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Everyone has good points

3 pad with FET sounds popular

I'm also finding out that with FET's when I go to a 9.7mm capsule there is =
room
to use an FET tthat gets me 65 insttead of tthe typical 58 from the fet tha=
t fits
6mm

So I'm thinkinng why not take the bigger fet and tack it onto the back of a=
6mm
instead of inside where it wont fit, or is the 3 wire linkwitz mod getting =
us there
anyway ???

What exactly is the linkwitz mod doing?

--- In micbuilders@..., Keith Nelsen <keith@n...> wrote:

I have been following the thread on the 60/61 replacement. Here is my 2 =

cents worth.

* Should have flat output like the 61 (20 to 20k ±3 db or better
would be good)
* Should be the 6 mm size for faster transit response
* Would prefer 2 wire output without FEET or opamp (User to provide
own amp depending on application)
* If FET is included, should have 3 pads for access to both source
and drain connection
* LOW noise a must
* Omni for first run - others to follow

Just some thoughts.
Keith

mstrong82 wrote:

LOL... NO preorders don't help. I'll make some, seed a bunch to
those who added
their input and if they get the seal of approval, then I'll stock
some, THEN I will accept
paid orders, not before.

THEN we can move on to figuring out what the next item should be and
making it.



--- In micbuilders@..., "umashankar mantravadi"
<umashanks@h...>
wrote:

i would like to see it in two sizes one as small as possible, and

the other

about 1/2 diameter.The small one as omni, and the larger one both

omni and

cardioid.

i would like to see, instead of a the tiny hole on all panasonic

capsules, a

diaphraghm fully open , protected by a wire mesh, if necessary.

No fet and fet (if very good are both ok. i think the small capsule

must

have an fet. both should have three pads, so linkwitz are any other

future

system can be implemented without cutting traces. if the pads are to =

be

joined, they can always be joined up at the other end of cable, if

only one

uses two conductor plus shield capbling.

is that a very big wish list?

i will preorder if that will help. ( i live in india, but these days =

i can

use my credit card to buy abroad(.

umashankar

We are putting our heads together to make a replacement for the

WM-61 that

is Linkwitz Mod ready, items to be nailed down are FET selection,

hole size

vs
no hole, etc.

I would like everyone's final input on the design so we do don't

have to do

it
over again.

It is being finalized over on micbuilders (the new group) If you

have any

input
on this, please post it over there as we just about ready to make

these and

anyone with input get's some to play with.

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[Non-text portions of this message have been removed]

mstrong82 wrote:

What exactly is the linkwitz mod doing?

Common source vs. common drain amplifier.

Actually, careful biasing with 2 resistors might be even more
beneficial.

Indrek

--
Indrek Rebane | Borthwick-Pignon
Electronics Engineer | Tartu Science Park
Phone: (+372) 7 302 641 | Riia 185, 51014 Tartu
Fax: (+372) 7 383 041 | Estonia
indrek@... | www.bps.co.ee

mstrong82 wrote:

Everyone has good points

3 pad with FET sounds popular

I'm also finding out that with FET's when I go to a 9.7mm capsule there is =

room
to use an FET tthat gets me 65 insttead of tthe typical 58 from the fet tha=

t fits
6mm

Yummy.

So I'm thinkinng why not take the bigger fet and tack it onto the back of a=

6mm
instead of inside where it wont fit,

The only thing I can think of is that putting it on the back
could give less shielding but I have no idea how signifigant
that is.

or is the 3 wire linkwitz mod getting us there
anyway ???

That has no (little) effect on self noise.

What exactly is the linkwitz mod doing?

It changes the topology of the FET amplifier from common
source to source follower. This has the advantage of
putting the gate into a feedback loop which linearizes the
amplifier (lowers the high SPL distortion) and makes the
sensitivity of the mic less dependant on the
transconductance of the FET. Sensitivity in source follower
mode will be almost entirely determined by the dimensions
and spacing of the diaphragm and not sensitive to the fairly
wide transconductance spread of FETs.


Bob
--

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

A. Einstein