P1 and P2 makes the resistors adjustable. They set the frequency for each block/stage. This a fully adjustable crossover and the goal is to set everything to suit your speakers not to go for know responses like Linkwitz-Riley, Butterworth, Bessel etc. The potentiometers can be replaced by resistors if you have found your own response.
Yes, they move the frequency. Q will change if too, the "corner" of the will look different. Butterworth, Linkwitz-Riley and Bessel have a different looking roll-offs. It is the combination of R and C that sets the roll-off for each section. A 4th order have 4 sets of R and C. It can be set in many ways.
The jumpers set the maximum slope. I believe you will only get this if all the trimmers are set to the same value. Different trimmer combinations will yield different slopes. For example, setting P2 at 1/2 the value of P1 with jumpers set for 24 dB/oct will approximate the L-R slopes which is more gentle than 24 dB/oct.
The C values should be the same for all sections for standard crossovers.
However, different values will probably yield different response curves. I've been playing with the idea of using a lower roll off in the crossover range and have it get steeper further away from it.
Thank you. If I read 732 posts, I can't remember all of them. Especially if I come up with a new question after I've read it. I DO attempt to use search, but often there really is no good way to query a question. Thank you for putting-up with my Rookieness. 
That app looks awesome. Again, THANK YOU!
But all of that said, what I'm really looking for is a way to understand what a passive crossover does to a signal. Not an active one. Such as the circuit attached.
That app looks awesome. Again, THANK YOU!But all of that said, what I'm really looking for is a way to understand what a passive crossover does to a signal. Not an active one. Such as the circuit attached.
Last edited:
And cap values for 45 Hz. ?
Hi Dirk: I came up with 15nF/7.5nF (6.8 actually) for a 45 Hz. target x-over.
Could you -if possible- verify whether my values are correct ?
(Or any one else who may be reading this and may know)
Many thanks,
peter
mrpjasz@gmail.com
Hello bullitt5094,
I have chosen 100nF amd 47nF for my 6-24XO-build for subwoofer use.
My target crossover frequency was around 80Hz.
Greets
Dirk
Hi Dirk: I came up with 15nF/7.5nF (6.8 actually) for a 45 Hz. target x-over.
Could you -if possible- verify whether my values are correct ?
(Or any one else who may be reading this and may know)
Many thanks,
peter
mrpjasz@gmail.com
to allhifi #437
I was playing around with Mike Rothachers simulator for a crossover frequency around 45-50Hz (24db-slope).
I would assume you will need caps between 150nF to 220nF.
This was only a short try. I don't know if this would work in real life!!!
So, don't take that pic of the sim below as a recipe!
And I don't know what speakers you want to drive? What the phase response will do....
You can play with the cap values and the resistor values on your own.
CodePen - PASS XO5
And there are also other simulators out there in the web for calculating
Sallen-Key-filters.
Greets
Dirk
I was playing around with Mike Rothachers simulator for a crossover frequency around 45-50Hz (24db-slope).
I would assume you will need caps between 150nF to 220nF.
This was only a short try. I don't know if this would work in real life!!!
So, don't take that pic of the sim below as a recipe!
And I don't know what speakers you want to drive? What the phase response will do....
You can play with the cap values and the resistor values on your own.
CodePen - PASS XO5
And there are also other simulators out there in the web for calculating
Sallen-Key-filters.
Greets
Dirk
Attachments
Ouch .. !
Hi SL: Thanks for that. I wasn;t the one that didthe math but I'll let him know !
Thank you,
Hi SL: Thanks for that. I wasn;t the one that didthe math but I'll let him know !
Thank you,
Oh boy ...
Hi Dirk: Thanks so much for your reply. Looks like some cap values must be changed ! Argghh.
Yes, I believe 45 Hz. is ideal crossing over subwoofer-to-mains (LR/24 db/Oct.)
Withat that said, perhaps it maybe 50/55 Hz but not much higher. To my mind, I wish the main loudspeakers to reproduce all but the last octave in the audio band -it's the number I come up with time/time again. Anything higher and we have the very important sub-harmonics to many music instruments -and voice- being "covered" by the subwoofer and that clearly imposes a 'smearing' of the main's signal.
Thx for your reply,
peter
Hi Dirk: Thanks so much for your reply. Looks like some cap values must be changed ! Argghh.
Yes, I believe 45 Hz. is ideal crossing over subwoofer-to-mains (LR/24 db/Oct.)
Withat that said, perhaps it maybe 50/55 Hz but not much higher. To my mind, I wish the main loudspeakers to reproduce all but the last octave in the audio band -it's the number I come up with time/time again. Anything higher and we have the very important sub-harmonics to many music instruments -and voice- being "covered" by the subwoofer and that clearly imposes a 'smearing' of the main's signal.
Thx for your reply,
peter