Michael A. Terrell wrote:

Adrian Tuddenham wrote:

Dave Plowman (News) wrote:

In article ,
Michael A. Terrell wrote:
Indeed - and the pro audio lot certainly didn't use the name 'phantom'
for the first line powered mics. That was called AB or T power.


Ever seen a phantom phone line? If anyone has the right to claim the
name, it is Western Electric.

A phantom circuit is a different thing. Usually only used in desperation
as the quality isn't as good as the discrete pairs.

If the lines were designed to be phantomed, as many long-distance
telephone circuits were, the phantom should meet the same spec as the
main pairs.


They did. The quality didn't suffer, until there were multiple
layers of phantom circuits. Some places used so many phantom circuits
in downtown areas that a problem on a single pair would affect dozens of
circuits. They were quite common in the days when each phone line was a
pair of single wires run between poles. They quickly ran out of room
for more pairs, and had to be creative until multiple pair lead sheathed
cable was developed.

As a slightly quirky aside: starquad cable uses the 'phantom' for the
main circuit with the side pairs short-circuited. The 'phantom' in this
particular case gives better immunity to localised inteference than the
side pairs would on their own.


--
~ Adrian Tuddenham ~
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