I suggest, for best performance, a thick silver case, which might be possible, now that hi end prices have far exceeded the price that the original CTC Blowtorch cost, ($10-20 thousand dollars). It would make a better shield than aluminum, and would be an investment for your old age. '-) Personally, I doubt that I will ever make a better design-execution than the Blowtorch, so I am now concentrating on making more affordable stuff, but the Blowtorch has held up well, all less than 50 of them that exist in the world somewhere.
Silver tarnishes and doesn't look good, gold or platinum would be so much better.
This is a problem Waly. However, don't you agree that the superior conductivity of silver will make a better EMI shield? So, we have to determine how to protect the silver from tarnishing. Gold or platinum would be worse than aluminum in this situation. Of course, gold plating the silver case, might be a wonderful solution.
Damian's selection is unfortunately lousy too, because of lower conductivity of the base material. We need both acoustic damping and adequate EMI shielding, to make a successful case.
Damian's selection is unfortunately lousy too, because of lower conductivity of the base material. We need both acoustic damping and adequate EMI shielding, to make a successful case.
When it comes to the silver wire that we used, we can't buy it anymore, although we have tried.
No it won't. Order is silver, copper, gold, aluminum.
But the best of the best would be graphene. Has 50% lower resistivity compared to silver. Not to mention the huge, almost symmetrical and temperature independent, electron/hole mobility.
Not sure though if people would want to pay for a greyish piece of coal, unless somebody creates a catchy story about the effect of massive electrons, charged particles moving as a Dirac fluid and the anomalous Hall effect, on the sound quality.
Only in terms of volume, not weight. Aluminium seems pretty optimal to me for shielding. An aluminium case of certain weight and outside dimensions will shield better than the same in silver.
Heavier is OK. People like 'heavy'. Graphene is still too exotic for us to use for a case.
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Today, I had lunch with my old friend, Jack Bybee. He is still working on improving audio. I won't bore you with what he is doing, but I hope to try something new in future that is based on physics and apparently improves the air itself, when activated by sound waves.
Yes, once the frequency gets high enough.
Steve Lampen at Belden writes about their new coax:
It’s easy to compare Belden’s new 4K coax cable design to other coax cables. Simply compare them side by side. Strip off the jacket, foil, braid and dielectric, and examine the conductor. The center conductor looks different– it’s not even copper colored. Instead, it is silver-coated copper. Silver is the best conductor; using it reduces the resistance for all signals and is especially effective for those high frequency signals that ride on the skin. Because of “skin effect”, it is important to make sure the conductor’s surface is as perfect as possible. In all our digital video cables, the surface of the center conductor has a mirror finish. In this 4K cable, it is a silver layer with a mirror finish.
Silver plated aluminium with a lick of paint works well enough. Of course for RF its as much to keep the wanted E-Field in place. Given all the LNAs people have build for their test benches usually require 3 boxes to get adequate screening surely that is the next step? With some mu metal chucked in to keep pesky magnetic fields out.
First as to case material. There is one metal that is extra dense and offers shielding that is superb. Lots of it is now government surplus, but still hard to get. There just might be a downside besides just cost preventing making the case out of plutonium.
As to titanium, there is a local industrial park that was once a major metal mill site. Ground level one of the bays had a gas fired temperature controlled tempering oven more than big enough to house a car. Next bay over grinding swarf rich in titanium dust. Even more interesting was the very very thick floor concealed a basement under the entire mill with a remote secret entrance via a tunnel. No idea what actually got made there more than 40 years ago.
I did get a titanium knife with a blade .040" thick that you could not bend.
As to silver plated coax, Commscope has been the major supplier of RG59 HEC for many decades. (Head End Cable). Used in virtually all the CATV systems I have played with.
Demian good idea for the switch. But thanks I have a very nice collection of the GR stuff from when they closed the Philadelphia Naval Yard.
Now a gold plated silver case would be cute, but the best way to make that would be lost wax casting. Not a process I have had success with for large pieces. Now milling aluminum with a sharp mill, decent lubricant/coolant and a way too many horse power vertical mill almost seems like cutting butter. Boeing actually makes wings out of solid billets.
The issue becomes which aluminum alloy. 7075 was actually a Japanese military secret in WW II giving the Mitsubishi Zero some of its' advantage. 2024 is cheaper and also takes a nice polish. 6061 is the most common and cheaper but is gummy to mill. Other alloys like the 3000 or 5000 series probably not available in the right sizes and not really the righ alloy either.
As to titanium, there is a local industrial park that was once a major metal mill site. Ground level one of the bays had a gas fired temperature controlled tempering oven more than big enough to house a car. Next bay over grinding swarf rich in titanium dust. Even more interesting was the very very thick floor concealed a basement under the entire mill with a remote secret entrance via a tunnel. No idea what actually got made there more than 40 years ago.
I did get a titanium knife with a blade .040" thick that you could not bend.
As to silver plated coax, Commscope has been the major supplier of RG59 HEC for many decades. (Head End Cable). Used in virtually all the CATV systems I have played with.
Demian good idea for the switch. But thanks I have a very nice collection of the GR stuff from when they closed the Philadelphia Naval Yard.
Now a gold plated silver case would be cute, but the best way to make that would be lost wax casting. Not a process I have had success with for large pieces. Now milling aluminum with a sharp mill, decent lubricant/coolant and a way too many horse power vertical mill almost seems like cutting butter. Boeing actually makes wings out of solid billets.
The issue becomes which aluminum alloy. 7075 was actually a Japanese military secret in WW II giving the Mitsubishi Zero some of its' advantage. 2024 is cheaper and also takes a nice polish. 6061 is the most common and cheaper but is gummy to mill. Other alloys like the 3000 or 5000 series probably not available in the right sizes and not really the righ alloy either.
For microwave the surface finish is important. The digital video over coax for 4K would need to pass 18 Gbps or really 30 GHz. I'm sure it would help your audio.
You can put a white cold (gold-platnium) plating over silver to look like silver and not tarnish. It needs to be substantial however to last. 250u should be enough. For RF the base metal matters less. To keep audio magnetic fields out you need something magnetic. Mumetal is fine for sheet metal boxes but not well suited to these casings. However an inner cast iron shell (min 1/4" thick) would do the job. And no one would steal it, it would be too heavy, also good for vibration isolation.
You can put a white cold (gold-platnium) plating over silver to look like silver and not tarnish. It needs to be substantial however to last. 250u should be enough. For RF the base metal matters less. To keep audio magnetic fields out you need something magnetic. Mumetal is fine for sheet metal boxes but not well suited to these casings. However an inner cast iron shell (min 1/4" thick) would do the job. And no one would steal it, it would be too heavy, also good for vibration isolation.
Demian,
There are some interesting aluminum iron metal foams that would do the job, but just about as hard to get as plutonium and as far as I know only made in very small quantities.
Probably could also be one of the weird loaded ceramics. Not sure if these ever left the materials lab.
RNM may actually know of a few better materials, if he can admit to them.
There are some interesting aluminum iron metal foams that would do the job, but just about as hard to get as plutonium and as far as I know only made in very small quantities.
Probably could also be one of the weird loaded ceramics. Not sure if these ever left the materials lab.
RNM may actually know of a few better materials, if he can admit to them.
RNM may have brought back a really good material from the test site- Depleted uranium, but I'm not sure I want it in my universe.
I met with some guys from Mcdonnall -Douglas a few years ago that had a carbon nanotube material in blocks. The material had the tubes aligned in the matrix. It looked really good for headphones and they said they could make it in commercial quantities. They never got back to me on going forward. Uncle Sam may have had something to do with it.
I met with some guys from Mcdonnall -Douglas a few years ago that had a carbon nanotube material in blocks. The material had the tubes aligned in the matrix. It looked really good for headphones and they said they could make it in commercial quantities. They never got back to me on going forward. Uncle Sam may have had something to do with it.
At 20g/cc, DU would certainly be dense. Not sure what the alpha radiation would do to your noise measurements. Old-time beam-balances in chem labs used a small chunk of natural U to dissipate any static build-up.
NO STEEL or IRON! That is what we are trying to avoid! Of course a steel box would be easy to make, and is often used for audio products, but it can make a serious difference in sound quality, and that is what the Blowtorch was all about, best sound possible.
Steel or mumetal will interact with magnetic fields but if the box is large enough it should not interact with internal fields. How large would it need to be?
I built some preamps using 1" delrin for the case. it worked quite well. The openings even for the cables were made air tight and by extension sound tight. It was not showy but it really worked and seemed to sound better.
I built some preamps using 1" delrin for the case. it worked quite well. The openings even for the cables were made air tight and by extension sound tight. It was not showy but it really worked and seemed to sound better.
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