KungFuNat Posted March 15, 2005 Share Posted March 15, 2005 so as i like to listen to a bit of music before going to bed each night, i have been noticing a slight buzzing noise comming from my speakers, at first i just chalked it up to the hyper-sesitivity of my cornwalls... but it seemed to be getting worse this evening. i walked up to the speaker and put my ear right up againsed it. what did i hear? a local radio station comming through on my cornwalls!! so i started moving around the speaker cables, moving the power cables, everything i could think of to find out if the RFI was comming from my wires, or componants. through process elimination i found that it is my interconnects from preamp to amp that are the culprits. i unplugged them from my preamp and the interferance was still there, if i unplugged them from the power amp, the noise dissapears.. the interconnects i used are cheap tributaries cable reccomended by my local dealer... well, these things absolutely have to go, but the question is: will i have the problem with just about any cable, or do i need to specifically look for something with a heavy duty sheild... i dont beleive in spending megabucks on cables, any suggestions? ive been looking at signal cables, but none of them have a 100% sheild coverage. HELP! Quote Link to comment Share on other sites More sharing options...
Erik Mandaville Posted March 15, 2005 Share Posted March 15, 2005 Nat: I understand this frustration. Sometimes common coaxial cable ICs are not the most suitable for audio, especially in areas of high RFI. The reason is, is that the shield, which is what is supposed to sheild the conductor from noise problems, is also the ground return for the circuit. In other words, it can still pick up noise, almost like an antenna. You might try using a cable based on twinaxial geometry, which uses two conductors (1 hot, the other common) plus shield, where the shield is grounded at one end, only -- experiment with what works best in terms of which end (amp or preamp)the grounded shield is connected. This provides the necessary ground connection, plus the benefit of an active shield (which only needs to be grounded at one end)without the influx of RFI/EMI. This can really help -- I hope it provides some relief. Athough a little more complicated, a very small capacitive filter can be used, as well. BTW: You can use some good, two conductor mic cable for this purpose, and make your own cables. It's a little more difficult to work with but you can give it a try. Radio Shack sells two conductor plus shield audio cable that, while not the best available, will give you an idea if it's the coaxial shield connection that's causing the problem. They have the necessary RCA jacks, too. If you don't know how to solder, you could practice for a couple of hours and master it. It's easy! If you want to try, but aren't sure where to begin, send me an email, and I'll give you some step-by-step instructions. Erik Quote Link to comment Share on other sites More sharing options...
LarryC Posted March 15, 2005 Share Posted March 15, 2005 ---------------- On 3/15/2005 5:46:27 AM Erik Mandaville wrote: Sometimes common coaxial cable ICs are not the most suitable for audio, especially in areas of high RFI. The reason is, is that the shield, which is what is supposed to sheild the conductor from noise problems, is also the ground return for the circuit. In other words, it can still pick up noise, almost like an antenna. You might try using a cable based on twinaxial geometry, which uses two conductors (1 hot, the other common) plus shield, where the shield is grounded at one end, only -- experiment with what works best in terms of which end (amp or preamp)the grounded shield is connected. This provides the necessary ground connection, plus the benefit of an active shield (which only needs to be grounded at one end)without the influx of RFI/EMI. This can really help -- I hope it provides some relief. Athough a little more complicated, a very small capacitive filter can be used, as well. Erik ---------------- Monster Cable "Interlink" I/C's are frequently available on A-gon or Ebay for around $30-$35 for a 1-m. pair, and to my knowledge those MCs are the twin-axial design Erik so nicely describes. The product description of this Ebay item mentions the foil shield, and aluminum is supposed be good at blocking RFI. Note that there probably are little arrows on the I/C (a point of contention in a recent thread), that point to the end where the shield is grounded. Conventional wisdom says that's the "output" end for best RFI control. Larry Quote Link to comment Share on other sites More sharing options...
hwatkins Posted March 15, 2005 Share Posted March 15, 2005 Wrapping your house in aluminum foil works and cuts down on future painting costs. Otherwise, if this is a brand new thing it is pretty safe to assume that a station just finished some transmitter work and is, for now, a bit over powered for the type of broadcast antenna used. Doesn't fix your problem, but the FCC is pretty darn stringent and should catch this soon. Of the solutions noted - coax is a pretty good idea. Manufacturing standards for coax have been around for quite some time so you usually get an excellent product. Quote Link to comment Share on other sites More sharing options...
boom3 Posted March 15, 2005 Share Posted March 15, 2005 "Misery loves company" so the saying goes. My household has 6 computers (three Macs, three PCs), two aquariums, two electrostatic air cleaners, one HEPA air cleaner, and one humidifier. The RFI, especially from 2-5 MHz is pretty bad. Good thing I am only a casual shortwave listener and not a ham! Despite all this, I have no interference with the HT set-up. Quote Link to comment Share on other sites More sharing options...
boom3 Posted March 15, 2005 Share Posted March 15, 2005 "Misery loves company" so the saying goes. My household has 6 computers (three Macs, three PCs), two aquariums, two electrostatic air cleaners, one HEPA air cleaner, and one humidifier. The RFI, especially from 2-5 MHz is pretty bad. Good thing I am only a casual shortwave listener and not a ham! Despite all this, I have no interference with the HT set-up. Quote Link to comment Share on other sites More sharing options...
Frzninvt Posted March 15, 2005 Share Posted March 15, 2005 A good set of twisted pair interconnects should solve the problem unless you have a ground loop issue to boot. Quote Link to comment Share on other sites More sharing options...
Colin Posted March 15, 2005 Share Posted March 15, 2005 doesn't a surge protector with RFI do this? or is it only RFI for the eletical current? what about some of those isolation "blankets" that go over the components, would one or two of them work? Quote Link to comment Share on other sites More sharing options...
KungFuNat Posted March 15, 2005 Author Share Posted March 15, 2005 do you guys have any specific reccomendations besides the monster cable? preferably something under $100/pair Quote Link to comment Share on other sites More sharing options...
3dzapper Posted March 15, 2005 Share Posted March 15, 2005 Natgun, How about the cost of parts ($15?) and mailing? I can build you a good pair today and mail them tomorrow. Shouldn't take long to get from RI to Boston. Just tell me how long and if you would rather have fat blue. or thin white. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 15, 2005 Share Posted March 15, 2005 Rick I'll take 10 pairs all 3 foot at that price LOL !! Let's go all out and do the fat blue. Quote Link to comment Share on other sites More sharing options...
3dzapper Posted March 15, 2005 Share Posted March 15, 2005 I've got nearly a thousand feet of the pretty blue and bought a couple hundred more feet of that white wire I sent you. Do you want some blue Belden Craig? You'll have to solder on your own ends. Do you think your daughter can do that for you? Quote Link to comment Share on other sites More sharing options...
NOSValves Posted March 15, 2005 Share Posted March 15, 2005 Actually I would like to buy some of the Belden from you if you have a bunch to spare. Craig Quote Link to comment Share on other sites More sharing options...
hwatkins Posted March 15, 2005 Share Posted March 15, 2005 ---------------- On 3/15/2005 1:16:25 PM 3dzapper wrote: You'll have to solder on your own ends. Do you think your daughter can do that for you? ---------------- Only if you want it done right Quote Link to comment Share on other sites More sharing options...
customsteve01 Posted March 15, 2005 Share Posted March 15, 2005 Rick, Could you pm me or post your parts list of those cables if you don't mind. I want to clean up my rack and DIY is the way I want to go. In advance, Thanks Steve Quote Link to comment Share on other sites More sharing options...
D-MAN Posted March 15, 2005 Share Posted March 15, 2005 I've heard that RFI comes in on the AC line more so than the interconnects or speaker wires. Check that out and let us know... DM Quote Link to comment Share on other sites More sharing options...
KungFuNat Posted March 15, 2005 Author Share Posted March 15, 2005 as i said before, if i remove the interconnects completely from my amp, the RFI completely dissapears. i also have all my commponants plugged into a tripplite surge-protector which provides complete RFI and EMI filtering... it is without a doubt the analog interconnects. i too would like to know the exact parts for those $15 interconnects... Quote Link to comment Share on other sites More sharing options...
D-MAN Posted March 15, 2005 Share Posted March 15, 2005 It's not being amplified when you disconnect the interconnects. If you've tried OTHER interconnects and it stopped, then there is no argument here... It is most likely NOT coming from the interconnects. Interconnects are usually too short to act as radio antennas, that is, 1/4 wave stubs and the impedance of the connections is too high. I'm thinking AC to the preamp? Even moving or rearranging the AC cable could help. However, it could be that the local station is new or using a higher output, and THAT could effect EMF in practically ANY cabling, including interconnects. But I would think that careful arrangement of the cables at odd angles could help the wires to not "cut" the lines of EMF at right angles. DM Quote Link to comment Share on other sites More sharing options...
3dzapper Posted March 15, 2005 Share Posted March 15, 2005 These are the RCA plugs (link) that I use. And the cables, The blue is twin silver plated copper Beldin mike wire with Belfoil shield and drain wire, the white is NASA silver plated copper twin conductor with silver plated braid shield: Edit: sorry Steve I messed up. There is only one link. What a difference a little / makes! Quote Link to comment Share on other sites More sharing options...
customsteve01 Posted March 15, 2005 Share Posted March 15, 2005 Rick, Both links are the same. it pulls up the plugs on both Steve Quote Link to comment Share on other sites More sharing options...
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