Hey All, I have a feeling that I may alienate myself a bit with my first post here....but here goes... I dont belive Don tried the Carbon Fiber as a shot-in-the-dark kind of whim. I've been reading-up on Carbon Fiber (CF) for audio applications for a short time. What I've found seems quite interesting to me. I'll pontificate for a bit and then paste some quotes/info that caught my eye, but what Im posting here is by no means the end-all-be-all on the subject. So please take all that I post "with a grain of salt". Also note that most of what I'm posting is NOT in direct reference to SB3 or Transporter, though it is totally on topic with the thread started by Don.
1: DeafCat, check this out: http://www.twpinc.com/twpinc/control/category/~category_id=TWPCAT_11 If you do a web-search for RFI/EMI fabrics, mesh, screen etc... a TON of options come-up, many are coated or metalized fabrics that pass air in/out. Good Luck! 2: I recently purchased some CF sleeves and a small sheet to test. I did this before reading Dons post(s). I do not know if the CF will have any audible impact in my system, but Ill report back to the group on my impressions, if anyones interested that is. 3: Heres a bit of my thought process behind my decision to spend ~$60 and some DIY-time on some CF sleeves and fabric to test in my system: I think most of us can agree that RFI can/will degrade a systems sound quality to some degree or another. Also, depending on where one is living (near industry, in a big city, radio transmitter/relay towers, etc... vs. miles from anything) also affect the relative amounts of transmitted and airborne RFI pollution ones system may have to overcome. We all know that certain gear (sources, amps, pre, cables, etc) rejects or limits the intrusion/transmission/radiation of RFI/EMI better than others. So, that means the potential audible benefits of RFI attenuation will be both system and locale dependant. Consider that someone owning a high-end system where theres no RFI will likely not benefit much from RFI shielding/attenuation. The converse is also very true. I know all of you posting here already know this stuff; the above is primarily for those whore reading and not posting. Knowing that CF absorbs RFI (think original Stealth Technology) then, theoretically speaking, if each individual piece of audio gear (cables and all) were completely encased in carbon, then externally radiated RFI would be attenuated and internally generated radiated RFI generated in each component would also be limited in its ability to escape and impact other parts of the audio system. Interesting enough, but this CF application does nothing for the RFI transmitted via cables and connectors....or does it? I've read but I don't claim to understand the discourse between a pair of electrical engineers discussing the benefits of CF in their own audio DIY projects. One of them suggests that CF can, when placed at the ends of cables, limit harmonic-ringing and standing waves....which in some cases can have audible benefits. This may account for some of the success of Furutech and Oyaide have had with using carbon fiber in outlet covers and certain manufacturers have had with creating the IEC and plug ends out of CF (Acrolink maybe, cant recall, sorry?). This sounds ridiculous to me, especially at the prices being asked for these things, but the number of people (well respected and otherwise) that have reported positive audible benefits that these products supposedly provide can not (at least not by me) be dismissed out-of-hand.... So, that and the below quotes were the foundation of my reasoning for thinking that I should get some of this carbon fiber and try it out for myeslf .$60, heh, if it doesnt work no biggie, at least my system wont be picked-up on radar! 4: OK, here are those quotes I promised. All credit goes to the original posters'. Begin Quote: The carbon damps RF resonances on the power cords. - Al Sekela 16:43:28 05/30/07 (0) In Reply to: RE: Add some carbon fiber to the face plate. posted by Soundripples on May 30, 2007 at 11:00:39 It is essentially the same technique used to make stealth aircraft. Electromagnetic waves are reflected by good conductors, such as the aluminum plate in your project or aircraft skin. If the waves encounter a resistive surface, such as the carbon fiber or the secret materials used on stealth aircraft (hint: see Stillpoints ERS cloth), they are converted to heat and little of their energy is reflected. If the resistance is too high, they pass through until they hit the underlying metal, and then they are reflected. There is some optimum value of surface resistivity that will totally absorb the waves. I don't know what it is, but typical carbon fiber material seems to be reasonably close. Lucky for us that carbon fiber is also used to make golf club shafts and the like, and the materials are available at non-audio prices. Power cords support electromagnetic resonances, both in normal- and common-mode. This resonance makes RF noise worse for audio equipment. The carbon fiber on the surface of your aluminum plate would act to absorb the common-mode resonance waves on power cords plugged into it. If you covered your power cords with carbon fiber sleeve, also available from Soler, it would act to absorb both normal- and common-modes. Note that Oyaide makes AC plugs with carbon fiber outer shell material, and AC power cable that incorporates carbon fiber. Thus, this is not something I invented, but I've used the ideas in my DIY projects. End Quote: Begin Quote: Carbon fiber applications - Al Sekela 15:58:51 05/13/06 (2) In Reply to: First carbon fiber experiments - DIY posted by bartc on May 9, 2006 at 06:31:00: The benefit of carbon fiber is that it presents a resistive load to all frequencies of electromagnetic wave that impinge upon it. The resistance is high enough to absorb energy from the electric part of the electromagnetic wave. There is no enhancement of the magnetic permeability, so there is no frequency limit imposed by the detailed behavior of the magnetic response. Metal shielding has such low resistance that it reflects the energy in the wave. Insulators have such high resistance that they are transparent to the wave. ERS cloth is an alternative RF-absorbing material, reportedly derived from the same military purpose (to make aircraft present a smaller radar reflection), but it contains conductive and highly-permeable materials. The particular use of carbon fiber cloth, for the wall plate and plug barrels of audio AC line cords, favors resistive rather than permeable materials. This is because the standing waves on AC cables have most of their energy in the common-mode waves, and have electric maxima at the ends of the cables. The magnetic maxima are at the center and higher-order nodal points along the cables. Of course, the higher-order modes will have electric maxima at alternative points along the cable as well. However, as a general rule of thumb, it is more effective to put the electric dampers (the carbon fiber or carbon paper) at the cable ends, where the cable impedance changes, and the magnetic dampers (ERS cloth, Power Wraps) at the cable centers. Note that it is better to put the electric dampers where the cable geometry changes upon entry into the connector. The Oyaide plug barrel application is close to ideal, while the wall plate is a little farther away from the impedance change. End Quote: If anyone wants to get brave and put some $$ down, heres a link that one can find CF sleeves and sheets: http://www.sollercomposites.com/ Hope this was of interest to at least one of you out there. Best regards to all, Doug -- Dyak ------------------------------------------------------------------------ Dyak's Profile: http://forums.slimdevices.com/member.php?userid=13365 View this thread: http://forums.slimdevices.com/showthread.php?t=38628
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