repairing an electret microphone

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.

Arfa wrote, "... they are polarity sensitive, as they contain a FET preamp ..."

On the Altec, I had the polarity wrong. Should have trusted the mark I applied before removing the wires.

The headset works as well as ever now.

In this poor picture, the original capsule from the Creative/Telex desktop mic is on the left.

The replacement, on the right, has no silver trace from a solder pad to the capsule. Half of the head of the capsule is a brown Bakelite color typical of a PCB. The other half is black. Is that a conductive layer to connect one pad to the capsule?

In any case, I can buy another mic and try again.

Thanks everyone for the help, ... Peter E.

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. 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.

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. 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.

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" ?

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

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 ?

Arfa

A phantom circuit is a different thing. Usually only used in desperation as the quality isn't as good as the discrete pairs. Other problems with it too. Did Western Electric invent it?

Pot, kettle.

Fine. Let's call apples oranges. Makes sense in your world.

That is called line powering. Says what it is with no doubt. Why would you want to call it anything else?

No it's not. It is a specific way of line powering.

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.

'Phantom powered via a Power Injector'

If that's your example of a concise technical spec gawd help us.

Perhaps I'm old enough to remember the appalling quality of those early systems. And some of the newer ones too.

Whoosh

Arfa

Ah. Another term you don't understand.

--

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW To e-mail, change noise into sound.

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.

Have you ever used a real WE designed phantom phone line? The quality was only dependent on the frequency response of the special phantom transformers, and how good the support pairs were. Properly installed, you couldn't tell the difference. If you phantomed already bad pairs, you got the noise and hum from both bad pairs.

Desperation? How about: "It was developed to provide telephone service where it was impossible to run new lines."

Have you ever used 100 miles of old telephone trunkline for a network feed at a remote radio station? Or, in a pinch, connected a spare audio console directly to a phone line to do and emergency live remote feed to the station?

Who do you think invented it?

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. :(

You could fill a dozen phone books with terms you don't understand.

Explain: :Long Loop Video Combiner".

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.

I must admit I was thinking of where a telephone line is used as a 'music' circuit for broadcast. A phantom one wasn't capable of the same performance. But might well have been near identical at the sorts of frequencies a telephone needs.

I doubt you'd get your broadband feed through one. ;_)

That goes against all I was taught. For sure they may have been adequate, but in practice too many variables.

Think you've answered your point...

It's never 'impossible' to run new lines. Otherwise none would ever be installed. It was used as a stopgap until they were - I doubt you'd find many in use today.

That really was what I was basing things on. A phantom music circuit never performed as well as a discrete pair - even when that pair was an ordinary telephone circuit.

I dunno. That's why I was asking you if you were sure or just guessing. They may well have been the first to use them in the US, of course. But that's not the same thing.

Whoosh.

Along with all the ones you don't then . I was implying that I was contemplating sticking red hot needles in my eyes as a happier way of spending my time than arguing with you, thus I was 'letting' it all whoosh over my head ...

Arfa

At one time it was. there are pictures of New York and other major US cities with so many phone lines that the sidewalks were dark. They literally ran out of room for new wire, under the original designs. Some phantom circuits were only a few blocks, on pairs that went much further. In some cases, the phantom circuit was cleaner than the other pairs.

I saw several sets while in the US military. All were made by WE, and had the parent numbers on them. WE wouldn't include the numbers if they didn't own the patent.