Budget "C12" capsules

[ricardo]

I'm doing some detailed measurements for a friend on  a mike with C12 capsule from the GroupDIY group buy.

Does anyone know where this came from?  It's obviously an edge terminated k67 type.

I've been looking for detailed measurements of C12 / C12A / C414 but they are scarce.  The best appears to be

www.proaudioeurope.com/info/sound-bites/soundbites-a-very-rough-guide-to-the-akg-c12c414

which looks like early AKG published spec.  ...  perhaps measured by Bernhard Weingartner, who designed the CK12 brass capsule and the C12.

I last measured C12/414 circa 1980 when the BBC asked Calrec ... cos some of their engineers thought C12 sounded better than the 'new' C414.

C24 (stereo C12) was the main pickup in the Royal Albert Hall for the Proms ...  almost always set to Fig8.  Bernhard's curves & what I remember from my Jurassic measurements was a sorta 'flat' response.  But of course C12 mythology gives it raised HF.

This 'CK12' clone has decent omni & cardioid response but Fig8 is wonky.  You see some of the wonky Fig8 in the cardioid 180 degree response.  it has the expected Fig8 roll-off c/f omni with perhaps slightly less plumminess on male voice than the BBC.

My feeling is that if you can match Bernhard's curves for Fig8 & omni with an edge-terminated double diaphragm 34mm capsule, you would have something like what he wanted it to sound.

Of course this would not be commercial as it wouldn't look like CK12 .. and would also not have hyped HF.  But Bernhard thought it could be done with a Debenham Robinson & Stebbings (DRS) design which he really liked.

Anyone else got a link to detailed measurements of genuine C12/C12A/various C414 etc?  I'm looking for response on-axis, 90, 180 degrees and preferably 45, 135, 225, 270 & 315 degrees too.  Omni, cardioid & Fig8.

 

[zephyrmic]

I remember it was Banzai who organized the group buy. I will try to locate when.
Kindest regards,
zephyrmic

 

[zephyrmic]

I think I am correct about the group buy,  Memory is a bit hazy from that long ago, but must have been about 2011, because I was inquiring about screw sizes for mounting in Feb 2012.
zephyrmic

 

[Khron]

No idea if there was another group buy that long ago, but i got my "K47"s and "CK12"s from a 2016 group buy put together by Banzai

I think I am correct about the group buy,  Memory is a bit hazy from that long ago, but must have been about 2011, because I was inquiring about screw sizes for mounting in Feb 2012.
zephyrmic

 

[ricardo]

I'm really interested in these K67s pretending to be CK12s.

Anyone seen a pic which shows K67 construction?

Something like
http://www.saturn-sound.com/Curio's/akg's%20ck12%20capsule.htm#What%20makes%20the%20CK12%20so%20special
for CK12

 

[Khron]

I did a bit of a teardown / Frankenstein-ing, a couple years ago ;D

https://khronscave.blogspot.com/2017/05/a-litle-k67-microphone-capsule-fun.html

And so did Henry Spragens, back in 2013 - http://audioimprov.com/AudioImprov/Mics/Entries/2013/2/19_K67_Capsule_Take-apart.html

 

[kingkorg]

Anyone else got a link to detailed measurements of genuine C12/C12A/various C414 etc?  I'm looking for response on-axis, 90, 180 degrees and preferably 45, 135, 225, 270 & 315 degrees too.  Omni, cardioid & Fig8.

There is some data from MBHO and their CK12.

Here:

http://www.mbho.de/products03_26b_2.htm

http://www.mbho.de/products03_25b_1.htm

http://www.mbho.de/products03_25b_2.htm

 

[ricardo]

I did a bit of a teardown / Frankenstein-ing, a couple years ago ;D

https://khronscave.blogspot.com/2017/05/a-litle-k67-microphone-capsule-fun.html

And so did Henry Spragens, back in 2013 - http://audioimprov.com/AudioImprov/Mics/Entries/2013/2/19_K67_Capsule_Take-apart.html

Thanks Khron.

Standing as far back as possible, it looks like

• DRS has no internal cavity
• K67 & copies have single internal cavity
• CK12 & family have 3 internal cavities

Gotta swot up on  Double Diaphragm capsules to see what Bernhard meant 

 

[ricardo]

There is some data from MBHO and their CK12.

Thanks for this kingkorg.

But I don't trust the MBHO curves. eg the red 90 degree response on their cardioid curve is BS ... and doesn't tally with their polars either.
http://www.mbho.de/products02_06b_1.htm

But their Fig8 response is very like my K67edge capsule than pukka AKG CK12s 

 

[zephyrmic]

No idea if there was another group buy that long ago, but i got my "K47"s and "CK12"s from a 2016 group buy put together by Banzai

I posted the completed mics (stainless steel bodies) in early October 2013 on micbuilders Photos, and I was asking about mounting screws for these capsules in Feb 2012, so that is how I arrived at 2011 date for the group buy. I know that I had the capsules for some time before I got around to making bodies etc. for them.
Come to think of it, I am not sure whether Banzai was the originator of this group buy, or whether it was someone else. A bit too long ago for my memory.
Regards,
zephyrmic

 

[zephyrmic]

I found my original post re these capsules. It is dated October 21, 2011. Here is the link.
https://groupdiy.com/index.php?topic=45458.msg579892#msg579892
It is entitled Has anyone tried these microphone capsules? It is an interesting read.
Reply #111 is when I received these capsules on January 05 2012.
Check out the thread. It gives some useful info.
Hope this history helps to fill in a few blanks.
Kindest regards,
zephyrmic

 

[Banzai]

I'm doing some detailed measurements for a friend on  a mike with C12 capsule from the GroupDIY group buy.

Does anyone know where this came from?  It's obviously an edge terminated k67 type.

Both groupbuys were ISK capsules (WGT is a reseller)

Factory price is around $20 for single, $25-$30 for double.

 

[kiestor]

Hi everybody... I have a replica capsule mic from the C12.

I bought it to replace the capsule of a Blue blueberry
but it seems that the problem of the mic wasnt the capsule...,
so I think to put the capsule to another mic body
So, what's the cheapest large diaphragm mic I could get to replace his=
with this one?