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Recently, I angered someone with my answer to a thread. Not unusual, but I reread the OP and saw something I missed on first pass.
OP was concerned, apparentlly with conductor resistance in rsisitors. And had settled on an alloy of copper called Manganin. This is interesting stuff when I looked into it.
It has a VERY low temp coefficient which means the resistance change is very very low as temp increases....as it may when heated as by internal resistance or even external forces.
As it turns out, this change in resistance is one of the problems with dynamic drivers. As they heat up, resistance increases which causes MORE heating. This can have one of 2 results. Either the driver CAN burn up.....if temp exceeds insulation temp OR the characteristics of the driver change enough to cause audible.....problems or differences.....compared to the 'cold' driver.
Of course, at some point in adding heat, the radiation from the driver may balance out and the temp stabalize. Drivers which 'pump' the voice coil may be configured in such a way as to push air thru the coil for cooling. And some use Ferofluid to help transmit such heat away and radiate it away.
It may even be possible to VOICE a speaker to sound best when 'hot'......say after 30 minutes use at a given power / output level. But I've never seen reference to THAT, either.
I'm sure the the inside of a speaker enclosure can get pretty warm when pressed. I'd like to know more about this but have never seen any data.
The article I link is worth a glance for those who DIY speakers. Or who have an interest in this sort of physics based material.
There ARE a few materials with NEGATIVE temp coefficients. But I don't think they make wires out of any of 'em......Maybe one day Graphene or some really exotic material may qualify.....
Too much is never enough
Follow Ups:
Modulation of driver properties due to heating and cooling of the copper coil and the change in characteristics is a well known, well understood issue. Coupled with magnetic saturation, it formed conceptually "compression" in speaker drivers. Unfortunately graphene is a 2D conductor so not well suited to cables ..... ignoring all the highly amusing claims audio products vendors assign to their products from simply mixing in some graphene (when in most cases graphite / carbon black would be far more sensible).
W.r.t. that comment about someone's wasted education. It's a B.A.Sc. in aeronautical engineering from the 60's ... take that as you may.
The fact is Graphene with thickness larger than a 2D sheet or Graphene flakes mixed in an organic paste can still maintain much of the properties of 2D Graphene; for example, the Graphene composite used in bicycle tires and HEAD tennis rackets provides very high stiffness and strength.Isn't some speaker company now applying Graphene to speaker drivers? You know, for stiffness. I suspect much of the benefit of using Graphene in audio related stuff is it's very good RFI shielding properties. I use Graphene paste on fuse caps and other electrical contacts and it's quite obviously effective.. You should try it sometime, you might learn something.
Generally speaking, people would be much better off if they believed in too much rather than too little. - PT Barnum
An ordinary man has no *means* of deliverance. - Old audiophile axiom
Edits: 03/04/22 03/04/22 03/04/22 03/04/22 03/04/22
They've been making cables with Graphene and contact enhancers even speaker drivers with Graphene for years. I just painted the battery end caps of my Portable cassette player with Graphene yesterday. Physics to the rescue!
Edits: 10/07/20
I'm talking SHEETS of the stuff, not flakes /
Once a Solar Sail is fabricated......now THAT'S a good use for graphene.
Right now? Advertising and one-upsmanship stuff. Real benefits TBD
Too much is never enough
Sheets of real Graphene would be impossible to handle, being only one molecule thick. Besides flakes and multiple sheets work very well, so where's the beef? Rule no. 1 - it has to be doable. Recall the silver and gold contact enhancers? They contained flakes, too. Remember the little train that could: "I think I can, I think I can..."
Edits: 10/07/20 10/07/20
The ONE rule I'm totally on board with?
When an 'expert' says it is impossible, they are almost certainly WRONG. Might be a good time to get ZERO GEE manufacturing online? First rolls? Maybe 1/2 meter wide and 50 meters long? cost in the MILLIONS but will kickstart a whole new set of industries.
All sorts of interesting techniques. Even 'sacrificial' where a layer of grphene is grown on a substrate which is later etched or 'discolved' away. One technique used in semiconductor processing.
Nobody though OLED screens would work...or be manufacturable? Now we have a 77" from LG which is not even at the profane or obscene price level.
Battery chemistry continues to evolve. Someone is working on the BETTER version right now which will replace LION and be even lighter and more power dense.
Solar Cell physics will eventually make far more efficient cells than currently available.
Smart People saying what can and can't be done should learn from history that they are usually simply WRONG.
As usual?
Stay Tuned!
Too much is never enough
You almost convinced me it's impossible. Lol. Check out threads over on Audiogon on the dodgy subject of Total Contact Graphene based contact enhancer from now defunct PPT.. I'm afraid Audio Asylum might be the victim of "stove piping" low these many years since my abstinence, I mean absence. The Graphene cables from Cerious also look interesting. Of course Graphene has many advantages for audio, much better conductivity being only one. I think I can, I think I can, I think I can...toot, toot! When you control the mail you control ...information.Then there's this,
Edits: 10/08/20
In semiconductor processing, NOT advertising or dealing with 'flakes', either of the executive or mechanical type.....I saw many processes.
One technique is to deposit or grow a film on a substrate. You can successfully deal with films down to 200 Angstroms or less. I had a machine to measure thin films to 20 angstroms or less, using UV light.
Some films do NOT stick to one another. For example? the backside of a device needed a conductive layer for bonding and as part of the circuit. The Silicon was 'roughed' up. Than a layer of Chrome followed by Nickel than Silver was applied. Very low ohmic contact resistance and all the films when applied IN ORDER stuck to one another with minimal induced stress. Film stress is critical in this sort of work and can be measured as Compressive or Tensile, depending on the BOW of the objct measured. Excess stress leads to problems of delimitation and cracking.
Sheet Graphene in useful sizes is still in the future.
I want speakers liike Magnepan make from Graphene. And in SPACE? Experiment with solar sails and launch a probe to a close star, as proof of principle.
People RIGHT THIS MINUTE are doubtless working on ways to make SHEETS of Graphene. First small, than larger.
you might even find some RailRoad uses for Graphene. I have NO idea why you are hung up on trains. Maybe you didn't get your Lionel for Christmas when you were a kid?
Too much is never enough
Sputter the graphene or use multiple sheets of 2D Graphene. Or put Graphene flakes into solution with something that works. Whatever is doable and achieves a high percentage of effectiveness is still better than whatever else ya got. If you wait until someone figures out how to handle or even see a single sheet of 2D Graphene you'll be an old man. The future is now!
Edits: 10/08/20
They are Reverse Engineering some fallen UFOs even as we speak to try to figure this out.
Too much is never enough
Just for the record my early career involved reverse engineering of UFOs. I used to work right next to US Air Force Office Investigating UFOs, aka Operation Bluebook, in a pink building with no windows.
Wow! Do you know Bob Lazar?
Check this out,
Just LAST NITE.......8-29-21, 60Minutes did an updated to UFOs....
Now called something else.
One part of the segment was a rehas of some of the Navy footage of chasing tictacs around. to No effect.
But the part I really liked was when at 2 seperate points they mentioned that the RADAR SYSTEMS of the ships and planes had just been upgraded. THAN they started seeing these guys on the scope and the planes started seeing them as well AND in the IR gunsight viewer.current physics doesn'tseem to allow for the perfornace seen. That's gonna let the Chinese and Russians OUT. Also not mentioned? Does Russian and China and a few others have SIMILAR or identical sightings?
Nobody in the government is Prepared to say 'Allien' but that's where it's headed.....
Too much is never enough
Edits: 08/30/21
I'm not at Liberty to discuss the Navy videos but in my opinion they're aren't very convincing.
Footage is declassified. Even a couple pilots were on camera and free to discuss, and Never Once invoked 'security' or 'classified'.
Did the military / government lay ALL its cards on the table? Of course not. Plenty of logical holes thru which you could fly an aircraft carrier.
One thing which particularly caught my ear was the mention (2X) of the upgrades to radar on the ships and aircraft PRIOR to being able to 'see' these objects which preumably had either gone unnoticed or seen infrequently.
Knowing the nature of the new gear MIGHT help in an investigation. It's no accident that the new gear was mentioned TWICE a couple minutes apart.
And ZERO mention of USOs. I'm certain that access to SOSUS recordings would disclose far more than Russian subs and whale farts.
Too much is never enough
I can neither confirm nor deny anything in your post.
Yes. I was his spiritual advisor.
This conversation can serve no purpose any more.
I don't know what purpose it served in the FIRST place! You don't 'conversere' bur rather tend to lecutre and look down from your high seat.
Too much is never enough
Guilty as charged. I speak from experience and education. How about yourself?
I have done nothing with my life at all.
Never had a job and always subject to public dole.
I have a decent library and know how to boil water in a paper cup.
I'm in awe of all that eductaion of yours, gone to waste.
Cheers.
Too much is never enough
Yipes! I get it now, So Cal. Lol
Edits: 10/09/20
I DO have a serious question.
Nobody has been able to give even a good guess answer without invoking somevery weird physics.
But HOW.
HOW do 'they' get here? Nearest star is roughly 4 light years distant which at speecds even attainable with a good 'slingshot' acceleration, are hundreds if not thousands of years away.
Voyager I and II are in the 35 to 38 Thousand miles per hour range. No Where NEAR fast enough.
some people had pinned theri hopes on Gravity / Gravity wave 'surfing' but that is a speed of light phenom.
What's the best guess of what has been MISSED in modern physics which may provide a way to get someplace quicly and without breaking the bank.
Too much is never enough
My guess is whatever they used in the movies Contact (wormhole 🐛) and Interstellar, both movies employed Kip Thorne (Gravity waves) as advisor, he knows a thing or two about worm holes and near lightspeed travel. If near lightspeed travel is feasible a spacecraft from their 👽👽 home planet would perhaps "only" need 5-10 years to reach earth. They could also have set up a mid-way station a long time ago, like they did in Prometheus, assuming they've been around for tens of thousands of years. Mankind discovered unpowered flight only about 100 years ago and Manned rockets 🚀 60 years ago.
Edits: 10/10/20 10/10/20
My LIMITED understanding of Worm Holes tells me they are both theoretical AND incredibly energy intensive if possible.
I approach this from a completely UnEducated viewpoint.
Here goes. For ANY scheme of interstellar travel to be practical, and to the degree which it is apparently done, based on world wide sightings in both quantity and duration, it must be farily EASY from a technological standpoint and will NOT BANKRUPT the divilization doing it. We can NOT go the way of the Cargo Cult societies.
Sure, I can see the entire Plantet Earth bending its back to hollow out an Asteroid and use it for a multi-generational space ship. We might do that ONCE before the big collapse. If we get it launched? The ULTIMATE Hail Mary.
My gut feeling is that something in Physics HAS BEEN OVERLOOKED. MOND may straighten out this Dark Stuff nonsense while providing the 'edge' needed for FTL to be practical.
I intentionally avoided the WIKI article, which you of course, can look up at your leisure.
Trouble with travel in the 'real' universe of lightspeed being the limit is that you must accelerate THAN later slow down. Usual scenario calls for a 'flip' somewhere around the 1/2 point so you can begin slowing down. This is the mistake made in the movie Passangers with the easy-to-look-at Jennifer Lawrence.
So while PEAK speed may reach 0.7c, (simply a GUESS) the Average Speed will be quite a bit less.
Of course, this is all speculation based on being completely uneducated and having only simple shop-math skills.
But if you are not familiar? DO check out MOND. Something may click with other stuff you know....???
Too much is never enough
One thing I can think of is the time travel dilation Effect is not related to direction of travel, only relative velocities, so you can't rely on getting back to 🌎 the same age by reversing direction. The idea is that time travels more slowly on rapidly moving inertial frame than on a stationary frame, so it doesn't matter which direction the spacecraft 🚀 moving at near light speed is going. Since I didn't watch the last half of Interstellar so I don't Know if the travelers came back the same age as they left or whatever. I believe they were able to actually prove this time dilation by measuring atomic clocks on jet aircraft ✈️ circling the Earth vs one on the earth. In fact the aircraft would be traveling toward the stationary clock half the time.
Edits: 10/10/20 10/10/20 10/10/20
If that physics IS THE LIMIT than all UFO travelers are on a ONE WAY trip to Earth.
Spending a couple years each way....at relativistic speeds means you 'get home' a LONG time after everyone you knew or even KNEW of you are long gone. It's possible the language has evolved or even the culture changed enough to no longer be recognized by the Alienauts who returned home.
Quite a sacrifice, any way you slice it.
The support and we KNEW IT GOING IN for what you state about frame of reference and speed of light was nailed down by the Michelson-Morley experiments. Light traveled the same speed when reflected at right angles.....so not cosmic 'ether' slowing or speeding the flow.
In Interstellar? the Hero of this picture came back in time to see his DAUGHTER just before she died of old age!
I'm looking for 'The Big Cheat' in which simultanaity is NOT violated and you have near instant (but does take time) travel at speeds exceeding that of light. Would you mind taking a MONTH or so to reach out 10 light years or so? I wouldn't mind one bit.
I think it is possible that not only does the universe have symmetry as we know it, but also in the realm above and below th speed of light. the proposed and as yet unobserved tachyon is part of the solution....
Too much is never enough
They used to say the same thing about flight, it can't be done. And they used to say the same thing about flying faster than the speed of sound. The vibrations would tear the plane apart. And they used to say there is no such thing as black holes, even Einstein's said it.They also said there's no such thing as quantum mechanics, they still do. Even Einstein said it. They said you can have quantum teleportation. People still do. So, for traveling faster than the speed of light I think I'll reserve judgement.
I already described how an advanced civilization can reach earth in a reasonable amount of time using way stations without traveling faster than the speed of light. They wouldn't have to travel faster than 1/2 the speed of light. Just bring lots of videos. Lol. One assumes they, whoever they are, are exploring other things in the universe, too. Once upon a time I was Day Analyst for ICEE-3 satellite, stationed at Lagrange point at zero gravity pt. Between Sun and Earth, where NASA was planning on colony in space back then. That's how we were planning on conquering space back then and now, a little bit at a time.
Edits: 10/11/20
So, it's a ONE WAY trip. 'No Going Back'......
Too much is never enough
For you it's a one way trip. For me it's a two way trip.Mo spend most of my time in the future but come back here frequently. Mostly because they don't have audio forums in the future but also for the jokes.
AS it turns out?
Stereophile has a decent summary article:
Too much is never enough
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