Hello All,
The conversation and posts regarding types of crossovers and linier vs. nonlinear distortion are interesting. I bet that the testing now being done will show that these effects will be at least 30 db’s down and (IMHO) will not be leading design considerations that need correction for the ZDL to excel. Put it another way simple is good!
I see the complexity coming in integrating the square edged woofer enclosure with the organic shape of the mid enclosure and the tweeter with the mid as the challenges. The integration will include the achievable center distances of the drivers and crossover points (minimize beaming, doing it on purpose). Tying those physical shapes together smoothly will require some relaxed thinking.
DT
All just for fun!
The conversation and posts regarding types of crossovers and linier vs. nonlinear distortion are interesting. I bet that the testing now being done will show that these effects will be at least 30 db’s down and (IMHO) will not be leading design considerations that need correction for the ZDL to excel. Put it another way simple is good!
I see the complexity coming in integrating the square edged woofer enclosure with the organic shape of the mid enclosure and the tweeter with the mid as the challenges. The integration will include the achievable center distances of the drivers and crossover points (minimize beaming, doing it on purpose). Tying those physical shapes together smoothly will require some relaxed thinking.
DT
All just for fun!
Trying to update to SE ver17 is taking me weeks now – several emails to Bohdan plus money sent - no luck.
(well, luckily I'm a patient guy in such things...)
Seems someone is a little bit afraid I may demonstrate some limitations to „ULTIMATE“
Michael
My apologies to Bohdan - SE ver 17 upgrade arrived just a few hours ago !
Now another fun work can start...
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Still on the Bodzio Software site. This version has some options to apply it to home theater systems. Very interesting.
Note that Bohdan has spent time over the years to generate some good stuff for DIYers even though it's not enough to really make a living out of; more importantly, he's relatively open to different ideas.
Hey, wait a minute. I posted exactly that the roll of the LCR was to make the driver impedance look purely resistive so that the cap of a simple HP filter does not resonant with the VC Z. So please don't include me in saying that type of artifact is B**S. I don't mind arguing on different side of things we might disagree on, but please don't include me in someones elses rap.
Ok, I'll be more specific. Your take on it was that resonance is linear and doesn't have non linear affects (such as the energy spike observed in the driver operating near resonance without an LCR)
Sorry, it's a little bit of work trying to keep track of everybody's exact position on things.
The only one whose position is inexact would be yours and I'm not the only one whose noticed that:Ok, I'll be more specific. Your take on it was that resonance is linear and doesn't have non linear affects (such as the energy spike observed in the driver operating near resonance without an LCR)
Sorry, it's a little bit of work trying to keep track of everybody's exact position on things.
To quote Dr. Geddes earlier:
The rest of us have been very clear as to our positions. You have consistently mis-stated what many of us have said and it's not appreciated. I would ask the moderators if consistent behavior such as this is acceptable. If so, fine, I'll just go to other boards. This is more than tedious.
Dave
Ok, I'll be more specific. Your take on it was that resonance is linear and doesn't have non linear affects (such as the energy spike observed in the driver operating near resonance without an LCR)
Sorry, it's a little bit of work trying to keep track of everybody's exact position on things.
The problem is that you keep on referring to nonlinear that isn't there, or if it is, it is not the dominant factor. If there are nonlinear effects then they defeat the role of the LRC shunt as well because the LRC shunt has to be tuned to compensate for some specific impedance peak. If that peak changes nonlinearly with conditions, then the LRC will not compensate correctly.
There are 3 issues; 1) the damping of the driver, 2) the electrical transfer function which defines the voltage across the driver's terminals, 3) and the transfer function which describes the acoustic output of the driver.
When a line level crossover is used, say a cap before the amp, the voltage applied across the driver is dependent only on the diver's impedance and the amplifier output Z, ignoring things like cable Z. If the amp's output Z is very small (high damping factor) then the the voltage is essentially independent of the driver's Z. The damping of the driver is defined by the DC resistance of the VC in series with the amplifier output Z. The acoustic transfer function is the product of the acoustic transfer function of the driver connected directly to the amp times the transfer function of the voltage applied across the terminals.
In the case where a passive crossover is used with a shunt, the voltage across the drivers terminals will be constant provided the driver's impedance doesn't change with conditions and the shunt is designed to reduce the driver Z to purely resistive at and around resoance (not necessarly a cup of tea). Assuming that to be the case, the voltage across the driver's terminals could, in theory, match that of the line level crossover. However, the acoustic output of the driver will not be the same because now the damping is defined by the DC resistance of the VC in series with the impedance found as the shunt in parallel with 'the cap in series with the amplifier output Z'. This means that Qt of the driver is different than when connected directly to the amp and while the applied signal is the same, the driver responds differently to it and yields a different acoustic output. If the cap in series with the amps Z is ignored then the damping at resoance would be the DC R of the driver in series with the R of the shunt. Since R of the shunt is typically of a similar value to that of the VC DC R, then Qts will increase because Qes would effectively double.
If the driver's impedance is nonlinear at resonance (due to all that nonlinear stored energy you are so fond of), your LRC will be miss-tuned onder some operationg conditions and the cap will still have the potential to resonate with what ever reactive component is present that the shunt fails to compensate for. So now even the voltage applied across the driver will vary because the crossover cap will not see a constant load.
You can not wave the nonlinearity flag when it suits you and ignore it when it doesn't.
The same thing applies to your TL damping. You can't change the rules to favor you side of the argument. As I said before, it is not possible to correct nonlinear behavior with a linear correction be it active or passive.
I think that cuts both ways, Dave . . . I don't find "your positions" at all clear or consistent (except the ongoing promotional efforts for UE . . . which belong down in the vendor section, not here). And you commonly mis-state other commenters positions for the purpose of your own arguments. If you were less tainted in such things yourself your objections (where accurate) to such behavior in others would carry more weight. Having a hammer does not make everything into nails, and over dependence on a single model can blind one to a lot of the complexity that reality presents. That not everyone sees things through your narrow window doesn't make them "wrong". That they don't express everything they see (hear) in the narrow terms of your model doesn't make them "wrong" either. "Personalizing" everything (usually for the apparent purpose of shutting out "non-conforming" ideas) doesn't help either . . .
Yes, the LCR trap only works perfect if there is no dynamic change of the fundamental resonance. Nevertheless in praxis it works surprisingly well when the crossover frequency is not too low. Concerning the audibility of distortion i attended a test put together by Klippel. I could just identify low order distortion of -40dB. Higher order distortion like the 5th and the 7th are more audible but we can safely asume that well made drivers produce mostly 2nd and 3rd and most of the time 3rd is lower then second. In the bass it is well known that the ear is even more tolerant. 10% low order distortion at 20Hz is still OK. Also when the level goes over say 93dB the ear starts to distort itself. I whould asume that a modern speaker well made can have low enough harmonic distortion so that it is not annoying at listening levels that are safe for the ear even if there are short duration peaks of say 100dB. This was confirmed when Dr.Irrgang of Klippel visited me and heard a well designed speaker in my house. Nevertheless the Klippel system was instrumental and drivers i get now from SEAS ( they use Klippel ) have around 10dB more dynamic range then they had say 15 years ago. They simply can play louder without ( audible ) distortion. Klippel today is very active concerning smaller loudspeakers put into cell phones, computers, cars and the like. If he likes it or not, even Mr.Geddes is profitting from Klippel. B&C that make drivers for Geddes use Klippel intensively. Anyway, i agree with Geddes generally that well designed speakers not driven into compression have low enough distortion that we can say that they are "good enough" so that lowering distortion even more seems not very important.
DT, i now will reveil my bass strategy. It will be an isobaric system vertically mounted so the midrange sits on the top of the bass driver magnet.
DT, i now will reveil my bass strategy. It will be an isobaric system vertically mounted so the midrange sits on the top of the bass driver magnet.
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