Hi tmuikku,
that's what I'd like to see....if the driver motor itself produces significant 3rd harmonics with a 1.7kHz fundamental.....(in the absence of any drive signal to the driver at 5kHz). back to wanting to see a single 1.7kHz sine THD test.
If there is measured 3rd harmonic THD at the single 1.7kHz sine, that gets significantly reduced by adding the passive notches, then I'm convinced.
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The way I understand it, the third harmonic of 5/3 khz is at 5 Khz where the driver resonance/peak occurs. if the driver were flat it would be down 40 or 50 db and we wouldn't think twice about it. Since the driver peak brings it up 20 db at 5 khz, its only down 20 or 30 db. A low slope passive crossover only pushes it down another 12 db to -32 to -42 db which is marginal In that scenario, the difference between the series vs parallel notch is significant. with DSP, we can push it down out of sight. with only passives, we have to be clever. I think it was wise that we chose to go active long ago.
The question I have is whether the high Z from the from the notch filter suppresses the nonlinearity near 5/3 khz in the first place. If that were the case, then I might be temped to do a hybrid crossover. If its just another way of filtering then its only the end result that matters.
The design I have on the drawing board crosses over to a CD/tweeter near 1 Khz so that 5/3 khz fundamental is outside my midwoofers passband but not very far down its low pass filter's slope. I would put a -20 db IIR PEQd on 5/3 khz amd 5 khz in addition to the FIR auto-eq flattening then application of textbook low pass filter.
The question I have is whether the high Z from the from the notch filter suppresses the nonlinearity near 5/3 khz in the first place. If that were the case, then I might be temped to do a hybrid crossover. If its just another way of filtering then its only the end result that matters.
The design I have on the drawing board crosses over to a CD/tweeter near 1 Khz so that 5/3 khz fundamental is outside my midwoofers passband but not very far down its low pass filter's slope. I would put a -20 db IIR PEQd on 5/3 khz amd 5 khz in addition to the FIR auto-eq flattening then application of textbook low pass filter.
Hi, sorry forgot to say hi on last post 😀 Yes, and if you can do IMD as well it would be cool since the distortion in driver motor worsens with excursion. I've got no idea how audible this is and thats the ultimate test, there is of course no point complicate things if its not audible.
4 way MEH system, not sure there is any point to it... and direct radiating two way would benefit most as the woofer does some serious excursion in the application.
On a MEH this "out of band" distortion are also point source, perhaps masked fine by tweeter for example. Take traditional speaker and the distortion of woofer comes from different location (than tweeter) perhaps adding to audibility.
MEH is such a good concept in so many ways 😀
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Well, if its a problem I think you could see in RTA that slope of 96db/octave is something less? If there is distortion products -40db down they should make the slope appear much shallower I think. Just pink noise to some woofer you have around, apply 16th order low pass and look RTA if it really is 96db down octave above, or much less. Then, if you have some spare inductor somewhere hook it in series and see if the slope gets steeper.
Hi, check out the purifi paper, THD really goes down. But then again THD does not correlate to perceived quality so, we need to test it in our applications to believe 😀
Yeah its easy to deal with the direct sound, but distortion originating at the driver is not affected no matter how much we suppress in DSP, we need good drivers and limit current in the driver to cut down the distortion. Cone breakup happens still for what ever current is left there flowing through voice coil at the breakup frequency.
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what you describe is exactly what happens: 1.7k sine results in 5k harmonic back emf in the motor which gets converted to current depending on the driver circuit impedance (the impedance the driver sees). If it is a regular amp with low output impedance then then the conversion factor is 1/Re. if you then insert the notch that provides high impedance at 5k then the current is significantly reduced which results in a suppressed 5k 3rd harmonic and the distortion at 1.7k will be reduced. The distortion reduction requires that the speaker load impedance is changed and this is not possible with just an active filter and ordinary amp irrespective of the filter order (of course if the filter cuts below 1.7k then the distortion peaks go away )
If you attenuate 5 khz, the distortion at 1.67 Khz will be reduced because the signal at 5 khz IS part of the distortion at 1.67 khz. There is more of the distortion of 1.67 khz distortion at 10 and 15 khz. Its counter intuitive but that is simply the definition of harmonic distortion.
I now see that the parallel trap isn't just a filter - it also reduces the conversion of back emf into harmonic current which the driver then turns into sound.
I now see that the parallel trap isn't just a filter - it also reduces the conversion of back emf into harmonic current which the driver then turns into sound.
Thanks for that !
i guess i'm still most interested in, is the passive notch step a worthwhile addition to the steep linear phase xovers I use.
I'm 100% sold on those xovers....it's just a question to me if there is more SQ on the table from another step like the passive notch.
If you ever test your driver with a steep linear phase low pass, I'd love to see the results....especially both with and without the passive notches in place.
The passive notches look like more work than I'd like to be involved with, but if clear advantages are there, i could see doing such. Thx.
Hi Steffen, yes, as you asked in another thread, the IIR work I've been doing is for syn10.
I've put all my main speaker DIY attention into trying to find processing improvements. I don't really want to build any more syn versions, and even if i did, baltic birch (russian) is not available. Lesser quality ply is just too hard to work with ime.
Anyway, I made some nice sonic improvements with FIR, by studying the actual electrical FIR filters, in addition to measured acoustic response.
Getting the electrical filters impulse responses as clean as possible, while maintaining the desired acoustic target response, has had a positive effect maybe best described as subtly lowering the noise floor. Just sounds like there a little more contrast between quiet parts and the music....a little more real.
The IIR work now, is because that FIR work seems maxed out. IIR is all that left Lol. And what a pain it is...
That said, the sound from my first all-out attempt is very nice. I could live with it. Doesn't quite have the grab-me capability that some songs under FIR have, but damn close.
First attempt has been using all 2nd order crossovers at 120, 300, 800, and 3500Hz.
Second one I just finished uses all first order at same xover points. I haven't yet listened to it. here's its on-ax measurement. 1/24th.
As far as 'zeroeth order'....that's not something I'd try...well....... maybe I better also say I'm not sure I fully understand it, either.
If it involves no attenuation from high-pass and low pass filters on any driver sections, I say no way I'm doing that......I'm not about to put that much thermal bandwidth load on the driver sections. I have a hard time imagining DSL would either as the boxes are meant for PA and SPL.
I also think the SH-50 shows phase rotation that disavows the idea of anything less than first order electrical xovers. Looking at DSL's spec sheet, I'd say there is about 360 degrees of phase rotation between high and low, ignoring the phase tails at the very bottom and very top.
Given there are two crossovers in play, let's just call it 180 degrees for each. Very nice indeed !
Anyway, seems to me there has to be something probably close to first order electrical on top of natural drivers rolloffs.
If you look at my first order mag and phase graph above, there's about 540 degrees of rotation from the high end down to about 80Hz. Syn10 is meant to be crossed at 120Hz, so it's phase tail will kick in sooner that sh-50.
Syn10 also has an extra xover compared to the sh50 due to the coaxial CD, so I dunno, first orders on top of natural rolloffs seem to make decent sense.
I've put all my main speaker DIY attention into trying to find processing improvements. I don't really want to build any more syn versions, and even if i did, baltic birch (russian) is not available. Lesser quality ply is just too hard to work with ime.
Anyway, I made some nice sonic improvements with FIR, by studying the actual electrical FIR filters, in addition to measured acoustic response.
Getting the electrical filters impulse responses as clean as possible, while maintaining the desired acoustic target response, has had a positive effect maybe best described as subtly lowering the noise floor. Just sounds like there a little more contrast between quiet parts and the music....a little more real.
The IIR work now, is because that FIR work seems maxed out. IIR is all that left Lol. And what a pain it is...
That said, the sound from my first all-out attempt is very nice. I could live with it. Doesn't quite have the grab-me capability that some songs under FIR have, but damn close.
First attempt has been using all 2nd order crossovers at 120, 300, 800, and 3500Hz.
Second one I just finished uses all first order at same xover points. I haven't yet listened to it. here's its on-ax measurement. 1/24th.
As far as 'zeroeth order'....that's not something I'd try...well....... maybe I better also say I'm not sure I fully understand it, either.
If it involves no attenuation from high-pass and low pass filters on any driver sections, I say no way I'm doing that......I'm not about to put that much thermal bandwidth load on the driver sections. I have a hard time imagining DSL would either as the boxes are meant for PA and SPL.
I also think the SH-50 shows phase rotation that disavows the idea of anything less than first order electrical xovers. Looking at DSL's spec sheet, I'd say there is about 360 degrees of phase rotation between high and low, ignoring the phase tails at the very bottom and very top.
Given there are two crossovers in play, let's just call it 180 degrees for each. Very nice indeed !
Anyway, seems to me there has to be something probably close to first order electrical on top of natural drivers rolloffs.
If you look at my first order mag and phase graph above, there's about 540 degrees of rotation from the high end down to about 80Hz. Syn10 is meant to be crossed at 120Hz, so it's phase tail will kick in sooner that sh-50.
Syn10 also has an extra xover compared to the sh50 due to the coaxial CD, so I dunno, first orders on top of natural rolloffs seem to make decent sense.
Hi Mark
Thank you for answering my question.
As I have understood the "zeroeth order" crossover-approach, it´s all about using PEQ´s and maybe also shelving filters? Maybe even not using (complementary) target-curves, as the sound-sources are kind of summing together, due to being placed on one axis, the z-axis (behind each other instead of on top of each other) and then "filling out holes" / correcting the FR with PEQ´s? It is a bit fluffy, and I don´t have any experience with yet.
I have collected a lot of link´s to places on diyaudio where Chris has "explained" his approach, but my memory of them is a bit rusty.
Came to think of @Speedysteve7 and his SH50 and SH60 builds, it looks like he uses the "zeroeth order" crossover-approach? He definitely uses IIR anyway. Maybe he will chime in and share some knowledge?
Regards
Steffen
Thank you for answering my question.
As I have understood the "zeroeth order" crossover-approach, it´s all about using PEQ´s and maybe also shelving filters? Maybe even not using (complementary) target-curves, as the sound-sources are kind of summing together, due to being placed on one axis, the z-axis (behind each other instead of on top of each other) and then "filling out holes" / correcting the FR with PEQ´s? It is a bit fluffy, and I don´t have any experience with yet.
I have collected a lot of link´s to places on diyaudio where Chris has "explained" his approach, but my memory of them is a bit rusty.
Came to think of @Speedysteve7 and his SH50 and SH60 builds, it looks like he uses the "zeroeth order" crossover-approach? He definitely uses IIR anyway. Maybe he will chime in and share some knowledge?
Regards
Steffen
Hi again
Are your Subs also going to be crossed first order at 120 Hz? The reason you build closed boxes for your woofers?
Are your Subs also going to be crossed first order at 120 Hz? The reason you build closed boxes for your woofers?
i would love for you guys to try an ole school analog ashly xr1001 4 way crossover and compare..
Maybe You're thinking of this? https://www.diyaudio.com/community/...y-design-challenge.406711/page-3#post-7539441
I use a 1st order cap on the HF (mainly because I've always used that on all my HF horns (from 12 sided conicals, to tractrix 600/550/400s, to Le Cléach 550s) - provides a neat smoothing of the driver peak and gives protection etc just where it's needed.
This was the X/O with zero other filters I used for years on those setups.
Less is more with the Vitavox S2 compression driver.
That's specific to that driver though..
Then on the MEHs I use some DSP PEQs below that X/O point which have the effect of phase flattening.
On the MF (2 or 4 x 5" sealed back) cone drivers there are no X/Os at all.
Just some unwanted peak frequency PEQ flatteners, esp around 3 or 4KHz and around 10KHz.
The acoustic filters of the taps etc do the most of the X/O lifting.
A couple of extra PEQs around the 325Hz and 954Hz acoustic XO points further aid things.
On the 2 X 12" LFs I have a 1st order low pass DSP X/O at 325Hz kills off the unwanted high frequencues a bit, also does something with the phase too. There are also some higher Freq kill off PEQs.
The phase is then further levelled by tweaking the delays between the HF, MF and HF.
Then there are a couple of strategically placed low dB level PEQs that are just ahead of the odd phase rise that just flatten things.
With DSP PEQs less is more.
Paying attention to the phase via time delays and these small PEQs has as big a sound quality upgrade as going from a cheap MM cartridge to a nice MC / SUT setup - I kid you not!
I listen and then sometimes reduce/increase the dB levels of the PEQs on the fly until I'm satisfied.
Very small changes, not straying from the measured ideas much.
The SH50 set up was 95% there for the SH60s.
Forgot to say the Danley / Volvotreter inspired tapped horns are on a 6th order DSP low pass at around 55Hz.
I have a room mode controller at 30Hz (10dB cut!).
This was the X/O with zero other filters I used for years on those setups.
Less is more with the Vitavox S2 compression driver.
That's specific to that driver though..
Then on the MEHs I use some DSP PEQs below that X/O point which have the effect of phase flattening.
On the MF (2 or 4 x 5" sealed back) cone drivers there are no X/Os at all.
Just some unwanted peak frequency PEQ flatteners, esp around 3 or 4KHz and around 10KHz.
The acoustic filters of the taps etc do the most of the X/O lifting.
A couple of extra PEQs around the 325Hz and 954Hz acoustic XO points further aid things.
On the 2 X 12" LFs I have a 1st order low pass DSP X/O at 325Hz kills off the unwanted high frequencues a bit, also does something with the phase too. There are also some higher Freq kill off PEQs.
The phase is then further levelled by tweaking the delays between the HF, MF and HF.
Then there are a couple of strategically placed low dB level PEQs that are just ahead of the odd phase rise that just flatten things.
With DSP PEQs less is more.
Paying attention to the phase via time delays and these small PEQs has as big a sound quality upgrade as going from a cheap MM cartridge to a nice MC / SUT setup - I kid you not!
I listen and then sometimes reduce/increase the dB levels of the PEQs on the fly until I'm satisfied.
Very small changes, not straying from the measured ideas much.
The SH50 set up was 95% there for the SH60s.
Forgot to say the Danley / Volvotreter inspired tapped horns are on a 6th order DSP low pass at around 55Hz.
I have a room mode controller at 30Hz (10dB cut!).
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I'm sure I can emulate such a thing in Najda.
I believe the XR1001 uses 2nd order XOs throughout.
I did listen to my SH50 style MEHs without any PEQs, just the 1st order XOs on the LF and the 1st order cap on the HF.
It wasn't too bad. Nowhere near as refined and coherent as with.
Losing the time alignment all together would be a bigger deal I think.
What I hear when things are setup as I like is greater clarity / distortion free with great image depth and coherence both from each left and right channel and also good stereo imaging - track dependant..
Going 2nd order on each driver would introduce 180° phase rotations and be as far from a Synergy set up as can be.
It would definitely play music though.
Perhaps I will try it!
Could be fun to play to visitors.
Here's a 2nd order Ashley emulation, listen to that for a while, then switch over to my preferred set up and listen again.
Thx Steffen !, for filling in my memory about fthe zeroeth order stuff. Yeah, just about using PEQs and/or shelves to do the job of high-pass or low-pass.
Personally, I think making much of a distinction is a waste of time. Because the net filters applied, however put together are all that count in the end.
I also think 'order' pragmatically means the degree of rolloff....it doesn't necessarily come from high-pass of low-pass. PEQs do the same thing.
Here's a fun, albeit rather overcooked example of using IIR PEQs to accomplish high-pass and low pass...
This is the lower section of the dcx464 CD, filtered with only PEQs to give a LR24 1k to 4k bandpass.
The green stuff is the PEQs.
Thx Steve, for posting your filter details.
Could not agree more about the MM vs MC comment..!!!!
And also with the less DSP is more. I know you meant IIR...I agree with that, as well as with FIR.
Although that said, the above overcooked IIR filtering for the dcx really sounds nice too. As does the same thing via FIR.
A guy like can get really sonically confused sometimes, as I compare strategies /alternatives. I've found I need to live with the different setups for a while, to form conclusions.
Personally, I think making much of a distinction is a waste of time. Because the net filters applied, however put together are all that count in the end.
I also think 'order' pragmatically means the degree of rolloff....it doesn't necessarily come from high-pass of low-pass. PEQs do the same thing.
Here's a fun, albeit rather overcooked example of using IIR PEQs to accomplish high-pass and low pass...
This is the lower section of the dcx464 CD, filtered with only PEQs to give a LR24 1k to 4k bandpass.
The green stuff is the PEQs.
Thx Steve, for posting your filter details.
Could not agree more about the MM vs MC comment..!!!!
And also with the less DSP is more. I know you meant IIR...I agree with that, as well as with FIR.
Although that said, the above overcooked IIR filtering for the dcx really sounds nice too. As does the same thing via FIR.
A guy like can get really sonically confused sometimes, as I compare strategies /alternatives. I've found I need to live with the different setups for a while, to form conclusions.
Oh, i dunno there. I need to get both syn10 and subs out on the driveway, and build a few presets to bring inside and try.
The reason for the sealed subs is solely about the very bottom....sealed vs vented.
Not about the xover to syn10...although I want to try to find an optimal order there too.
I can tell you from experience that none of the slopes, frequencies or amplitudes will match what the front panel indicates using the Analog Ashly crossovers.
In other words, they don't compare well at all, even considering the limited scope of what is possible with them compared to the most basic IIR DSP.
No HP in stereo mode, and 40Hz the lowest in 3 way mono 🙄
One thing to add from my side.
Now I've built the SH60 alikes, The SH50's will be used for a couple of weddings in marquees. 50 to 70 pers.
I will revisit the setup and perhaps impose more HF driver safety for the BMS 4550 that will be used.
It's reportedly pretty robust but want to be within safety margins - even if that means using a 2nd order along the way.
PA is new to me and I guess I'm likely to underestimate somethings, but aim to compensate with a cautious measure and test approach to build my understanding of how things respond.
Art will be pleased to hear I am routing clearance depths in the mounting baffles for the 12" LF drivers. The 5" MFs, as pointed out before don't have much Xmax, and have a deep gasket.
I don't yet know how much we'll be pushing these to make enough sound, but have 4 months to trial and error test outside until the first big day 🙂
I anticipate wanting at least another LAB12 sub.
Hifi and PA - different animals.
Now I've built the SH60 alikes, The SH50's will be used for a couple of weddings in marquees. 50 to 70 pers.
I will revisit the setup and perhaps impose more HF driver safety for the BMS 4550 that will be used.
It's reportedly pretty robust but want to be within safety margins - even if that means using a 2nd order along the way.
PA is new to me and I guess I'm likely to underestimate somethings, but aim to compensate with a cautious measure and test approach to build my understanding of how things respond.
Art will be pleased to hear I am routing clearance depths in the mounting baffles for the 12" LF drivers. The 5" MFs, as pointed out before don't have much Xmax, and have a deep gasket.
I don't yet know how much we'll be pushing these to make enough sound, but have 4 months to trial and error test outside until the first big day 🙂
I anticipate wanting at least another LAB12 sub.
Hifi and PA - different animals.