Official C12 Clone - Build and Support Thread

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
no i don't need to buy one...
i have plenty of low cost pcb mounted mics in the back of my cupboards
your's has one of the worst HiZ design i've ever seen with its non damped tube and tube socket vibrating near the stiroflex caps, the HiZ resistors on a cantilever pcb, all that in perpetual contact with the body, and its great long curved HiZ wires....

but you will surely explain us that your product is revolutionary ....

did you ever try to reinvent the wheel ?

PS:for styroflex caps : THANK YOU, that's exactly what i'm trying to explain : the HiZ section is highly microphonic and must be carefully designed to avoid internal resonances !


BEFORE YOU POST BACK: https://www.youtube.com/watch?v=ex-UVjawnvU  ;D

 
granger.frederic said:
Oh, please kidvybes, don't be offensive by comparing the recreation of a CK12 (the most difficult capsule  ever made) and putting components on a PCB (with all the respect...), thanks!

...clearly you know nothing of what Chunger has taken on in creating/running his Studio 939 shop...many of his products required custom tooling, numerous prototype revisions, financial commitments based on minimum quantities, customs paperwork, arranging consolidation of shipments, stocking of components, packing and shipping orders, handling customer service, all while maintaining a real job and family (not to mention posting the most concise instructional build threads on the DIY site)...no one is directly comparing the individual achievement, but all the time, effort (aggravation), and expense should not be underestimated either...

granger.frederic said:
no i don't need to buy one...
i have plenty of low cost pcb mounted mics in the back of my cupboards
your's has one of the worst HiZ design i've ever seen with its non damped tube and tube socket vibrating near the stiroflex caps, the HiZ resistors on a cantilever pcb, all that in perpetual contact with the body, and its great long curved HiZ wires....


...so let me get this straight...the guy who is consistently harassing the designers of this project has never built, nor used the product?...
 
granger.frederic said:
no i don't need to buy one...
i have plenty of low cost pcb mounted mics in the back of my cupboards
your's has one of the worst HiZ design i've ever seen with its non damped tube and tube socket vibrating near the stiroflex caps, the HiZ resistors on a cantilever pcb, all that in perpetual contact with the body, and its great long curved HiZ wires....

but you will surely explain us that your product is revolutionary ....

did you ever try to reinvent the wheel ?

PS:for styroflex caps : THANK YOU, that's exactly what i'm trying to explain : the HiZ section is highly microphonic and must be carefully designed to avoid internal resonances !


BEFORE YOU POST BACK: https://www.youtube.com/watch?v=ex-UVjawnvU  ;D

Actually they are microphonic in the air in a ptp mic as well.  In this case the pcb could be seen as an advantage since it gives a rigid base they can be glued to which helps a lot. 

No doubt, pcbs pose design challenges for mics but you seem to have it out for these guys.  I've built a few of these and they sound really great. I Haven't run into any of the issues you're suggesting.  Anything's possible man, including some of the scenarios you present, but the new pcb material, and coating are worth checking out.  If the pcb compares to teflon then there may be little advantage to isolating with teflon on top of that.

If these mics prove problematic, sound bad or are unusable due to their design Matador can answer for that when the complaints roll in. If they don't maybe he's on to something.
 
I have to give credit where credit is due, and indeed Granger does have a point with respect to resonances on the PCB, which is something I've already tackled in my next microphone design project.

I've been experimenting with replacing the capsule coupling cap with a new type of capacitor called a flux capacitor.  It was quite challenging to get it in the narrow Alctron HT-11A body, but it just fits with some PCB trimming.  The funny thing is, it takes a TON of power: 1.21 gigawatts to be exact, which required tweaking some of the series resistances in the PSU (and my power company asked for a few months utility bills in advance).

The coolest thing about this new design is that once the resonant PCB frequency exceeds 88 Hz, the microphone actually goes back in time to sense in incoming signal before it's actually sent from the source.  Thus there is no phase cancellation, pesky room acoustic modes, nor any tube resonances to worry about.  In fact, you can actually record all the necessary takes before even setting up the mike, because the microphone hears all of them before they are actually played.  Great Scott, this will be very cool when I can release it!

In any case, it may be some time before Chunger offers a PCB kit, as I hear Libyan terrorists are looking for him and some missing plutonium.
 
Oh my gosh !

I just say it could sound better with a HiZ improved section, but it appears very complicated to make any comment here (for a long time now ....)

Some call that the big-headed syndrome but this may be reversible if recognised and treated promptly...

Oh, and it was not necessary to  invoke the Libyan terrorists ... !

Here in France, our sense of humor is rock solid, fortunately, but however there's a limit....

For those who want to see how important is the internal design , take a look at the attached picture of a U47 clone that i'm building at that time.
Yes, the extra cash is important (1000€ for the body) but it worth the effort .That's what a Thiersch capsule deserves !
 

Attachments

  • photo 1.JPG
    photo 1.JPG
    426.4 KB
p1094795219.jpg
 
granger.frederic said:
Oh my gosh !

I just say it could sound better with a HiZ improved section, but it appears very complicated to make any comment here (for a long time now ....)

Some call that the big-headed syndrome but this may be reversible if recognised and treated promptly...

Oh, and it was not necessary to  invoke the Libyan terrorists ... !

Here in France, our sense of humor is rock solid, fortunately, but however there's a limit....

For those who want to see how important is the internal design , take a look at the attached picture of a U47 clone that i'm building at that time.
Yes, the extra cash is important (1000€ for the body) but it worth the effort .That's what a Thiersch capsule deserves !

Looks nice Frederic.  Did FLEA do the body?  That's a lot for just the body (which does look excellent) but there are a couple of equally nice options floating around on GDIY for maybe a bit less.  Also curious why you mounted the transformer around the bobbin rather than the lams as is traditional?  Is the Cinemag too long?  Careful not compress it too much.

A fine build indeed, and though this is a C12 thread at least it's getting back to the true spirit of GDIY, to share ideas and designs peacefully.
 
All the Flea mic bodys are world class and historically correct, i use them a lot.

the transformer is a cinemag, the mount cannot be historically correct, but the impact is null

at this time someone's order me a U47 but i'll post some pictures of a C12 asap

i've heard that Flea is working on a ELAM 251 body...

my conception is that if you invest in a world class capsule (Campbell, Thiersch, Haun , Neumann ....), it's just too bad to mount it in a low cost chinese body....
the risk is too high to obtain reduced performances (min THD) on loud sources ( with high sustain and powerful transients especially), because of the poor metalwork, components implementation, random mounted HiZ sections, etc......

My opinion is that when you use botchy internal designs, the performances cannot be top class nor near historically correct.
It might be ok for various applications but not for all.
After all, we're talking about CLONING unrivaled microphones like the AKG C12, ELAM251...

it worth the effort and the final self satisfaction is huge

i add that a singer is more inspired in front of a identifiable classic mic body (the well known placebo effect) ::)
 
Edited:

Was looking for help because I just completed 99.9% of a C12 build  but can't figure out how to wire the capsule  because the RK12 http://microphone-parts.com/rk12-microphone-capsule/  has only 3 wires; a single Backplane wire and one each for the front and rear diaphragms.

But I think I located the needed changes from Matador:
http://www.musicalsparks.com/images/c12/c12_to_ela251_v2.jpg


Thanks
 
HHH said:
Edited:

Was looking for help because I just completed 99.9% of a C12 build  but can't figure out how to wire the capsule  because the RK12 http://microphone-parts.com/rk12-microphone-capsule/  has only 3 wires; a single Backplane wire and one each for the front and rear diaphragms.

But I think I located the needed changes from Matador:
http://www.musicalsparks.com/images/c12/c12_to_ela251_v2.jpg

Thanks

Careful - that link is to the ELA M251 conversion schematic, so there are several changes.

Using a 3-terminal capsule is easy:  just run both the front backplate and rear backplate connections to the single backplate on your capsule.  Even 4-terminal capsules have both separate backplate connections bridged together to convert it to a 3-terminal capsule, so you just get once bonus step for free. :)
 
Matador said:
HHH said:
Edited:

Was looking for help because I just completed 99.9% of a C12 build  but can't figure out how to wire the capsule  because the RK12 http://microphone-parts.com/rk12-microphone-capsule/  has only 3 wires; a single Backplane wire and one each for the front and rear diaphragms.

But I think I located the needed changes from Matador:
http://www.musicalsparks.com/images/c12/c12_to_ela251_v2.jpg

Thanks

Careful - that link is to the ELA M251 conversion schematic, so there are several changes.

Using a 3-terminal capsule is easy:  just run both the front backplate and rear backplate connections to the single backplate on your capsule.  Even 4-terminal capsules have both separate backplate connections bridged together to convert it to a 3-terminal capsule, so you just get once bonus step for free. :)

Thanks...
Oh so R14, from the R12/13 voltage divider, is actually connected to the C13 Grid capacitor on the C12 layout?

RE: the 251 option:
I now know that RK-12 capsule has it's backplates internally connected. So there's no way to use one separate from the other.  Does that mean I can't use the 251 option that shows one backplate floating?

How would a 3 connector capsule [with connected backplates] be wired for the 251 option - just for cardioid? Would the FC and FB stay as shown and the BC just be disconnected from the Polarization?
 
My 251 retrofit retains the stock C12 polarization mechanism, not the original ELA M251 one:  so that part doesn't change.  Both designs implement a 3-terminal capsule connection scheme.  If you were implementing the original 251 polarization scheme, then yes, you'd need a capsule that has two isolated backplates.

Regardless of the design, in general, capsule polarization for a 3 terminal capsule looks something like this:

Cardioid - front membrane 0V, backplate +60V, rear membrane disconnected, or set to +60V (same as backplate)
Omni - front membrane 0V, backplate +60V, rear membrane at 0V
Figure 8 - fron membrane 0V, backplate +60V, rear membrane 120V (or backplate is -60V wrt. rear)

The standard Neumann trick to get figure 8 with a 4-terminal capsule is to always keep the front backplate at +60V, but to ground the rear backplate in figure 8 mode.  This makes each half appear to be in cardioid mode, however the polarity is reversed to each other, meaning that sounds from the side are cancelled.
 
There is no doubt the Flea mic body is very nice and precisely machined to vintage specs.  On a similar point, Shaggy, whose shop is just a few minutes away from me, hand machines all of his bodies on meticulously maintained vintage mill and lathe equipment and holds to the highest quality levels for tolerance and finish, and in my opinion under-charges for his labor of love.  He made me a delrin spacer for a U67 clone so beautifully machined, it puts the rest of the imported microphone body to shame.  I always like checking in with him to see what he is tinkering with in high-end microphone land.

But, one of my primary goals is to make functionally outstanding microphones available and well within reach of "the common man".  I strongly disagree with the assertion that these low-cost, imported bodies are categorically inadequate for the job of supporting a well functioning (Matador would argue "optimally functioning"  within the circuits operating parameters) microphone system for the lifetime of the user and beyond.  Certainly, you can spend 10x the amount to attain the highest quality construction, but the microphone body is nowhere near highly stressed component and does not need to be a precision machined instrument to work correctly in its intended application. 

Tim Campbell, Eric Heiserman, Thiersch, and all of the other high end capsule manufacturers can make new capsules pretty much indefinitely.  Same with cinemag, Marik, and the other transformer manufacturers.  Projects like these that are able to gain good traction have to play at least a small role to stabilize and financially protect very small-scale operations like the manufacturers mentioned here.  I don't understand the mindset that deploying the best available capsules in builds in this price bracket is somehow offensive or a waste of effort and resources.  In fact, it is somewhat the entire point of the endeavor. . . that is to figure out a way to bring the full sonic potential of the premium capsule to light in an affordable, accessible package and allow people everywhere to experience and enjoy it.

The only item in this microphone that will run out eventually is the GE 6072A tube, and I have tried to the best of my abilities to call attention the practice of pairing NOS tubes with premium capsules only.  If you want to make an argument about if a kit is "deserving" of a part, it makes more sense to base the argument on the non-renewable resource. . . the 50's - 70's era GE 6072A's.

This kit is  often a  "gateway" project.  One that often times is an entry point for people into DIY.  As such, ease of build is a consideration that is not even on the radar for a ~$3000 custom microphone.  As a gateway project, success by the end user, and by that, I mean not only functional completion of the build, but an extremely positive sonic outcome emboldens the new builder to take on more technically complex builds (many of which are available on this forum).

I will leave the technical explanations of why the system works to those more qualified, but i will say that on the development side, Matador has never discounted any of my specific technical concerns about the kit's performance and specification. . . Even the ridiculous, obviously ill-informed ones. . . and in person, in studio,  and on forum carefully explained/presented his evidence as well as make changes when testing identifies a deficiency or the performance of a material or part does not meet published specification in the real world.

I find it ironic that we improve one operating parameter of a kit that already has a track record of build success and sonic performance in the real world. . . introduce the use of a material that has great future potential for audio DIY applications (and incidentally HAS been tested to exceed quite a few of NASA's materials standards for deep space application), and people come out of the woodwork to go for another round of re-hashing arguments that have already been discussed ad-nauseum in this thread.  But, since we have already diluted the support content of this thread this far already, I will summarize the entrenched positions of the parties involved:

- Matador after careful consideration of all of his design variables (per calculations and his real-world experience/intuition) maintains that all of the operating parameters for the C12 circuit as expressed in this kit are functioning optimally. . . meaning there is a LARGE margin built-in.  In other words, "other factors" overwhelmingly intrude upon the performance envelope  of the microphone system well before any layout, construction, or material limitations related to the board design and layout come into play.

- Mr. Granger and others contend that the HiZ isolation properties are inadequate.  The microphone body has severe design defects precluding the delivery of sonics on par with the vintage original.  The physical layout of the HiZ section is "haphazardly" laid out, and the tube is not mounted in an mechanically dampened manner generating unacceptable microphonics. 


Matador is not defensive because he is lazy, selling snake oil,  or doesn't want to change the layout.  In fact, I feel we print more test iterations of boards before "official release" quite often.  There is never hesitation to re-try or make changes.  He defends based on his reasoned engineering and belief that the system is sound. . . and he puts his stake in the ground upon rubber stamping his kit design and let users judge based on results.

I'm sure Mr. Granger feels just as strongly that the traditional methods of microphone construction are vastly superior to the substandard scheme being implemented here.  I have not seen or heard one of his creations, but I have no reason to doubt they are in fact outstanding pieces that perform as advertised.

Sure, I have commercial interests in this specific kit and collaboration to make it widely available.  I do contend that I have always accurately and conservatively described the nature of this kit publicly and privately without any wild claims advocating the clone as an "exact replica" of the vintage AKG C12 or guaranteeing precise sonic duplication or verbiage suggesting the clone is "just like" a vintage original.  This is Matador's implementation of the vintage C12 circuit.  We feel it is a great one on a lot of levels and we will continue to improve and iterate based on feedback and our particular design objectives.  We think it's fun to explore leveraging  modern high-performance materials and processes for audio application.

The only exception to the statement above is my assertion that the yellow colored PCB is sonically superior in all applications.
 
Well said.  I am curious when the new kits look like they will be available.  I really am just looking for a general time frame, no specifics.  It makes it quite a bit easier to budget, money and time.  Thanks again for making nice equipment so easy to obtain.
Patrick

Also, I have green, black, white, and red circuit boards on projects, but no yellow to compare.  This needs to be fixed, as I am sure that it will be a revelation.
 
I don't see why anyone here should be criticized for anything, all things considered. I ordered parts from Chung because I couldn't find some things anywhere else; and certainly not for less.

More importantly  ;D  I was just checking voltages before attaching the capsule, and don't understand why the 60V that appears on one side of the 250M R14 resistor shows up only as 2.5 volts on the other end. Shouldn't it still read 60V even running through 250M of resistance?

I tried measuring through another resistor to eliminate the board, and the reading is the same. If the voltage is only 2.5V going to the backplate, how is the backplate getting 60V?
 
HHH said:
More importantly  ;D  I was just checking voltages before attaching the capsule, and don't understand why the 60V that appears on one side of the 250M R14 resistor shows up only as 2.5 volts on the other end. Shouldn't it still read 60V even running through 250M of resistance?

You can't read that high of an impedance with a normal DVM.  Remember that most DVM's 'look' to the circuit like 10M resistors (some cheaper ones look like 1M)...which means all other things being equal, a small bias current will be sampled from the circuit.  For a 10M meter measuring a 250M resistor connected to 60V, this would be (60V/250M+10M) = 0.23uA.  0.23uA draw through 250M will drop 57.7V, leaving about 2.5V to read on the meter. :) 

In short, you read "upstream" (or 'before') the resistance to read the real voltage, so the fact you are reading 60V tells you that you are good with those readings.  To measure at the capsule requires 1G+ impedances or other methods.
 
Banzai said:
Whether designers then take on the feedback received to improve their designs, or in contrast take on a defensive stance, that's their problem.

...there is a differentiation  between "feedback received to improve their designs" and blatant harassment, as has clearly been displayed thru GF's behavior here..


granger.frederic said:
you know what's sublime : my first name is in my pseudo and you can't spell it correctly...

Actually your's is the French derivation of the Germanic origin which is "Friduric":
http://www.behindthename.com/name/frederick
...so Tony's English form is no less valid then your own French "psueudo" avatar...and if your namesake happens to be this gentleman, then it is you who have spelled it incorrectly:
http://en.wikipedia.org/wiki/Frederick_G._Williams

...now please, back to those requested sound-files which are actually relevant to this thread's subject...
 
I was hoping the trollish behavior would cease, if you have something to add, I'd enjoy reading it.  However, using this thread to insult (The worst HiZ design...) pimp your own product, or just troll does seem to have annoyed more people than just myself.  It is the support thread to a listing in the white market.  They had to pay for that so let's move on and talk about the kit, building the kit, or troubleshooting the kit.  Thank you for your opinion about the build Frederic, but unless you have anything of merit to add, please quit with the childish behavior.  Thanks.
Patrick

 
Matador said:
HHH said:
More importantly  ;D  I was just checking voltages before attaching the capsule, and don't understand why the 60V that appears on one side of the 250M R14 resistor shows up only as 2.5 volts on the other end. Shouldn't it still read 60V even running through 250M of resistance?

You can't read that high of an impedance with a normal DVM.  Remember that most DVM's 'look' to the circuit like 10M resistors (some cheaper ones look like 1M)...which means all other things being equal, a small bias current will be sampled from the circuit.  For a 10M meter measuring a 250M resistor connected to 60V, this would be (60V/250M+10M) = 0.23uA.  0.23uA draw through 250M will drop 57.7V, leaving about 2.5V to read on the meter. :) 

In short, you read "upstream" (or 'before') the resistance to read the real voltage, so the fact you are reading 60V tells you that you are good with those readings.  To measure at the capsule requires 1G+ impedances or other methods.

Oh.

PS: The Mic is working in the C12 configuration. But I still have to reverse those PS's Pol wires to swap the Figure 8 and Omni switch markers. Thanks for all the help.
 
Back
Top