!

kinser · 3rd July 2006, 02:45 PM

Hey all,

After building this http://www.lcaudio.com/index.php?page=27 subwoofer filter using it in 2nd order, it was not running well at, and i found out that i used a 50k Dual Pot insted of a 100k, i cant source a 100k dual pot here so the 50k is all i can use.
What i need is to calculate the resistor and cap values for a cut off freq' of Minimum 60Hz to a Maximum 300Hz or maby even 200Hz or 160Hz, whichever you see as best.

Thanks Alot!

David Resnik

F1 FAN · 3rd July 2006, 05:43 PM

hi kinser, that looks like a nice versatile sub crossover design.

If you can't get the right value pots then I believe if you double the value of the .047 and .022 caps and change the four 22k resistors to 11k(10k would due) that should get the results you want.

kinser · 3rd July 2006, 05:48 PM

F1 FAN,

Thanks, i asked another user which i speak to often (sss_thug)
he told me the exact same thing, and thats what i did, now i need to find out why the phase pot is not doing anything, and why there is not much gain (probbly due to the problem with the phase).

Thanks!

David Resnik

F1 FAN · 3rd July 2006, 06:29 PM

Does the gain still seem low with the gain x10 switch engaged?

Are you certain that the phase control is not working?
Because differences in the phase setting will show up more dramatically if you try adjusting it while playing some bass test tones. With music the changes may not be apparent.

kinser · 4th July 2006, 01:57 PM

i dont use the 10x gain, it sounded real bad (wene i first built it a year ago).
There was just bass playing wene i was testing the phase, but no change what so ever. i know what it sould sound like. but it was the same whether it was on 0 or 180 degres.
the boost works well, wene u pull it up to 150Hz the amount of bass reduces, the Q also works, but its a little hard to hear a change in soud sometimes. just the damn phase POT that dosnt work!!

anyways, thanks!

David Resnik

3rd July 2006, 02:45 PM	#1
kinser diyAudio Member Join Date: Jan 2004 Location: R'aanana	Need help with 2nd Order LPF! Hey all, After building this http://www.lcaudio.com/index.php?page=27 subwoofer filter using it in 2nd order, it was not running well at, and i found out that i used a 50k Dual Pot insted of a 100k, i cant source a 100k dual pot here so the 50k is all i can use. What i need is to calculate the resistor and cap values for a cut off freq' of Minimum 60Hz to a Maximum 300Hz or maby even 200Hz or 160Hz, whichever you see as best. Thanks Alot! David Resnik

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3rd July 2006, 05:43 PM	#2
F1 FAN diyAudio Member Join Date: Jun 2006	hi kinser, that looks like a nice versatile sub crossover design. If you can't get the right value pots then I believe if you double the value of the .047 and .022 caps and change the four 22k resistors to 11k(10k would due) that should get the results you want.

3rd July 2006, 05:48 PM	#3
kinser diyAudio Member Join Date: Jan 2004 Location: R'aanana	F1 FAN, Thanks, i asked another user which i speak to often (sss_thug) he told me the exact same thing, and thats what i did, now i need to find out why the phase pot is not doing anything, and why there is not much gain (probbly due to the problem with the phase). Thanks! David Resnik

3rd July 2006, 06:29 PM	#4
F1 FAN diyAudio Member Join Date: Jun 2006	Does the gain still seem low with the gain x10 switch engaged? Are you certain that the phase control is not working? Because differences in the phase setting will show up more dramatically if you try adjusting it while playing some bass test tones. With music the changes may not be apparent.

4th July 2006, 01:57 PM	#5
kinser diyAudio Member Join Date: Jan 2004 Location: R'aanana	i dont use the 10x gain, it sounded real bad (wene i first built it a year ago). There was just bass playing wene i was testing the phase, but no change what so ever. i know what it sould sound like. but it was the same whether it was on 0 or 180 degres. the boost works well, wene u pull it up to 150Hz the amount of bass reduces, the Q also works, but its a little hard to hear a change in soud sometimes. just the damn phase POT that dosnt work!! anyways, thanks! David Resnik

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