Hi!
I was wondering if someone has already built a subsonic filter to prevent excessive cone motion.
Using BassBox 6 at the External tab in the Driver Properties window I could experience with capacitor and inductance values but it looks like I would need 200-1000 microFarad and 20-60 mH (3-8 Ohm DCR) values which are very expensive.
As long as I read on other forums that they sell Behringer 2×3 way active crossovers for $200 I'm not shure the passive is the right choice.
Daniel
I was wondering if someone has already built a subsonic filter to prevent excessive cone motion.
Using BassBox 6 at the External tab in the Driver Properties window I could experience with capacitor and inductance values but it looks like I would need 200-1000 microFarad and 20-60 mH (3-8 Ohm DCR) values which are very expensive.
As long as I read on other forums that they sell Behringer 2×3 way active crossovers for $200 I'm not shure the passive is the right choice.
Daniel
You would not want to make a passive subsonic filter for the reasons you have already pointed out. The components required would be too large and expensive.
I have always used a steep active subsonic filter.
I have always used a steep active subsonic filter.
Not to mention that it's much easier to build a steeper active filter and you do not suffer from wavering frequency response nor lack of damping at the cutoff frequency.
You can even build a nice neat active subsonic filter complete for under $50 all in, and that's being generous.
You can even build a nice neat active subsonic filter complete for under $50 all in, and that's being generous.
For the coil, you could use a big iron core, or wiring your inductor on a big transformer core.
The DCR will be near 0.
As others said, probably better to go active hehe!
The DCR will be near 0.
As others said, probably better to go active hehe!
Thanks for the reply's.
In Thiele's calssic paper he writes about the passive filter assisted bassreflex alignments. If a passive low frequency high pass filter is so expensive then these aligments: B5, B6, C6 are not good choices I can conclude.
Daniel
In Thiele's calssic paper he writes about the passive filter assisted bassreflex alignments. If a passive low frequency high pass filter is so expensive then these aligments: B5, B6, C6 are not good choices I can conclude.
Daniel
I see no reason why one shouldn't attempt a passive subsonic filter !
Just don't put it at the amp's output !!!!!
Regards
Charles
Just don't put it at the amp's output !!!!!
Regards
Charles
Thiele's paper was written in the 60's before op-amps were readily available. Electro-Voice and others came out with electronic "bass boost" circuits (~B6 alignments) in the 70's. Some of these circuits may be interesting for you.
re passive filters
If you are making your own power amplifier you can get a second order high pass filter by choosing the value of the input coupling capacitor, and the capacitor that shunts the feedback leg to ground. This has a fixed Qt=.5, and is suitable as a part of the SC6,C6, QB5 class III alignments.
If only a single capacitor can be used then this can be part of a B5 alignment, in practice a back to back pair of electrolytics that has a nominal total capacity of around twice the one called for in theory will give a result that only varies by a few db. from the ideal if put in series with the driver, this can also be used as a second order filter if you choose an input coupling capacitor that is equal to the theoretical value.
If you are making your own power amplifier you can get a second order high pass filter by choosing the value of the input coupling capacitor, and the capacitor that shunts the feedback leg to ground. This has a fixed Qt=.5, and is suitable as a part of the SC6,C6, QB5 class III alignments.
If only a single capacitor can be used then this can be part of a B5 alignment, in practice a back to back pair of electrolytics that has a nominal total capacity of around twice the one called for in theory will give a result that only varies by a few db. from the ideal if put in series with the driver, this can also be used as a second order filter if you choose an input coupling capacitor that is equal to the theoretical value.
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