I see we think alike..
That must put insane requirements on the surface durability and harness of the prop. I can see them being chewed up rather quickly.
jn
Attachments
Excellent, thanks..
jn
I've been busy machining the hardware portion. The setup requires 3 watchmaker lathe setups on one assembly. Two are in line coaxial, with runout under a tenth of a mil, and a third one parallel. I've chosen brass on brass conical bushings instead of bearings, due to the immersion part. I've been trying to get a nice dry lubricant to coat the brass bearing surfaces, but the manu seems intent on e-mailing me to death rather than sell me product. I've been able to measure about 1/4 mil runout, but don't yet have the ability to go lower..
The electronics is easy by comparison, I've designed the pass through resistor set, purchased the resistors and brass sheet, as well as some 0000 centering drills, they're in the mail as we speak.
I had to re-furbish the lathe bed, it was being cranky. I made one steadyrest, and now I'm waiting delivery of a morse 2 taper for the female bushings. I tried using the lathe to produce an inner taper, but my skills are not up to it so I'm punting with the morse tools. I'll turn the male conical sections to match the morse 2 taper.
Till the reamers come in, I'm working on a hot wire cutter to make foam based windmill blades for a STEM project at a local middle school. Got 400 feet of 26AWG nichrome C, made the setup for supporting the blank and a bow for the wire, and have been machining the parts for a generator set for testing various blade geometries and angles of attack. I'll be using a surplus 19 inch box fan feeding a tunnel, with a 2.5 inch thick soda straw stacked collimator to remove the spiral turbulence coming out of the fan.
The kids will be tasked with designing their own airfoil, figuring out the taper of the blades (3), cutting the blades, and then testing efficiency vs attack angle. For now, I'll use a simple resistor as the load, but may build a variable shunt regulator to force the generator into constant rpm mode. Since it's 8th grade, the teacher will be determining the level of the program, I'm not aware of his class's level of ability.
jn
What I discuss is what I do at home. It takes a long time because I can only devote 2 or 3 hours per week to it. At the present time, building the tools I need is half of the effort.
jn
Jan and PMA you mentioned the ExtemeA amplifier last week. I took a quick look and is looks to me like another version of closed-loop buffer output but with the quiescent bias in the same loop. Geometric-mean biasing is related but here it looks more like arithmetic mean with output current max only 2X the bias current. Is this really practical with load phase and magnitude variance of a wide range of speakers?
It does enclose the Vbe's of the output triple in a feedback loop, similar to other error correction schemes. However a class A/B biased at half max output does not have that much Vbe modulation or crossover.
It does enclose the Vbe's of the output triple in a feedback loop, similar to other error correction schemes. However a class A/B biased at half max output does not have that much Vbe modulation or crossover.
Or other issues of far more importance...sigh..And that's without the article for Linear Audio
Jan
jn
Contradiction in terms
Jan
One can only hope. Health of loved ones tends to induce tunnel vision.
jn
Thread Dead?
Say it ain't so! I've learned a lot from people here. Thanks to all of you who have shared knowledge!
Cheers,
Howie - WA4PSC
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
Say it ain't so! I've learned a lot from people here. Thanks to all of you who have shared knowledge!
Cheers,
Howie - WA4PSC
Howard Hoyt
CE - WXYC-FM 89.3
UNC Chapel Hill, NC
www.wxyc.org
I have learned a thing or two, here as well. Mostly from links and measurements supplied by others.
The problems and debates that started this thread are still real, at least to my colleagues, who still toil at making better audio designs.
There have been recent developments, like Ron Quan's recent AES paper on FM related distortion, first given at the AES this week. I just read through it, and it will take more than a first look to get the most out of this paper. Ron wanted to make a 30 page paper, but he was forced to reduce it to 11 pages, or else pay extra for the added length. He wrote about 3 papers and put them into one. Therefore there is lots of data but it is hard to fully comprehend at a glance, that's for sure.
This gives me hope that someday we will learn what is really important in audio design, especially with electronics, and overcome the 'hear no difference' bias that is prevalent today.
The problems and debates that started this thread are still real, at least to my colleagues, who still toil at making better audio designs.
There have been recent developments, like Ron Quan's recent AES paper on FM related distortion, first given at the AES this week. I just read through it, and it will take more than a first look to get the most out of this paper. Ron wanted to make a 30 page paper, but he was forced to reduce it to 11 pages, or else pay extra for the added length. He wrote about 3 papers and put them into one. Therefore there is lots of data but it is hard to fully comprehend at a glance, that's for sure.
This gives me hope that someday we will learn what is really important in audio design, especially with electronics, and overcome the 'hear no difference' bias that is prevalent today.
It's true than anything ever made can be improved upon in the absolute sense, but as far as I've noticed John, you haven't done half badly yourself.
And remember, even haters are fans (negative, but still fans).
I believe that, in audio electronic, when active components will be 10 time faster, most of our problems will be solved. And some new technologies will take the head of the market, digital power amps, or things near class D ?
I'm quite sure that new technologies, like graphene active devices will bring their own new evils too, and that fun will remain the same ;-)
One thing i had discovered in this forum is this strange war between objectivists, you know, the ones who believe in numbers, simulation and pure theory and the ones who "listen".
We for sure, still need very different measurement equipment to bring-us peace on this subject. Like distortiometers comparing real musical signals before/after, computing the differences. I don't understand why it is not done yet.
One thing seems to stay unchanged, with no real progress since half a century, it is electro-acoustic components, mics, speakers etc.
And one thing seems for sure: When (and if) technology will achieve this "hear no difference", fun will be dead as well as forums like this one
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