Shelving pass filter-Active

Raka · 28th September 2004, 10:40 AM

I have one question about this filter, as explained in the Linkwitz site
www.linkwitzlab.com/images/graphics/shlv-lpf.gif

but I don't know which is the ratio between f1 and the gain G1. It can't be the standard 3dB, because the gain is user defined and can be whatever value you need.
If I want to compensate the BS, then a gain of 6dB is required, so f2 would be two times f1 (non inverting configuration), how can then compensate for a baffle step starting at 250Hz until the 20Hz?, do I need to cascade two stages?

BobEllis · 28th September 2004, 10:55 AM

Look here: http://www.t-linespeakers.org/tech/b...stepcompo.html

It is the same math, just more thoroghly explained. SL seems to assume that his readers are more advanced than I am. The t-line page also starts from the midpoint of the step, I used that formula and got the repsonse that I expected.

Davey · 29th September 2004, 01:53 AM

Raka,

In theory baffle step correction should have a maximum adjustment of 6db....based on the 4pi to 2pi radiation change. Some systems may not require as much, but none should require more. (If you're referring to baffle-step correction exclusively.) A correction for a typical baffle width might be centered around 150Hz and the EQ would range from 100 to 200 with a 6db boost.

A 250Hz to 20Hz correction is 22db, and MUCH more than a simple baffle-step correction. This sounds like a compensation that might be used for a dipole roll-off or similar.

Cheers,

Davey.

28th September 2004, 10:40 AM	#1
Raka diyAudio Member Join Date: Aug 2002 Location: Close to Oistrakh	Shelving pass filter-Active I have one question about this filter, as explained in the Linkwitz site www.linkwitzlab.com/images/graphics/shlv-lpf.gif but I don't know which is the ratio between f1 and the gain G1. It can't be the standard 3dB, because the gain is user defined and can be whatever value you need. If I want to compensate the BS, then a gain of 6dB is required, so f2 would be two times f1 (non inverting configuration), how can then compensate for a baffle step starting at 250Hz until the 20Hz?, do I need to cascade two stages? __________________ What is beyond the speaker?

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28th September 2004, 10:55 AM	#2
BobEllis diyAudio Member Join Date: Sep 2003 Location: Upstate NY	Look here: http://www.t-linespeakers.org/tech/b...stepcompo.html It is the same math, just more thoroghly explained. SL seems to assume that his readers are more advanced than I am. The t-line page also starts from the midpoint of the step, I used that formula and got the repsonse that I expected.

29th September 2004, 01:53 AM	#3
Davey diyAudio Member Join Date: Dec 2001 Location: Bremerton, WA.	Raka, In theory baffle step correction should have a maximum adjustment of 6db....based on the 4pi to 2pi radiation change. Some systems may not require as much, but none should require more. (If you're referring to baffle-step correction exclusively.) A correction for a typical baffle width might be centered around 150Hz and the EQ would range from 100 to 200 with a 6db boost. A 250Hz to 20Hz correction is 22db, and MUCH more than a simple baffle-step correction. This sounds like a compensation that might be used for a dipole roll-off or similar. Cheers, Davey.