Circuit Ideas for C12-style Capsule

[callgrlmusic]

hey all,

just purchased a few capsules from Guosheng at 3u audio. awesome dude, very helpful—thank you to some users here for the recommendation.

i’ve got a lot of MXL 990s lying around that i think would make useful donor bodies for some C414-style mics—does anyone have any recs on a good microphone circuit to pair with these capsules in order to make them? open to kits but would also like to fully DIY these.

 

[callgrlmusic]

i’m going to add some context to this: the capsules will go into a modified mxl 990 body, and they will ideally be used as killer OH large diaphragm mics. i’m modifying some 991s as SDC overheads too, but they’re essentially finished already.

these don’t have to be C414 copies (and i know there are many). maybe a more broad question—are there any great mic circuits you’d pair with a C12-style capsule for this purpose generally speaking? how would you go about a project like this?

 

[OneRoomStudio]

Are you taking about the new authentic CK12 capsules from Guosheng, or the ones he’s had for a while (which are K67-style backplates with an edge-terminated diaphragm)?

If it’s the new ones, no one here has heard them yet (to my knowledge) and we are all very excited to hear them!

If it’s the older style ones, those are nice sounding capsules, but don’t sound exactly like a CK12 anyway, so no need to try to build a CK12-specific circuit. If it were me, I’d probably go with a “FET847” circuit or similar.

 

[callgrlmusic]

to be honest, i’m not sure. he asked me this when i ordered—that must be what he was talking about. i ordered the ones that were not “dark,” which im guessing may refer to the old ones based on the frequency charts. what do you think?

 

[pasarski]

Both are "Neumann style" so probably just different variations of the edge terminated K67. I would also probably go for a KM84 -style circuit. Just adjust the drain to gate cap so that the mic can handle the SPL or include a pad.

If you don't need "vintage color" you might check @rogs 's OPIC circuits for LDC capsules: https://www.opic.jp137.com/index-ldc.html

 

[Accelerator]

@callgrlmusic​

The “Standard Version Neumann Style CK12” capsules that you ordered from Guosheng at 3u audio, are sonically just different variations of the “edge terminated” K67.

The “Dark Version Neumann Style CK12” capsules that you didn’t ordered try sonically to “looks like” what a CK12 capsule “looks like”, although as you already know & clearly you understand “This is not a real Jim Beam…”

With the “Standard Version Neumann Style CK12” capsules that you ordered from Guosheng at 3u audio, you can make some nice Neumann U-67 style microphones or to be clear you need microphones with de-emphasis circuit, so no in anyway an AKG C-414-style microphone…

If you sonically desperately needs some ”very flat AKG C-414B-ULS style microphone(s)” for instruments and for Drums O/H, it will be a better choice to place an order for some Arianne Audio Flat K47 capsules and use them in a flat circuit…

P.S. Just to let you know, not to be fooled again…

They weren’t any “Neumann Style CK12” capsules in any time…

The CK12 “Brass Capsule” produced back in time only by the AKG, not in any way by the Neumann…

 

[callgrlmusic]

@callgrlmusic​

The “Standard Version Neumann Style CK12” capsules that you ordered from Guosheng at 3u audio, are sonically just different variations of the “edge terminated” K67.

The “Dark Version Neumann Style CK12” capsules that you didn’t ordered try sonically to “looks like” what a CK12 capsule “looks like”, although as you already know & clearly you understand “This is not a real Jim Beam…”

With the “Standard Version Neumann Style CK12” capsules that you ordered from Guosheng at 3u audio, you can make some nice Neumann U-67 style microphones or to be clear you need microphones with de-emphasis circuit, so no in anyway an AKG C-414-style microphone…

If you sonically desperately needs some ”very flat AKG C-414B-ULS style microphone(s)” for instruments and for Drums O/H, it will be a better choice to place an order for some Arianne Audio Flat K47 capsules and use them in a flat circuit…

P.S. Just to let you know, not to be fooled again…

They weren’t any “Neumann Style CK12” capsules in any time…

The CK12 “Brass Capsule” produced back in time only by the AKG, not in any way by the Neumann…

thank you for the specific info!!! that’s totally alright—ideally i just want to make two great mics with those capsules. i’ve done quite a bit of reading up on the de-emphasis circuit and i am happy to make sure that’s a part of the design.

more or less, im at a place in my EE journey where i know that 48 volts goes in and ~60v should go to the capsule, but im trying to get my hands dirty and learn the “why” of every part of the circuit with this project.

 

[pasarski]

If you want the brightness tamed check ORS87: https://groupdiy.com/threads/open-source-diy-mic-project-ors-87-stripped-down-u87.86814/

I don't mind my OH's to be bright. But it's totally up to ones preferences how OH's should sound.

Also, you don't need 60V for overheads IMO. With signal that loud it's counterintuitive. You're good what's left out of 48V after the drop caused by the circuits current draw.

 

[kingkorg]

thank you for the specific info!!! that’s totally alright—ideally i just want to make two great mics with those capsules. i’ve done quite a bit of reading up on the de-emphasis circuit and i am happy to make sure that’s a part of the design.

more or less, im at a place in my EE journey where i know that 48 volts goes in and ~60v should go to the capsule, but im trying to get my hands dirty and learn the “why” of every part of the circuit with this project.

If you want anything that resembles 414, or anything else CK12 based, you don't want de-emphasis. You can just put this capsule in your 990 mic, and that's it. Maybe adjust bias if needed. Biasing the mic will give you probably more than enough to experiment with, it's a tricky process, and you will learn a lot.

De-emphasis will remove too much above say 12K with this capsule. If you wanted a darker sounding mic, you should have picked the other capsule he offered. It is also more suited for 414 voicing, as these are more flat than c12.

990 is Schoeps based mic, you can try adding @RuudNL daughter board, or mic parts style HF filter.

If you absolutely want some HF filtering, try adding corrective curve using an EQ in your DAW before building anything, and see if you like how it sounds. De-emphasis or simple EQ in post give the same results.

Today I did some measurements on the circuit I described before.
Core of the circuit is the generic Schoeps circuit, as seen in many commercial microphones.
It proves that it is possible to create exactly the U87 de-emphasis: - 3 dB @ 40 Hz and -4 dB @ 16 KHz.
Of course you can increase the value of the 47 nF capacitor, if you don't need the LF rolloff.
In fact, it should be possible to create a small add-on PCB, to add de-emphasis to an existing (Chinese?) microphone.
In the circuit diagram the PNP output stage is omitted, but this is not important to understand the principle.

Eq:

https://audioimprov.com/AudioImprov/Mics/Entries/2014/2/8_EQ_Pt.3_-_Transformerless_Mics.html

 

[callgrlmusic]

If you want anything that resembles 414, or anything else CK12 based, you don't want de-emphasis. You can just put this capsule in your 990 mic, and that's it. Maybe adjust bias if needed. Biasing the mic will give you probably more than enough to experiment with, it's a tricky process, and you will learn a lot.

De-emphasis will remove too much above say 12K with this capsule. If you wanted a darker sounding mic, you should have picked the other capsule he offered. It is also more suited for 414 voicing, as these are more flat than c12.

990 is Schoeps based mic, you can try adding @RuudNL daughter board, or mic parts style HF filter.

If you absolutely want some HF filtering, try adding corrective curve using an EQ in your DAW before building anything, and see if you like how it sounds. De-emphasis or simple EQ in post give the same results.



Eq:

https://audioimprov.com/AudioImprov/Mics/Entries/2014/2/8_EQ_Pt.3_-_Transformerless_Mics.html

this is an incredible wealth of information and i appreciate you taking the time. by the way, is it you who runs Audio Improv? between that and Khron’s Cave i’ve been keeping up with that stuff for years, long before i joined this forum. incredibly cool and valuable resources both.

 

[Khron]

by the way, is it you who runs Audio Improv?

No, that would be Henry Spragens - pretty sure he's not a member here though.

 

[Tim Campbell]

A real CK12 on it's own sounds wonderful and so a simple, clean circuit can allow it to really excel. Many of the best sounding edge terminated K67 capsules sound at least similar.