repairing an electret microphone

P

Peter

Guest
To replace a wire which broke in the swivel
of the boom, I reconstructed the boom of an
Altec Lansing headset. This included
resoldering the wires to the back of the
electret capsule. The speakers still work
but the mic does not after this repair.

Found a similar failure after soldering a
new electret onto the wires of an inexpensive
Creative/Telex desktop mic.

Is the electret mic particularly heat sensitive?
If so, what technique is recommended? Already
I was careful to apply minimal heating.

Thanks, ... Peter Easthope
 
"Peter" <peasthope@shaw.ca> wrote in message
news:9fab5f70-43d1-4a12-bedb-a30c51d5be45@v28g2000vbb.googlegroups.com...
To replace a wire which broke in the swivel
of the boom, I reconstructed the boom of an
Altec Lansing headset. This included
resoldering the wires to the back of the
electret capsule. The speakers still work
but the mic does not after this repair.

Found a similar failure after soldering a
new electret onto the wires of an inexpensive
Creative/Telex desktop mic.

Is the electret mic particularly heat sensitive?
If so, what technique is recommended? Already
I was careful to apply minimal heating.

Thanks, ... Peter Easthope
Click to expand...
I've never found them to be particularly heat sensitive within common sense
limits, but note that they are polarity sensitive, as they contain a FET
preamp which is phantom powered via the output terminal ...

Arfa
 
In article <yu5Dl.155$E45.14@newsfe26.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I've never found them to be particularly heat sensitive within common
sense limits, but note that they are polarity sensitive, as they
contain a FET preamp which is phantom powered via the output terminal
...
Click to expand...
A few electret mic are phantom powered but the majority use a form of AB
power for the capsule.

--
*Gun Control: Use both hands.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50494b63bbdave@davenoise.co.uk...
In article <yu5Dl.155$E45.14@newsfe26.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I've never found them to be particularly heat sensitive within common
sense limits, but note that they are polarity sensitive, as they
contain a FET preamp which is phantom powered via the output terminal
...

A few electret mic are phantom powered but the majority use a form of AB
power for the capsule.

--
*Gun Control: Use both hands.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
Click to expand...

I'm using the term "phantom powered" loosely Dave, in that the audio out is
floating on the DC in, because there are only two connections, one of which
is the FET drain terminal, the series DC 'feed' resistor therefore actually
being the drain load resistor. The other terminal (also the capsule case) is
of course ground or FET source. Where there is this type of power / signal
setup, it is often considered generically, to be 'phantom powered' ...
Excuse my ignorance, but what's "AB power" ?

Arfa
 
On Thu, 9 Apr 2009 16:42:16 +0100, "Arfa Daily"
<arfa.daily@ntlworld.com>wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50494b63bbdave@davenoise.co.uk...
In article <yu5Dl.155$E45.14@newsfe26.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I've never found them to be particularly heat sensitive within common
sense limits, but note that they are polarity sensitive, as they
contain a FET preamp which is phantom powered via the output terminal
...

A few electret mic are phantom powered but the majority use a form of AB
power for the capsule.

--
*Gun Control: Use both hands.

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


I'm using the term "phantom powered" loosely Dave, in that the audio out is
floating on the DC in, because there are only two connections, one of which
is the FET drain terminal, the series DC 'feed' resistor therefore actually
being the drain load resistor. The other terminal (also the capsule case) is
of course ground or FET source. Where there is this type of power / signal
setup, it is often considered generically, to be 'phantom powered' ...
Excuse my ignorance, but what's "AB power" ?

Arfa
Click to expand...
http://richardhess.com/notes/2009/03/04/microphone-powering-schema/

Scroll down to A-B or T power.

I've never run across any T power mics or adaptors in my 35 years of
being around the equipment.
 
In article <vHoDl.20412$mh4.702@newsfe19.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50494b63bbdave@davenoise.co.uk...
In article <yu5Dl.155$E45.14@newsfe26.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I've never found them to be particularly heat sensitive within common
sense limits, but note that they are polarity sensitive, as they
contain a FET preamp which is phantom powered via the output terminal
...

A few electret mic are phantom powered but the majority use a form of
AB power for the capsule.
Click to expand...

I'm using the term "phantom powered" loosely Dave, in that the audio out
is floating on the DC in, because there are only two connections, one
of which is the FET drain terminal, the series DC 'feed' resistor
therefore actually being the drain load resistor. The other terminal
(also the capsule case) is of course ground or FET source. Where there
is this type of power / signal setup, it is often considered
generically, to be 'phantom powered' ... Excuse my ignorance, but
what's "AB power" ?
Click to expand...
Not a good idea to use it where mics are concerned, though. Can cause
confusion.

Other thing is not all electrets have the same ground polarity. But
hopefully are marked.

AB or T power is where the DC is fed up the audio pair on a balanced mic.
Dates from before true phantom and has the disadvantage it puts DC across
a moving coil mic - although when it was common many used a PS for each
mic, rather than getting it from the mixer.
Arfa
Click to expand...
--
*Age is a very high price to pay for maturity.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
In article <2nhs84.cci.19.4@news.alt.net>,
Meat Plow <meat@petitmorte.net> wrote:
http://richardhess.com/notes/2009/03/04/microphone-powering-schema/

Scroll down to A-B or T power.

I've never run across any T power mics or adaptors in my 35 years of
being around the equipment.
Click to expand...
Only really used on some older top end mics. Mainly Sennheiser. Favoured
by outside broadcast types as it's more robust over long runs than
phantom.

Certainly still commonly in use 35 years ago in broadcasting. But some
mics that could use it also had an internal battery as an option.

Phantom to T power adaptors are the spawn of the devil. ;-)

--
*Why does the sun lighten our hair, but darken our skin?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
On Thu, 09 Apr 2009 18:43:16 +0100, "Dave Plowman (News)"
<dave@davenoise.co.uk>wrote:

In article <2nhs84.cci.19.4@news.alt.net>,
Meat Plow <meat@petitmorte.net> wrote:
http://richardhess.com/notes/2009/03/04/microphone-powering-schema/

Scroll down to A-B or T power.

I've never run across any T power mics or adaptors in my 35 years of
being around the equipment.

Only really used on some older top end mics. Mainly Sennheiser. Favoured
by outside broadcast types as it's more robust over long runs than
phantom.

Certainly still commonly in use 35 years ago in broadcasting. But some
mics that could use it also had an internal battery as an option.

Phantom to T power adaptors are the spawn of the devil. ;-)
Click to expand...
I've never seen T powered and I run a music studio that has some
pricey vocal mics. Must be a broadcast studio/remote site favorite as
you mention.

Would you know what makes them more robust? Can't be just the fact
that they run on 12 volts rather than 48. I suppose the voltage is an
advantage for remote use requiring less batteries or a more standard
available source.
 
In article <2ni5tb.t6s.17.2@news.alt.net>,
Meat Plow <meat@petitmorte.net> wrote:
I've never seen T powered and I run a music studio that has some
pricey vocal mics. Must be a broadcast studio/remote site favorite as
you mention.
Click to expand...
They pre-date phantom mics - and good quality mics have a long, long life.

But they may well have been originally designed for location drama etc -
where they could get the power from a Nagra.

Would you know what makes them more robust? Can't be just the fact
that they run on 12 volts rather than 48.
Click to expand...
Plenty of theories but can't be definite. Perhaps the fact they will
always work if the audio pair is ok - unlike phantom which needs the
screen. So one less pin/cable to go wrong. Perhaps a lower impedance
supply?

I suppose the voltage is an advantage for remote use requiring less
batteries or a more standard available source.
Click to expand...
You still see new pro equipment with phantom and T power switchable - the
ubiquitous SQN, for one

--
*If you tell the truth, you don't have to remember anything.*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:504964fce3dave@davenoise.co.uk...
In article <vHoDl.20412$mh4.702@newsfe19.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50494b63bbdave@davenoise.co.uk...
In article <yu5Dl.155$E45.14@newsfe26.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I've never found them to be particularly heat sensitive within common
sense limits, but note that they are polarity sensitive, as they
contain a FET preamp which is phantom powered via the output terminal
...

A few electret mic are phantom powered but the majority use a form of
AB power for the capsule.


I'm using the term "phantom powered" loosely Dave, in that the audio out
is floating on the DC in, because there are only two connections, one
of which is the FET drain terminal, the series DC 'feed' resistor
therefore actually being the drain load resistor. The other terminal
(also the capsule case) is of course ground or FET source. Where there
is this type of power / signal setup, it is often considered
generically, to be 'phantom powered' ... Excuse my ignorance, but
what's "AB power" ?

Not a good idea to use it where mics are concerned, though. Can cause
confusion.

Other thing is not all electrets have the same ground polarity. But
hopefully are marked.

AB or T power is where the DC is fed up the audio pair on a balanced mic.
Dates from before true phantom and has the disadvantage it puts DC across
a moving coil mic - although when it was common many used a PS for each
mic, rather than getting it from the mixer.
Click to expand...

OK, but seems that all of this is tending to look at 'whole' mics as in
something that a newsreader would clip to himself, whereas the original
poster was talking about just the capsule inside, which was also what I was
referring to. As far as the polarity of electret mics varying, I can't
remember ever seeing a capsule where the case wasn't a negative-side ground,
and over the years, I have dealt with and replaced many in cordless phones
and similar.

I appreciate that to a sound engineer, the term "phantom power" has a
slightly special meaning in terms of voltage level etc, but that still
doesn't change the fact that generically, any system where DC power is
supplied to an active signal source, using only the wires that are carrying
the signal rather than any additional power carrying wire, are considered to
be 'phantom' powered, irrespective of the voltage involved. TV antenna
amplifiers for instance, are often described as being phantom powered, as
also are satellite LNBs.

However, all that said, I do take your point that it could give rise to
confusion between a sound engineer reading it, and an electronics engineer,
who might better understand the overall concept. Perhaps it would be better
to call the electret capsule 'line powered' ...

Arfa
 
In article <65xDl.6509$Rh1.5417@newsfe10.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
However, all that said, I do take your point that it could give rise to
confusion between a sound engineer reading it, and an electronics
engineer, who might better understand the overall concept. Perhaps it
would be better to call the electret capsule 'line powered' ...
Click to expand...
Indeed - that's always how aerial pre-amps etc which use this technique
are described. At least in my experience.

Phantom power is so called because it is invisible to the actual required
signal. Line power doesn't qualify in this way.

--
*Microsoft broke Volkswagen's record: They only made 21.4 million bugs.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
On Thu, 9 April 16:42, Arfa Daily wrote:

"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:50494b63bbdave@davenoise.co.uk...
In article <yu5Dl.155$E45.14@newsfe26.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
I've never found them to be particularly heat sensitive
within common sense limits, but note that they are polarity
sensitive, as they contain a FET preamp which is phantom
powered via the output terminal ...

A few electret mic are phantom powered but the majority use a
form of AB power for the capsule.


I'm using the term "phantom powered" loosely Dave, in that the
audio out is floating on the DC in, because there are only two
connections, one of which is the FET drain terminal, the
series DC 'feed' resistor therefore actually being the drain
load resistor. The other terminal (also the capsule case) is
of course ground or FET source. Where there is this type of
power / signal setup, it is often considered generically, to
be 'phantom powered' ... Excuse my ignorance, but what's "AB
power" ?

Arfa
Click to expand...
Makes sense to me. Unfortunately the term Phantom Powered can be
used too loosely and gets misinterpreted.
 
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:5049be1a67dave@davenoise.co.uk...
In article <65xDl.6509$Rh1.5417@newsfe10.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
However, all that said, I do take your point that it could give rise to
confusion between a sound engineer reading it, and an electronics
engineer, who might better understand the overall concept. Perhaps it
would be better to call the electret capsule 'line powered' ...

Indeed - that's always how aerial pre-amps etc which use this technique
are described. At least in my experience.
Click to expand...

No Dave, they aren't. The term "phantom power" is used for many situations
where an active device needs powering and only the signal cable is
available. Antenna amplifiers, satellite LNBs, cable operators' distribution
amplifiers and so on, are all routinely described as being "phantom
powered". There are plenty of web references to the technique of phantom
powering in these applications. Long ago, when I worked in the early days of
cable TV, all of our line amplifiers were powered in this way, and it was
always referred to as phantom powering, both by all of the high-end network
engineering bods, and also our in-house lecturers, responsible for training
of all of the company's engineers.

In fact I would go as far as to say that the technique has been around and
called that for a very long time, and the 'hi-jacking' of the term by sound
engineering to try to mean something very specific, is actually the
questionable use of the phrase.


Phantom power is so called because it is invisible to the actual required
signal. Line power doesn't qualify in this way.
Click to expand...

How so ? What do you perceive as being the difference ? If DC is travelling
one way, and signal the other on a single cable, they must be mutually
invisible (or made so by appropriate circuitry techniques at the active
device, and what it's feeding at the far end of its cable). I have never
seen any distinction made before. As far as I am aware, "Line powered" is
just a slightly more technically descriptive way of expressing "phantom
power".

Arfa
 
In article <0KKDl.10612$bq4.6752@newsfe29.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
No Dave, they aren't. The term "phantom power" is used for many
situations where an active device needs powering and only the signal
cable is available. Antenna amplifiers, satellite LNBs, cable
operators' distribution amplifiers and so on, are all routinely
described as being "phantom powered". There are plenty of web
references to the technique of phantom powering in these applications.
Long ago, when I worked in the early days of cable TV, all of our line
amplifiers were powered in this way, and it was always referred to as
phantom powering, both by all of the high-end network engineering bods,
and also our in-house lecturers, responsible for training of all of the
company's engineers.

In fact I would go as far as to say that the technique has been around
and called that for a very long time, and the 'hi-jacking' of the term
by sound engineering to try to mean something very specific, is
actually the questionable use of the phrase.
Click to expand...
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.

--
*The closest I ever got to a 4.0 in school was my blood alcohol content*

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
"Dave Plowman (News)" wrote:
In article <0KKDl.10612$bq4.6752@newsfe29.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
No Dave, they aren't. The term "phantom power" is used for many
situations where an active device needs powering and only the signal
cable is available. Antenna amplifiers, satellite LNBs, cable
operators' distribution amplifiers and so on, are all routinely
described as being "phantom powered". There are plenty of web
references to the technique of phantom powering in these applications.
Long ago, when I worked in the early days of cable TV, all of our line
amplifiers were powered in this way, and it was always referred to as
phantom powering, both by all of the high-end network engineering bods,
and also our in-house lecturers, responsible for training of all of the
company's engineers.

In fact I would go as far as to say that the technique has been around
and called that for a very long time, and the 'hi-jacking' of the term
by sound engineering to try to mean something very specific, is
actually the questionable use of the phrase.

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.
Click to expand...

The telephone system was based on the same battery powered model the
early telegraph lines used. In fact, the early hand crank phones used a
local dry cell battery to power the line to the operator's switchboard.
Then there were the 20 and 60 mA teletype circuits where the power to
drive the mechanical decoder was remote powered over the data lines. It
is an obvious technology, being used by quite a few fields. As usual,
some group wants to claim to be the 'One true prophet' for their phony
religion. :(

--
And another motherboard bites the dust!
 
In article <05adnZee9rITMULUnZ2dnUVZ_rGdnZ2d@earthlink.com>,
Michael A. Terrell <mike.terrell@earthlink.net> 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.
Click to expand...

The telephone system was based on the same battery powered model the
early telegraph lines used. In fact, the early hand crank phones used a
local dry cell battery to power the line to the operator's switchboard.
Then there were the 20 and 60 mA teletype circuits where the power to
drive the mechanical decoder was remote powered over the data lines. It
is an obvious technology, being used by quite a few fields. As usual,
some group wants to claim to be the 'One true prophet' for their phony
religion. :(
Click to expand...
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.

--
*Keep honking...I'm reloading.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
"Dave Plowman (News)" wrote:
In article <05adnZee9rITMULUnZ2dnUVZ_rGdnZ2d@earthlink.com>,
Michael A. Terrell <mike.terrell@earthlink.net> 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.

The telephone system was based on the same battery powered model the
early telegraph lines used. In fact, the early hand crank phones used a
local dry cell battery to power the line to the operator's switchboard.
Then there were the 20 and 60 mA teletype circuits where the power to
drive the mechanical decoder was remote powered over the data lines. It
is an obvious technology, being used by quite a few fields. As usual,
some group wants to claim to be the 'One true prophet' for their phony
religion. :(

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.
Click to expand...

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

--
And another motherboard bites the dust!
 
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.

http://carnot.yi.org/Mics.jpg

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.
 
"Dave Plowman (News)" <dave@davenoise.co.uk> wrote in message
news:5049ecbf52dave@davenoise.co.uk...
In article <0KKDl.10612$bq4.6752@newsfe29.ams2>,
Arfa Daily <arfa.daily@ntlworld.com> wrote:
No Dave, they aren't. The term "phantom power" is used for many
situations where an active device needs powering and only the signal
cable is available. Antenna amplifiers, satellite LNBs, cable
operators' distribution amplifiers and so on, are all routinely
described as being "phantom powered". There are plenty of web
references to the technique of phantom powering in these applications.
Long ago, when I worked in the early days of cable TV, all of our line
amplifiers were powered in this way, and it was always referred to as
phantom powering, both by all of the high-end network engineering bods,
and also our in-house lecturers, responsible for training of all of the
company's engineers.

In fact I would go as far as to say that the technique has been around
and called that for a very long time, and the 'hi-jacking' of the term
by sound engineering to try to mean something very specific, is
actually the questionable use of the phrase.

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.
Click to expand...
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

http://www.lashen.com/vendors/channelvision/CVT-RF-Amps.asp

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
 
In article <LvOdnf4d1Kb0RULUnZ2dnUVZ_oJi4p2d@earthlink.com>,
Michael A. Terrell <mike.terrell@earthlink.net> 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.
Click to expand...

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

--
*Confession is good for the soul, but bad for your career.

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