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TLRT

AKG C12 / Siemens SM204 help needed
« on: May 23, 2016, 02:23:33 PM »
Hello All,

I get this mic for restoration, is it possible to find the mic connector part? (old owner modified it to 5pin tuchel) I have the orginal connector for the mic cable. Btw the Siemens SM204 has the same schematics as the C12?


micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #1 on: May 23, 2016, 02:28:15 PM »
Very interesting mic.

I was going to mention it here, but now I don't have to.  :)

From what I know the schematic is not exactly the same as C12.

And some say the Siemens is the better microphone.  :o

Henry Radio tranny?
« Last Edit: May 23, 2016, 02:42:47 PM by micaddict »

ln76d

Re: AKG C12 / Siemens SM204 help needed
« Reply #2 on: May 23, 2016, 03:51:01 PM »
These circuits are little bit different.
I didn't found schematic for SIemens.
There were here pictures of Siemens internals, but i don't remember which topic it was.
From what i remember there was pF range capacitor to damp HF like in ELA M.
Your circuit doesn't look original - partialy.
For connector you could ask FLEA, "Telefunken" (ehem) USA and Andriejus here on forum (spoiler).

TLRT

Re: AKG C12 / Siemens SM204 help needed
« Reply #3 on: May 23, 2016, 04:06:37 PM »
Yes, the electonics was modded to ECC83, all electrolytic caps(at least 5pieces, and diodes on the tranny, but why?:) Tranny says "June 1955" and it has the C12 capsule, this is the important. I have the all original N12 psu and S36 pattern box.

micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #4 on: May 23, 2016, 04:38:17 PM »
I believe Voxorama (Andreas Grosser) makes a clone FWIW.

He sells parts, too.
http://www.voxorama.com/ersatzteile/detail/steckverbinder-preis-auf-anfrage.html
« Last Edit: May 23, 2016, 04:46:30 PM by micaddict »

Tim Campbell

Re: AKG C12 / Siemens SM204 help needed
« Reply #5 on: May 23, 2016, 04:57:33 PM »
I worked on a pair of these last year. The main differences are the Henry Radio transformer and early style CK12 capsule. I believe most, if not all of these were manufactured as part of the very first production run of C12's.
"Sound better" is quite subjective. They have a slightly lower output and more midrange, a bit like a mix between a C12 and a U47.
Most people, when given the choice prefer the sound of later revisions of the capsule.
Andreas Grosser uses MBHO CK12 type capsules almost exclusively and would mean that his version of this mic would sound very different.

micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #6 on: May 23, 2016, 05:47:57 PM »
Quote
"Sound better" is quite subjective.

I fully agree.
And I haven't tried one myself.
Just echoing some (!) sentiments.  ;)


Quote
They have a slightly lower output and more midrange,

This is interesting, though.
They are reported to to be less easy to overdrive and to be more verstatile on vocal applications than a "typical" C12.
I see some possible (!) relation with your comment there.


Quote
a bit like a mix between a C12 and a U47.

Well, you could do worse than that.  :)
« Last Edit: May 23, 2016, 06:11:22 PM by micaddict »

Tim Campbell

Re: AKG C12 / Siemens SM204 help needed
« Reply #7 on: May 24, 2016, 03:29:43 AM »
Here's an internal pic.

micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #8 on: May 24, 2016, 06:36:48 AM »
Thanks, Tim.  :P

OPR, are you there?



Back to the OP's question.
You can take a look and/or ask here, too:
http://www.akzent-audio.de/hardware/hardware-l-z/steckverbinder



Henk

TLRT

Re: AKG C12 / Siemens SM204 help needed
« Reply #9 on: May 24, 2016, 02:49:37 PM »


ln76d

« Last Edit: May 24, 2016, 03:16:24 PM by ln76d »

micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #11 on: May 24, 2016, 03:23:46 PM »
Yeah, seems like most of us were in that one, too.

Thanks for the reminder and the pictures.   :)

Re: AKG C12 / Siemens SM204 help needed
« Reply #12 on: May 24, 2016, 04:32:09 PM »
Here is the schematic for the SM204/23 , the version that I have, and which is posted in the other thread.

The /23 indicates that it is named "C23" in AKG names, and is a refit for the AKG C2, the predecessor to the C12.
Quite interesting, they changed the circuit to the self-biasing C24 type.

Also  my /23 does not use the Henry Radio V2148 xformer, but a V2545, allegedly built by Rohde & Schwarz.

« Last Edit: May 24, 2016, 04:38:08 PM by tonzauber »

ln76d

Re: AKG C12 / Siemens SM204 help needed
« Reply #13 on: May 24, 2016, 04:46:28 PM »
I would give you a kiss!
But i don't want soo much ;)
Thanks for schematic!!!!!

TLRT

Re: AKG C12 / Siemens SM204 help needed
« Reply #14 on: May 24, 2016, 05:15:45 PM »
Here is the schematic for the SM204/23 , the version that I have, and which is posted in the other thread.

The /23 indicates that it is named "C23" in AKG names, and is a refit for the AKG C2, the predecessor to the C12.
Quite interesting, they changed the circuit to the self-biasing C24 type.

Also  my /23 does not use the Henry Radio V2148 xformer, but a V2545, allegedly built by Rohde & Schwarz.

Thanks!!! This will help a lot!!!

micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #15 on: May 24, 2016, 05:53:01 PM »
Looks like this is evolving into a great thread.
 
Believe it or not, but I was one second away from starting one about the Siemens SM204 myself.

So thanks, OP and further contributors, for this present.  :)

And keep it coming, please.

OPR

Re: AKG C12 / Siemens SM204 help needed
« Reply #16 on: May 24, 2016, 08:52:17 PM »
Wow! Great thread!! :) 8)
They always get interesting when Micaddict gets involved  ;)
The sm204 schematic looks like the mic would sound more like a 251 then a c12 looking the biasing scheme,
although there's a capsule to grid coupling capacitor which is a c12 thing... Let's call it a hybrid between the two :) Along with the shallow dish capsule I'd say the Sm204 circuit would also enhance the mids even further with the way it's biased.

I've made quite a few experiments making my own C12 copy capsules adjusting the chamber sizes, set up and tuning options. .etc and It seems the shallower the dish the flatter and more mid forward it becomes along with the slightest lowering  in output, the highs and lows can be adjusted with diaphragm tuning and back-plate spacers.  I'd agree with what Tim said in someways that it's somewhere between an 47 and c12,But only  frequency wise. Due to the mechanical properties of it's design  it still behaves with all of the typical ck12 edge terminated multi-chambered benefits in the way transients are captured and the way it can sound smooth yet airy when set up is a certain way.



It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

Tim Campbell

Re: AKG C12 / Siemens SM204 help needed
« Reply #17 on: May 25, 2016, 03:41:38 AM »
Quote
Also  my /23 does not use the Henry Radio V2148 xformer, but a V2545, allegedly built by Rohde & Schwarz.

Now, looking at my picture, I can see this pair also had the Rohde & Schwarz transformers. Apparently there were only 512 SM204's built.

Although the pair I worked on didn't sound like your classic C12 sound, I and everyone else who heard them thought they sounded fantastic in their own unique way.

micaddict

Re: AKG C12 / Siemens SM204 help needed
« Reply #18 on: May 25, 2016, 05:06:08 AM »
Wow! Great thread!! :) 8)
They always get interesting when Micaddict gets involved  ;)
The sm204 schematic looks like the mic would sound more like a 251 then a c12 looking the biasing scheme,
although there's a capsule to grid coupling capacitor which is a c12 thing... Let's call it a hybrid between the two :) Along with the shallow dish capsule I'd say the Sm204 circuit would also enhance the mids even further with the way it's biased.

I've made quite a few experiments making my own C12 copy capsules adjusting the chamber sizes, set up and tuning options. .etc and It seems the shallower the dish the flatter and more mid forward it becomes along with the slightest lowering  in output, the highs and lows can be adjusted with diaphragm tuning and back-plate spacers.  I'd agree with what Tim said in someways that it's somewhere between an 47 and c12,But only  frequency wise. Due to the mechanical properties of it's design  it still behaves with all of the typical ck12 edge terminated multi-chambered benefits in the way transients are captured and the way it can sound smooth yet airy when set up is a certain way.

There he is, all the way from down under.
Welcome to the party.  :)

Interesting stuff. Edge terminated capsules (of that size) and the mics they're in, fantastic as they can be, can lack some midrange punch needed for some sources. In the right hands, the capsule as well as the circuit can be tuned to lift the mids. The question is how far do we want to take this. There's always the chance you'll throw away the child with the bath water. In other words, you may lose what makes a CK12, or a C12 for that matter, special. In that case, it would seem wiser to just use a mic with a center terminated capsule, if mid punch is needed. Yin and yang.
Still, it seems this SM204/C23 is actually a very versatile beast while still sounding magical. And perhaps it's even more versatile than the Ela M251.



Tim wrote:
Quote
Andreas Grosser uses MBHO CK12 type capsules almost exclusively and would mean that his version of this mic would sound very different.
From what I understand, if and when Andreas builds in very small numbers, he tries to source the original parts first. I know the SM204s he made have original transformers. So they may have original CK12 capsules too, though maybe not period correct. (?)



@TLRT
The person to ask at Akzent Audio is Jean Hund.

TLRT

Re: AKG C12 / Siemens SM204 help needed
« Reply #19 on: May 25, 2016, 05:10:31 AM »
Wow! Great thread!! :) 8)
They always get interesting when Micaddict gets involved  ;)
The sm204 schematic looks like the mic would sound more like a 251 then a c12 looking the biasing scheme,
although there's a capsule to grid coupling capacitor which is a c12 thing... Let's call it a hybrid between the two :) Along with the shallow dish capsule I'd say the Sm204 circuit would also enhance the mids even further with the way it's biased.

I've made quite a few experiments making my own C12 copy capsules adjusting the chamber sizes, set up and tuning options. .etc and It seems the shallower the dish the flatter and more mid forward it becomes along with the slightest lowering  in output, the highs and lows can be adjusted with diaphragm tuning and back-plate spacers.  I'd agree with what Tim said in someways that it's somewhere between an 47 and c12,But only  frequency wise. Due to the mechanical properties of it's design  it still behaves with all of the typical ck12 edge terminated multi-chambered benefits in the way transients are captured and the way it can sound smooth yet airy when set up is a certain way.

There he is, all the way from down under.
Welcome to the party.  :)

Interesting stuff. Edge terminated capsules (of that size) and the mics they're in, fantastic as they can be, can lack some midrange punch needed for some sources. In the right hands, the capsule as well as the circuit can be tuned to lift the mids. The question is how far do we want to take this. There's always the chance you'll throw away the child with the bath water. In other words, you may lose what makes a CK12, or a C12 for that matter, special. In that case, it would seem wiser to just use a mic with a center terminated capsule, if mid punch is needed. Yin and yang.
Still, it seems this SM204/C23 is actually a very versatile beast while still sounding magical. And perhaps it's even more versatile than the Ela M251.



Tim wrote:
Quote
Andreas Grosser uses MBHO CK12 type capsules almost exclusively and would mean that his version of this mic would sound very different.
From what I understand, if and when Andreas builds in very small numbers, he tries to source the original parts first. I know the SM204s he made have original transformers. So they may have original CK12 capsules too, though maybe not period correct. (?)



@TLRT
The person to ask at Akzent Audio is Jean Hund.

Hi,

I got negative answer from Akzent/Jean, FLEA can make me a custom connector, probably I'll order from them(not cheap)
The full plan is to make a complete restoration I have original N12 PSU, S36 pattern selector also (I need the connecors also for S36 -3pin  tuchel and 5 pin tuchel, but those I can find easier maybe)