Check my user info 
https://www.diyaudio.com/community/members/tnt.4571/#about
I didn't know until after about that site - a nice site.
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https://www.diyaudio.com/community/members/tnt.4571/#aboutI didn't know until after about that site - a nice site.
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Made 3 new measurements on CD/WG; 1) no R nor L, 2) only R (R) and 3) with the above 8R/0,33mH filter.
70cm, calibrated levels. 800hz 4th HP in DSP for all 3 meas.
I had to do some FR compensation in DSP to get to the same output level at 1k - especially for the R/L filter one. I think here is where one can get fooled - its really important to compare the exact same FR and level or it can be misleading... I first got a really nice result for the R/L but then started to look at the FR and levels.. had to redo them all...
No R&L:
Only R:
R&L:
Comment on last: little lack of energy around 1,5k and more level at 5-6k... to be considered...
This is consistent with one of my guru friends that say that there should really not be any difference between using DSP and LRC filters..
I'm still unsure... but here it was not much in it... or?
First "hooray" measurement looked like this after inserting the filter:
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70cm, calibrated levels. 800hz 4th HP in DSP for all 3 meas.
I had to do some FR compensation in DSP to get to the same output level at 1k - especially for the R/L filter one. I think here is where one can get fooled - its really important to compare the exact same FR and level or it can be misleading... I first got a really nice result for the R/L but then started to look at the FR and levels.. had to redo them all...
No R&L:
Only R:
R&L:
Comment on last: little lack of energy around 1,5k and more level at 5-6k... to be considered...
This is consistent with one of my guru friends that say that there should really not be any difference between using DSP and LRC filters..
I'm still unsure... but here it was not much in it... or?
First "hooray" measurement looked like this after inserting the filter:
//
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Hi, I don't know
On a compression driver excursion is very small, also Le is small and so on, so perhaps there is not too much difference as your results indicate, so in that sense perhaps driver motor quality is high, high enough for not much meaningful difference here. I would think it also matters how the driver and horn play together, if the horn/waveguide limits/reduces excursion it's also "damping" similarly as maintaining low series impedance to have electrical damping.
What I'm thinking with damping is that it prevents the transducer doing any extra movement at resonance, where it likes to move easily with any excitation. Any (low frequency) movement would distort the whole bandwidth of said transducer, and in this sense effective high pass filtering to reduce any unnecessary movement, especially one which maintains electrical damping, is very important in regards of distortion performance of any dynamic transducer if distortion is a concern in the first place.
Comparing the first two images, with and without R, everything seems as they should, but it's weird why on the third image with both R and L would have increased 3rd order distortion higher up and why the HF is louder, these HF stuff ought to look pretty much the same as in the only R case. Could there be some error? Regardless, what your results indicate all of this seem quite marginal in your case, and likely have no audible difference at all.
Swept distortion measurements aren't showing everything though, it might be that there is some difference in system context, if external sounds like bass hits affect the compression driver somehow (external excitation) and better electrical damping (with R and L) could make a difference. This is just theory and not sure how to test and is it audible or not and in which circumstances.
I haven't yet done similar test with equalized acoustic output, or any other extensive testing so all this is academic for now, from my part.
On a compression driver excursion is very small, also Le is small and so on, so perhaps there is not too much difference as your results indicate, so in that sense perhaps driver motor quality is high, high enough for not much meaningful difference here. I would think it also matters how the driver and horn play together, if the horn/waveguide limits/reduces excursion it's also "damping" similarly as maintaining low series impedance to have electrical damping.
What I'm thinking with damping is that it prevents the transducer doing any extra movement at resonance, where it likes to move easily with any excitation. Any (low frequency) movement would distort the whole bandwidth of said transducer, and in this sense effective high pass filtering to reduce any unnecessary movement, especially one which maintains electrical damping, is very important in regards of distortion performance of any dynamic transducer if distortion is a concern in the first place.
Comparing the first two images, with and without R, everything seems as they should, but it's weird why on the third image with both R and L would have increased 3rd order distortion higher up and why the HF is louder, these HF stuff ought to look pretty much the same as in the only R case. Could there be some error? Regardless, what your results indicate all of this seem quite marginal in your case, and likely have no audible difference at all.
Swept distortion measurements aren't showing everything though, it might be that there is some difference in system context, if external sounds like bass hits affect the compression driver somehow (external excitation) and better electrical damping (with R and L) could make a difference. This is just theory and not sure how to test and is it audible or not and in which circumstances.
I haven't yet done similar test with equalized acoustic output, or any other extensive testing so all this is academic for now, from my part.
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The more one does mistakes the more there is to be learnt and the more there is progress, so it would be a good thing to mess up, right?
Logically, you'd want to have the resistor with the compression driver to pad it down, as you have, as it would reduce noise from amplifier compared to attenuation with DSP. So the question is whether adding also an inductor is meaninful. As in discussion so far, adding an inductor could improve sound if it restores electrical damping at resonance.
So, you could simplify the test to just compare difference of resistor and resistor with inductor. If you have time, try to make DSP presets for both to get as close frequency responses as possible, very close to each other and what you'd have in application. If you do this, you can take a recording with the measurement microphone and have a chance to A/B test it with headphones if there is any meaninful audible difference. You might try record the whole speaker playing as well, if there is more difference in system context.
Well, if difference is miniscule so that you struggle to hear any you could be quite sure what to think about the stuff at least for the current project at hand. If there is difference you clearly hear, you'd now know which to prefer.
Logically, you'd want to have the resistor with the compression driver to pad it down, as you have, as it would reduce noise from amplifier compared to attenuation with DSP. So the question is whether adding also an inductor is meaninful. As in discussion so far, adding an inductor could improve sound if it restores electrical damping at resonance.
So, you could simplify the test to just compare difference of resistor and resistor with inductor. If you have time, try to make DSP presets for both to get as close frequency responses as possible, very close to each other and what you'd have in application. If you do this, you can take a recording with the measurement microphone and have a chance to A/B test it with headphones if there is any meaninful audible difference. You might try record the whole speaker playing as well, if there is more difference in system context.
Well, if difference is miniscule so that you struggle to hear any you could be quite sure what to think about the stuff at least for the current project at hand. If there is difference you clearly hear, you'd now know which to prefer.
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I find this kind of tests quite fun, it's good exercise for measurements an listening and how they relate, have some understanding of magnitude of things. Even if there isn't any meaningful difference in this particular experiment your measurement and listening skill got up a notch and you should be heading toward better sound anyway
If you go the extra mile, do abother set of measurements and match frequency responses very close, you could do it for the other speaker as well to match left and right while you are at it. A good opportunity to tweak things a bit more and learn even more listening, this time whether matching left and right very close helped with stereo image and how and so on. Have fun!
If you go the extra mile, do abother set of measurements and match frequency responses very close, you could do it for the other speaker as well to match left and right while you are at it. A good opportunity to tweak things a bit more and learn even more listening, this time whether matching left and right very close helped with stereo image and how and so on. Have fun!
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Hah, yeah, caught myself doing just that every once in a while. I think it's another of these occasions which really provide perspective, and the dumb feel likely drops very soon, the minute one has learned something from it
By the way, for all the listening experiments, good way to get perspective and some measure of own listening skill is to do listening tests. For example the harman how to listen test https://harmanhowtolisten.blogspot.com/2011/01/welcome-to-how-to-listen.html?m=1
Found somewhere on internets that reaching level 8, or completing it don't know, would get qualified as "trained listener" participating in their scientific listening studies. So, some kind of a benchmark. If you get way beyond, you can likely trust what you hear, and if not, then probably not, so perhaps keep on training some.
By the way, for all the listening experiments, good way to get perspective and some measure of own listening skill is to do listening tests. For example the harman how to listen test https://harmanhowtolisten.blogspot.com/2011/01/welcome-to-how-to-listen.html?m=1
Found somewhere on internets that reaching level 8, or completing it don't know, would get qualified as "trained listener" participating in their scientific listening studies. So, some kind of a benchmark. If you get way beyond, you can likely trust what you hear, and if not, then probably not, so perhaps keep on training some.
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