I would also like to buy/build/listen to your system as well. Is it available to buy or to build from plans? Thx-RNM
Yes, they are. The best studio monitors I ever heard. But they are different. The point is, to compare two completely different approaches that can lead to very similar results.
Who is a genius?
Marilyn vos Savant - certified by the Guiness Book of World records has the highest recorded IQ of any living person. But, never inspired a new genre in any field. Many exceptional achievers do not attain genius-level IQs. W. Shockley had an IQ well below 140. But, B.Pascal IQ was in the 180's. So, IQ is not the best indicator of genius.
Genius goes to those who produce original and exemplary accomplishments.
Interesting research on creativity -Scientific American Mind: Think Like a Genius. How exceptional intelligence and creativity arise. Nov/Dec 2012.
Marilyn vos Savant - certified by the Guiness Book of World records has the highest recorded IQ of any living person. But, never inspired a new genre in any field. Many exceptional achievers do not attain genius-level IQs. W. Shockley had an IQ well below 140. But, B.Pascal IQ was in the 180's. So, IQ is not the best indicator of genius.
Genius goes to those who produce original and exemplary accomplishments.
Interesting research on creativity -Scientific American Mind: Think Like a Genius. How exceptional intelligence and creativity arise. Nov/Dec 2012.
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Good point. But if air is treated as an elastic medium being worked by pressure variations in it’s linear range, would things differ much or at all from optical/EM phenomena (apart from philosophical issues)?
Problem is when air is stressed in closed or semi- closed "conduits", we enter the territory of it’s local non linear behavior. Time scale of phenomena play a role there too.
(this is a question from my part: In electromagnetics, with high energy, short time bursts, does vacuum properties (eo, μο) change values locally?)
George
It is a sad story.
The author had leaved the shop, long time ago. After a while, the bass loudspeaker was not available any more. A new guy started to redesign-it with a new loudspeaker and a new filter.
The original filter was pretty complex, with correction for response curve and flat impedance, symmetrical, big coils...The new one look to simple to be honnest
Too, i doubt if they continue to sort and pair the JBL drivers too...It is a sad story...The machined plain wood big horn is available, i believe it has not changed...
There is some pairs of enclosures on the second hand market, but need to be sure it was the good version.
My version at home is unique. Active filter now.
About digital active filters, how many of you use them ? And , if some, what is your comments about equalization and group delay tuning ?
I had some trouble at the begining with coherency between the transducers at hight transients... until i used the same power supply for the two ways power amps (bass+treble).
Same feeling that the stereo image stability problems with mono-blocs.
Am-i alone to prefer a unique PSU for the 2 stereo ways ?
I had some trouble at the begining with coherency between the transducers at hight transients... until i used the same power supply for the two ways power amps (bass+treble).
Same feeling that the stereo image stability problems with mono-blocs.
Am-i alone to prefer a unique PSU for the 2 stereo ways ?
I do not think that a lens is a good comparison. Chromatic aberation is comparable to frequency response aberation, but that's about all.
The lowest mode in a waveguide is spherical, but the HOMs are not. HOMs are created when the boundaries of the device deviate from those that allow a spherical wavefront to develope. There is precisely one boundary that allows for the developement of a spherical wavefront from a flat circular source and that is the OS. The physics of wave motion will decide what the shape has to be for this to happen, not the horn designer. One cannot simply assume that a wave will follow a given boundary, the correct boundary has to be determined not specified.
The radius of the throat determines the cut-in frequency of the modes. This is all discussed in detail in my papers and my book. My book is now avaialble on-line at Geddes on Audio
Sound is a wave not a particle, this analogy is not valid.
The nonlinearity of air is not an issue at reasonable SPL levels.
I did not say that they were not measureable, I said that they were very hard to measure. I have done some tests that show some results, but its like looking for a needle in a haystack. It takes very high resolution and complex signal processing.
The question is, to me at least, what would be the point? Just to prove to people that what I have been saying is correct. I am not in any doubt. All of the theory has played out so far why would HOMs be any different? In my designs I know the HOMs are as low as they can be, hence measuring them is not going to change that. Do measurements to compare them to other designs? I'm not interested in that either. I know my designs and I've see the results form others, I am not interested the alternatives. I am not new to this, I have been studying and writing about horns and waveguides for more than 40 years now. There is not much left for me to learn. There are some things that I am doing, but as all know research takes time.
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Hi, how do you deal with the ground loops in this case? Or is it a non-issue?
Maybe the inputs of your amps are differential and you lift the shield of the cables?
Thanks
-Alex
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Where is the difference between preamp and amp on this point ? Star grounding.
I use symmetric cables, and the shields are connected only source side (no current). If asymmetrical cabling, the second signal cable carry the reference.
In amps circuits themselves, it is better to have separated ground returning to the ground point for input stages including VAS and power stages. It is well known.
I use to measure, before connecting elements, the AC leakages between them respective grounds, and chose the AC sens of oultlets measuring the less V. Toroidal transformers are not the best regarding this problem of AC leakages.
Chromatic aberration is just a difference of deviation angle in regard with wave lenghs.
Like in a prism.
That is when the walls of the horn are perpendicular all the way to the wave front, i presume ?
So, there is a shape that will produce no or little of those HOMs. And designing horns for pseudo spherical waves (depending on the driver) was not a stupid idea... I will try, one of these days, to build a horn with silicon on the first centimeters of the throat, like in human ears, to see if any added damping...
Well, at the end, i can understand the effects on those HOMs on spatial response curves, not on distortions, if air non linearity is not an issue.
Happy to know that comparing distortion and spacial frequency responses curves is enough to evaluate horns. My nights were full of HOMs nightmares. (smiley here)
Thanks for your explanations, Mr. Gedlee.
I think you mean balanced/differential cables? In this case I too would lift the shield at receiver side, like it is done in studios.
Maybe because of higher parasitic capacitance between windings. I like the R-Core types, but they are expensive above 100VA.
Thanks
-Alex
In studios it is done usually after failed attempts to find guilty part in mixed symmetrical and asymmetrical interconnects.
I would think that at the extremes the tests would have huge error bars because we simply don't understand.
Maybe it should be done this way by design. I have seen this recommendation in a console installation manual. They recommended a true star ground, with all interconnects balanced and the ground connections being through the AC outlets only.
thx
alex
Current-feedback, but you can leave the original differential stage - input for quasi symmetrical input, and improve CMR and PSRR.
(Wolfman jack's voice: "Yeah, man, i used two acronyms !")
I once heard from a professor that the true inventors of the transistor were Bardeen and Brattain, with Shockley entering later as the project supervisor. And that they weren´t too happy when Shockley took the lead for the famous picture:
An externally hosted image should be here but it was not working when we last tested it.
thx
alex
Shockley was a clever and complex character, quite a promoter. Anyone in here old enough to remember his four-layer diodes? I mean, besides me
And then he associated himself with the genius sperm bank stuff, hilariously parodied on Saturday Night Live when Rodney Dangerfield hosted.Bardeen was amazingly bright and insightful, apparently rather self-effacing, and is the B of the BCS theory of superconductivity. To date he remains the only double-Nobelist in the field of physics.
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