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Old 8th October 2012, 11:11 PM   #11
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OK so it is 400hz and 1 khz and a 4db peak
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Old 9th October 2012, 09:22 AM   #12
tvrgeek is offline tvrgeek  United States
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You need to measure the center of the peak and the -3dB points to either side of it. It is helpful to know the impedance in that region too.

Per chance, are you sure this is not an artifact of misaligned BSC and crossover? We need a lot more data to help.
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Old 9th October 2012, 12:10 PM   #13
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Quote:
Originally Posted by tvrgeek View Post
You need to measure the center of the peak and the -3dB points to either side of it. It is helpful to know the impedance in that region too.

Per chance, are you sure this is not an artifact of misaligned BSC and crossover? We need a lot more data to help.

OK I will get the -3db pts. As far as impeadance you don't mean the "published" driver impeadance at that frequency do you?

True, I am not sure if this is an artifact of BSC/crossover. i do not have any BSC.
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Old 9th October 2012, 01:21 PM   #14
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Hmm, I was looking at 2 software tools Edge and PCD. Edge looks like it is easier to use.
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Old 9th October 2012, 04:26 PM   #15
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Edge is very simple and easy to use, PCD has a different usage. If you have good frequency and impedance measurements you can use PCD to figure your notch filter. Knowing the cause of the peaks is important, there may be a better way to fix it than the notch filter.
As Jay points out, 1150Hz is going to be tough. You'll hear every little thing you do there, so you might want to make the notch broader and shallower than the FR indicates.

Listen, try, listen.
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Old 9th October 2012, 04:30 PM   #16
tvrgeek is offline tvrgeek  United States
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Edge is very helpful. Great place to start, but the real world is never quite what you model. Build and measure. Think. Build and measure again. Look at the simulations and see if they can explain what you measure. They are a tool, not an answer.

Ignore the published nominal impedance. You should measure it in the range where the filter will be working. If you use a Zobel, that should be in place.

The reason I bring up BSC, is depending on baffle size, the 1K region is not atypical to be getting a big edge induced boost. Lowering the first pole may do a better job than adding a notch. Sometimes you can just increase the size of the first inductor in the crossover for the same basic effect.
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Old 9th October 2012, 04:32 PM   #17
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Agreed. Open baffle low pass means big inductors. It really works.
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Old 9th October 2012, 04:56 PM   #18
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Wow. Ok I have lots I want to communicate but in writing it is a bit much. Let me start with this. Someone on the PE forum offered to Sim my XO. The LP (on dayton rs270) is a 4th order. I questioned the 10mh L1. He said it was needed even though calculated values showed it to be 4.7mh. I changed it to 4.7 and the speaker sounds much better but, with the bump. Now i guess that is why it was such a large inductor. For those that are interested in the background info on the speaker and how it came about with all the gory details a link is provided. i hope this gives perspective.

Lambda Speaker Thread
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Old 9th October 2012, 07:11 PM   #19
Pano is offline Pano  United States
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Most people don't understand Open Baffle crossovers. (I say this having heard a lot of bad ones). Not surprising as OB and box are not the same. Most of what you read and learn about crossovers is for box speakers.
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Old 9th October 2012, 08:27 PM   #20
tvrgeek is offline tvrgeek  United States
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Linkawitz does a pretty good discussion of them.
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