Hi pelanj, sorry for the slow reply.
Just moved my Win10 OS and drives off a pretty old Intel Core duo mobo/cpu, to a new AMD Ryzen setup.
I've always done fresh OS installations before on DIY PC builds ...never tried moving the OS before. Trickier. Working well so far...we'll see...
The corners on mine aren't the greatest because I built them to BWaslo's sheet dimensions, but instead of beveling the primary horn flares to work with secondary flares like the sheet is set up for, i simply let the mouth ends stay square, and did a 1/4" roundover on them, inside and out.. That leaves a little angle gap in the backs of the corners.
I was gonna epoxy the corners' backs in to make them look really nice, but since i'm leaving drivers exposed ....i thought wtf..."what price pretty?" Lol
Besides Duratex black is still my favorite finish haha Although i'm loving the electric Chrysler blue in the horns
here's a pict...not sure it shows much.
also followed by top and back in case it helps...
ask away if needed....
Just moved my Win10 OS and drives off a pretty old Intel Core duo mobo/cpu, to a new AMD Ryzen setup.
I've always done fresh OS installations before on DIY PC builds ...never tried moving the OS before. Trickier. Working well so far...we'll see...
The corners on mine aren't the greatest because I built them to BWaslo's sheet dimensions, but instead of beveling the primary horn flares to work with secondary flares like the sheet is set up for, i simply let the mouth ends stay square, and did a 1/4" roundover on them, inside and out.. That leaves a little angle gap in the backs of the corners.
I was gonna epoxy the corners' backs in to make them look really nice, but since i'm leaving drivers exposed ....i thought wtf..."what price pretty?" Lol
Besides Duratex black is still my favorite finish haha Although i'm loving the electric Chrysler blue in the horns
here's a pict...not sure it shows much.
also followed by top and back in case it helps...
ask away if needed....
I just went with a 5600G. Nothing i do is CPU constrained.
I couldn't run a new measurement program, ADL_TDA Real Time, because i was graphic constrained. The integrated Ryzen graphics should work fine, until video cards come back into reasonable supply.
But now i just noticed ADL_TPA app isn't showing up....migrating the OS has indeed been tricky....mainly due to licensing issues it seems, Windows being the worst !!!
(edit...found it , yea!!!)
That's a NL8 on the bottom left.
I
also put two NL4's on the right, as i have different amp feeds at times..
I couldn't run a new measurement program, ADL_TDA Real Time, because i was graphic constrained. The integrated Ryzen graphics should work fine, until video cards come back into reasonable supply.
But now i just noticed ADL_TPA app isn't showing up....migrating the OS has indeed been tricky....mainly due to licensing issues it seems, Windows being the worst !!!
(edit...found it , yea!!!)
That's a NL8 on the bottom left.
I
Hi mark,
was reading this paper https://acoustics.ippt.pan.pl/index.php/aa/article/view/1780/pdf_255 yesterday, about back-EMF and current drive and remembered we using compression driver as mic to try and see what comes back to throat, few years back Then it occured similar thing might be happening here with your experience of coaxial compression driver mid section not sounding as good as four cone midranges in your multiple entry horns. There might be any reason why that is, could it be that the low frequencies in the horn make strong back-EMF currents on the coax mid but not so much with the four mids? Did you listen the speaker without LF drivers playing, just with the mids and highs and compare if clarity is now similar with either the coax mid or with the four cone mids? IMD test on the beginning of this thread is with the mid playing alone, what if you have the low section playing as well, does IMD products increase? Play the low tone with the woofers ( or around crossover so that both play) and the higher one with the mid?
Anyway, just something that came to mind and thought to post
was reading this paper https://acoustics.ippt.pan.pl/index.php/aa/article/view/1780/pdf_255 yesterday, about back-EMF and current drive and remembered we using compression driver as mic to try and see what comes back to throat, few years back
Then it occured similar thing might be happening here with your experience of coaxial compression driver mid section not sounding as good as four cone midranges in your multiple entry horns. There might be any reason why that is, could it be that the low frequencies in the horn make strong back-EMF currents on the coax mid but not so much with the four mids? Did you listen the speaker without LF drivers playing, just with the mids and highs and compare if clarity is now similar with either the coax mid or with the four cone mids? IMD test on the beginning of this thread is with the mid playing alone, what if you have the low section playing as well, does IMD products increase? Play the low tone with the woofers ( or around crossover so that both play) and the higher one with the mid?Anyway, just something that came to mind and thought to post
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Hi tmuikku, yes i remember the experiments using one section of the CD as a mic.....that was fun!
You know, i picked that idea up again, but also using cone drivers as microphones, when playing with wavelets and tonebursts.
Measured one section of the synergy as the driver....and then another as a microphone. The short wavelets give pretty exact "short circuit" ToFs between the sections.
Exact timing and phase are really interesting to me...
I've come to believe there are two timings that are easy to confuse. One being the time of signal origination like when/where the wavelet impulse pops a driver, and the other being the time/place of apparent acoustic integration between driver sections, which has to be downstream from multiple originations ....but alas, I've wandered away from what you've brought up...
Anyway, I kind or gave up trying to measure/quantify why the addition of the small mids improved clarity so much vs the CD going straight to large cones.. I'm still inclined to think it's some kind of reduction, in some form of modulation, but I've been happy just enjoying how great it's sounding for now.
My focus has been on LCR... trying various matrix techniques to enhance stereo...compare to mono, etc etc.
LCR Results have been mixed so far, very song/album dependent. That said, when it's right, it's right.
Funny you should reply to this syn 10 thread today....as just today I made the last step I think, in maybe bringing LCR home.
My center syn 10 is identical to the left and right...all 3 exactly the same. But the subs under them were different . Left and right syns sit on dual 18" PPSL subs. I've been trying to get away with a couple of 15" reflex boxes i threw together from unused drivers/cabinets..but i could tell things weren't right by how the image could wonder when lower freq stuff was being matrixed.
So I pulled out the wallet, and this morning the center syn just got a another pair of the bms 18n862 to sit under !!!! Yay big time!
So all three subs now have the same drivers, with the same reflex tuning.
It took 20 seconds to hear how the center gained both focus and body when running a matrix. It seems matching the center to left and right, is just as important as left and right being exactly matched. I'm psyched....i
You know, i picked that idea up again, but also using cone drivers as microphones, when playing with wavelets and tonebursts.
Measured one section of the synergy as the driver....and then another as a microphone. The short wavelets give pretty exact "short circuit" ToFs between the sections.
Exact timing and phase are really interesting to me...
I've come to believe there are two timings that are easy to confuse. One being the time of signal origination like when/where the wavelet impulse pops a driver, and the other being the time/place of apparent acoustic integration between driver sections, which has to be downstream from multiple originations ....but alas, I've wandered away from what you've brought up...
Anyway, I kind or gave up trying to measure/quantify why the addition of the small mids improved clarity so much vs the CD going straight to large cones.. I'm still inclined to think it's some kind of reduction, in some form of modulation, but I've been happy just enjoying how great it's sounding for now.
My focus has been on LCR... trying various matrix techniques to enhance stereo...compare to mono, etc etc.
LCR Results have been mixed so far, very song/album dependent. That said, when it's right, it's right.
Funny you should reply to this syn 10 thread today....as just today I made the last step I think, in maybe bringing LCR home.
My center syn 10 is identical to the left and right...all 3 exactly the same. But the subs under them were different . Left and right syns sit on dual 18" PPSL subs. I've been trying to get away with a couple of 15" reflex boxes i threw together from unused drivers/cabinets..but i could tell things weren't right by how the image could wonder when lower freq stuff was being matrixed.
So I pulled out the wallet, and this morning the center syn just got a another pair of the bms 18n862 to sit under !!!! Yay big time!
So all three subs now have the same drivers, with the same reflex tuning.
It took 20 seconds to hear how the center gained both focus and body when running a matrix. It seems matching the center to left and right, is just as important as left and right being exactly matched. I'm psyched....i
Nice info nugget, thanks posting the link! So there might be something to this.
I'm not sure if I've understood correctly how the damping works TD talks about. I imagine it currently as magnetic damping which happens by making a short between the driver terminals that allows the driver motor generate force to resist the change by external pressure affecting the driver, trying to make it move. But, as mark has active system amplifier is connected directly to the driver terminals and should already appear as ~0 impedance between driver terminals for low frequencies at least. Except, there is some resistance in the cabling, and there might be a protection cap in series like I have in my system, which is high impedance for low frequencies, no magnetic damping, unless inductor between terminals. So a parallel inductor could help the coaxial compression driver sound better in the application
Also the tweeter would benefit this parallel inductor, especially if the cabling is long in an active system. Definitely parallel inductor looks better alternative for series capacitor as protection, with active system. YSDR brought it up on another thread about active systems using passive crossover parts and tried if it would be something for my system and it looks like it would make better response and reduce resonance of the driver, opposite to series capacitor.
ps. this is something I've come across only recently and trying to figure out how it plays out and above text might contain error. But we could take what TD says as granted and come to similar conclusion reasoning based on his post
I'm not sure if I've understood correctly how the damping works TD talks about. I imagine it currently as magnetic damping which happens by making a short between the driver terminals that allows the driver motor generate force to resist the change by external pressure affecting the driver, trying to make it move. But, as mark has active system amplifier is connected directly to the driver terminals and should already appear as ~0 impedance between driver terminals for low frequencies at least. Except, there is some resistance in the cabling, and there might be a protection cap in series like I have in my system, which is high impedance for low frequencies, no magnetic damping, unless inductor between terminals. So a parallel inductor could help the coaxial compression driver sound better in the application
Also the tweeter would benefit this parallel inductor, especially if the cabling is long in an active system. Definitely parallel inductor looks better alternative for series capacitor as protection, with active system. YSDR brought it up on another thread about active systems using passive crossover parts and tried if it would be something for my system and it looks like it would make better response and reduce resonance of the driver, opposite to series capacitor.
ps. this is something I've come across only recently and trying to figure out how it plays out and above text might contain error. But we could take what TD says as granted and come to similar conclusion reasoning based on his post
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Hi guys,
Rob, thx for the TD link....i try to follow all the nuggets he's given out...
It's easy to see how an inductor can help benefit damping in a passive xover system.
Tmuikku, like you say, I'm all active with amplifier control of each section.
I've measured response of driven sections, where the undriven sections were shorted either by wire, or by an amp tuned on with no signal.
I've yet to see a discernable difference, so i just do whatever is easiest, given the stage of testing/tuning.
Without shorting undriven sections, it always amazes me how much response changes.
Even an unshorted CD changes large cones' response. I guess this is due to the increased pressure a horn exerts the smaller its cross sectional area....pressure an unshorted CD would be more likely to absorb/resonate....
Rob, thx for the TD link....i try to follow all the nuggets he's given out...
It's easy to see how an inductor can help benefit damping in a passive xover system.
Tmuikku, like you say, I'm all active with amplifier control of each section.
I've measured response of driven sections, where the undriven sections were shorted either by wire, or by an amp tuned on with no signal.
I've yet to see a discernable difference, so i just do whatever is easiest, given the stage of testing/tuning.
Without shorting undriven sections, it always amazes me how much response changes.
Even an unshorted CD changes large cones' response. I guess this is due to the increased pressure a horn exerts the smaller its cross sectional area....pressure an unshorted CD would be more likely to absorb/resonate....
Thanks Rob for the Tom Danley link. I´ve read it years ago and remembered but couldn´t find it again. Stored!
Tmuikko, I don´t think there is any magnetic damping!?
As I understand it the parallel inductor is part of a second order high-pass-filter (with a series capacitor). So the amplifier sees the second order filter, the compression-driver sees a short circuit in the form of the dc-resistance of the coil.
I hope it makes sense and that I am right, please correct me if not.
Steffen
Tmuikko, I don´t think there is any magnetic damping!?
As I understand it the parallel inductor is part of a second order high-pass-filter (with a series capacitor). So the amplifier sees the second order filter, the compression-driver sees a short circuit in the form of the dc-resistance of the coil.
I hope it makes sense and that I am right, please correct me if not.
Steffen
This is something I've been trying to figure out just past week or so, and its been refining that there is but only for drivers fundamental resonance, roughly. Above that there also is but drivers mechanical damping is greater and it doesn't matter, an even makes things worse.
Basically, shortcircuit with inductor allows driver generated current to flow which makes magnetic field in the driver that opposes the movement. More officially, eddy current makes magnetic damping. If there is no short circuit, or impedance is high due to long thin cables or crossover network, then the eddy current generated by driver stays low and less of movement opposing magnetic field happens in the driver. In this case the system then relies on mechanical damping for example, or just resonates freely and bump happens in response, high Q alignment situation.
This is my current understanding on the subject, which seems to be true, but never know as I'm new to this. See the Elsinore thread, Joe has been talking about the stuff this month and there are my amusings as well, latest one without response yet. Some links to resources there as well.
Here few resources, although they all seem to write the same just using different wording. The scientific texts are bit hard to cipher for imagination to process how the stuff works out in loudspeaker systems. These two have nice understandable way of saying the same thing, about this magnetic or electronic damping:
https://www.thebroadcastbridge.com/content/entry/7831/loudspeaker-technology-part-6
https://www.powersoft.com/wp-content/uploads/2019/01/powersoft_TN011_DampingControl_en_v1.0.pdf
Here an article with math and nice breakdown what a driver impedance consists of and how mangetic, or electornic, damping works and how it doesn't. This article has bitter tone to it but the content seems legit
https://www.edn.com/loudspeaker-operation-the-superiority-of-current-drive-over-voltage-drive/
Here is the plain physics https://en.wikipedia.org/wiki/Magnetic_damping
So, please make your own conclusions on the subject, I'm no professional Although it seems very logical to me how it plays out, I'm imagining driver as generator, amplifier + cabling + possible passive parts as its load. High impedance = less current, low impedance = more current generated by the driver. Driver works as generator when at its resonance, and by other factors affecting its movement like pressure from other drivers nearby, or reflections from back of the box. In MEH context woofers would make pressure inside the horn which affects the compression driver, like Tom danley writes the pressure is highest at the throat and maximal effect on the driver there. Compression driver "microphones" the signal, unless its very well damped. It microphones it anyway, its just how much it moves, how much the movement makes voltage in the coil (back-EMF) and what the load impedance is for this voltage to make current, eddy current, and what effect the eddy current is for the system.
Basically, shortcircuit with inductor allows driver generated current to flow which makes magnetic field in the driver that opposes the movement. More officially, eddy current makes magnetic damping. If there is no short circuit, or impedance is high due to long thin cables or crossover network, then the eddy current generated by driver stays low and less of movement opposing magnetic field happens in the driver. In this case the system then relies on mechanical damping for example, or just resonates freely and bump happens in response, high Q alignment situation.
This is my current understanding on the subject, which seems to be true, but never know as I'm new to this. See the Elsinore thread, Joe has been talking about the stuff this month and there are my amusings as well, latest one without response yet. Some links to resources there as well.
Here few resources, although they all seem to write the same just using different wording. The scientific texts are bit hard to cipher for imagination to process how the stuff works out in loudspeaker systems. These two have nice understandable way of saying the same thing, about this magnetic or electronic damping:
https://www.thebroadcastbridge.com/content/entry/7831/loudspeaker-technology-part-6
https://www.powersoft.com/wp-content/uploads/2019/01/powersoft_TN011_DampingControl_en_v1.0.pdf
Here an article with math and nice breakdown what a driver impedance consists of and how mangetic, or electornic, damping works and how it doesn't. This article has bitter tone to it but the content seems legit
https://www.edn.com/loudspeaker-operation-the-superiority-of-current-drive-over-voltage-drive/
Here is the plain physics https://en.wikipedia.org/wiki/Magnetic_damping
So, please make your own conclusions on the subject, I'm no professional
Although it seems very logical to me how it plays out, I'm imagining driver as generator, amplifier + cabling + possible passive parts as its load. High impedance = less current, low impedance = more current generated by the driver. Driver works as generator when at its resonance, and by other factors affecting its movement like pressure from other drivers nearby, or reflections from back of the box. In MEH context woofers would make pressure inside the horn which affects the compression driver, like Tom danley writes the pressure is highest at the throat and maximal effect on the driver there. Compression driver "microphones" the signal, unless its very well damped. It microphones it anyway, its just how much it moves, how much the movement makes voltage in the coil (back-EMF) and what the load impedance is for this voltage to make current, eddy current, and what effect the eddy current is for the system.
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edit time over, continuing the last paragraph:
If eddy current flows, with low impedance circuit as load for the driver, the compression driver diaphragm doesn't move much. If there is no eddy current, the CD not connected to anything, or decoupled from the amplifier with a capacitor circuit for example, then the diaphragm probably moves quite wild due to this external sound pressure affecting it. How this all affects sound produced with the compression driver can be altered by manipulating the impedance seen by the driver. In an active system, and short cabling, the driver sees pretty much a short as load between its terminals (impedance of the driver is also in the circuit) and has relatively strong eddy current generated and relatively strong magnetic damping happens keeping the diaphragm pretty much in place, damped. If there was a capacitor for example, just for protecting the compression driver on an active system for accidents, it would increase impedance on the low frequency, perhaps around where the compression driver resonance is (impedance peak), less current flows and the diaphragm moves due to this external excitation unless its damped by other means than with this magnetic damping.
Alright, flip side for this eddy current to flow, is that when the mechanical damping of driver takes hold as frequency rises and inductance dominated impedance takes over the mechanical related inductance the eddy current can be seen as distortion, see Esa Meriläinen article linked on previous post. Well, perhaps its also distortion at low frequencies as well but there it has the bonus side make the magnetic damping happen if its something useful for the system. Otherwise we would better not introduce this extra current to the system, so better use high impedance between driver terminals.
Parallel inductor very close to the driver does just this, it gives very low impedance load for the compression driver on low frequencies and allows magnetic damping if its something useful, resisting effects of the external sound pressure to the driver. It does not short high frequencies, in other words rest of the stuff in series makes the impedance for highs, from drivers perspective, other crossover components and cabling. This circuit can be tuned to reduce eddy current on high frequencies, reduce distortion like current drive.
Also, don't forget what the impedance is from amplifiers perspective, there is probability for distortion in the amplifier due to impedance variations in the load.
In the end the objective is of course get understanding that corresponds with reality so we can realize better sound systems If I'm wrong with the above then I'd like to be corrected, thanks.
If eddy current flows, with low impedance circuit as load for the driver, the compression driver diaphragm doesn't move much. If there is no eddy current, the CD not connected to anything, or decoupled from the amplifier with a capacitor circuit for example, then the diaphragm probably moves quite wild due to this external sound pressure affecting it. How this all affects sound produced with the compression driver can be altered by manipulating the impedance seen by the driver. In an active system, and short cabling, the driver sees pretty much a short as load between its terminals (impedance of the driver is also in the circuit) and has relatively strong eddy current generated and relatively strong magnetic damping happens keeping the diaphragm pretty much in place, damped. If there was a capacitor for example, just for protecting the compression driver on an active system for accidents, it would increase impedance on the low frequency, perhaps around where the compression driver resonance is (impedance peak), less current flows and the diaphragm moves due to this external excitation unless its damped by other means than with this magnetic damping.
Alright, flip side for this eddy current to flow, is that when the mechanical damping of driver takes hold as frequency rises and inductance dominated impedance takes over the mechanical related inductance the eddy current can be seen as distortion, see Esa Meriläinen article linked on previous post. Well, perhaps its also distortion at low frequencies as well but there it has the bonus side make the magnetic damping happen if its something useful for the system. Otherwise we would better not introduce this extra current to the system, so better use high impedance between driver terminals.
Parallel inductor very close to the driver does just this, it gives very low impedance load for the compression driver on low frequencies and allows magnetic damping if its something useful, resisting effects of the external sound pressure to the driver. It does not short high frequencies, in other words rest of the stuff in series makes the impedance for highs, from drivers perspective, other crossover components and cabling. This circuit can be tuned to reduce eddy current on high frequencies, reduce distortion like current drive.
Also, don't forget what the impedance is from amplifiers perspective, there is probability for distortion in the amplifier due to impedance variations in the load.
In the end the objective is of course get understanding that corresponds with reality so we can realize better sound systems
If I'm wrong with the above then I'd like to be corrected, thanks.
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So given the above explanations I think you and I are thinking alike, what each "source" sees as load impedance. Hopefully the magnetic damping part also makes sense now? If not, then perhaps could you comment how you think about it? perhaps I don't have required understanding yet.
As I read the above text there is some inconsistency like first sentence from above post "If eddy current flows, with low impedance circuit as load for the driver, the compression driver diaphragm doesn't move much. " which should of course read more accurately "If eddy current flows, with low impedance circuit as load for the driver on its resonant frequency, the compression driver diaphragm doesn't move much on its resonant frequency as magnetic damping resists the movement. ". Writing in a hurry is never a good thing, possibility to increase confusion rather than understanding so sorry for this, was in a hurry but wanted to let it out
See the links for better delivery.
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How this relates to active systems? We can somewhat optimize load of amplifier and load for driver introducing some passive parts between, if we want to, and if it yields audible benefits. I don't know, surely looks like THD would reduce but that doesn't correlate with perceived quality so the stuff would need to be listened in each application if it was worth it or not. After all, passive and active system is about double the cost and trouble Small coil and a resistor, for compression driver in domestic application doesn't cost much though, so perhaps easy and cheap test. Cost is about as much as L-pad and protection cap would. Plan to test this some day soon after get opportunity to find good values for my system and make an order.
Small coil and a resistor, for compression driver in domestic application doesn't cost much though, so perhaps easy and cheap test. Cost is about as much as L-pad and protection cap would. Plan to test this some day soon after get opportunity to find good values for my system and make an order.This just reminded me an article by Purifi - where they discuss distortion reduction with a passive crossover. Maybe it is a bit relevant to this topic. https://purifi-audio.com/tech/ - the first article on top of the page.
It is, and I used it in the Elsinore thread as reference. The paper shows that affecting load seen by the driver affects non-linear distortion, at least this is what I harvested from it. There is useful trick for VituixCAD users how to scope load impedance for the driver. The paper is for passive crossover system but we can use the trick/information with active systems as well, adapt the main message to our applications.
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Hi Tmuikku
Hmm, you might be right with that eddy current and magnetic damping. That´s a bit over my head.
For me it´s about being practical. If I go active with my MEH I have to be aware that I need to have a series capacitor AND a parallel inductor (for protection) or NOTHING between driver and amp!
Steffen
Hmm, you might be right with that eddy current and magnetic damping. That´s a bit over my head.
For me it´s about being practical. If I go active with my MEH I have to be aware that I need to have a series capacitor AND a parallel inductor (for protection) or NOTHING between driver and amp!
Steffen
Yeah its not necessary for active systems, extra complexity, and I don't know how much audible difference there is and for each SPL level.
But, don't miss the possibility here if you have these as your ultimate HiFi system at home listening levels For example I have series capacitor and L-pad for my compression drivers to reduce noise of my poor amplifier and provide protection just in case. Instead, I could use series resistor and the shunt coil for similar response and utility and for about same cost. Both implementations give protection and attenuation but the coil version also dampens the driver resonance better. Or more accurately allows the driver magnetic damping happen. I guess your 2nd order filter does about the same thing so you are good.
Also nothing between the driver and amp is good for the damping to happen at resonance, but there is some aspects raised on the links I posted that past the main resonance, at higher frequencies, it would be worthwhile to reduce current generated by the driver in the system. Not sure about audibility, as this kind of systems are very low distortion at home listening levels anyway.
See the attachments, both implementations fullfills same criteria for my system, but the version with coil makes the driver resonances damped better.
Perhaps all this is very familiar to most speaker designers I'm enthusiastic for it now as this is something new I've learned
But, don't miss the possibility here if you have these as your ultimate HiFi system at home listening levels
For example I have series capacitor and L-pad for my compression drivers to reduce noise of my poor amplifier and provide protection just in case. Instead, I could use series resistor and the shunt coil for similar response and utility and for about same cost. Both implementations give protection and attenuation but the coil version also dampens the driver resonance better. Or more accurately allows the driver magnetic damping happen. I guess your 2nd order filter does about the same thing so you are good.Also nothing between the driver and amp is good for the damping to happen at resonance, but there is some aspects raised on the links I posted that past the main resonance, at higher frequencies, it would be worthwhile to reduce current generated by the driver in the system. Not sure about audibility, as this kind of systems are very low distortion at home listening levels anyway.
See the attachments, both implementations fullfills same criteria for my system, but the version with coil makes the driver resonances damped better.
Perhaps all this is very familiar to most speaker designers
I'm enthusiastic for it now as this is something new I've learned
I'm not great with passive xo stuff, have used digital for years. When I looked for calculators to work out a 1st order high pass using an inductor I could not find much info. Did I miss something simple or does it have to be a 2nd order slope ? (I'm working on re-doing my meh xo using 1st order slopes at the minute)
Rob
Rob
Do you have active system as well? You could use just first order filter if you wish, and if it has benefit in sense as discused here before. Just adjust your DSP accordingly. You could make second oder filter if you wanted to. All that matters is the acoustic slope in the end (and now you have changed the impedance in the circuitry with passive parts, hopefully for better performance) even though the frequency response now looks exactly the same as before