"Eeyore" wrote
in message
Arny Krueger wrote:

"Dave Plowman (News)" wrote in
message
Eeyore
wrote:

Mere pence when you include decent XLRs? Love to know
where you buy them for that...

Do you know how cheap the Chinese copy XLRs are now ?
They're perfectly decent for the job.

My experiences of cheap XLRs isn't positive - I tend to
stick to Neutric. But then they're used for the purpose
intended.

The Neutrik clone XLRs are IME pretty good. Never saw
one fail, although I've seen the cables they are
attached to fail many times.

I've actually NEVER seen a bad 'copy' XLR, certainly
compared to certain other styles of connector around.

Plugging them in and out HUNDREDS of times might wear the
contacts but just try that with an RCA ! I have some XLR
leads here that are nearly 40 years old and still in
perfect working order, despite HUNDREDS of times being
used.

I just had to replace a Neutrik clone because the plastic twist-on part
pretty much disintegrated.

David Looser wrote:

"Eeyore" wrote

Why do you think broadcast kit is all BNC for video ?

Well it isn't of course. MUSAs are still used for video jackfields (and it
was the standard video connector for many years in this country at least).
And the PL259 design has also been widely used as a video connector in
broadcast kit. Neither of these are any better than phono in terms of
return-loss. What all three do have is robustness and, in the case of BNCs
and PL259s, a locking mechanism.

Virtually everything I've seen has BNCs. You're splitting hairs. And I'm sure
it has a better VSWR than an RCA phono POS.

Graham


--
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David Looser wrote:

"Keith G" wrote
"Eeyore" wrote

Well, the video could be on BNCs which needn't be that expensive either
( think of how many used to be used in networking ) so you'd only need a
few
XLRs.

The trouble with those connectors and co-ax/optical digital connections (I
gather) is they can't deal with the bandwidth required for 7.1 channels of
'HD' sound or digital video.

D-Cinema servers use BNC connectors to carry the digital video to the
projector, and 25-pin D connectors to carry the 8 channel LPCM digital audio
(as 4 x 2-channel AES/EBU streams) to the audio processor.

I'll point out here that AES/EBU is 'balanced' digital too. Now why might that
be ? As is all modern networking etc etc. Even POTS is balanced after a fashion.

Graham

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Serge Auckland wrote:

Maybe I have lead a sheltered life since I moved to the country.... :-) My
experience is otherwise, that decent equipment doesn't hum or pick up RF if
half-decent screened cable is used. I do accept that I've had some trouble
with SOME switched-mode powered equipment which was cured by the use of an
isolating transformer. I assumed that was an isolated example.

On the contrary, it's increasing daily and is all the more reason to go
balanced since you don't share the screen ( and any associated earth leakage
currents ) with signal return. I've even modelled typical equipment using SMPS
supplies and a very experienced colleague of mine got a shock at how much
voltage there is on the screen of much unterminated equipment these days.
Laptops PCs are a case in note. When it's earthed to its destination it
produces a ground current in the input stage, the effect of which depends on
quality of the EMC design of the receiving equipment. Namely ALL screens should
be terminated to CHASSIS. The very reverse of how it was once done.

Graham


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"Dave Plowman (News)" wrote:

Serge Auckland wrote:
Maybe I have lead a sheltered life since I moved to the country.... :-)
My experience is otherwise, that decent equipment doesn't hum or pick
up RF if half-decent screened cable is used. I do accept that I've had
some trouble with SOME switched-mode powered equipment which was cured
by the use of an isolating transformer. I assumed that was an isolated
example.

Indeed. I've got a pretty big installation here with some stuff in one
part of the room - TV, PVR, satellite receiver - and the main audio stuff
at another. All interconnected unbalanced. It's also linked to sound and
vision in the kitchen so I can have the same thing playing etc while
wandering between the two. And no problems whatsoever with hum. It would
be a poor piece of design which has high levels of nasties on an audio
ground.

Try measuring one. Cable screen to mains earth either on AC voltage or low
current. It may surprise you. Mind you, if it's ALL Class II equipment the
return path to ground doesn't exist so you may get away with it.

Graham


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to my email address

In article , Eeyore rabbitsfriendsan
scribeth thus


David Looser wrote:

"Eeyore" wrote

Why do you think broadcast kit is all BNC for video ?

Well it isn't of course. MUSAs are still used for video jackfields (and it
was the standard video connector for many years in this country at least).
And the PL259 design has also been widely used as a video connector in
broadcast kit. Neither of these are any better than phono in terms of
return-loss. What all three do have is robustness and, in the case of BNCs
and PL259s, a locking mechanism.

Virtually everything I've seen has BNCs. You're splitting hairs. And I'm sure
it has a better VSWR than an RCA phono POS.


Urrrgh!..

PL 259 plugs!.. The spawn of Satan;!..

--
Tony Sayer

"Eeyore" wrote in message
...


Even POTS is balanced after a fashion.


More than "after a fashion". POTS is very well balanced, and of course
balancing was invented by and for the telephone industry.

David.

On Tue, 30 Jun 2009 11:18:44 +0100, "David Looser"
wrote:

"Eeyore" wrote in message
...


Even POTS is balanced after a fashion.


More than "after a fashion". POTS is very well balanced, and of course
balancing was invented by and for the telephone industry.

David.


Pots is both balanced and unbalanced - that is how it manages full
duplex over a single pair.

d

"Don Pearce" wrote in message
news:4a54e8a0.1490496031@localhost...
On Tue, 30 Jun 2009 11:18:44 +0100, "David Looser"
wrote:

"Eeyore" wrote in message
...


Even POTS is balanced after a fashion.


More than "after a fashion". POTS is very well balanced, and of course
balancing was invented by and for the telephone industry.

David.


Pots is both balanced and unbalanced - that is how it manages full
duplex over a single pair.

d

I've always been fascinated by telephone hybrids that separate out the send
and return audio. I can understand how modern digital hybrids work, buggered
if I can understand how the original hybrid transformers work though.

S.
--
http://audiopages.googlepages.com

On Tue, 30 Jun 2009 11:52:24 +0100, "Serge Auckland"
wrote:


"Don Pearce" wrote in message
news:4a54e8a0.1490496031@localhost...
On Tue, 30 Jun 2009 11:18:44 +0100, "David Looser"
wrote:

"Eeyore" wrote in message
...


Even POTS is balanced after a fashion.


More than "after a fashion". POTS is very well balanced, and of course
balancing was invented by and for the telephone industry.

David.


Pots is both balanced and unbalanced - that is how it manages full
duplex over a single pair.

d

I've always been fascinated by telephone hybrids that separate out the send
and return audio. I can understand how modern digital hybrids work, buggered
if I can understand how the original hybrid transformers work though.

S.

I wonder if I can explain without pictures - probably not. The
transformer has a single winding for the line (and yes, it really is
balanced both ways). Facing the handset is a centre tapped winding.
with exactly the same impedance load to ground from all three points.
One of these windings will be for the microphone, the other for the
earpiece. A signal arriving along the line goes to both the earpiece
and the microphone - doesn't matter about the one hitting the mic, as
long as the earpiece gets some too. So there is no discrimination in
the incoming direction.

The clever bit is when you talk into the microphone. Obviously the
transformer sends some of it along the line, but an equal signal will
appear at the centre tap (equal because all the resistive loads are
the same. At the same time, the second half of the winding generates
the identical voltage, but this time out of phase with the centre tap.
So the net voltage at this end of the winding is the vector sum of two
identical, opposite phase signals. Ie zero. This goes to the earphone.

Did that make any sense?

d