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Old 1st May 2009, 06:00 PM   #1071
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by gedlee


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But it would still work. I have done CAD software and never used the concept of minimum phase at all, it works fine. I will repeat again, for the umpteenth time, you will not find the notion of minimum phase used in any text in acoustics. That it can be applied in SOME circumstances is, to me, completely beside the point.
I take it that you feel time alignment is not important?
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Old 1st May 2009, 06:33 PM   #1072
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Originally posted by markus76
Thanks for pointing me in the right direction, suddenly all of your posts make so much more sense: "This person is on your Ignore List. To view this post click [here]"

Bye and have a good life

wow, thanks for pointing out this functionality... I didn't know it was possible. It's great!
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Old 1st May 2009, 06:38 PM   #1073
gedlee is offline gedlee  United States
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Originally posted by dlr


I have followed your references to your software and I recognize the absence of MP in them. However, I am unaware of any commercial software that does not rely upon MP to some degree. Are you aware of any commercial software that provides similar functions, yet does not rely upon MP? Your software is not commercially available to the public if I'm not mistaken.

Dave

My software is and has been commercially available, although now it is free, so I suppose that's not commercial anymore. I am not an authourity on what software exists or how it is implimemented. But let me ask, just what is it that MP makes easier or is required in "CAD" software? (By CAD I was assuming that you mean array and speaker predictions in rooms. Otherwise I don;t understand.)

Quite honestly though, I am just not that interested in a continued MP discussion. It's just not that important to me. If it makes your life easier then fine use it. I just do everything complex in all cases and if its MP or not is of no matter. The concept does allow some simplifications for EQ discussions, but only in as much as we are talking about single points and not sound fields.
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Old 1st May 2009, 06:47 PM   #1074
gedlee is offline gedlee  United States
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Quote:
Originally posted by soongsc

I take it that you feel time alignment is not important?
Soongsc

Sorry you are taking such heat, but you are well known for speaking about things with an air of authority that is apparently unjustified. Questioning might be a better tact in your situation that making such bold statements.

Time alignment is important in that it has a major effect on the polar pattern at the crossover. One finds that obtaining a good polar response at crossover necessitates a near time alignment of the drivers to come out right. But the need is for a good polar response and not for some belief that phase matching or phase itself is an audible characteristic. What is audible is the poor polar response that one gets when the two drivers do not have the minimum time differential between their signals.
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Old 1st May 2009, 06:57 PM   #1075
xpert is offline xpert  Afghanistan
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Quote:
Originally posted by gedlee

Well you are both wrong. Morse is one of the formost Physicists of the 20th century and doesn't get things like this wrong. Read it in his book - Morse, P.M., "Vibration and Sound" - last page of the book pg. 429 Do a "further analysis" if you dare! If you have the capability to do that! Show its wrong or recind your comments!

Sorry Earl,

The context is lost a bit now. I've got a degree in high energy physics. So people once ment that i've got some capabilities. Thats for the record only.

Your claim was:
In it he shows how a mode in steady state will vibrate at the driven frequency even if its not precisely on that frequency, but, and this is the NON-minimum phase part, the decay occurs AT the resonant frequency. For example, lets say we have a mode at 51 Hz and we drive it at 49 Hz. In the steady state the enclosure has 49 Hz in the sound field, but when I turn off this source, the sound field slowly (relative to the decay rate) changes from 49 Hz to 51 Hz. No electronic system can do this and to call this kind of phenomina "minimum phase" is certainly not correct. Acoustics is not electronics and behaves quite differently.

I think using the term "AT frequency" provoces a missconception. Switching the power source off is the same as driving the system with an anti-signal. This anti signal will not consist of one special frequency but of a broader spectrum. The system will -linearly- react to all that new stuff on its input. It is not easy explained to common people, but I think You're educated enough to check out things.

Regarding these basics all systems called resonators do the same. That is the use in models, abstracions etc.

Again. If we talk about a single certain -frequency- then by pure logic (math) we talk about steady state. No temporal development. If we talk about -time-, temporal development of systems states we should use the term -spectrum. Would have been doing so many anger could have been avoided in the past.

As a first example lets get te misleading term "decay on resonance frequency" right. If the systems energy decays, it will show a spectral distribution around its defined resonance frequency. The width of that distribution is determined by the "Q".

Terms like "minimum phase" etc have to do with the transfer function of a system. These characteristics can not be derived from the basic mechanical or electric model as being a resonator. The transfer component is missing in the first place.

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Old 1st May 2009, 07:07 PM   #1076
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by gedlee


Soongsc

Sorry you are taking such heat, but you are well known for speaking about things with an air of authority that is apparently unjustified. Questioning might be a better tact in your situation that making such bold statements.

Time alignment is important in that it has a major effect on the polar pattern at the crossover. One finds that obtaining a good polar response at crossover necessitates a near time alignment of the drivers to come out right. But the need is for a good polar response and not for some belief that phase matching or phase itself is an audible characteristic. What is audible is the poor polar response that one gets when the two drivers do not have the minimum time differential between their signals.
I understand your point concerning time alignment.

I don't mind taking heat. Most people don't have the knowledge to prove me wrong, thus the conflict. I think any new point of view will face this kind of rejection. The ultimate decision is made by customers, optinions of which I always spend time to try to understand rather than reject. I do communicate with audiophiles, and in many cases, they find similar trends that I predict. Some of which are related with horns/guides.

Anyway, anyone with an open mind will learn faster and have more fun than those that don't. I think we will be making some news a few months from now.
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Old 1st May 2009, 07:14 PM   #1077
gedlee is offline gedlee  United States
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Your analysis is lost on me - sorry. I don't follow it at all. And some phrases are not even sentences like:

"As a first example lets get te misleading term "decay on resonance frequency" right. "

I never used the phrase "decay on resonance frequency" so I have no idea what the quotes mean. The rest of the discussion is just as illusive. If you want to have an intelligent discussion about the math thats fine, but you at least need to write in complete sentences and in a comprehensive manner.
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Old 1st May 2009, 07:16 PM   #1078
gedlee is offline gedlee  United States
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Quote:
Originally posted by soongsc
Most people don't have the knowledge to prove me wrong, thus the conflict.
I do. I have. You ignore it. That's the conflict.
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Old 1st May 2009, 08:01 PM   #1079
xpert is offline xpert  Afghanistan
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Quote:
Originally posted by gedlee
Your analysis is lost on me - sorry. I don't follow it at all. And some phrases are not even sentences like:

"As a first example lets get te misleading term "decay on resonance frequency" right. "

I never used the phrase "decay on resonance frequency" so I have no idea what the quotes mean. The rest of the discussion is just as illusive. If you want to have an intelligent discussion about the math thats fine, but you at least need to write in complete sentences and in a comprehensive manner.

Earl,

You wrote:

"For example, lets say we have a mode at 51 Hz and we drive it at 49 Hz. In the steady state the enclosure has 49 Hz in the sound field, but when I turn off this source, the sound field slowly (relative to the decay rate) changes from 49 Hz to 51 Hz. No electronic system can do this and to call this kind of phenomina "minimum phase" is certainly not correct. Acoustics is not electronics and behaves quite differently."

Sorry for being insistently. What You wrote above is in no way supported by contemporary knowledge (remember my degree in physics?). Neither is the maths of mechanical systems in any way different from that of electronic systems in this scope. Nor does the decay mechanism drift from one frequency to an other. Neither abrupt nor gardually. If so it could never be called linear, that simple.

Again, there is no relation to any phase, especially no so called minimum phase.

You have to admit a misstake. Anybody is prone to such anytime, nearly. So, as You are a native speaker please forgive my incomplete whackey so called sentences. I'll try to live up to Your expectations. I wish You would live up to mine.

thanks a lot
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Old 1st May 2009, 09:07 PM   #1080
gedlee is offline gedlee  United States
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Quote:
Originally posted by xpert



Earl,

You wrote:

"For example, lets say we have a mode at 51 Hz and we drive it at 49 Hz. In the steady state the enclosure has 49 Hz in the sound field, but when I turn off this source, the sound field slowly (relative to the decay rate) changes from 49 Hz to 51 Hz. No electronic system can do this and to call this kind of phenomina "minimum phase" is certainly not correct. Acoustics is not electronics and behaves quite differently."

Sorry for being insistently. What You wrote above is in no way supported by contemporary knowledge (remember my degree in physics?). Neither is the maths of mechanical systems in any way different from that of electronic systems in this scope. Nor does the decay mechanism drift from one frequency to an other. Neither abrupt nor gardually. If so it could never be called linear, that simple.

Again, there is no relation to any phase, especially no so called minimum phase.

You have to admit a misstake. Anybody is prone to such anytime, nearly. So, as You are a native speaker please forgive my incomplete whackey so called sentences. I'll try to live up to Your expectations. I wish You would live up to mine.

thanks a lot

Lets forget about the minimum phase comment, thats a whole other can of worms.

If you dod not recall I too have a PhD in Physics, in Theoretical Physics to be precise, and my math skills are not rudimentary.

I stand by my statements as correct as shown by Morse in said text and they are not wrong simply because YOU say that they are wrong. The burdon of proof is on you since I have attached my proof from the work that I described.
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