You're making other unsubstantiated claims. Rather than sidestepping, how about actually responding and supporting the various claims you keep making. This one was a direct claim and made today:soongsc said:
Studies? Many things? Detail those, please. If you don't have valid, competent measurements to support this, how can anyone accept what you say without seeing it as pure speculation and conjecture? You seem to base your conclusions on limited data that "seem to show" results. Do you have anything, anything at all, to fully substantiate any of your (undetailed) claims?
Dave
Well there is no measurement data showing showing that the OS will have a spherical wave front at all frequencies in the range it is designed for either. So let's see what will surface.dlr said:
Totally immaterial and completely lacking any technical merit. Why don't you simply admit that you have no competent data to support your claims nor any that refutes the claims you contest. I see nothing, nothing at all relevant at this point. You're getting seriously close to hand-waving with that response.soongsc said:
Dave
Well, if you can do better, please provide your own. I certainly have no objection to looking into various data taken by various individual.dlr said:
soongsc said:
YOU can't support YOUR claims, so I am supposed to "do better"??? YOU should do better or stop making your as yet unsupported claims that OTHERS who HAVE done credible research are wrong. I am not the one making the claims.
Dave
Well, based I what I have explained. If there is anything wrong, please feel free to point them out in the level of detail as I have done. 😉 Right now nobody has pointed this out. Some choose not to accept it, and it's fine.🙂dlr said:
soongsc said:
Soongsc,
I as well as others feel that you have added nothing of value to this thread. You have been pointed out many times by Geddes to not understand some basic concepts yet you keep making claims against more advanced subjects. The items that you do mention don't make any sense.
Again, I urge you to start your own thread where others may contribute to the vast amount of data and goals that you have. The contributions that you have brought to this thread are confusing at best.
Just my humble opinion of course.
Throught the thread, if any pointed out very specifically what was wrong, and I did find it to be wrong, I would admit it. But such general accusations such as "you don't understand the basics", four fingers are pointing the oposite way.goskers said:
It's going to be a while till I have anything new. So as long as nobody gets personal with me, I'll be quiet for the time being.
Member
Joined 2003
Hi Earl,
I believe you've mentioned that the OS generates the lowest diffraction possible. To further my understanding, can/would you point me to drawings illustrating how the OS curve generates the least diffraction?
Thanks,
Paul
I believe you've mentioned that the OS generates the lowest diffraction possible. To further my understanding, can/would you point me to drawings illustrating how the OS curve generates the least diffraction?
Thanks,
Paul
Paul W said:
Think of it this way. Diffraction is created by a change in the slope of the waveguides bounding surface. The amount of difraction therefor depends on the second derivative of this bounding curve. If you calculate that curve that has to start out straight (to match the driver, assuming a plane wave) and end up at some angle and has the smallest second derivative, you will find that the curve that minimizes this function is in fact the OS contour. Its a simple double integration. Its called a catenoid, and is also the minimum surface area connecting a flat disk to another larger flat disk. where the initial slope at the smaller disk is given.
If you don't follow the math then there is no way to actually prove this statement and drawings don't help.
A straight sided cone has, of course, zero second derivative, but it doesn't meet the condition of zero initial slope. So a cone is minimum, but only if you can somehow get a spherical wavefront at its opening. That would not be easy even if at all possible.
Member
Joined 2003
Paul W said:
There isn't a lot of velocity at the boundary so I don't see this as a major effect. Its not like the port on a woofer, which has very high velocities along its entirety.
454Casull said:
This source radiates a omni directional spherical wave right? OK, The waveguide admits only a small solid angle of a spherical wave, not the whole sphere. What do you do with the rest of the wave? Absorb it? Well maybe, but no absorption is that good and any reflected portion of the wavefront arriving at the waveguide throat is a disaster as it would completely defeat any advantage that the conical waveguide would have. Further this all assumes that the wavefront is "perfectly spherical" which is a big assumption. And let's not forget about the heat from a plasma source completely enclosed in a thermal blanket. Wow! I would not want to be the engineer on that project. You can hypothesize about these kinds of sources all day long, but actually producing them effectively is another thing altogether.
gedlee said:
I comprehend the basic statement here.. but it does not address if an "..OS generates the lowest diffraction possible".
In fact I don't think such a claim *could* be correct without a multitude of caveats and/or a seriously limiting definition of "lowest diffraction possible".
Perhaps "lowest overall diffraction throughout the usable extended pass-band with an appropriate high-pass filter".
"Overall" would have to be generous.. but not unreasonably so. 😉 "Extended Pass-band" would also have to be defined.
In any event..
What is audibly important and why?
In other words: is a decrease in diffraction from one "conical'esq" profile audibly better than another? If so, why? Or is perhaps which profile has the "lowest overall diffraction throughout the usable extended pass-band with an appropriate high-pass filter" MOOT?
Without answers to such questions its all just posturing.
gedlee said:
Hi Earl,
I was just wondering if you have had a chance yet to start working on the polar plots. I will be very interested to see the OS waveguide / Le Cléac'h horn comparison, and to read any comments that you might have on the results. Many thanks for volunteering to do this.
Kind regards,
David
Thanks for the explanation. I don't think complete absorption of the non-admitted wave is impossible, but the thermal issue does seem to be a bit difficult. Diffraction from the throat of the waveguide could be an issue as well.gedlee said:
ScottG said:
Sounds like semantics to me, but your words are fine, its the same thing for alol practical purposes.
ScottG said:
We know that HOM are not good, but we don't know precisely at what level they become audible or objectional. But we also know that their audibility is SPL level dependent (our AES paper). Hence the "best guess" at this point is that the lower the HOM are the louder the device will play before they are objectionable. That appears to be the hypothesis that is best supported by the data at this point. Hence it is anything but MOOT for a loudspeaker whose design intent is to achieve very high SPLs. It is MOOT for low level SPLs.
As anyone who has heard my speakers will tell you their ability to play extremely high SPLs without audible distortions is second to none. This is strong support for the hypothesis given above.