| goldyrathore |
I am making a small vented subwoofer but have some questions before I start.
1> I believe I will have to have a high pass filter somewhere around Fb since the
cone gets unloaded below this frequency. What sort of filter should I use and
how do I arrive at the right frequency?
2> I will also need a variable low pass filter. What should be the slope of this filter and what kind should it be?
3> I also need a high slope filter fixed at 200Hz so thet the Sub stays quiet above this and
does not reveal its location. I have read that sonodyne sub uses this approach. As per review it sounds great.
What sort of filter should I use and what should be the slope?
Thanks in advance,
Goldy |
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| roddyama |
| quote: | Originally posted by goldyrathore
I am making a small vented subwoofer but have some questions before I start.
[QUOTE]Originally posted by goldyrathore
[B]1> I believe I will have to have a high pass filter somewhere around Fb since the
cone gets unloaded below this frequency. What sort of filter should I use and
how do I arrive at the right frequency? |
This is a typical sub-sonic filter. It is usually a steep (24db/oct) hi-pass filter with f3 between 15 to 20 Hz. This was very important back in the record warp days and before subs became a common part of the system. Today it is less important, but probably more good than bad.| quote: | Originally posted by goldyrathore
2> I will also need a variable low pass filter. What should be the slope of this filter and what kind should it be? |
I like a 3rd order (18db/oct) lo-pass slope. Your shoud be at least that, if not higher. Particularly if you plan to run the sub higher than 100Hz.| quote: | Originally posted by goldyrathore
3> I also need a high slope filter fixed at 200Hz so thet the Sub stays quiet above this and
does not reveal its location. I have read that sonodyne sub uses this approach. As per review it sounds great.
What sort of filter should I use and what should be the slope?
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I have to read about this one. 2 lo-pass filters you say? |
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| sreten |
| quote: | Originally posted by goldyrathore
I am making a small vented subwoofer but have some questions before I start.
1> I believe I will have to have a high pass filter somewhere around Fb since the
cone gets unloaded below this frequency. What sort of filter should I use and
how do I arrive at the right frequency?
2> I will also need a variable low pass filter. What should be the slope of this filter and what kind should it be?
3> I also need a high slope filter fixed at 200Hz so thet the Sub stays quiet above this and
does not reveal its location. I have read that sonodyne sub uses this approach. As per review it sounds great.
What sort of filter should I use and what should be the slope?
Thanks in advance,
Goldy |
1) sub-sonic filters are only mandatory with an LP source, it
could be worth investigating 6th order vented alignments as
these effectively include a 12/db octave sub-sonic filter.
If you go 6th order, recommend making the Q adjustable.
2) really depends on your main speakers characteristics,
whether mains are high pass filtered or not, and the trade
off between transient response (low order filters) vs. low
overlap (high order filters).
3) Whether this is necessary depends on the choice made in 2.
A 12/dB octave 2nd order Butterworth should be fine if needed.
:) sreten. |
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