OK to use TV coax for microphone?

Re: OK to use TV coax for microphone?

"Don Pearce" wrote...
> 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).

That may be the case over there (although I doubt it).
Over on our side of the earth, RF cables, and especially
those intended for television use are 100% shielded.
Because if they are not, it starts causing problems.
Problems for the cable operators when RF leaks (in
either direction) between the TV station on channel X
and the over-the-air signal of the same station on the
same frequency. This is a chronic problem in some of
the poorer-maintained systems.

And problems for individuals even with just a run of
several meters to a rooftoop antenna because of the
increased susceptability to RFI, particularly in remote
regions where the signal is weak to start with.

RF coax made for cable TV use have foil shields plus
a few strands of wire braid around the foil. In fact many
of them even have a double foil shield.

Don't mistake the wire braid (which may, indeed be only
10% coverage) for the actual outer shield of the coax
which is the active portion.

> Microphone signals are too small to mess around this way.
> Decent audio grade cable has screening approaching 100%.

And out in remote rural areas, RF signals are of the same
order.

Re: OK to use TV coax for microphone?

On Sun, 4 May 2008 08:32:49 -0700, "Richard Crowley"
<rcrowley@xp7rt,net > wrote:

>RF coax made for cable TV use have foil shields plus
>a few strands of wire braid around the foil. In fact many
>of them even have a double foil shield.
>
>Don't mistake the wire braid (which may, indeed be only
>10% coverage) for the actual outer shield of the coax
>which is the active portion.

Yup, but the stuff we are discussing here has just a very loose braid.
Have a look at the second pic on this page - low loss TV coax.

http :// www .megalithia,com /elect/cable/index.html

d
--
Pearce Consulting
http :// www .pearce.uk,com

Re: OK to use TV coax for microphone?

"Don Pearce" wrote ...
> "Richard Crowley"
> <rcrowley@xp7rt,net > wrote:
>
>>RF coax made for cable TV use have foil shields plus
>>a few strands of wire braid around the foil. In fact many
>>of them even have a double foil shield.
>>
>>Don't mistake the wire braid (which may, indeed be only
>>10% coverage) for the actual outer shield of the coax
>>which is the active portion.
>
> Yup, but the stuff we are discussing here has just a very loose braid.
> Have a look at the second pic on this page - low loss TV coax.
>
> http :// www .megalithia,com /elect/cable/index.html

What is that stuff good for?!
I've never seen anything like that over here. It can't be
useful for low-level signals (receiving, audio, etc.) any
place where there is any RFI.

OTOH, they make an intentionally "lossy" coaxial cable
(one brand name is "Radiax") which is used for distributed
Tx/Rx (such as running a cable through a tunnel to provide
cell service underground, etc.) That stuff has holes all along
the length to deliberately leak RF along the way.

Re: OK to use TV coax for microphone?

On Sun, 4 May 2008 10:09:34 -0700, "Richard Crowley"
<rcrowley@xp7rt,net > wrote:

>"Don Pearce" wrote ...
>> "Richard Crowley"
>> <rcrowley@xp7rt,net > wrote:
>>
>>>RF coax made for cable TV use have foil shields plus
>>>a few strands of wire braid around the foil. In fact many
>>>of them even have a double foil shield.
>>>
>>>Don't mistake the wire braid (which may, indeed be only
>>>10% coverage) for the actual outer shield of the coax
>>>which is the active portion.
>>
>> Yup, but the stuff we are discussing here has just a very loose braid.
>> Have a look at the second pic on this page - low loss TV coax.
>>
>> http :// www .megalithia,com /elect/cable/index.html
>
>What is that stuff good for?!
>I've never seen anything like that over here. It can't be
>useful for low-level signals (receiving, audio, etc.) any
>place where there is any RFI.
>
It is good for absolutely nothing, and nowadays resides only in cut
price electrical stores and old boxes in attics.

>OTOH, they make an intentionally "lossy" coaxial cable
>(one brand name is "Radiax") which is used for distributed
>Tx/Rx (such as running a cable through a tunnel to provide
>cell service underground, etc.) That stuff has holes all along
>the length to deliberately leak RF along the way.
>
I know Andrew's Radiax very well - I've specified it for distributing
VHF in tunnels.

d

--
Pearce Consulting
http :// www .pearce.uk,com

Re: OK to use TV coax for microphone?

On Sun, 04 May 2008 17:16:19 GMT, nospam@nospam,com (Don Pearce)
wrote:

>On Sun, 4 May 2008 10:09:34 -0700, "Richard Crowley"
><rcrowley@xp7rt,net > wrote:
>
>>"Don Pearce" wrote ...
>>> "Richard Crowley"
>>> <rcrowley@xp7rt,net > wrote:
>>>
>>>>RF coax made for cable TV use have foil shields plus
>>>>a few strands of wire braid around the foil. In fact many
>>>>of them even have a double foil shield.
>>>>
>>>>Don't mistake the wire braid (which may, indeed be only
>>>>10% coverage) for the actual outer shield of the coax
>>>>which is the active portion.
>>>
>>> Yup, but the stuff we are discussing here has just a very loose braid.
>>> Have a look at the second pic on this page - low loss TV coax.
>>>
>>> http :// www .megalithia,com /elect/cable/index.html
>>
>>What is that stuff good for?!
>>I've never seen anything like that over here. It can't be
>>useful for low-level signals (receiving, audio, etc.) any
>>place where there is any RFI.
>>
>It is good for absolutely nothing, and nowadays resides only in cut
>price electrical stores and old boxes in attics.
>
>>OTOH, they make an intentionally "lossy" coaxial cable
>>(one brand name is "Radiax") which is used for distributed
>>Tx/Rx (such as running a cable through a tunnel to provide
>>cell service underground, etc.) That stuff has holes all along
>>the length to deliberately leak RF along the way.
>>
>I know Andrew's Radiax very well - I've specified it for distributing
>VHF in tunnels.
>
>d

Now if there were more that only one minor competitor.

Re: OK to use TV coax for microphone?

On Sun, 04 May 2008 08:32:49 -0700, Richard Crowley wrote:

> "Don Pearce" wrote...
>> 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).
>
> That may be the case over there

Over there? Over here we find lots of 72 ohm tv coax on sale in the diy
stores which has very poor screening. In fact I'd say the majority of
terrestrial tv antennas in the Uk are wired with it.

> (although I doubt it). Over on our side of
> the earth, RF cables, and especially those intended for television use are
> 100% shielded. Because if they are not, it starts causing problems.
> Problems for the cable operators

Well yes, cable tv operators even over here use much higher quality coax.

<snip>

> Don't mistake the wire braid (which may, indeed be only 10% coverage) for
> the actual outer shield of the coax which is the active portion.

I don't think any regular in this ng is going to make a mistake like that.

>> Microphone signals are too small to mess around this way. Decent audio
>> grade cable has screening approaching 100%.
>
> And out in remote rural areas, RF signals are of the same order.

Most areas here (UK) have excellent analogue signal strength.

--
___ _______ ___ ___ ___ __ ____
/ _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
/ // / _// __ |/ // / / ___/ __ / /_/ / /__
/____/___/_/ |_/____/ /_/ /_/ |_\____/____/

Re: OK to use TV coax for microphone?

"Dead Paul" wrote in ...
> 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.

There is no "impedance mismatch" at audio frequencies in this
application.

Re: OK to use TV coax for microphone?


"Dead Paul" <dead_paul@no.reply> wrote in message news:fvjvod$mej$1@news.datemas.de...
> 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.
>
>
> --
> ___ _______ ___ ___ ___ __ ____
> / _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
> / // / _// __ |/ // / / ___/ __ / /_/ / /__
> /____/___/_/ |_/____/ /_/ /_/ |_\____/____/
>

Impedances are almost never matched, source to load, or source to transmission line to load
in audio. Telephone lines are the only case that comes to mind. Mics, speakers, preamps to
amps -- just not done. In short, we don't match source to cable, nor cable to load. Nor
source to load. Not only that, the impedance of a typical cable, such as rg-59, though 75
Ohms above 100KHz, is much much higher in the audio range.

Earl

Re: OK to use TV coax for microphone?


"don pearce PITA smug wanker "
>
> "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 - fuckwit.


> has only a part of the first of those ..


** Not true of co-axial cable in general.

Do learn to read sometime - fuckwit.


so this claim is clearly nonsensical.

** Not at all -

your irrelevant & asinine claims are nonsensical

- fuckwit.


> 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 - fuckwit.

Since you are so PIG ignorant of the basic physics of co-axial cable.




...... Phil

Re: OK to use TV coax for microphone?


Phil Allison wrote:
> "don pearce PITA smug wanker "
>> "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 - fuckwit.
>

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 - fuckwit.
>
>
> so this claim is clearly nonsensical.
>
> ** Not at all -
>
> your irrelevant & asinine claims are nonsensical
>
> - fuckwit.
>
>
>> 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 - fuckwit.
>
> 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

Re: OK to use TV coax for microphone?


"don pearce ASININE PITA smug wanker "
>
>>
>>> "Richard Crowley Vile 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?


** Go no idea what the term " mic cable " refers to - eh ??

FUCKWIT ??

Do go have a look at some one day.



> (yes, I saw yours, and that is what prompted this question, the relevance
> obviously passed you by).


** Go get utterly fucked -

you VILE, SMUG ILLITERATE pile of autistic shit !!



>>> 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 - fuckwit.
>>
>
> we know exactly what this cable is - and yes it is poorly screened.


** It ain't necessarily poorly screened and it ain't necessarily what I
just
posted about.

Do learn to read sometime -

you stinking, arrogant pile of demented SHIT.



>>> has only a part of the first of those ..
>>
>>
>> ** Not true of co-axial cable in general.
>>
>> Do learn to read sometime - fuckwit.
>>
>>
>> so this claim is clearly nonsensical.
>>
>> ** Not at all -
>>
>> your irrelevant & asinine claims are nonsensical
>>
>> - fuckwit.
>>
>>
>>> 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?


** Your illogical point is what is irrelevant.

Do learn to read sometime -

you stinking, arrogant pile of demented SHIT.


> Tell that to Neve, Neumann, Shure, Sennheiser, Leevers Rich - need I go
> on?


** Feel free to top yourself anytime - Don.

It would do the whole planet a small favour.

One less ASD fucked arsehole stinking it up.




>> " 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 - fuckwit.
>>
>> 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,


** You appear to have a monstrous, malignant tumour growing in you fat,
stupid head.

At least, I sincerely hope that is indeed the case.



> not surprising really when you consider that I have designed ultra low
> noise microwave measuring equipment.


** Whaaaaaaaatttttt ???????????

ROTFLMAO !!!

What totally IRRELEVANT BOLLOCKS !!!

Typical smug puke from the " Don Pearce " cretin

wot a FUCKING ARROGANT NUT CASE !!!




.... Phil

Re: OK to use TV coax for microphone?

"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 !!
>
> 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.

Don, please don't feed the troll.

The signal-to-noise ratio from Mr. Allison is so poor that he is
better to be filtered completely out.

Re: OK to use TV coax for microphone?

On Sun, 4 May 2008 08:20:22 -0700, "Richard Crowley"
<rcrowley@xp7rt,net > wrote:

>"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 !!
>>
>> 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.
>
>Don, please don't feed the troll.
>
>The signal-to-noise ratio from Mr. Allison is so poor that he is
>better to be filtered completely out.
>

Sorry, he normally resides in my killfile where he belongs, but every
now and then I have to reconfigure something and he gets out.

He's back in there with a shot of Ketamine now.

d

--
Pearce Consulting
http :// www .pearce.uk,com

Re: OK to use TV coax for microphone?


"Richard Arse Licker Crowley"



** Gawd -

what a low life piece of autistic scum this human turd is.




.... Phil

Re: OK to use TV coax for microphone?


"Chris Siz" <default@default.invalid> wrote in message
news:Xns9A936FA2EF13F451E7A@127.0.0.1...
>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]

It's fine for connecting a cheapo mic so long as it's kept stationary - as
the coax is nearly rigid and non-pliant compared to good mic cable. If your
mic o/p is balanced, use a 3-conductor [screen + twisted pair] cable and bin
the coax!
Any 2-wire cable (co-ax or not) will do for an aerial feed, if it's kept
short!
Jim
>