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Old 1st November 2010, 01:28 PM   #1
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Default Question about segmentation crossover

Hi

i wonder if this filter is a 6dB filter or is it a higher order? Its confusing me a little bit
the rectangles in serial are the resistors and the capcacitors in parallel are the segments


Carsten
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File Type: jpg xover.jpg (12.6 KB, 182 views)
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Old 10th March 2011, 09:21 AM   #2
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Can anyone tell me if ic can insert small parallel-caps for a seperate ESL-bass-crossover to simulate the original freuqency-response?
that would be ~800 pF

I am not sure to do this, because i don't know if the small caps can really survive this

would be nice if someone could give me the answer

Carsten
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Old 10th March 2011, 03:13 PM   #3
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Quote:
Originally Posted by Quongelvis View Post
Hi

i wonder if this filter is a 6dB filter or is it a higher order? Its confusing me a little bit
the rectangles in serial are the resistors and the capacitors in parallel are the segments
Hello Quongelvis,

This type of filter is commonly known as a ladder network and is used with segmented line source ESLs.
The filtering is 6dB for each section of the filter.

In your circuit:
- the HT segment would receive no filtering.
- the MT segment would receive 6dB low pass filtering
- the BASS segment would receive 12dB low pass filtering

If you simulate your circuit for an ideal ESL with no mass and an ideal transformer with no losses you will get responses similar to what is shown in Attachment #1.
When simulating with SPICE, SPL is proportional to:
20*LOG[(current in ESL segment capacitor) / sqrt(frequency)]

In practice, the mass of the diaphragm and transformer losses roll off the high frequency response and you would get response more like that shown in Attachment #2
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File Type: jpg 3segment_ideal.jpg (69.9 KB, 113 views)
File Type: jpg 3segment_losses.jpg (67.2 KB, 112 views)
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Old 11th March 2011, 05:21 AM   #4
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thanks for your answer- interesting simulation

can i replace the capacity of the MT +HT panel by small caps in the passive bass-crossoveror is this not a good ides?
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Old 11th March 2011, 07:07 PM   #5
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Quote:
Originally Posted by Quongelvis View Post
thanks for your answer- interesting simulation

can i replace the capacity of the MT +HT panel by small caps in the passive bass-crossoveror is this not a good ides?
You can use capacitors in place of the HT and MT ESL panel capacitance to produce a 12dB crossover for a bass panel. But, the capacitors will need to be rated for very high AC voltage, not just DC. These are difficult to find and usually expensive.


If you want to use a passive crossover for a bass panel, it would be easier to to do it on the primary side of the step-up transformer since you would be able to use crossover parts values normally stocked for dynamic driver crossovers.
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Old 14th March 2011, 09:11 PM   #6
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Hi Bolserst,

Finaly i got an cheap 12 dBactive xover for evaluating bass-filtering. Works fine. I have made to much thoughts because i did not really understand the passive crossover, i always thought that the parallel-capacity of the panels add a 6dB lowpass for each segement...

Carsten
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