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Posted to sci.electronics.repair
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repairing an electret microphone
Arfa Daily wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
Arfa Daily wrote:
Phantom powering was first used by the telephone industry long before
TV of any sort. If the cable TV industry - hardly a bastion of good
practice - hijacked it for something which is patently not phantom,
they're the ones that are wrong.
This is getting out of hand, and you seem to be being deliberately
obtuse, as you sometimes are about some subjects that seem to release a
swarm of bees in your bonnet.
Pot, kettle.
It was you who suggested that the term
"phantom powered" had some particular meaning, specifically with regard
to microphones, and that it shouldn't be used in other contexts. I
never particularly suggested that it was a term 'belonging' to the TV
industry, or indeed any other industry. As a sound engineer, I'm sure
that you believe that it has this specific meaning in the context of
microphones only, but that isn't so.
Fine. Let's call apples oranges. Makes sense in your world.
It is a general purpose term that describes the feeding of DC power to
any active device, using only the signal pair from that device.
That is called line powering. Says what it is with no doubt. Why would you
want to call it anything else?
The telephone people may well be the original users of the technique,
and coiners of the name "phantom power" for it, but it is just as valid
to use the term for any similar system, including microphone powering,
and various items that I happened to pick from the TV business.
No it's not. It is a specific way of line powering.
And I'm still not clear what distinction in technique that you believe
there to be, between 'phantom powering' and 'line powering' ? Why do
you believe the powering scheme that they are using for their line
amplifiers to be "patently not phantom" ?
You don't know the difference?
I'll explain again, then. Line powering applies volts to anything on that
signal line. Phantom power doesn't - only to those devices configured to
use it. It also only applies to balanced circuits. So it follows the
meaning of phantom - invisible to some. Connect a DC meter to line power
and you'll see it. You won't with phantom.
If you don't believe me that the manufacturers of TV distribution
equipment consider that what they are doing is employing 'phantom
powering', then take a look at for example
http://www.lashen.com/vendors/channe...VT-RF-Amps.asp
'Phantom powered via a Power Injector'
If that's your example of a concise technical spec gawd help us.
And why do you believe the cable TV industry to be "hardly a bastion of
good practice"? What is it you feel that they do wrong, or could do
better ?
Perhaps I'm old enough to remember the appalling quality of those early
systems. And some of the newer ones too.
--
*Forget about World Peace...Visualize using your turn signal.
Dave Plowman London SW
To e-mail, change noise into sound.
Whoosh
Arfa
Definately. Early CATV systems required AC power at each pole
mounted 12 channel amplifer. I'll bet he believes all the hype about
'Monster Cable' too. 
--
And another motherboard bites the dust!
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