Cable question regarding Linkwitz mod to WM61a

[Brad]

Hello,
I am going to build a pair of mini binaural microphones using the 3
wire Linkwitz mod to the Panasonic WM-61a capsule.

http://www.linkwitzlab.com/images/graphics/microph1.gif/

My question is regarding the cable I should use. I would like to use
some very small gauge balanced audio cable. Considering that there
are 3 connections though, is it advisable to run it on 2 conductor
cable with a braided copper shield as the 3rd conductor, or does it
make more sense to try to find a 3 conductor cable?

thanks
Brad

[Scott Dorsey]

Brad > wrote:
>
>My question is regarding the cable I should use. I would like to use
>some very small gauge balanced audio cable. Considering that there
>are 3 connections though, is it advisable to run it on 2 conductor
>cable with a braided copper shield as the 3rd conductor, or does it
>make more sense to try to find a 3 conductor cable?

Well, one of those 3 lines is ground anyway, so there is no reason not
to use it as the shield. You might get marginally better RF rejection
with a three-wire line and the shield telescoped.

Belden makes a lavalier mike cable that is a star-quad if you are really
set on splitting the ground return and the shield.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Scott Dorsey]

Brad > wrote:
>
>My question is regarding the cable I should use. I would like to use
>some very small gauge balanced audio cable. Considering that there
>are 3 connections though, is it advisable to run it on 2 conductor
>cable with a braided copper shield as the 3rd conductor, or does it
>make more sense to try to find a 3 conductor cable?

Well, one of those 3 lines is ground anyway, so there is no reason not
to use it as the shield. You might get marginally better RF rejection
with a three-wire line and the shield telescoped.

Belden makes a lavalier mike cable that is a star-quad if you are really
set on splitting the ground return and the shield.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Jay Kadis]

In article >,
(Brad) wrote:

> Hello,
> I am going to build a pair of mini binaural microphones using the 3
> wire Linkwitz mod to the Panasonic WM-61a capsule.
>
> http://www.linkwitzlab.com/images/graphics/microph1.gif/
>
> My question is regarding the cable I should use. I would like to use
> some very small gauge balanced audio cable. Considering that there
> are 3 connections though, is it advisable to run it on 2 conductor
> cable with a braided copper shield as the 3rd conductor, or does it
> make more sense to try to find a 3 conductor cable?
>
> thanks
> Brad


You should be fine with 2 conductor using the shield as the ground connection.
You will need to use very fine diameter wire if you want to be able to solder it
directly to the capsules, at least in my experience. I have sometimes used
short jumpers of fine insulated wire to connect larger shielded cable, which
works as long as the unshielded jumpers are short.

Does anyone know if Panasonic intends to reintroduce these capsules? They're
currently out of production and there's some note on their web site about lead
content that leads me to believe they may have been phased out for that reason.
(Or, more cynically, because they were too good for $3.)

-Jay
--
x------- Jay Kadis ------- x---- Jay's Attic Studio ------x
x Lecturer, Audio Engineer x Dexter Records x
x CCRMA, Stanford University x http://www.offbeats.com/ x
x---------- http://ccrma.stanford.edu/~jay/ ------------x

[Jay Kadis]

In article >,
(Brad) wrote:

> Hello,
> I am going to build a pair of mini binaural microphones using the 3
> wire Linkwitz mod to the Panasonic WM-61a capsule.
>
> http://www.linkwitzlab.com/images/graphics/microph1.gif/
>
> My question is regarding the cable I should use. I would like to use
> some very small gauge balanced audio cable. Considering that there
> are 3 connections though, is it advisable to run it on 2 conductor
> cable with a braided copper shield as the 3rd conductor, or does it
> make more sense to try to find a 3 conductor cable?
>
> thanks
> Brad


You should be fine with 2 conductor using the shield as the ground connection.
You will need to use very fine diameter wire if you want to be able to solder it
directly to the capsules, at least in my experience. I have sometimes used
short jumpers of fine insulated wire to connect larger shielded cable, which
works as long as the unshielded jumpers are short.

Does anyone know if Panasonic intends to reintroduce these capsules? They're
currently out of production and there's some note on their web site about lead
content that leads me to believe they may have been phased out for that reason.
(Or, more cynically, because they were too good for $3.)

-Jay
--
x------- Jay Kadis ------- x---- Jay's Attic Studio ------x
x Lecturer, Audio Engineer x Dexter Records x
x CCRMA, Stanford University x http://www.offbeats.com/ x
x---------- http://ccrma.stanford.edu/~jay/ ------------x

[Bob Cain]

Brad wrote:
> Hello,
> I am going to build a pair of mini binaural microphones using the 3
> wire Linkwitz mod to the Panasonic WM-61a capsule.

FWIW, there is no performance advantage with three wire.
The two and three wire are identical from an AC circuit
point of view and perform identically.

In the three wire, the gate sees ground through the varying
diaphragm capacitance and in the two wire it sees the supply
rail. Both are at AC ground. Between the two there is a
reversal of the static charge on the diaphragm/backplate
capacitor but this has no effect on operation.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Brad wrote:
> Hello,
> I am going to build a pair of mini binaural microphones using the 3
> wire Linkwitz mod to the Panasonic WM-61a capsule.

FWIW, there is no performance advantage with three wire.
The two and three wire are identical from an AC circuit
point of view and perform identically.

In the three wire, the gate sees ground through the varying
diaphragm capacitance and in the two wire it sees the supply
rail. Both are at AC ground. Between the two there is a
reversal of the static charge on the diaphragm/backplate
capacitor but this has no effect on operation.


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Len Moskowitz]

Brad > wrote:

>Hello,
>I am going to build a pair of mini binaural microphones using the 3
>wire Linkwitz mod to the Panasonic WM-61a capsule.

This modification should rightly be called the "Miller Mod" after Lyman
Miller, the fellow who developed it. Linkwitz has popularized it in the
DIY mic community, but Lyman should get the credit.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

[Len Moskowitz]

Brad > wrote:

>Hello,
>I am going to build a pair of mini binaural microphones using the 3
>wire Linkwitz mod to the Panasonic WM-61a capsule.

This modification should rightly be called the "Miller Mod" after Lyman
Miller, the fellow who developed it. Linkwitz has popularized it in the
DIY mic community, but Lyman should get the credit.

--
Len Moskowitz PDAudio, Binaural Mics, Cables, DPA, M-Audio
Core Sound http://www.stealthmicrophones.com
Teaneck, New Jersey USA http://www.core-sound.com
Tel: 201-801-0812, FAX: 201-801-0912

[Bob Cain]

Len Moskowitz wrote:
> Brad > wrote:
>
>
>>Hello,
>>I am going to build a pair of mini binaural microphones using the 3
>>wire Linkwitz mod to the Panasonic WM-61a capsule.
>
> This modification should rightly be called the "Miller Mod" after Lyman
> Miller, the fellow who developed it. Linkwitz has popularized it in the
> DIY mic community, but Lyman should get the credit.

Actually, it is the 2-wire mod that Siegfried attributes to
Miller. It was his clever insight that the diaphragm could
be connected to either ground or to Vcc to yield the
identical source follower operation and that a simple
reconnection at the capsule would effect that while leaving
only 2 wires going back.

When Siegfried realized it was being given his name he
updated his site to give the correct attribution but I fear
it is too late to correct the widespread usage of "Linkwitz
mod." :-(


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein

[Bob Cain]

Len Moskowitz wrote:
> Brad > wrote:
>
>
>>Hello,
>>I am going to build a pair of mini binaural microphones using the 3
>>wire Linkwitz mod to the Panasonic WM-61a capsule.
>
> This modification should rightly be called the "Miller Mod" after Lyman
> Miller, the fellow who developed it. Linkwitz has popularized it in the
> DIY mic community, but Lyman should get the credit.

Actually, it is the 2-wire mod that Siegfried attributes to
Miller. It was his clever insight that the diaphragm could
be connected to either ground or to Vcc to yield the
identical source follower operation and that a simple
reconnection at the capsule would effect that while leaving
only 2 wires going back.

When Siegfried realized it was being given his name he
updated his site to give the correct attribution but I fear
it is too late to correct the widespread usage of "Linkwitz
mod." :-(


Bob
--

"Things should be described as simply as possible, but no
simpler."

A. Einstein