Hi,
I please need your advice about the polarity for a 3 ways passive filter.
Tweeter : 24db slope electrical
medium : High pass : 12 db slope electrical - Low pass : 12 db slope electrical
woofer : 12 db slope electrical
Which driver should have its polarity reversed ?
I please need your advice about the polarity for a 3 ways passive filter.
Tweeter : 24db slope electrical
medium : High pass : 12 db slope electrical - Low pass : 12 db slope electrical
woofer : 12 db slope electrical
Which driver should have its polarity reversed ?
It's impossible to tell from that data, because what matters is the acoustical slopes, not the electricals.
This is true. However if we ignore that part...
Reverse the mid and tweeter. This is the same as reversing only the woofer (some prefer to leave a woofer at + by default).
Reverse the mid and tweeter. This is the same as reversing only the woofer (some prefer to leave a woofer at + by default).
Many thanks.
Ok I have no idea, I just believed with two 12 db slope, one had to be reversed for the 180° phase at the output of the filter, but not sure on how it translates indeed on the whole (electrical + acoustical of the driver on a plane front baffle)
Not easy to measure the loudspeaker in a room below the Schroeder frequency... rahhhhh !
(you changed your avatar?)
Ok I have no idea, I just believed with two 12 db slope, one had to be reversed for the 180° phase at the output of the filter, but not sure on how it translates indeed on the whole (electrical + acoustical of the driver on a plane front baffle)
Not easy to measure the loudspeaker in a room below the Schroeder frequency... rahhhhh !
(you changed your avatar?)
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Thank you Allen : I will try it and I assume my ears tell me what is the best solution. I mean without the possibility of an acurate measurment and good true simulation.
So I reverse both the mid AND tweet to try, ok ! 🙂
So I reverse both the mid AND tweet to try, ok ! 🙂
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Yes this has been a guess, more a guestimate.
Why don't you measure each lower cross driver nearfield. Their relative levels and crossing points. Then pull the mic back just a little to get both. This is just to see whether phase is better or worse.
Why don't you measure each lower cross driver nearfield. Their relative levels and crossing points. Then pull the mic back just a little to get both. This is just to see whether phase is better or worse.
Is it really possible to measure a bass cabinet inside ?
Mic on the floor near the driver or port ?
For the tweeter and mid, nearfield is meaning mic at few inches then back 50 inches (more or less 1 meter) ?
Mic on the floor near the driver or port ?
For the tweeter and mid, nearfield is meaning mic at few inches then back 50 inches (more or less 1 meter) ?
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That is a good idea. With the speaker on its side in the middle of the floor and the mic nearby on the floor, you will get less room effects included while checking the polarity of your lower cross. It isn't exact, but it should do what you want.
I don't believe this will work. Normally, the mid would be inverted to match the woofer and tweeter, with all being 2nd order filters.
In this case, the mid will still want to be inverted to match the woofer but can't match the tweeter because the 4th order filter on it will want to rotate the phase 360 at the xo frequency you've picked. That'll put the tweeter 90 degrees out from the mid, inverted or not inverted. This will create a null in either the top end of the mids passband or the lower end of the tweeters passband depending on INV or NON-INV tweeter circuit.
I peaked at a crossover app to verify.
In this case, the mid will still want to be inverted to match the woofer but can't match the tweeter because the 4th order filter on it will want to rotate the phase 360 at the xo frequency you've picked. That'll put the tweeter 90 degrees out from the mid, inverted or not inverted. This will create a null in either the top end of the mids passband or the lower end of the tweeters passband depending on INV or NON-INV tweeter circuit.
I peaked at a crossover app to verify.
Thanks for that,
I just have been modeling it in XSim with the filters value with the impedance of the driver at cut-offs but with ideal 8 ohms flat drivers of XSims.
The reversed mid is what is working the best on the superior windows (power response curve + acoustical phase I assume).
If I invert the tweeter only, there is a null in the bass area.
Both tweeter and mid inverted gives a null in the treble area at cut-off
Only the inverted mid is giving a flat power response between the audio band... and the phase roll off is cleaner
Well this without the true measurement of the acoustical power response of the drivers, but their impedance at cut-off in my sim are corect.
Let see tomorrow what it gives in the real world 🙂. If the non inverted tweeter is giving a null in its low end it could be eventually seen as a notch to protect it if the mid is overlapping the null ?!
I just have been modeling it in XSim with the filters value with the impedance of the driver at cut-offs but with ideal 8 ohms flat drivers of XSims.
The reversed mid is what is working the best on the superior windows (power response curve + acoustical phase I assume).
If I invert the tweeter only, there is a null in the bass area.
Both tweeter and mid inverted gives a null in the treble area at cut-off
Only the inverted mid is giving a flat power response between the audio band... and the phase roll off is cleaner
Well this without the true measurement of the acoustical power response of the drivers, but their impedance at cut-off in my sim are corect.
Let see tomorrow what it gives in the real world 🙂. If the non inverted tweeter is giving a null in its low end it could be eventually seen as a notch to protect it if the mid is overlapping the null ?!
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I'm pretty sure that as you start to overlap (mid/tweeter) the response null will become shallower but a new peak will be produced on the other side of the xo point. So, cancellation then addition in the acoustic response.
Might make more sense to apply a 4th order low-pass filter to the mid. You'd be looking to INV polarity on the woofer in that case. (woofer to mid, 2nd order ... mid to tweeter, 4th order)
Might make more sense to apply a 4th order low-pass filter to the mid. You'd be looking to INV polarity on the woofer in that case. (woofer to mid, 2nd order ... mid to tweeter, 4th order)
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Hi,
Thanks.
One thing is sure, in all positive polarity, something is strange, aka a null- at the end of the mid and tweeter for my ears... Give me 1 hour before I invert first the mid and I come back soon...
Not sure i want to make a low pass at 24 dB for many reasons - cost + the bass is a band-pass and may need a second order electrical overlap - 125 hz Bessel-
Thanks.
One thing is sure, in all positive polarity, something is strange, aka a null- at the end of the mid and tweeter for my ears... Give me 1 hour before I invert first the mid and I come back soon...
Not sure i want to make a low pass at 24 dB for many reasons - cost + the bass is a band-pass and may need a second order electrical overlap - 125 hz Bessel-
It's all a guess, because what is important is the acoustical slope and not the electrical order (as been said in post #2). However:
As an example, if the 3-way is a 8" bass 4" mid and 1" high, with 500Hz and 4KHz crossover points, then the crossover point between bass and mid is in a range where both drivers have pretty constant FR and impedance, and thus a 2nd order electrical order crossover for both LP and HP translates easily into 2nd order acoustic slopes. So you need to reverse the mid against the bass. However at 4KHz the mid is already starting to roll-off, so a carefully designed 2nd order filter gives a 4th order acoustic LP slope, whereas the tweeter needs a 3rd or 4th order filter for the same 4th order acoustic HP slope. In this case the mid and tweeter should have the same polarity, bot reversed against the bass.
In all my designs I had success in obtaining LR4 slopes between mid and tweeter with a 2nd order electrical filter on the mid and 3rd order one on the tweeter.
Ralf
As an example, if the 3-way is a 8" bass 4" mid and 1" high, with 500Hz and 4KHz crossover points, then the crossover point between bass and mid is in a range where both drivers have pretty constant FR and impedance, and thus a 2nd order electrical order crossover for both LP and HP translates easily into 2nd order acoustic slopes. So you need to reverse the mid against the bass. However at 4KHz the mid is already starting to roll-off, so a carefully designed 2nd order filter gives a 4th order acoustic LP slope, whereas the tweeter needs a 3rd or 4th order filter for the same 4th order acoustic HP slope. In this case the mid and tweeter should have the same polarity, bot reversed against the bass.
In all my designs I had success in obtaining LR4 slopes between mid and tweeter with a 2nd order electrical filter on the mid and 3rd order one on the tweeter.
Ralf
Thanks Ralf,
The tweeter seems to be 2850 Hz 24 dB...
Yep, noticed the post #2 , will go further when I finish my Arta box -do you believe it, I'm waiting for two month a resistor purchased at Banzai Music Germany, serious guys but they hadn't not the resistor anymore after receiving the PP- to measure all the coils and driver I only simulated for now. I never done phase measurement and it will be a first time here. In the meantime proceed to some caps swap due to the age of the loudspeaker - 30 years old- and proceed with my ears only because not having anything else for the moment but all the good advices here o course 🙂
Thanks guys
The tweeter seems to be 2850 Hz 24 dB...
Yep, noticed the post #2 , will go further when I finish my Arta box -do you believe it, I'm waiting for two month a resistor purchased at Banzai Music Germany, serious guys but they hadn't not the resistor anymore after receiving the PP- to measure all the coils and driver I only simulated for now. I never done phase measurement and it will be a first time here. In the meantime proceed to some caps swap due to the age of the loudspeaker - 30 years old- and proceed with my ears only because not having anything else for the moment but all the good advices here o course 🙂
Thanks guys
I'm back. Inverted mid is working much much better - my half sim just based on ideal drivers but with te values of the filter worked well here, the deep seen here despite not knowing the acoustical slope of the raw drivers worked quite well enough.
All seems ok now after ten minutes of listening but will go further wih measurements later. For the moment woofer and tweet in positive polarity and mid inverted works fine!
🙂
All seems ok now after ten minutes of listening but will go further wih measurements later. For the moment woofer and tweet in positive polarity and mid inverted works fine!
🙂
pictures for the fun. Transcients are working fine here : Wild thing - YouTube
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Hi,
coils values are not the real ones, just an abstraction from sim on line. However the design was made with something 260 uf to 280 uf for real 😉. Don't forget this is not the measurement seen by a mic yet. Cut-offs aare from the owner manual. The other caps value are the originals.
Btw again, on the tweeter network I find strange to find C1 & C2 inverted in the loudspeaker I have in relation to the on line sims. I mean 6 uF should be seen first then 14 uF after only ????
The 1 uF // to 10R to climb up the post 10K hz are non an evidence for me, I find it better without.
coils values are not the real ones, just an abstraction from sim on line. However the design was made with something 260 uf to 280 uf for real 😉. Don't forget this is not the measurement seen by a mic yet. Cut-offs aare from the owner manual. The other caps value are the originals.
Btw again, on the tweeter network I find strange to find C1 & C2 inverted in the loudspeaker I have in relation to the on line sims. I mean 6 uF should be seen first then 14 uF after only ????
The 1 uF // to 10R to climb up the post 10K hz are non an evidence for me, I find it better without.
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With respect, the whole thing looks a muddle... 😱
This is how you do a 4th order 3kHz tweeter:
Impedance is then good:
Your bass to mid crossover seems unecessarily low, entailing huge components, Troels does it differently.;
SEAS-3-Way-Classic
Not much difference between third and fourth order tweeters IMO. Probably wire the same. Mid and tweet in phase.
This is how you do a 4th order 3kHz tweeter:
Impedance is then good:
Your bass to mid crossover seems unecessarily low, entailing huge components, Troels does it differently.;
SEAS-3-Way-Classic
Not much difference between third and fourth order tweeters IMO. Probably wire the same. Mid and tweet in phase.