Adapting a microphone to remote phantom power

  • Thread starter David Nebenzahl
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David Nebenzahl

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OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.

I have the WM-D6C Walkman "Professional" recorder and a Sony ECM-737
stereo microphone. The rig still makes very nice recordings. (No, I
don't usually use it for music, and I'm not pushing cassette as the
ultimate recording medium.)

The annoying thing about it is that while the microphone requires a
battery (a single AA cell), the recorder is apparently perfectly capable
of supplying power to the mike. The mike jack is marked "PLUG IN POWER",
which I suppose is Sony's way of identifying phantom power. (This may
not be "phantom power" in the sense of standard supply voltage, but
instead a proprietary Sony level.) I can't tell you how many times I've
had problems recording which turned out to be a low or dead battery in
the microphone. Probably my bad for not buying the next-better mike,
which I think did run on the recorder's power.

So I'm thinking I could modify the microphone to accept power from the
recorder, without modifying the recorder in any way. There are a few
things I don't know, however:

o The voltage of the power supplied by the recorder, which runs on 4 AA
cells. (48 volts? I'm guessing not, but who knows?)

o The configuration of the microphone jack. My mike uses a 3-conductor
plug, so what happens to the power contact in the jack?

o The wiring inside the mike and the difficulty of rewiring it (haven't
opened it up yet to look).

Anyone familiar at all with this equipment? Care to give some advice on
how to proceed?

Thanks in advance.


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
On 4/9/2009 4:36 PM David Nebenzahl spake thus:

So I'm thinking I could modify the microphone to accept power from the
recorder, without modifying the recorder in any way. There are a few
things I don't know, however:

o The voltage of the power supplied by the recorder, which runs on 4 AA
cells. (48 volts? I'm guessing not, but who knows?)
Click to expand...
Further research reveals that the recorder supplies 2.8 volts on both
channels of the microphone input.

o The configuration of the microphone jack. My mike uses a 3-conductor
plug, so what happens to the power contact in the jack?
Click to expand...
See above; power carried on the inputs.

o The wiring inside the mike and the difficulty of rewiring it (haven't
opened it up yet to look).
Click to expand...
There's a small circuit board inside (surface-mount, surprisingly
complicated for a microphone preamp). Battery power comes in on two
separate wires. If battery - goes to ground, then I might be able just
to connect battery + to one of the inputs, perhaps with a 1.5 volt zener
diode to limit voltage. If not, I'd be afraid of messing it up. Time to
look for a schematic?


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
On 4/9/2009 8:27 PM David Nebenzahl spake thus:

There's a small circuit board inside (surface-mount, surprisingly
complicated for a microphone preamp). Battery power comes in on two
separate wires. If battery - goes to ground, then I might be able just
to connect battery + to one of the inputs, perhaps with a 1.5 volt zener
diode to limit voltage. If not, I'd be afraid of messing it up. Time to
look for a schematic?
Click to expand...
Whaddya know? Found a schematic, in this copy of the ECM-737 service
manual: http://www.coutant.org/ecm737/ecm737serv.pdf (from this page:
http://www.coutant.org/ecm737/index.html).

So looking at the schematic (page 4 of the manual), I'm wondering if a
guy couldn't just connect the battery power input to one of the outputs
through a 1.5v voltage regulator. While that would provide power to run
the mike, I'm wondering what detrimental effects that would have on the
channel it's connected to. Any way to isolate the signal from the DC power?


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
David Nebenzahl wrote:

OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.
Click to expand...
I doubt it'll be that simple but here's the service manual for you as a
starting point with schematics.

http://www.coutant.org/ecm737/ecm737serv.pdf

Graham
 
David Nebenzahl wrote:

OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.
Click to expand...
From a quick glance it uses a lot ( relatively for a mic ) of 1.5V power. So
the powering scheme from the walkman is unlikely to be compatible and even
if it was, you'd run the battery(ies) dry in that in no time.

Graham
 
David Nebenzahl wrote:

On 4/9/2009 8:27 PM David Nebenzahl spake thus:

There's a small circuit board inside (surface-mount, surprisingly
complicated for a microphone preamp). Battery power comes in on two
separate wires. If battery - goes to ground, then I might be able just
to connect battery + to one of the inputs, perhaps with a 1.5 volt zener
diode to limit voltage. If not, I'd be afraid of messing it up. Time to
look for a schematic?

Whaddya know? Found a schematic, in this copy of the ECM-737 service
manual: http://www.coutant.org/ecm737/ecm737serv.pdf (from this page:
http://www.coutant.org/ecm737/index.html).

So looking at the schematic (page 4 of the manual), I'm wondering if a
guy couldn't just connect the battery power input to one of the outputs
through a 1.5v voltage regulator.
Click to expand...
No, the 2.8V supply is likely VERY current limited. Sounds more like a sound
card powering method that's good for about 1 mA.

Graham
 
In article <49de8695$0$2712$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:
OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.

I have the WM-D6C Walkman "Professional" recorder and a Sony ECM-737
stereo microphone. The rig still makes very nice recordings. (No, I
don't usually use it for music, and I'm not pushing cassette as the
ultimate recording medium.)

The annoying thing about it is that while the microphone requires a
battery (a single AA cell), the recorder is apparently perfectly capable
of supplying power to the mike. The mike jack is marked "PLUG IN POWER",
which I suppose is Sony's way of identifying phantom power. (This may
not be "phantom power" in the sense of standard supply voltage, but
instead a proprietary Sony level.) I can't tell you how many times I've
had problems recording which turned out to be a low or dead battery in
the microphone. Probably my bad for not buying the next-better mike,
which I think did run on the recorder's power.

So I'm thinking I could modify the microphone to accept power from the
recorder, without modifying the recorder in any way. There are a few
things I don't know, however:

o The voltage of the power supplied by the recorder, which runs on 4 AA
cells. (48 volts? I'm guessing not, but who knows?)

o The configuration of the microphone jack. My mike uses a 3-conductor
plug, so what happens to the power contact in the jack?

o The wiring inside the mike and the difficulty of rewiring it (haven't
opened it up yet to look).

Anyone familiar at all with this equipment? Care to give some advice on
how to proceed?
Click to expand...
Phantom power - as regards mics - is only applicable to balanced mics and
inputs. A stereo balanced mic has five connections. Mono balanced
connectors are usually a 3 pin XLR, stereo 5 pin.

The DC is between both balanced audios and screen - the idea being there
is no potential difference across the audio allowing a non phantom powered
balance mic to be used on a phantom powered input.

You can feed DC to an unbalanced mic - but my guess is the mic has to be
designed for this.

--
*Laugh alone and the world thinks you're an idiot.

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

David Nebenzahl wrote:

On 4/9/2009 8:27 PM David Nebenzahl spake thus:

There's a small circuit board inside (surface-mount, surprisingly
complicated for a microphone preamp). Battery power comes in on two
separate wires. If battery - goes to ground, then I might be able just
to connect battery + to one of the inputs, perhaps with a 1.5 volt zener
diode to limit voltage. If not, I'd be afraid of messing it up. Time to
look for a schematic?

Whaddya know? Found a schematic, in this copy of the ECM-737 service
manual: http://www.coutant.org/ecm737/ecm737serv.pdf (from this page:
http://www.coutant.org/ecm737/index.html).

So looking at the schematic (page 4 of the manual), I'm wondering if a
guy couldn't just connect the battery power input to one of the outputs
through a 1.5v voltage regulator.

No, the 2.8V supply is likely VERY current limited. Sounds more like a sound
card powering method that's good for about 1 mA.
Click to expand...
Note that the schematic shows 16mA current draw. I'd invest in some good AA
batteries. Wikipedia says you can get up to 3Ah which would be nearly 200 hours
of use.
http://en.wikipedia.org/wiki/AA_battery

" Alkaline batteries from 1700 mAh to almost 3000 mAh cost a little more, but
last proportionally longer. "

Graham
 
On 4/10/2009 2:43 AM Dave Plowman (News) spake thus:

In article <49de8695$0$2712$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

So I'm thinking I could modify the microphone to accept power from the
recorder, without modifying the recorder in any way. There are a few
things I don't know, however:

Phantom power - as regards mics - is only applicable to balanced mics and
inputs. A stereo balanced mic has five connections. Mono balanced
connectors are usually a 3 pin XLR, stereo 5 pin.

The DC is between both balanced audios and screen - the idea being there
is no potential difference across the audio allowing a non phantom powered
balance mic to be used on a phantom powered input.

You can feed DC to an unbalanced mic - but my guess is the mic has to be
designed for this.
Click to expand...
Well, as I pointed out in a follow-up post above (don't know if you saw
it), the Sony Walkman in this case applies power (2.8V) across both
inputs at the microphone jack. The mike input uses just 3 connections.
They call it "Plug-in power", which may be Sony's own version of phantom
power. And yes, the voltage is present even if one uses a
non-phantom-powered mike; presumably, the voltage is low enough not to
damage any unpowered microphones. (In my case, the phantom power is just
wasted.)


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
On 4/10/2009 2:38 AM Eeyore spake thus:

David Nebenzahl wrote:

On 4/9/2009 8:27 PM David Nebenzahl spake thus:

There's a small circuit board inside (surface-mount, surprisingly
complicated for a microphone preamp). Battery power comes in on two
separate wires. If battery - goes to ground, then I might be able just
to connect battery + to one of the inputs, perhaps with a 1.5 volt zener
diode to limit voltage. If not, I'd be afraid of messing it up. Time to
look for a schematic?

Whaddya know? Found a schematic, in this copy of the ECM-737 service
manual: http://www.coutant.org/ecm737/ecm737serv.pdf (from this page:
http://www.coutant.org/ecm737/index.html).

So looking at the schematic (page 4 of the manual), I'm wondering if a
guy couldn't just connect the battery power input to one of the outputs
through a 1.5v voltage regulator.

No, the 2.8V supply is likely VERY current limited. Sounds more like a sound
card powering method that's good for about 1 mA.
Click to expand...
Hmmm; I could run it through a dummy load (resistor) and measure the
current draw and find out. You may well be right. Now I need to get a
service manual for the Walkman (WM-D5C); ugh. Finding the microphone
manual was easy; I struck out looking for one for the recorder.


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
In article <49df8507$0$2702$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:
On 4/10/2009 2:43 AM Dave Plowman (News) spake thus:

In article <49de8695$0$2712$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

So I'm thinking I could modify the microphone to accept power from
the recorder, without modifying the recorder in any way. There are a
few things I don't know, however:

Phantom power - as regards mics - is only applicable to balanced mics
and inputs. A stereo balanced mic has five connections. Mono balanced
connectors are usually a 3 pin XLR, stereo 5 pin.

The DC is between both balanced audios and screen - the idea being
there is no potential difference across the audio allowing a non
phantom powered balance mic to be used on a phantom powered input.

You can feed DC to an unbalanced mic - but my guess is the mic has to
be designed for this.

Well, as I pointed out in a follow-up post above (don't know if you saw
it), the Sony Walkman in this case applies power (2.8V) across both
inputs at the microphone jack. The mike input uses just 3 connections.
They call it "Plug-in power", which may be Sony's own version of phantom
power. And yes, the voltage is present even if one uses a
non-phantom-powered mike; presumably, the voltage is low enough not to
damage any unpowered microphones. (In my case, the phantom power is just
wasted.)
Click to expand...
But both inputs in this case are the 'hot' connections of a stereo input?

There are no 'versions' of phantom power - it's a universal standard.
Anything else would be a nonsense.

--
*Tell me to 'stuff it' - I'm a taxidermist.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
On 4/10/2009 11:12 AM Dave Plowman (News) spake thus:

In article <49df8507$0$2702$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

On 4/10/2009 2:43 AM Dave Plowman (News) spake thus:

In article <49de8695$0$2712$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

So I'm thinking I could modify the microphone to accept power from
the recorder, without modifying the recorder in any way. There are a
few things I don't know, however:

Phantom power - as regards mics - is only applicable to balanced mics
and inputs. A stereo balanced mic has five connections. Mono balanced
connectors are usually a 3 pin XLR, stereo 5 pin.

The DC is between both balanced audios and screen - the idea being
there is no potential difference across the audio allowing a non
phantom powered balance mic to be used on a phantom powered input.

You can feed DC to an unbalanced mic - but my guess is the mic has to
be designed for this.

Well, as I pointed out in a follow-up post above (don't know if you saw
it), the Sony Walkman in this case applies power (2.8V) across both
inputs at the microphone jack. The mike input uses just 3 connections.
They call it "Plug-in power", which may be Sony's own version of phantom
power. And yes, the voltage is present even if one uses a
non-phantom-powered mike; presumably, the voltage is low enough not to
damage any unpowered microphones. (In my case, the phantom power is just
wasted.)

But both inputs in this case are the 'hot' connections of a stereo input?
Click to expand...
Yes. The 2.8V DC is carried on both mike inputs (+2.8V = L/R inputs,
with respect to common ground).

There are no 'versions' of phantom power - it's a universal standard.
Anything else would be a nonsense.
Click to expand...
Apparently this disproves that theory. (I thought the standard for
phantom power was 48 volts.) Talk to Sony. (And remember that this is
"Plug-in power"(R)(TM), whatever that is.)


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
On 4/10/2009 2:36 AM Eeyore spake thus:

David Nebenzahl wrote:

OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.

From a quick glance it uses a lot ( relatively for a mic ) of 1.5V power. So
the powering scheme from the walkman is unlikely to be compatible and even
if it was, you'd run the battery(ies) dry in that in no time.
Click to expand...
Another unrelated question, since you've obviously looked at the
schematic: what do you think the function is of the LEDs in each buffer
output stage (D1 & D2)? I'm puzzled since I saw these inside the mike;
they're both clear LEDs which are completely hidden once the cover is in
place. The one visible LED is the power-good indicator, D5.

Are these used for some kind of voltage regulation or current
restriction? Maybe I could just clip them out and reduce that 16mA power
draw ...


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
Hi!

Further research reveals that the recorder supplies 2.8 volts on both
channels of the microphone input.
Click to expand...
I was just going to say...

I have what must be a very similar Sony microphone that takes a CR2032
cell in its underside. The battery cover is also the on-off switch.

If I didn't loan it to my brother (which probably means it is now
permanently "his"...) I will get a model #.

I've used it with a battletank of a late 70s Panasonic tape recorder
and a computer to produce recordings of an acoustic guitar. It works
fine, and the audio quality is decent.

William
 
In article <49df97dc$0$2709$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:
But both inputs in this case are the 'hot' connections of a stereo
input?

Yes. The 2.8V DC is carried on both mike inputs (+2.8V = L/R inputs,
with respect to common ground).

There are no 'versions' of phantom power - it's a universal standard.
Anything else would be a nonsense.

Apparently this disproves that theory. (I thought the standard for
phantom power was 48 volts.) Talk to Sony. (And remember that this is
"Plug-in power"(R)(TM), whatever that is.)
Click to expand...
Seems to be a problem here with what is phantom power. Perhaps you'd read
my earlier post on the subject. What you have is a form of line powering -
not the same as phantom powering.

--
*I'm not a complete idiot, some parts are missing *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.
 
On Fri, 10 Apr 2009 12:13:16 -0700, David Nebenzahl
<nobody@but.us.chickens> put finger to keyboard and composed:

On 4/10/2009 2:36 AM Eeyore spake thus:

David Nebenzahl wrote:

OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.

From a quick glance it uses a lot ( relatively for a mic ) of 1.5V power. So
the powering scheme from the walkman is unlikely to be compatible and even
if it was, you'd run the battery(ies) dry in that in no time.

Another unrelated question, since you've obviously looked at the
schematic: what do you think the function is of the LEDs in each buffer
output stage (D1 & D2)? I'm puzzled since I saw these inside the mike;
they're both clear LEDs which are completely hidden once the cover is in
place. The one visible LED is the power-good indicator, D5.

Are these used for some kind of voltage regulation or current
restriction? Maybe I could just clip them out and reduce that 16mA power
draw ...
Click to expand...
They set the bias current for the output transistors, approximately
0.45mA.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
On 4/10/2009 3:31 PM Dave Plowman (News) spake thus:

In article <49df97dc$0$2709$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

But both inputs in this case are the 'hot' connections of a stereo
input?

Yes. The 2.8V DC is carried on both mike inputs (+2.8V = L/R inputs,
with respect to common ground).

There are no 'versions' of phantom power - it's a universal standard.
Anything else would be a nonsense.

Apparently this disproves that theory. (I thought the standard for
phantom power was 48 volts.) Talk to Sony. (And remember that this is
"Plug-in power"(R)(TM), whatever that is.)

Seems to be a problem here with what is phantom power. Perhaps you'd read
my earlier post on the subject. What you have is a form of line powering -
not the same as phantom powering.
Click to expand...
Aaaaargh.

I've read all the posts here on the subject, as well as other material
out there in the greater world, and most people seem to agree that
phantom powering = line powering, always. (But not necessarily the
reverse, or obverse.)

To use another analogy, if phantom powering is a square and line
powering is a rectangle, one can say that all squares are rectangles,
but not all rectangles are squares.

Or something like that.


--
Save the Planet
Kill Yourself

- motto of the Church of Euthanasia (http://www.churchofeuthanasia.org/)
 
On Fri, 10 Apr 2009 10:44:30 -0700, David Nebenzahl
<nobody@but.us.chickens> put finger to keyboard and composed:

On 4/10/2009 2:38 AM Eeyore spake thus:

David Nebenzahl wrote:

On 4/9/2009 8:27 PM David Nebenzahl spake thus:

There's a small circuit board inside (surface-mount, surprisingly
complicated for a microphone preamp). Battery power comes in on two
separate wires. If battery - goes to ground, then I might be able just
to connect battery + to one of the inputs, perhaps with a 1.5 volt zener
diode to limit voltage. If not, I'd be afraid of messing it up. Time to
look for a schematic?

Whaddya know? Found a schematic, in this copy of the ECM-737 service
manual: http://www.coutant.org/ecm737/ecm737serv.pdf (from this page:
http://www.coutant.org/ecm737/index.html).

So looking at the schematic (page 4 of the manual), I'm wondering if a
guy couldn't just connect the battery power input to one of the outputs
through a 1.5v voltage regulator.

No, the 2.8V supply is likely VERY current limited. Sounds more like a sound
card powering method that's good for about 1 mA.

Hmmm; I could run it through a dummy load (resistor) and measure the
current draw and find out. You may well be right. Now I need to get a
service manual for the Walkman (WM-D5C); ugh. Finding the microphone
manual was easy; I struck out looking for one for the recorder.
Click to expand...
Each channel of the mike amp PCB has a 2K2 load resistor. The current
draw is therefore ...

2.8V / 2K2 = 1.3mA

I suspect that the Walkman has an internal series resistor of around
1.8K and an O/C supply voltage of 5.0V.

If you could bring the Walkman's 5V (?) supply out to a separate
connector, and bypass the preamp's DC-DC converter by connecting the
Walkman's 5V supply directly to the preamp's B+, then you would have a
mike that drew around 5mA or less from the Walkman, plus the 2.6mA of
wasted line power via R12 and R32. The latter could possibly be
recouped by removing R12, R32, and the two 1.8K series resistors
alluded to above.

FWIW, I notice that in the present configuration both C8 and C23 are
slightly reverse biased by 0.4V (= 2.8 - 4.8 / 2).

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
 
"Dave Plowman (News)" wrote:

In article <49de8695$0$2712$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:
OK, another potential project: re-jiggering the mike for my Sony Walkman
Professional cassette recorder to use phantom power.

I have the WM-D6C Walkman "Professional" recorder and a Sony ECM-737
stereo microphone. The rig still makes very nice recordings. (No, I
don't usually use it for music, and I'm not pushing cassette as the
ultimate recording medium.)

The annoying thing about it is that while the microphone requires a
battery (a single AA cell), the recorder is apparently perfectly capable
of supplying power to the mike. The mike jack is marked "PLUG IN POWER",
which I suppose is Sony's way of identifying phantom power. (This may
not be "phantom power" in the sense of standard supply voltage, but
instead a proprietary Sony level.) I can't tell you how many times I've
had problems recording which turned out to be a low or dead battery in
the microphone. Probably my bad for not buying the next-better mike,
which I think did run on the recorder's power.

So I'm thinking I could modify the microphone to accept power from the
recorder, without modifying the recorder in any way. There are a few
things I don't know, however:

o The voltage of the power supplied by the recorder, which runs on 4 AA
cells. (48 volts? I'm guessing not, but who knows?)

o The configuration of the microphone jack. My mike uses a 3-conductor
plug, so what happens to the power contact in the jack?

o The wiring inside the mike and the difficulty of rewiring it (haven't
opened it up yet to look).

Anyone familiar at all with this equipment? Care to give some advice on
how to proceed?

Phantom power - as regards mics - is only applicable to balanced mics and
inputs. A stereo balanced mic has five connections. Mono balanced
connectors are usually a 3 pin XLR, stereo 5 pin.

The DC is between both balanced audios and screen - the idea being there
is no potential difference across the audio allowing a non phantom powered
balance mic to be used on a phantom powered input.

You can feed DC to an unbalanced mic - but my guess is the mic has to be
designed for this.
Click to expand...
It's the standard 'computer mike' way. Not very elegant. And don't twist the
connector in use because it's carrying DC and will crackle nicely.

Graham
 
David Nebenzahl wrote:

On 4/10/2009 2:43 AM Dave Plowman (News) spake thus:

In article <49de8695$0$2712$822641b3@news.adtechcomputers.com>,
David Nebenzahl <nobody@but.us.chickens> wrote:

So I'm thinking I could modify the microphone to accept power from the
recorder, without modifying the recorder in any way. There are a few
things I don't know, however:

Phantom power - as regards mics - is only applicable to balanced mics and
inputs. A stereo balanced mic has five connections. Mono balanced
connectors are usually a 3 pin XLR, stereo 5 pin.

The DC is between both balanced audios and screen - the idea being there
is no potential difference across the audio allowing a non phantom powered
balance mic to be used on a phantom powered input.

You can feed DC to an unbalanced mic - but my guess is the mic has to be
designed for this.

Well, as I pointed out in a follow-up post above (don't know if you saw
it), the Sony Walkman in this case applies power (2.8V) across both
inputs at the microphone jack. The mike input uses just 3 connections.
They call it "Plug-in power", which may be Sony's own version of phantom
power. And yes, the voltage is present even if one uses a
non-phantom-powered mike; presumably, the voltage is low enough not to
damage any unpowered microphones. (In my case, the phantom power is just
wasted.)
Click to expand...
Google computer mike / mic power and you'll see how it works. Very different
from your ECM.

Graham
 
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