Yes, the problem areas can certainly be inside the amp, in fact in earlier years I found most power amps to be problematic, at least on casual listening. The latest breed seem to be considerably improved in key areas, another example that made the right noises for me was the Technical Brain monoblocks, but a system problem can still originate from the power amp, definitely ...
Frank
OMHO, high HOMs due to brutal angle, damped by foam ...
You should read IMHO, the threads: "Hornresp"; "horn versus waveguide"; "Geddes on waveguides", "reviving the Onken", "Beyond the Ariel"...
Several BEM simulations done by Bjørn Kolbrek:
http://www.diyaudio.com/forums/showt...postid=1765863
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I have a pair of kits that were supposed to be for my listening room, but the return of my unemployed offspring has put that on hold.
They'll probably end up in CA. I made sure we had at least one room with NO abbutters.
"Never having to finish anything." Applies for kid's education as well as loudspeakers kits.
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Well, I'm back on the measurement track. I hope to have somewhat 'better' test equipment in future. I certainly saw some nice equipment at the AES. The Stanford Research audio distortion analyzer is a dream to wish for. I hope to get one, if I can get enough work to justify it.
Of course, I will only measure AM distortion. I will have to rely on the work of my colleague Ron Quan to help me sort things in that department. Still, I have hope for even better audio products coming in future.
Of course, I will only measure AM distortion. I will have to rely on the work of my colleague Ron Quan to help me sort things in that department. Still, I have hope for even better audio products coming in future.
You have this wrong I am sorry to say. My waveguides can be proven to have the least HOMs not "high HOMs". The foam is not to reduce them because they are high, the foam is to reduce them even further than the design allows because they are so low. The foam does little to nothing in a device with already high HOMs.
For example, lets say that we have a device with HOMs of some arbitray number, 100, and we have another devices with low HOMs of say 20. The foam reduces each by 10. The poor device is now at 90, hardly even a noticable change, while the better device has had its HOMs cut in half, a major audible improvement.
Please, let's not continue to disseminate false ideas.
horns et al
I read them.... same stuff.... only Geddes has something new to offer. A lot of re inventing the many horn issues....short length, fast expansion etal. And, his seems to be done the most thoroughly and completely including new designs and original and more complete theory. I'd try them just for that reason alone..... need the bass extension as I would only be happy with high quality to 30Hz. Thx-RNM
I read them.... same stuff.... only Geddes has something new to offer. A lot of re inventing the many horn issues....short length, fast expansion etal. And, his seems to be done the most thoroughly and completely including new designs and original and more complete theory. I'd try them just for that reason alone..... need the bass extension as I would only be happy with high quality to 30Hz. Thx-RNM
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Can-you, please, provide third party numbers, compared to some JMLC, as an example ?
Can you provide otherwise? I know of no way to directly measure the HOMs (practically that is) and so I know of no one who has actually done this. I have seen what Mr Leclearc (SP?) claims to be a measurement of them, but it is not, its not that simple. Until someone actually does come up with a way to directly measure them then theory is all that we have. I will stand on that.
I can show in the theory how an OS waveguide will generate the least HOMs because it is a catenoid of revolution and hence has the minimum of rate of change of the boundary slope with axial propagation. Since diffraction and HOMs are directly dependent on the slope change the OS will have the least for a given throat size and entrance angle and mouth angle. Nothing can be lower. A cone is lower, because there is no slope change, except that there is a large slope dsicontinuity at the throat which generates a large amount of HOMs.
Hence, if you can find me some measurements of HOMs that are believable and show my claim to not be true then I would love to see it.
You need to understand that one cannot use the incorrect Webster Horn equation and compare the results to the exact formulation of "Waveguide Theory". It's just not possible or reasonable. HOMs do not even exist in Horn theory.
I would bet that you would write that.
And the French always see things the way that you do, and propagate misinformation about anything to the contrary.
So how can-you justify your "My waveguides can be proven to have the least HOMs "
And blacks have great sens of rhythm, while whites, not.
One thing is true, about French, some of us had been tough to not believe blind to commercial arguments. JMLC have this advantage, he do not pretend, nor sell anything, he just provide calculation sheets with a very scientific attitude.
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I just did, or didn't you read it.
I have no interest in arguing with you about this, it has all been said before in "Geddes on Waveguides", for example. I stand by my work since no one has ever shown it to be faulty and all tests of it have found it to be completely correct, not to mention the wide acceptance of it in the marketplace. I just want to state here that I do not agree with your statements and I have shown why. A responsible scientist would cease using questionable statements until HE can prove them to be correct. And you cannot.
I have no interest in arguing with you about this, it has all been said before in "Geddes on Waveguides", for example. I stand by my work since no one has ever shown it to be faulty and all tests of it have found it to be completely correct, not to mention the wide acceptance of it in the marketplace. I just want to state here that I do not agree with your statements and I have shown why. A responsible scientist would cease using questionable statements until HE can prove them to be correct. And you cannot.
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"And the French always see things the way that you do, and propagate misinformation about anything to the contrary. "
Actually, you said you can show it by theory. You didn't provide a measured proof, but it seems you can provide a mathematical proof.
I assume you mean by "shown faulty", is to prove it mathematically incorrect?
What tests were done to show it correct?
I ask only because it is an interesting set of comments in a really really boring argument..
I've no problem with theoretical proofs by the way..seeings as I kinda live in that world.
Oh, btw. What is HOM, and why is it bad?
Cheers, jn
According to Mr. Gedlee himself:
"Higher Order Mode, its a term that I coined to define waves that propagate in a waveguide that do not go down the axis, but travel by bouncing off of the walls. They are not predicted by the Horn Equation, so most people didn't even know that they existed (I was the first person to hypothesize there existance). The Waveguide Theory predicts them, and low and behold, it turns out that they are quite significant to audibility. Minimizing them yields a far better sound quality. But with "horns" its not possible to minimize them because you don't know what to do - the equations aren't rigorous enough to predict them so they are simply ignored."
Now, you can appreciate my initial joke and all what follows
(Happy to see you here, jneutron)
OH...thanks. Very interesting. It's like fiber cables.According to Mr. Gedlee himself:
"Higher Order Mode, its a term that I coined to define waves that propagate in a waveguide that do not go down the axis, but travel by bouncing off of the walls. They are not predicted by the Horn Equation, so most people didn't even know that they existed (I was the first person to hypothesize there existance). The Waveguide Theory predicts them, and low and behold, it turns out that they are quite significant to audibility. Minimizing them yields a far better sound quality. But with "horns" its not possible to minimize them because you don't know what to do - the equations aren't rigorous enough to predict them so they are simply ignored."
Now, you can appreciate my initial joke and all what follows
(Happy to see you here, jneutron)
Man, I can see how that would be very difficult to measure. The path length differences would cause response variations in frequency, time, as well as horizontal/vertical dispersion patterns.
Trying to test the temporal/amplitude shifts across the entire front of the horn would be a test nightmare. It'd certainly require some kind of measurement which is "non contact", and trying to measure phase shifts in the 10's of microseconds would be a bit "difficult".
I guess the only way to really see the effect would be farfield measurements of dispersion. I don't believe that would be sensitive enough to detect localization perturbations caused by HOM though.
Difficult argument...glad my work involves really simple stuff.
jn
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