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#1
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
I am in the UK and have a 10m length of some cheap TV aerial coax. It
came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? -- [x-posted to 3 relevant groups] |
#2
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 03 May 2008 10:58:27 +0100, Chris Siz
wrote: I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? If you can get hold of some better cable do so. You have two problems here - first coax isn't balanced, which is sort of bad news for tiny signals such as you get from a mic. And secondly, to compound that, if you strip back a little of the outer sheath, you will find that the screen is 90% holes - in other words, the cable is just about unscreened. As for using it for UHF TV, go ahead - that is what it is meant for, and 10 meters is just about the maximum run length before you need to think about using something better. d -- Pearce Consulting http://www.pearce.uk.com |
#3
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
In message , Chris Siz
writes I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? While you might get away with using your cable, good screening/shielding becomes increasing important at the lower frequencies, as the interfering signals (on the outside of the coax) penetrate more easily through the outer shield. Well-screened audio would be better. In many cases, 'flimsy' screening may be adequate at UHF (and the cable may have low loss) but, again, well-screened cable will be better for preventing interference. Maybe it's a case of try it and see what happens? -- Ian |
#4
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"Ian Jackson" wrote in message ... In message , Chris Siz writes I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? While you might get away with using your cable, good screening/shielding becomes increasing important at the lower frequencies, as the interfering signals (on the outside of the coax) penetrate more easily through the outer shield. Well-screened audio would be better. In many cases, 'flimsy' screening may be adequate at UHF (and the cable may have low loss) but, again, well-screened cable will be better for preventing interference. Maybe it's a case of try it and see what happens? I would have thought the converse to be true, surely the "holes" in the screening braid would be less of a problem at audio frequencies than at UHF? I am thinking in terms of wavelength. |
#5
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"Chris Siz" wrote in message ... I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? Yes, it's OK to use coax for a mic cable assuming the mic is a single ended connection (one wire) with ground. The biggest issue is the cable capacitance. Depending on the mic's impedance, this capacitance will attenuate high frequencies. A low impedance mike will work better than a high impedance mic. The accumulated capacitance in four meters of cable will be a couple of hundred pico-farads, probably not a problem. For UHF TV cables are usually 72 ohms. If your cable is 72 ohms, it's probably OK. If it is 50 ohms it will still work but may degrade the picture quality because of reflections within the cable. Try and see. If the antenna is 300 ohms, the cable is not suitable unless matched with a balun or other impedance matching device. |
#6
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On May 3, 4:58 am, Chris Siz wrote:
I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? -- [x-posted to 3 relevant groups] Isn't coax kind of rigid? Will the microphone need to move around? |
#7
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
In message , Bob Eld
writes "Chris Siz" wrote in message ... I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? Yes, it's OK to use coax for a mic cable assuming the mic is a single ended connection (one wire) with ground. The biggest issue is the cable capacitance. Depending on the mic's impedance, this capacitance will attenuate high frequencies. A low impedance mike will work better than a high impedance mic. The accumulated capacitance in four meters of cable will be a couple of hundred pico-farads, probably not a problem. Out of interest, how does the capacitance of ordinary TV coax (which will be 75 ohms, of course) compare with 'proper' mic cable? Of course, a lot of audio is balanced (usually nominally 600 ohms), which makes things generally less prone to the pick-up of interference. Unbalanced connections via coax (even if proper screened audio cable) is less-tolerant. For UHF TV cables are usually 72 ohms. If your cable is 72 ohms, it's probably OK. If it is 50 ohms it will still work but may degrade the picture quality because of reflections within the cable. Try and see. As it's TV coax, it's unlikely to be 50 ohms. If the antenna is 300 ohms, the cable is not suitable unless matched with a balun or other impedance matching device. UK aerials are not 300 ohms (except for those indoor FM radio aerials made from 300 twin feeder). I believe that, these days, they are also a bit of rarity in the USA. -- Ian |
#8
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 3 May 2008 17:01:19 +0100, in sci.electronics.design Ian
Jackson wrote: Out of interest, how does the capacitance of ordinary TV coax (which will be 75 ohms, of course) compare with 'proper' mic cable? Of course, a lot of audio is balanced (usually nominally 600 ohms), which makes things generally less prone to the pick-up of interference. Unbalanced connections via coax (even if proper screened audio cable) is less-tolerant. 600 ohms is dead and buried, for the audio world.The only time it is mentioned is in data sheets, "will drive XXdB into 600R" etc martin |
#9
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
In article ,
Chris Siz wrote: I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? There are a few differences. TV coax will work in some conditions but not generally. TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. TV coax may not pass small audio signals well because of its aluminum shield. Aluminum is extremely reactive so it is always coated with a thin oxide layer. Higher voltages can spark through it and TV RF can capacitively couple through it. Microphone signals might become distorted. Cable for lower frequencies uses copper shielding. Good microphone and instrument cable has an insulation that drains away static electrical charges. RF coax can contain electrical charges in the insulation that causes it to act like condenser microphone. -- Block Google's spam and enjoy Usenet again. Reply with Google and I won't hear from you. |
#10
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Kevin McMurtrie wrote:
In article , Chris Siz wrote: I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? There are a few differences. TV coax will work in some conditions but not generally. TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. Not necessarily in fact a lot of TV coax is entirely copper. TV coax may not pass small audio signals well because of its aluminum shield. Aluminum is extremely reactive so it is always coated with a thin oxide layer. Yes, the laws of nature decided that. Higher voltages can spark through it and TV RF can capacitively couple through it. Microphone signals might become distorted. Cable for lower frequencies uses copper shielding. Rubbish. Good microphone and instrument cable has an insulation that drains away static electrical charges. RF coax can contain electrical charges in the insulation that causes it to act like condenser microphone. Rubbish again. Where do you get this knowledge from? Steve -- Say no to ISPs selling your private browsing history to advertisers who will then send you targeted adverts, as well as, potentially, compromising your security on line. Please visit: http://www.badphorm.co.uk/page.php?2 for more information and please sign the rapidly growing on line petition at http://petitions.pm.gov.uk/ispphorm/ if you don't want to see this happening. Thanks |
#11
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson
wrote: On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). 73 de G3NYY The stuff with foil is higher quality, used mostly for satellite dish feeder. TV coax is just a copper inner with about half a dozen fine strands for a screen. d -- Pearce Consulting http://www.pearce.uk.com |
#12
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Say no to ISPs selling your private browsing history to advertisers who will then send you targeted adverts, as well as, potentially, compromising your security on line. so that is why I get so much porno spam ....... |
#13
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
TV coax is very brittle. The inner wire is copper-plated steel and the
outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). 75-ohm with copper-coated steel center conductor is often used for outdoor cable-company coax runs. The steel core gives it enough tensile strength to allow long runs to hang between poles (and between pole and house) without stretching. This stuff is often a "hardline" coax, with an aluminum outer shield... very low RF leakage, which is an important issue for cable companies. Indoor TV coax is sometimes RG-59, sometimes RG-6. It usually seems to have a solid-copper center conductor (to allow for termination via a crimp-on F connector). The shield may be anything from one layer of braid with poor coverage, up to a quad shield (two layers of braid, two layers of foil). It may be fairly stiff. Coax which is optimized for microphone usage tends to be relatively flexible (stranded center conductor, compliant jacket), and I understand that the better varieties are designed to minimize the generation of triboelectric noise (which occurs when the cable is moved, as a result of static or piezoelectric effects). Using TV coax for a microphone ought not to be harmful, but it's probably not the best choice, and I'd do it only if a limited budget made it impossible to get something better suited to the purpose. Useful reference: http://www.belden.com/pdfs/Techpprs/tpbroad.htm -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#14
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
jim stewart wrote:
Say no to ISPs selling your private browsing history to advertisers who will then send you targeted adverts, as well as, potentially, compromising your security on line. so that is why I get so much porno spam ....... Well only you can answer that Jim ;-) But you are off the hook with Phorm as they promise not to profile that sort of stuff. That promise seems a bit hollow as Phorm, previously known as 121 media were involved in malware (people on page) before this. I wouldn't trust them one bit. Steve -- Say no to ISPs selling your private browsing history to advertisers who will then send you targeted adverts, as well as, potentially, compromising your security on line. Please visit: http://www.badphorm.co.uk/page.php?2 for more information and please sign the rapidly growing on line petition at http://petitions.pm.gov.uk/ispphorm/ if you don't want to see this happening. |
#15
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"Martin Griffith" wrote in message ... On Sat, 3 May 2008 17:01:19 +0100, in sci.electronics.design Ian Jackson wrote: 600 ohms is dead and buried, for the audio world.The only time it is mentioned is in data sheets, "will drive XXdB into 600R" etc martin Quite so. The concept of matching a microphone's impedance to get the best power transfer has not been practiced for a considerable time. Modern dynamic mics expect to look at a "bridging" impedance e.g. around 10K for a mic having a Z of 150-200 Ohms and to operate as a voltage, rather than a power source. The characteristic imedance of the feeder (over a few feet) may thus be disregarded. Les. |
#16
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Les. wrote:
"Martin Griffith" wrote in message ... On Sat, 3 May 2008 17:01:19 +0100, in sci.electronics.design Ian Jackson wrote: 600 ohms is dead and buried, for the audio world.The only time it is mentioned is in data sheets, "will drive XXdB into 600R" etc martin Quite so. The concept of matching a microphone's impedance to get the best power transfer has not been practiced for a considerable time. Modern dynamic mics expect to look at a "bridging" impedance e.g. around 10K for a mic having a Z of 150-200 Ohms and to operate as a voltage, rather than a power source. No they expect to see 1K2 to 2K not 10K and that is what most pro mic pres provide. 10K input impedance is for bridging line levels. Cheers Ian |
#17
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson wrote:
On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). You want to see the crap which passes for rg58 at maplin electronics. 73 de G3NYY -- ___ _______ ___ ___ ___ __ ____ / _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / / / // / _// __ |/ // / / ___/ __ / /_/ / /__ /____/___/_/ |_/____/ /_/ /_/ |_\____/____/ |
#18
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 03 May 2008 18:41:27 +0000, Don Pearce wrote:
On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson wrote: On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). 73 de G3NYY The stuff with foil is higher quality, used mostly for satellite dish feeder. TV coax is just a copper inner with about half a dozen fine strands for a screen. Yes, and i've seen rg58 like that at maplin electronics! Just for your information :-) d -- ___ _______ ___ ___ ___ __ ____ / _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / / / // / _// __ |/ // / / ___/ __ / /_/ / /__ /____/___/_/ |_/____/ /_/ /_/ |_\____/____/ |
#19
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Walt Davidson wrote: On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). Then you've never seen the wire used by cable TV and Satellite TV companies. Pure copper is too expensive these days, and too soft for repeated flexing. If you want to pay over a dollar a foot for copper core TV coax, go ahead. The last time I had to buy some it was about eight times the price of the foil shield W/braid TV coax, and useless for UHF. Use a magnet, and see for yourself. The copper plating smears when cut with dykes, and makes the coated steel appear to be solid copper. -- http://improve-usenet.org/index.html Use any search engine other than Google till they stop polluting USENET with porn and junk commercial SPAM If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm |
#20
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
In article ,
Walt Davidson wrote: On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). 73 de G3NYY It's all I've ever seen for RG-6 TV cabling. Try sanding the tip to see if it turns silver, or use a magnet. http://en.wikipedia.org/wiki/RG-6 It's really a TV-only thing. Copper plated steel wire won't work for many applications. -- Block Google's spam and enjoy Usenet again. Reply with Google and I won't hear from you. |
#21
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell"
wrote: Then you've never seen the wire used by cable TV and Satellite TV companies. Pure copper is too expensive these days, and too soft for repeated flexing. If you want to pay over a dollar a foot for copper core TV coax, go ahead. The last time I had to buy some it was about eight times the price of the foil shield W/braid TV coax, and useless for UHF. Use a magnet, and see for yourself. The copper plating smears when cut with dykes, and makes the coated steel appear to be solid copper. Well, I did just that. I grabbed a magnet off the fridge and went through my pile of RG-6/u CATV coax jumpers and cables. The really old stuff had an all copper center conductor. The fairly current stuff has a copperweld or CCS (copper clad steel) center conductor. I would guess that about 90% of what's in the pile (about 100 cables) is CCS. Amazing: http://www.fushiinternational.com/Products.aspx?p=Bimetallic http://www.fushiinternational.com/Pr...spx?p=CCSCable However, much of the RG-6/u cable is "satellite grade", which means it should work to about 2GHz with minimal loss. I've been using the quad shielded variety (apparently with a CCS center conductor) for years for Wi-Fi at 2.4GHz with about 10dB/100ft attenuation (measured). The loss is in the dielectric, not in the center conductor cladding. I would say that it works just fine at UHF (300-3000MHz). Incidentally, I blundered across this data sheet for RG-6/u. They can make it just about any way you want it, and still call it RG-6/u. Note the line with: 6) Braiding coverage: Between 30 - 97% available; I can't imagine who would want to buy 30% coverage outer shielding. http://www.tootoo.com/supplier/product-detail/6251149/RG6%252fU.html As for the coax being brittle, that's possible if it were plenum rated cable for running through air ducts. The stuff is suppose to be "low smoke" when burning. It tends to be rather stiff and brittle. For RG-6/u, the flexibility is largely in the type of braid and outer jacket. Quad shielded is going to be rather stiff. Judging by the mixture in my junk box, I have cables that range from super flexible (for the back of HDTV installs) to super stiff (gel filled for direct burial). Your mileage and stiffness may vary. As for the suitability as a microphone cable, I dunno. The original posting had no useful descriptions of the microphone, the found cable, or the equipment to which it will be connected. 4.8mm O.D. could be a wide variety of possible coax cables. I'm lazy and don't wanna guess. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#22
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"SteveE" wrote ...
Kevin McMurtrie wrote: Higher voltages can spark through it and TV RF can capacitively couple through it. Microphone signals might become distorted. Cable for lower frequencies uses copper shielding. Rubbish. Indeed. Take it out with the rest of the trash. Good microphone and instrument cable has an insulation that drains away static electrical charges. RF coax can contain electrical charges in the insulation that causes it to act like condenser microphone. Rubbish again. Where do you get this knowledge from? Looks like a reference to some hi-Z cable that is made with condctive fabric (or other such substance) to reduce the cable microphonic tendencies due to the triboelectric effect of some kinds of dielectric insulation. |
#23
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"Chris Siz" wrote ...
I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? Not enough details to answer your question adequately. First of all, the kinds of microphones used for audio applications (reinforcement, recording, etc.) are usually balanced and require cable with two inner wires and an outside shield/screen. If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. So, the biggest question is WHAT microphone? Equally helpful would be to reveal what it plugs in to. I don't want an impaired audio signal. "impairment" of the audio signal is unlikely to occur, and is probably not an issue here. The length I need to use is 3 to 4 metres. Not really important to the question. It wouldn't make much difference if it were 1 m or 1Km Note that even if you need unbalanced cable for your unidentified microphone, typical RF/antenna cable is very poorly suited for terminating in typical audio- type connectors. It is frequently aluminum and unsuitable for any kind of soldering, etc. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? Insufficient details to answer that question, also. There are hundreds of different kinds of antenna- type (RF) coax. Some of it might be perfect for UHF TV (whatever that means in your area?) And other kinds may be completely a disaster. Again, "interference" is not the most likely mode of failure of using the wrong kind of cable. |
#24
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell"
wrote: Use a magnet, and see for yourself. The copper plating smears when cut with dykes, and makes the coated steel appear to be solid copper. Trivia: Dike = Diagonal Cutters http://en.wikipedia.org/wiki/Diagonal_pliers Dyke = Lesbian http://en.wikipedia.org/wiki/Dyke_(lesbian) Dyke or Dike = Earthen wall or dam http://en.wikipedia.org/wiki/Dike_%28construction%29 Methinks "dikes" would be the correct spelling. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#25
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Jeff Liebermann wrote:
However, much of the RG-6/u cable is "satellite grade", which means it should work to about 2GHz with minimal loss. I've been using the quad shielded variety (apparently with a CCS center conductor) for years for Wi-Fi at 2.4GHz with about 10dB/100ft attenuation (measured). The loss is in the dielectric, not in the center conductor cladding. I would say that it works just fine at UHF (300-3000MHz). I was talking about higher losses in a copper braided shield, VS foil & steel braid. I used to test & specify all the passivies for a major MSO CATV company. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida |
#26
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"Richard Crowley" (1) Is it ok to use this sort of coax for a microphone? Not enough details to answer your question adequately. First of all, the kinds of microphones used for audio applications (reinforcement, recording, etc.) are usually balanced and require cable with two inner wires and an outside shield/screen. If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. The length I need to use is 3 to 4 metres. Not really important to the question. It wouldn't make much difference if it were 1 m or 1Km ** If the mic is high impedance ( ie 50 kohms), then more than 10 metres or so of cable will cause high frequency response peaking and early roll off as the cable capacitance loads the transformer inside the mic. If the mic is low impedance ( ie circa 250 ohms), then hundreds of metres can be used - but not kilometres. ....... Phil |
#27
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Phil Allison wrote: "Richard Crowley" (1) Is it ok to use this sort of coax for a microphone? Not enough details to answer your question adequately. First of all, the kinds of microphones used for audio applications (reinforcement, recording, etc.) are usually balanced and require cable with two inner wires and an outside shield/screen. If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. Of course a proper microphone cable is SCREENED balanced twisted pair, so it enjoys the multiple benefits of electric screening by the outer, the common mode nature of any residual interference and magnetic interference cancellation by the twist in the balanced pair. A poorly screened coax cable such as TV coax has only a part of the first of those so this claim is clearly nonsensical. If it were true, professional microphone and mixer companies would not be going to the trouble of designing balanced kit. The length I need to use is 3 to 4 metres. Not really important to the question. It wouldn't make much difference if it were 1 m or 1Km ** If the mic is high impedance ( ie 50 kohms), then more than 10 metres or so of cable will cause high frequency response peaking and early roll off as the cable capacitance loads the transformer inside the mic. If the mic is low impedance ( ie circa 250 ohms), then hundreds of metres can be used - but not kilometres. This is true. d |
#28
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
In message , Jeff Liebermann
writes On Sat, 03 May 2008 21:23:08 -0400, "Michael A. Terrell" wrote: Use a magnet, and see for yourself. The copper plating smears when cut with dykes, and makes the coated steel appear to be solid copper. Trivia: Dike = Diagonal Cutters http://en.wikipedia.org/wiki/Diagonal_pliers Dyke = Lesbian http://en.wikipedia.org/wiki/Dyke_(lesbian) Dyke or Dike = Earthen wall or dam http://en.wikipedia.org/wiki/Dike_%28construction%29 Methinks "dikes" would be the correct spelling. In the NE of England, 'dyke' also = 'ditch'. From Wiktionary: Dike or dyke (construction), either a long wall or bank built to keep out the sea or enclose or separate land, or the ditch from which the material was dug, or the combination of the two. Apologies for the digression.... -- Ian |
#29
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sun, 04 May 2008 08:13:12 +0100, don pearce wrote:
Phil Allison wrote: "Richard Crowley" (1) Is it ok to use this sort of coax for a microphone? Not enough details to answer your question adequately. First of all, the kinds of microphones used for audio applications (reinforcement, recording, etc.) are usually balanced and require cable with two inner wires and an outside shield/screen. If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. Of course a proper microphone cable is SCREENED balanced twisted pair, so it enjoys the multiple benefits of electric screening by the outer, the common mode nature of any residual interference and magnetic interference cancellation by the twist in the balanced pair. A poorly screened coax cable such as TV coax has only a part of the first of those so this claim is clearly nonsensical. If it were true, professional microphone and mixer companies would not be going to the trouble of designing balanced kit. The length I need to use is 3 to 4 metres. Not really important to the question. It wouldn't make much difference if it were 1 m or 1Km ** If the mic is high impedance ( ie 50 kohms), then more than 10 metres or so of cable will cause high frequency response peaking and early roll off as the cable capacitance loads the transformer inside the mic. If the mic is low impedance ( ie circa 250 ohms), then hundreds of metres can be used - but not kilometres. This is true. d Good quality coax will do the job if you don't mind the impedance mismatch and if you want balanced line then you could use a pair of coax feeds in parallel (impedance about 100 ohms for rg58). Also there's coax and there's coax, I've seen rg58 like TV down-lead and others like shrunk down UR67M. -- ___ _______ ___ ___ ___ __ ____ / _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / / / // / _// __ |/ // / / ___/ __ / /_/ / /__ /____/___/_/ |_/____/ /_/ /_/ |_\____/____/ |
#30
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sun, 04 May 2008 10:30:53 +0100, Dead Paul
wrote: On Sun, 04 May 2008 08:13:12 +0100, don pearce wrote: Phil Allison wrote: "Richard Crowley" (1) Is it ok to use this sort of coax for a microphone? Not enough details to answer your question adequately. First of all, the kinds of microphones used for audio applications (reinforcement, recording, etc.) are usually balanced and require cable with two inner wires and an outside shield/screen. If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. Of course a proper microphone cable is SCREENED balanced twisted pair, so it enjoys the multiple benefits of electric screening by the outer, the common mode nature of any residual interference and magnetic interference cancellation by the twist in the balanced pair. A poorly screened coax cable such as TV coax has only a part of the first of those so this claim is clearly nonsensical. If it were true, professional microphone and mixer companies would not be going to the trouble of designing balanced kit. The length I need to use is 3 to 4 metres. Not really important to the question. It wouldn't make much difference if it were 1 m or 1Km ** If the mic is high impedance ( ie 50 kohms), then more than 10 metres or so of cable will cause high frequency response peaking and early roll off as the cable capacitance loads the transformer inside the mic. If the mic is low impedance ( ie circa 250 ohms), then hundreds of metres can be used - but not kilometres. This is true. d Good quality coax will do the job if you don't mind the impedance mismatch and if you want balanced line then you could use a pair of coax feeds in parallel (impedance about 100 ohms for rg58). Also there's coax and there's coax, I've seen rg58 like TV down-lead and others like shrunk down UR67M. A pair of coaxes in parallel is balanced, but you miss out on the close proximity and twist. The first makes the magnetic loop very small, while the second causes the polarity of any residual pickup to swap every inch or so, giving a net cancellation. As I said in my first reply, if I was forced to use coax for a microphone, domestic TV grade would be a very poor choice because in general it has perhaps no more than 10% screening (just enough in fact to give the cable a stable characteristic impedance, but no more). Microphone signals are too small to mess around this way. Decent audio grade cable has screening approaching 100%. d -- Pearce Consulting http://www.pearce.uk.com |
#31
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat 03 May 2008 11:10:02, Don Pearce wrote:
On Sat, 03 May 2008 10:58:27 +0100, Chris Siz wrote: I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? If you can get hold of some better cable do so. You have two problems here - first coax isn't balanced, which is sort of bad news for tiny signals such as you get from a mic. And secondly, to compound that, if you strip back a little of the outer sheath, you will find that the screen is 90% holes - in other words, the cable is just about unscreened. Um, yes. It is exactly like that. I had thought maybe they were using very thin wires and that way getting a reasonable amount of physcial screening but the wires I found were so sparse that it must be more like what you describe! As for using it for UHF TV, go ahead - that is what it is meant for, and 10 meters is just about the maximum run length before you need to think about using something better. d |
#32
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"Ian Thompson-Bell" wrote in message ... No they expect to see 1K2 to 2K not 10K and that is what most pro mic pres provide. 10K input impedance is for bridging line levels. Cheers Ian Er, not in every case. In any case my point about the mic being regarded as a voltage source remains true. For speech use (3K) you can get away with just about anything! Les. |
#33
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat 03 May 2008 15:54:24, wrote:
On May 3, 4:58 am, Chris Siz wrote: I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? -- [x-posted to 3 relevant groups] Isn't coax kind of rigid? Will the microphone need to move around? This cheapo coax is quite flexible. It may an indication of poor physical resistance to squashing and also of limited copper content. |
#34
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat 03 May 2008 19:05:41, Kevin McMurtrie wrote:
In article , Chris Siz wrote: I am in the UK and have a 10m length of some cheap TV aerial coax. It came from a discount store as a TV coax extension cable. I measure the cable diameter as 4.8mm. (1) Is it ok to use this sort of coax for a microphone? I don't want an impaired audio signal. The length I need to use is 3 to 4 metres. (2) Is it ok for UHF TV or is it actually quite low grade coax and prone to interference or mess up the aerial signal? There are a few differences. TV coax will work in some conditions but not generally. TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. TV coax may not pass small audio signals well because of its aluminum shield. Aluminum is extremely reactive so it is always coated with a thin oxide layer. Higher voltages can spark through it and TV RF can capacitively couple through it. Microphone signals might become distorted. Cable for lower frequencies uses copper shielding. Good microphone and instrument cable has an insulation that drains away static electrical charges. RF coax can contain electrical charges in the insulation that causes it to act like condenser microphone. I am the OP and as you can probably tell I am no electronics or radio expert. However even my limited knowledge struggles to believe some of the points you have made. Forgive me if it's more obvious to others but your's is not some sort of funny posting is it? |
#35
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sun 04 May 2008 04:28:55, Jeff Liebermann wrote:
Incidentally, I blundered across this data sheet for RG-6/u. They can make it just about any way you want it, and still call it RG-6/u. Note the line with: 6) Braiding coverage: Between 30 - 97% available; I can't imagine who would want to buy 30% coverage outer shielding. http://www.tootoo.com/supplier/produ...9/RG6%252fU.ht ml I too have started to feeling that there is a heck of lot more variation than I realised in how coax cables can be made and yet are still conform to some particular technical specification. I came across some interesting articles at "abc cables". Here are some which caught my eye. http://www.abccables.com/technical-support.html Wire? or Cable? RG6 Copper vs. Copper Clad Steel RG59 vs. RG6 Better Copper? I would like to get other (supplier's) info as that site is quite useful. Has anyone got any links to these sort of explanatory articles? |
#36
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sun 04 May 2008 02:23:08, Michael A. Terrell wrote:
Walt Davidson wrote: On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). Then you've never seen the wire used by cable TV and Satellite TV companies. Pure copper is too expensive these days, and too soft for repeated flexing. If you want to pay over a dollar a foot for copper core TV coax, go ahead. The last time I had to buy some it was about eight times the price of the foil shield W/braid TV coax, and useless for UHF. Use a magnet, and see for yourself. The copper plating smears when cut with dykes, and makes the coated steel appear to be solid copper. If copper is soft then wouldn't that make it good for repeated flexing in the sense that copper isn't so stiff that it wouldn't split or crack? |
#37
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sat 03 May 2008 22:24:49, Dead Paul wrote:
On Sat, 03 May 2008 19:39:45 +0100, Walt Davidson wrote: On Sat, 03 May 2008 11:05:41 -0700, Kevin McMurtrie wrote: TV coax is very brittle. The inner wire is copper-plated steel and the outer shield is aluminum wire and aluminum foil. It will quickly crack where it meets the connectors. What planet do you live on? I have never seen TV coax as you describe. Coax with copper-plated steel inner conductor is mostly used as data cable (ethernet). You want to see the crap which passes for rg58 at maplin electronics. Maplins selling crap merchandise doesn't surprise me. (Though to be fair, it does sell the odd good item too.) But where would I go to get half-decent cables in relatively short lengths (not 50m drums) without paying a fortune for ultra quality dedicated-hobbyist stuff or exhorbitant delivery charges? |
#38
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
On Sun, 04 May 2008 09:37:50 +0000, Don Pearce wrote:
On Sun, 04 May 2008 10:30:53 +0100, Dead Paul wrote: On Sun, 04 May 2008 08:13:12 +0100, don pearce wrote: Phil Allison wrote: "Richard Crowley" (1) Is it ok to use this sort of coax for a microphone? Not enough details to answer your question adequately. First of all, the kinds of microphones used for audio applications (reinforcement, recording, etc.) are usually balanced and require cable with two inner wires and an outside shield/screen. If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. Of course a proper microphone cable is SCREENED balanced twisted pair, so it enjoys the multiple benefits of electric screening by the outer, the common mode nature of any residual interference and magnetic interference cancellation by the twist in the balanced pair. A poorly screened coax cable such as TV coax has only a part of the first of those so this claim is clearly nonsensical. If it were true, professional microphone and mixer companies would not be going to the trouble of designing balanced kit. The length I need to use is 3 to 4 metres. Not really important to the question. It wouldn't make much difference if it were 1 m or 1Km ** If the mic is high impedance ( ie 50 kohms), then more than 10 metres or so of cable will cause high frequency response peaking and early roll off as the cable capacitance loads the transformer inside the mic. If the mic is low impedance ( ie circa 250 ohms), then hundreds of metres can be used - but not kilometres. This is true. d Good quality coax will do the job if you don't mind the impedance mismatch and if you want balanced line then you could use a pair of coax feeds in parallel (impedance about 100 ohms for rg58). Also there's coax and there's coax, I've seen rg58 like TV down-lead and others like shrunk down UR67M. A pair of coaxes in parallel is balanced, but you miss out on the close proximity and twist. The first makes the magnetic loop very small, yeah but there is no "mag loop" outside of the shield with coax. while the second causes the polarity of any residual pickup to swap every inch or so, giving a net cancellation. no pickup inside coax. As I said in my first reply, if I was forced to use coax for a microphone, domestic TV grade would be a very poor choice because in general it has perhaps no more than 10% screening (just enough in fact to give the cable a stable characteristic impedance, but no more). Microphone signals are too small to mess around this way. Decent audio grade cable has screening approaching 100%. fully agree. d -- ___ _______ ___ ___ ___ __ ____ / _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / / / // / _// __ |/ // / / ___/ __ / /_/ / /__ /____/___/_/ |_/____/ /_/ /_/ |_\____/____/ |
#39
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
"don pearce PITA smug ****** " "Richard Crowley Arse Licker " If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. Of course a proper microphone cable is SCREENED balanced twisted pair, ** Exactly what I was referring to above. Mic cable IS a balanced twin wire cable. A poorly screened coax cable such as TV coax has only a part of the first of those ** It ain't necessarily poorly screened and it ain't necessarily what I just posted about. Do learn to read sometime - ****wit. has only a part of the first of those .. ** Not true of co-axial cable in general. Do learn to read sometime - ****wit. so this claim is clearly nonsensical. ** Not at all - your irrelevant & asinine claims are nonsensical - ****wit. If it were true, professional microphone and mixer companies would not be going to the trouble of designing balanced kit. ** More completely irrelevant nonsense. " Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. " Obviously YOU need to do this too - ****wit. Since you are so PIG ignorant of the basic physics of co-axial cable. ....... Phil |
#40
Posted to uk.radio.amateur,rec.audio.tech,sci.electronics.design
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OK to use TV coax for microphone?
Phil Allison wrote: "don pearce PITA smug ****** " "Richard Crowley Arse Licker " If you are trying to use a balanced mic, then the cable is unsuitable because it is unbalanced. ** Not true at all !! There is NO reason not to use a (suitable) co-axial type cable with a microphone - either low or high impedance. Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. Of course a proper microphone cable is SCREENED balanced twisted pair, ** Exactly what I was referring to above. Mic cable IS a balanced twin wire cable. Having trouble spotting the capital letters, are you? (yes, I saw yours, and that is what prompted this question, the relevance obviously passed you by). A poorly screened coax cable such as TV coax has only a part of the first of those ** It ain't necessarily poorly screened and it ain't necessarily what I just posted about. Do learn to read sometime - ****wit. we know exactly what this cable is - and yes it is poorly screened. Do try to follow the threads. And if you want to post about something else, start a new thread. has only a part of the first of those .. ** Not true of co-axial cable in general. Do learn to read sometime - ****wit. so this claim is clearly nonsensical. ** Not at all - your irrelevant & asinine claims are nonsensical - ****wit. If it were true, professional microphone and mixer companies would not be going to the trouble of designing balanced kit. ** More completely irrelevant nonsense. Irrelevant is it? Tell that to Neve, Neumann, Shure, Sennheiser, Leevers Rich - need I go on? " Despite all the nonsense you WILL have read elsewhere, co-axial cables have as good or better rejection of external hum and noise sources as do balanced twin wire cables. Try it out if you don't believe this. " Obviously YOU need to do this too - ****wit. Since you are so PIG ignorant of the basic physics of co-axial cable. I appear to have a vastly better grasp of the topic than you, not surprising really when you consider that I have designed ultra low noise microwave measuring equipment. d |
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