Familiar story, open baffle with 8 inch wide range, passing the lows (< 200Hz but yet to be determined) off to a 15 inch prosound driver. Just became bi-amp capable and going to try a 2nd order PLLXO for low pass.
Have found the T-line site helpful:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
but little else available on line or in forums. And I still have some questions:
Is a line level 2nd order (R's and C's, no L's) still going to cause a 180 degree phase change? I probably should know this.
2nd order PLLXO is a cascade of two 1st order while maintaining an impedance ratio (1:10) of the components (more or less with exceptions). What is the result if you reduce this ratio to 1:5 or 1:2?
Does it effect the slope of the xo or does it effect the frequency extremes-i.e., roll off the highs or lows?
Thanks,
Scott
Have found the T-line site helpful:
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
but little else available on line or in forums. And I still have some questions:
Is a line level 2nd order (R's and C's, no L's) still going to cause a 180 degree phase change? I probably should know this.
2nd order PLLXO is a cascade of two 1st order while maintaining an impedance ratio (1:10) of the components (more or less with exceptions). What is the result if you reduce this ratio to 1:5 or 1:2?
Does it effect the slope of the xo or does it effect the frequency extremes-i.e., roll off the highs or lows?
Thanks,
Scott
If you reduce the ratio, the 2nd section loads down the 1st section, so the XO starts shifting around. If you diyed your amps or are willing to go into them, inserting 2 1st order filters will get you more consistency.
The passive filters create the same phase rotation as any analog filter would.
dave
The passive filters create the same phase rotation as any analog filter would.
dave
Hey Scott. Ditto what was said above.
Plus as you change either source impedance or load impedance things will shift a bit. As they get closer to each other the overall attenuation will rise.
Do you know what your source impendance and load impedance are? Or can you give us an idea of what you are using?
Plus as you change either source impedance or load impedance things will shift a bit. As they get closer to each other the overall attenuation will rise.
Do you know what your source impendance and load impedance are? Or can you give us an idea of what you are using?
Thanks for the replies.
Hey Dave, do you mean put one 1st order in front of the amp and another in between stages in the amp? Might be tough to do cause I plan to try a number of xo points till I find what works. And this may be quasi-temporary.
Hmmm...Source is a TVC (S&B Mkiii) and the output impedance does vary; but in the range I listen it will usually be from a few Ohms to 100 Ohms (measured at 1kHz).
The amp for the lows is an integrated sand amp with around 50K input impedance-actually DCR stays at 55k till the volume gets to 75% then it tapers to 40K at full volume. It drives the 15's now with a speaker level 2nd order with this amps volume control at about 12 o'clock. So I've got room for a little insertion loss.
My original thinking is if I could cheat on the 1:10 ratio and increase the impedance it may help prevent loading the TVC too much. But it may not matter that much, I may just try it as recommended and see how it does.
Scott
Hey Dave, do you mean put one 1st order in front of the amp and another in between stages in the amp? Might be tough to do cause I plan to try a number of xo points till I find what works. And this may be quasi-temporary.
Hmmm...Source is a TVC (S&B Mkiii) and the output impedance does vary; but in the range I listen it will usually be from a few Ohms to 100 Ohms (measured at 1kHz).
The amp for the lows is an integrated sand amp with around 50K input impedance-actually DCR stays at 55k till the volume gets to 75% then it tapers to 40K at full volume. It drives the 15's now with a speaker level 2nd order with this amps volume control at about 12 o'clock. So I've got room for a little insertion loss.
My original thinking is if I could cheat on the 1:10 ratio and increase the impedance it may help prevent loading the TVC too much. But it may not matter that much, I may just try it as recommended and see how it does.
Scott
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