wrote:
I always thought the 104 would make a really cool housing for a DIY
ribbon mic...

There's no room inside there for the magnet assembly, though. The actual
element on the D-104 is pretty tiny.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

Scott Dorsey wrote:
There's no room inside there for the magnet assembly, though. The actual
element on the D-104 is pretty tiny.

The one in my parts drawer is about 1-1/2" diameter x 3/8" thick. Aside
from the dimensions, wouldn't a ribbon need an open back?

--
St. John, whose ribbon experience starts and ends with RCA 77 and 44 series

St. John Smythe wrote:
Scott Dorsey wrote:
There's no room inside there for the magnet assembly, though. The actual
element on the D-104 is pretty tiny.

The one in my parts drawer is about 1-1/2" diameter x 3/8" thick. Aside
from the dimensions, wouldn't a ribbon need an open back?

It would help. You could build a baffle behind the ribbon to make it a
cardioid or omni, but that would require more space inside.

St. John, whose ribbon experience starts and ends with RCA 77 and 44 series

You can make a ribbon assembly smaller than that these days, but the problem
is that the field needs to be uniform so whether the ribbon is fully forward
or fully back it's bathed in the same flux. This means the pole pieces on
the side need to be pretty deep. You can make them less wide by using
modern rare earth magnets but it's hard to reduce them in size and get an
even field, without making the ribbon smaller. Then, if the ribbon is
smaller the output is reduced.....

I think a Beyer assembly might just barely fit. The Shure SM33 assembly
won't.
-scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

In article .com, "Mike Rivers" wrote:

robert440 wrote:

The Silver Eagle version of the D104 has an amplifer (to work with modern
radios), so impedance is not an issue.
The mic does have a very high output (requires a 9V battery) that may easily
overload the mic input of a mixer, even with a pad engaged. There is a gain
control on the bottom of the mic.

Just for reference, where does info on the mic come from? Given the
built-in amplifier, it's obviously a recent version. Is it now
manufactured or sold by a company other than Astatic? I was surprised
not to find any data on the mic on the Astatic web sites other than a
mention in their company history article.

I'm familiar with the ham radio version of 50 years ago (which was
indeed a crystal element). It seems that while the basic model number
and appearance haven't changed significantly over the years, the inner
workings have evolved substantially.

Come to think of it, I have a version of the mike. Its came on the Astatic
Road Talker hand mic. Used the same ceramic as the D-104 but I believe
it had some kind of baffle to make it a noise canceler and has a built
in amplifier. I still have the schematic at home. The store I purchased it was very near the
factory in Ohio.

I was on the Astatic web site a while back and I thought it was strange also.

greg

In article , (GregS) wrote:
In article .com, "Mike
Rivers" wrote:

robert440 wrote:

The Silver Eagle version of the D104 has an amplifer (to work with modern
radios), so impedance is not an issue.
The mic does have a very high output (requires a 9V battery) that may easily
overload the mic input of a mixer, even with a pad engaged. There is a gain
control on the bottom of the mic.

Just for reference, where does info on the mic come from? Given the
built-in amplifier, it's obviously a recent version. Is it now
manufactured or sold by a company other than Astatic? I was surprised
not to find any data on the mic on the Astatic web sites other than a
mention in their company history article.

I'm familiar with the ham radio version of 50 years ago (which was
indeed a crystal element). It seems that while the basic model number
and appearance haven't changed significantly over the years, the inner
workings have evolved substantially.

Come to think of it, I have a version of the mike. Its came on the Astatic
Road Talker hand mic. Used the same ceramic as the D-104 but I believe
it had some kind of baffle to make it a noise canceler and has a built
in amplifier. I still have the schematic at home. The store I purchased it was
very near the
factory in Ohio.

I was on the Astatic web site a while back and I thought it was strange also.

I'm pretty sure my Road Talker came with a response plot.

greg

wrote:
I always thought the 104 would make a really cool housing for a DIY
ribbon mic...

They are a neat looking mic..I'd like to make a one hit bong out of one.

ps. I have an un-amplified model that I still use from time to time. (not
bong material)

Mike Rivers wrote:

Just for reference, where does info on the mic come from? Given the
built-in amplifier, it's obviously a recent version.

There have been versions of the D104 with built-in preamp
circuits since at least the mid '70s. Possibly an outgrowth
of the CB 'power mic' craze of the time.

rd

Just for reference, where does info on the mic come from?

I worked in engineering there for over 20 years so I have a little inside
info on it :-)
Since it's probably not documented anywhere, here is probably more then
anyone ever wanted to know about it…..
==============
As mentioned, amplified versions started in the 70's mainly to be compatible
with newer "transistorized" radios with low-z inputs.
That was indeed at the beginning of the "power mic" craze. The first
transistorized version was the T-UG8-D104.
Later came the T-UG9-D104 (adding more switch contacts and wires), and the
"Golden Eagle" which was a gold plated version done for the U.S.
Bicentennial. It also featured an eagle engraved on the back of the D104
head.
The Golden Eagle was so popular that the Silver Eagle version was created
(the Golden Eagle was a limited edition). It was actually a T-UP9-D104 and
added a push bar on the bottom as well on the side (Thus the "P" in the
model number).

There were both crystal (Rochelle salt) and ceramic versions of the D104
head, but the crystal version was always the most popular.
At one time Astatic made some of the crystal elements in house (fun to
watch), but only to supplement those made outside. The crystal element
consisted of two slabs of Rochelle salt, graphite, and gold leads that were
wrapped in foil and encased in epoxy. If you look at an old spec sheet, you
will see the “foil wrapped” crystal mentioned. This was supposed to improve
the life of the crystal. Rochelle salt has a high moisture content and after
a period of time the crystal will dehydrate and no longer operate, so it
must be well sealed and stored in a cool environment. The capsule had a
bakelite housing and an aluminum diaphragm. Except for the newest versions,
the diaphragm was attached with rubber cement and a special black wax that
was made in-house. To tame the huge resonant peak at around 2.5KHz, a round
disk of fiberglass insulation was glued to the front of the capsule. This
stuff, which we called “Magic Puff” (because it worked so well), was
actually aircraft insulation and either yellow or pink.

Eventually sources for the crystal started to go away. The company changed
hands in 87 and when I left in 2000, the only source for the crystals was
from a small company in Austria. This company made the crystals for the two
remaining crystal mics, the D104 and the various versions of the old JT-30
bullet harmonica mic, for a number of years.

My understanding is that the company in Austria finally folded, and so
production on those two mics finally ceased a couple of years ago.

At one point I did play with creating a dynamic version of the D104, but the
project never flew.
The original head consisted of three pieces. If you wanted to try to put
something like a ribbon inside one, the thing to do would be find two of the
older heads and use the front screens to create a head with screens on the
front and back.

The newer heads are only two piece (The back and middle section were die
cast as one part to save money).

Robert

robert440 wrote:
At one point I did play with creating a dynamic version of the D104, but the
project never flew.

Imagine my chagrin. I just took apart my D104 to check the markings on
the dynamic element I was sold in the '70s. It says MC-320, which,
according to a quick web lookup, is a crystal element.
blush

This may be a good time to install that Heil element...
--
St. John
Utility is when you have one telephone, luxury is when you have two,
opulence is when you have three -- and paradise is when you have none.
-Doug Larson

In article , "St. John Smythe" wrote:
robert440 wrote:
At one point I did play with creating a dynamic version of the D104, but the
project never flew.

Imagine my chagrin. I just took apart my D104 to check the markings on
the dynamic element I was sold in the '70s. It says MC-320, which,
according to a quick web lookup, is a crystal element.
blush

This may be a good time to install that Heil element...

That would seem a simple and easy way out. just hope it sounds the same.
Crystal do not last but ceramic does. The response of the D-104
is shown here.....
http://www.astatic.com/cb/d104m6b.htm
The handheld mic is supposed to have the same element, which is still available.
I would call them.

+22 dB at 3.2 kHz over 100 Hz.

The Heil is very different.

The classic D-104 sound is heard through a transmitter with cutoff's
and compression, and lots of garbling!!


greg