The AM Forum

Good Day All,

 I was wondering if any of the membership would like to bring in and discuss this microphone and it's vairants, Pictures, circuit diagrams of modifications, maybe service techniques for the Heads, how many different types of design packages that were employed etc.

 This microphone has alot of History and I think it would be a nice jesture to share with everyone any qurks or stories, Pictures, Collections that some of us have run into, there's alot that can be done with this little Gem.

Anyone like to run with this..?

Away back in 1930, two radio amateurs, C.M.Chorpening, W8WR (now W8MJM), and F.H.Woodworth, W8AHW, both of Youngstown Ohio, began searching for a better microphone for their phone transmitters. Up until this time they had been using various carbon type microphones. The condenser type appealed to them as an answer to their problem. Several units were designed and given trials on the air. Before long, other amateurs among their acquaintance began visiting their shacks, interested in either building or buying this new type of 'mike'. Chorpening and Woodworth, encouraged by this interest, decided to form a partnership and build these units for their friends. While the condenser unit proved reasonably satisfactory, it had certain limitations which it was hoped could eventually be overcome.

It was about this time that an old acquaintance, Mr Charles E. Semple of Cleveland, who had been visiting his "ham" freinds frequently, invited them to pay him a visit. With a background of phonograph and loud speaker experience, Mr Semple was then occupying bench space in the Brush Laboratories, experimenting nwith elements made from Rochelle Salts, (Sodium Potassium Tartrate). Through Mr. Semple, the two visitors met A.L.Williams, electrical and mechanical engineer, and Dr.C.B.Sawyer, scientist, who demonstrated the action of these new elements in relation to microphones, phonograph pickups, speakers, recording heads, earphones and other devices where it was desired to transform mechanical energy into electrical energy or the reverse. Here, it seemed, they had found the answer to a simple, low cost, dependable "mike" for the 'ham rig".

By 1933, Chorpening and Woodworth found it advisable to incorporate a manufacturing and sales company and to branch out with a line of Crystal Microphones, Crystal Phonograph Pickups and Recording heads for manufacturers and Radio Jobbers. Mr Semple was brought into the new organization as designer and later as General Manager until his death in 1939.

From the 1946 Astatic Catalogue

30's Vintage D-104
(http://www.amwindow.org/misc/d104.jpg)

Thank You Steven..Very well done.. :D

Anyone else like to add to the mix here, Pictures, Ideas..?

There are several notable differences between the early 30's D-104 and the contemporary version. By contemporary, I am referring to the last unamplified version they built with the classic G-stand.  I have had little experience with the "CB version" that has the solid state amplifier in the base, and the flaky G-stand swithing mechanism that comes with that version including the curved bar at the base, other than I have observed that the switch in the modern ones doesn't work as well as the one in the older unamplified version.

The very earliest version of the mic was suspended in a ring with springs just like the classic double button carbon mike.  I'm not sure if they thought it really needed to be shockmounted, or if this was a depression-era design to make it a drop-in replacement for a carbon mike so that one could use the existing mic stand. I picked up a ring-mounted D-104 at Dayton several years ago, and sometimes use it on the air.

The early mic was also available minus the spring mount assembly.  They offered an adaptor that would allow the "lollipop" to mount directly on a mic stand.  It did not come with the plug-in head assembly like the modern one.  The threaded rod on the mic stand screwed directly into the mic head, and a permanent cord was attached through the hollow tube, with the connector attached to the far end of the cord.

Apparently, the original xtal element was bolted down inside the head to the back of the unit, unlike the foam rubber mounting blocks held with glue as in the modern version.  Early mics have three  screws inserted through the back plate.  A large screw goes throuht the centre of the back plate, and two smaller ones near the rim.  The two smaller ones hold a clamp that keeps the permanently mounted cord in place.  Every mic I have seen simply has a nut attached to the large screw in the middle.  I suspect that early elements had a threaded hole in the back to accomodate this screw, and when newer elements came out minus the mounting screw, the nut was used to keep the large screw in place to stop up the empty hole in the back plate.

Another major difference is that the early heads are a full 1" thick, 3/16" thicker than the modern ones.  I have tested the same new element in a modern one and one of the older thicker heads, and I believe that with at least 5 megohms of load resistance, the thicker head sounds more mellow and has slightly more bass  response, but any difference is subtle and no doubt subjective to the listener (perhaps in the same manner as the "improved" sound the audiophools hear with a $600 power cord).

The knurled pattern on the outer rim of the older units has a slightly different pattern from the newer ones.  This is not very noticeable until you see the two side by side.

A little known feature of the D-104 (per a pre-WW2 Astatic user's manual) is that you can use the xtal element to directly drive a pushpull preamp stage without an input transformer.  All you need is a two-conductor shielded mic cord.  Instead of grounding one of the terminals on the element, you connect one conductor to each and ground the shield to the case.  The outboard pushpull preamp uses a grid leak resistor at each tube, and each conductor feeds one of the grids.  Each grid leak resistor is grounded to the shield of the mic cord and the chassis of the preamp.  The two gridleak resistors in series act as a midtapped load resistor and divide the output voltage equally between the two grids.  Of course, this arrangement leaves each grid with only half the voltage that a single grid unbalanced input would have, but the D-104 is well known for its more than ample output voltage, so this shouldn't be a problem.  By grounding the common point between the two load resistors, each grid is automatically fed 180 deg. out of phase with the other.

One note of caution when replacing the element.  The fibreglas "packing material" over the front of the diaphragm is part of the mic assembly and needs to go into the mic.  It acts as a damping mechanism for the diaphragm.  This is commonly thrown away on the mistaken notion that it is nothing more than protective material to protect the delicate diaphragm during shipping.  The mic will sound harsh without the damping material.  Another common misconception is that the element somehow got damaged in shipping, resulting an a hole being accidentally punched in the diaphragm.  This hole is intentional, to maintain equal air pressure on both sides of the diaphragm.  I once picked up a mic at a hamfest with the fibreglas packing removed from the element, and the air-pressure hole glued shut with a drop of epoxy! I don't know why Astatic never noted these two items in the instructions.

I understand that  replacement elements are no longer available.  Perhaps an aftermarket manufacturer will eventually fill the void.

Regarding the G-stand,  I once used one with the sidebar switch connected up as a t/r switch.  I used DC to switch the relays in the transmitter.  I noticed a very annoying audio spike that showed up on the scope and would sometimes even cause the final to arc over upon transmit.  It turned out to be induced by the surge of current through the wiring in the mic cord to the switch in the mic stand.  I changed to a separate t/r switch and the problem was gone.  I never liked a PTT mic switch anyway.  I mount  my microphones on a permanent boom, and use a separate spiral mic cord attached to a hand-held switch for t/r purposes.

What is the current state of affairs concerning the d-104?  CTI audio bought up Astatic a few years ago...  I called them about 2 years ago to order a couple crystal cartridges which they sent right away...They also told me at that time that they were not going to make the replacement cartridges any more and were considering discontinuing the D-104 as a manufactured item....At the time I thought it would be a swell deal for some entrepenurial type to buy up the tooling for the cartridges and produce them for sale.......There must be millions of these micophones out there!

Rochester salt. One of the stories out there is they are low on rochester salt used for the crystal elements. I read it somewhere. Do not know how true.

(http://www.astatic.com/cb/images/silver_eagle_dims.gif)

rochelle salts?  "found in Cream of Tarter"     "Soda Ash"

The famous D-104 Frequency response curve - which actually sounds great when dialed into outboard audio rack EQ's on flat response xmters.

(http://www.astatic.com/cb/images/D104_frequency_resp.gif)

(http://members.iinet.net.au/~vk6ft/micman/d104-2.jpg)
(http://members.iinet.net.au/~vk6ft/micman/d10437.jpg)
(http://members.iinet.net.au/~vk6ft/micman/d104-3.jpg)
(http://)

But you only get good low end response if the D-104 is loaded with a high impedance.

(http://www.amwindow.org/misc/d104loadresp.gif)

Rare photo of the D-104's predecessor....the D-103.....

(http://www.ralphmag.org/1/radio-boy-microphone290x398.gif)

Somebody oughta notify Jack Benny about this.

Another variant on the stand that I have seen was at the shack of a buddy Bill K8BAR. Bill lives in Conneaut Ohio and his wife Rosie use to work for Astatic. Bill has what amounts to the grip bar, complete with the grip to talk mechanism, and no base. It really make the whole thing look like a lollipop! The cord attaches to the bottom of the grip part and it become entirely a hand held microphone that lays on the desktop when not in use. It was an Astatic product somewhere in the life of the microphone but that is the only one I have ever seen.

--Larry W8ER

Here's an outfit that is offering a newer style head for Astatic users.

http://www.rmscomanagement.ca/canadianastatic/images/2002-05-08_018.jpg

http://www.canadianastatic.com/microphones/communication_microphones/products/1075_window_microphone.htm

As well here's an outfit that has some pics of some earlier Astatic Mics that they service.

http://www.west-techservices.com/p3.htm

Yes DATS it rochelle salts. No kidding. I really read that somewhere. Ill have to look around.

 

 I musta had them on my mind,(http://www.radioamber.com/Jack%20and%20Rochester%201940.jpg)

Here is the quote. I knew I read somewhere about how hard it was to get rochelle salt. Im sure Rochester is happy about that. This is from a Drake BB..............

Impedance matching is in part the reason for the preamp in the first
place.  Except that even the Astatic preamp doesn't have a high
enough input impedance to get the D-104 to sound as good as it
can.  That can be fixed by simply increasing the value of the input
resistor on the preamp.  Many alternate simple preamp designs,
some with variable input Z to allow tailoring of the mic's response
are around also.

The D-104 is an excellent element, and it's too bad that Astatic
finally dropped it from the product line.  Apparently, the primary
reason was the difficulty of obtaining the Rochelle salt crystals.  It
has a nice rise in its frequency response which adds clarity and
punch without  the screaching-parakeet sound of elements such as
the Heil HC-4.  And it has a good low end, IF you operate it into a
very high impedance.

Grant/NQ5T

Actually Ed, when I heard that they were going to stop making the D104 I called and ordered several elements for the shelf. The marketing gal that I spoke with said that the reason that they decided to halt production on the D104 was becasue the molds were needing reworked and the cost was staggering. In that year they only sold 35 D104's and there was no way to justifiy the cost of the mold work.

It appears to be a case where the product was so cheap and so good that obsolence became a big factor. I've got 3 D104's here and just about every ham I know has a few on the shelf. Why buy a new one when you could order a new element and get a few more good years with it?


--Larry W8ER

The advice on having a high impedance preamp is right on. See the response curves I posted previously.

Some info on preamps below.

 - A very simple one with tone controls from John, K1DEU.
http://hamelectronics.com/k1deu/pages/ham/audio/mic_preamp.jpg

 - A cleaned up schematic here. (Loads faster too!)
http://www.amwindow.org/misc/micamp.gif


 - A nicely designed op-amp based preamp with tone controls designed to fit in the G-stand base.
http://www.qsl.net/w2aew/myd104amp.html



** Another important thing to keep in mind if you don't use a preamp in the base of your D-104, and you are running it into a very Hi-Z input on your transmitter, is the length of the mic cable. I've seen some guys with 5 foot cables on their D-104s. Unless you have a cable with very low distributed capacitance, you will lose high frequency response. Keep that mic cord as short as possible.

I'm going to check this cartridge out:
http://www.mouser.com/catalog/specsheets/KT-400025.pdf

It's got the 3 KHz peak very much like the D-104 cartridge did, and it's only $4.17 in single unit quantities.  A lot of cartridges peak up around 4 to 6 KHz, and that's to high. Shure used to have a 3KHz-peaked crystal or ceramic mike back in the 70s, but they discontinued it.

Bacon....I tried the Mouser xtal and  another in ceramic from mouser... Both worked OK....Steve

Here's one for ya.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=4671&item=5760552757&rd=1

(http://members.iinet.net.au/~vk6ft/micman/d104-3.jpg)
What happened to the bottom springs and mic cord?

http://www.infoplease.com/ce6/sci/A0842135.html

Here's how to make your own.

http://www.seawhy.com/xlroch.html

Those spring mounted D-104s were the bees knees!

:idea: Shouldn't be too hard to make a ring and spring D-104. I got one in surgery already started....

(http://www.members.aol.com/turgebabonet/spring.jpeg)

  Yes I also heard that too. I have 3 d-104s here. One  modified with a j-fet preamp and a phase switch. Works nice. I also have a DN HZ dynamic Astatic mic. Is very tinny but it really cuts through the fog.

A closeup of the ring mounted D-104.

Careful examination of the photo reveals that the spring hooks are not spaced exactly 90 degrees apart around the rim of the head,  to avoid interference with the four screws and their spacer sleeves that hold the head together.  So the springs don't sit exactly symmetrically with the same tension when the mic is mounted in the ring.  In this photo, notice the horizontal springs at the top.  The one on the  left is stretched longer than the one on the right.  Same with the vertical springs.  On the left, the upper one is stretched longer, but on the right, the lower one is stretched  longer.  Of the bottom horizontal springs, notice the one on the right is stretched longer.

This head is a full 1" thick, unlike modern heads which are 13/16" thick.


(http://uv201.com/Photo%20Pages/Photo%20Images/w3iu_1a.jpg)

Wrong type of head.  Notice the difference in the knurling on the front and back plates, plus the difference in thickness.

(http://members.iinet.net.au/~vk6ft/micman/d104-3.jpg)

True, it would be a modern D-104 head with a HB ring and spring mount.

And depending on mounting points of the springs you can make the suspension a square or a diamond shape.

(Carbon example)

(http://uv201.com/Microphone_Pages/Microphones_Images/universal_mike.jpg)

Here's the schematic for the preamp for those who have the amplified D-104s.

(http://www.amwindow.org/misc/d104_schematic.gif)

You mean someone mixed "viagra" in with their D-Ten-Four??

The microphone in this picture is a "Universal" model BB double button carbon job.

Steve,
        How did the element stack up against a crystal Astatic element in frequency response and fit/function? I'd like to buy a few as replacements for D-Ten-Fours I have that have crapped out their crapstal elements. Any info will be appreciated.

I attempted to contact Canadian Astatic about their version of the D-104:

To: <sales@canadianastatic.com>
Sent: Monday, 21 March, 2005 09:30
Subject: D-104 replacement cartridges

> Do you supply replacement crystal elements that will fit the classic D-104
> with the flat profile screen?  I notice in the photo that the 1075 Window
> Microphone has a different screen on the front of the  head that protrudes
> outwards.  Would the element used in this microphone fit the older style
> head that lacks the bulge?
>
> Thank you.

This is the reply I got:

   ----- The following addresses had permanent fatal errors -----
sales@canadianastatic.com>

   ----- Transcript of session follows -----
<sales@canadianastatic.com>... Deferred: Connection refused by canadianastatic.com.
Message could not be delivered for 1 day
Message will be deleted from queue

Anyone replaced the Astatic cartridge with a Heil 5?  I have a number of 104's, an N 30, and a JT 30 and had thought this might be a workable swap when they require replacement.

Here's another version i found on the net:

http://bobscb.com/microphones/super_star/silver_salute.htm

Ed I tried this and was not pleased with the results. It worked but   :cry:

--Larry W8ER

Jack ... THAT is the ugliest microphone that I have ever seen!  :lol:  :lol:

--Larry W8ER

Hi Larry  :D ,

 http://bobscb.com/images/super_star/silver_salute.jpg

here's another pic of it:

http://www.wb0w.com/workman/images/silver-salute.jpg

It is kinda unique... :D

Here's the characteristics:

http://www.bellscb.com/products/microphones/Superstar/Superstar_Silver_Salute.htm

Joe....The mouser xtal element that I tried had sensitivity and freq response very similar to the Astatic xtal element...can't tell much difference in that respect......The outside diameter of the mouser element is smaller than the original and fit into the head easily...I used some foam from an old pop screen to make a doughnut shaped piece that  fills the voids and centers the element.. Someone with a little more acoustical savvy could come up with a better mounting I'm sure...The ceramic element is not as sensitive and requires more mic gain and it doesn't sound as good as the xtal ...The cartridges were tested on Viking 2 and 32V-1.....Currently using an Astatic Xtal on the 32v and the mouser is sitting on the shelf......

I kinda like it. It's real Art Deco/Moderne looking. I wonder if the fit and finish is as good as Astatic?

Good Morning Joe,

 I found this thing in passing on the net while looking around the CB web sites Lord there's a Guzillion of them.. :D , But Eham has a small write up on it , and i've read on the different CB Boards it's Not Bad...

I think it's unique... :D

Joe  .. it has a presence rise at 27 mhz!!!    :lol:  :lol:  :lol:

--Larry

Note that it's a dynamic mic, not xtal.  The ad says it "doesn't sound like a D-104."  It has the rising characteristic with the 3 kc/s peak like the D-104, but looks like the lows cut off sharply below about 150~.  It evidently is a "power mic" because it uses a battery.  I strongly suspect that, unlike the D-104, it would be impossible get better lows out of it by adjusting the load resistance on the mic element.