Well, normal textbook total response assume that damping is the same going positive and negative. If you model the system such that damping is not symmetric. Then the total response will not be symmetric. I just pulled the BL symmetry out as one apect because this means electrical damping will not be symmetric.dlr said:
Which reminds me the shocks of a car have asymmetric damping.
soongsc said:
What you are saying is that if the input waveform is symmetric, and the damping is not, then the output "waveform" will not be symmetric, which is true. But if the output is an acoustic wave in free space, the output "waveform" must still have to have an average response that is zero, symmetric or not.
And your last example is appropriate because by your argument one could design a cars shock damping that resulted in a DC output of the car and if properly done the car would float away. THAT would be a nice trick!!
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Joined 2003
Probably you missed this post
http://www.diyaudio.com/forums/showthread.php?postid=1763315#post1763315
http://www.diyaudio.com/forums/showthread.php?postid=1763315#post1763315
Very interesting things happen when you change the throat. Note now the directivity is not as good, but much smoother. Actually, at 19.8KHz the directivity is still quite good and still quite smooth.
I actually think if Earl's design had a specially designed driver with a well match with the wave guide, performance could really be such that possibly foam would not be necessary.
I actually think if Earl's design had a specially designed driver with a well match with the wave guide, performance could really be such that possibly foam would not be necessary.
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To me this is the same logic that had people removing phase plugs from tweeter and claiming cleaner more pure sound, when in reality it caused the exact problems it was designed to fix to come back.
If the "thing" in the signal path has linear loss, whats the big deal? The effect is known, linear, and predictable, so it can be corrected for in the crossover. What's left then, what's wrong with the foam plug?
I hear people make claims like, loss of resolution. I don't understand that, why? What scientific reason could something like grill cloth, a foam plug, a phase plug, etc. cause resolution loss. If it does, I'm pretty sure it would be measurable. In fact, in this particular case, it seems like removing the foam would have the opposite effect.
If the "thing" in the signal path has linear loss, whats the big deal? The effect is known, linear, and predictable, so it can be corrected for in the crossover. What's left then, what's wrong with the foam plug?
I hear people make claims like, loss of resolution. I don't understand that, why? What scientific reason could something like grill cloth, a foam plug, a phase plug, etc. cause resolution loss. If it does, I'm pretty sure it would be measurable. In fact, in this particular case, it seems like removing the foam would have the opposite effect.
Matt, you were typing while I was typing, but you beat me.
You are really catching on. Your comments are extremly perceptive and right on the money. Its envigorating to hear someone who has seen the light! I can only hope that in some way I helped you along this path. I wish that I had students like you!
You are really catching on. Your comments are extremly perceptive and right on the money. Its envigorating to hear someone who has seen the light! I can only hope that in some way I helped you along this path. I wish that I had students like you!
Well, if there is not other way that can be found such that a phase plug or foam has to be used, then so be it. But if there is another way to solve the problem so that the same effect is achieved, some people may take a different route. Most phase plugs on tweeters that I measured with and without were to suppress hight frequency cone breakup. So you mostly will see them on stiff domes. It is true that without the phase plug, there will be a little more resolution. But the cone breaup mode will cause harsh sound. So, if you only have two choices, most would likely select a smoother sound.
Yes, grill cloth does reduce resolution. Some people choose the good looks of the grill cloth and willing to give up that little resolution, some people remove the grill because they like better resolution. Just because one person cannot here a difference does not mean others cannot either.
Personally, I think if any designer thinks that there is not room for improvement. Then life becomes boring without any challenges. I like to see my students outperform me.
Yes, grill cloth does reduce resolution. Some people choose the good looks of the grill cloth and willing to give up that little resolution, some people remove the grill because they like better resolution. Just because one person cannot here a difference does not mean others cannot either.
Personally, I think if any designer thinks that there is not room for improvement. Then life becomes boring without any challenges. I like to see my students outperform me.
First post here, been following this thread for a while.
Earl, do you know anything of the SP technology designs? They are much lower efficiency (87db IIRC) and use soft domes in their waveguides and no foam. (I think they used t use ring radiators in previous evolutions).
As for the info I can find, people who have heard/used them are absolutely raving about them, which makes little sense to me, unless Bob has actually figured out a way to deal with the throat / dome surround termination dilemma.
So far the only skeptics I have come across have never heard them. This is not my own plug for them, but since I will probably never hear them, it would be interesting to hear somebody who may have heard them to give them a bad rap. I figured some people following this thread may have come across them since, like the summas were, are sold by a VERY small company with no real marketing division.
Earl, do you know anything of the SP technology designs? They are much lower efficiency (87db IIRC) and use soft domes in their waveguides and no foam. (I think they used t use ring radiators in previous evolutions).
As for the info I can find, people who have heard/used them are absolutely raving about them, which makes little sense to me, unless Bob has actually figured out a way to deal with the throat / dome surround termination dilemma.
So far the only skeptics I have come across have never heard them. This is not my own plug for them, but since I will probably never hear them, it would be interesting to hear somebody who may have heard them to give them a bad rap. I figured some people following this thread may have come across them since, like the summas were, are sold by a VERY small company with no real marketing division.