Official C12 Clone - Build and Support Thread

[jplebre]

Hey guys

I got a bit over-excited with the filing and I'm afraid I might have done some dudu. The cover for the traces is green, and so is other stuff like the cap boundaries etc.
I still have connection between R17 and plate, and P4 and R11, but there are other green traces around there that seem to be cut.

Is there anything else going right next to the cap (C12) box?

 

[Matador]

Hey guys

I got a bit over-excited with the filing and I'm afraid I might have done some dudu. The cover for the traces is green, and so is other stuff like the cap boundaries etc.
I still have connection between R17 and plate, and P4 and R11, but there are other green traces around there that seem to be cut.

Is there anything else going right next to the cap (C12) box?

There's nothing really near the C12 cutout.  Can you take some photo's of what you are referring to?  I can't make it out.

 

[jplebre]

Thanks for the reply. I've checked connections with continuity and all seems good just afraid I may have cut something that I'm missing.
You can see that on the bottom one I eat away a bit of the green line (solder mask? trace?) and on the top "cut" there's a glare of copper.

 

[Matador]

I see!  You should be fine.

Most of the cutout is surrounded by a ground pour, so that is the thin shiny line of copper that you see.  The green is the FR4 board material (the soldermask is the yellow part).  I don't see anything wrong there, just be sure of a few things:

1) There is no continuity between the P4 trace (the one that bends down on the top and goes alongside the cutout) and the ground pour (P6 node).  Based on the picture the space between them along the top looks clear but a whisker of copper will ruin your day.  Simple ohms check between the two points should read "infinite", or a continuity check should read "open" (or no sound if your meter uses a speaker)
2) Apply some nail polish (or clear lacquer) anywhere you see shiny copper exposed on the cutout:  the soldermask normally protects it from corrosion but now that it's exposed you'll want to reseal it

 

[ArnoldLayne]

Hello,
My mic has the same symptoms as Ericbazar had on page 20.
Apparently, he solved his problem by bridging FB and RB on his CT12, but I am using a RK-12, and had the same problem with the stock capsule.
Does it make sese to bridge FB and RB even though it's single backplate capsule ?

Also, I have found a continuity between xp2, P8 and ground on the mic PCB. I can't read the schematics, but surely this isn't normal ?

 

[jplebre]

Thanks Mat!
no continuity between P4 and ground! so all honky dory!

I keep telling myself I shouldn't put my favourite album of the month whilst I'm DIY, but I keep insisting on it. Then this happens! Too much headbanging  8)

So far, so good! PSU built in an hour and working fine (voltages read fine, HT takes a bit to ramp to 190v but other than that all good!

 

[chunger]

File only one side!!! . .  . the one without a critical trace. 

 

[zandru]

Greetings to all fellows Group Diy,

This particular C-12 clone build has kept me intrigued for quite some time.
I'm about to start this build. I've been a audio electronics designer & builder
beginning in the early 1970's, working closely will Tube mics, HiFi and pro
recording equipment since then. A professional spanning my earliest days.

I very much enjoy the follow-up after posts to chunger's easy to understand
and follow instructions.

It's also nice to read that Diy'ers have pointed out a some inconsistencies
and many questions of interest pertaining to this or that , and also making
suggestions.

I have a sizable hoard of original CK-12 capsules , mostly collected from
Noreclo, AKG C12A's-B's and some other later mics that used the CK-12.
I will not be using any one of these high quality CK-12's for this build.

My only true concern revolves around Tim Campbell's CT12 capsule,
"mystery / availably". I'm curious about Tim's manufacturing process etc!.

It would be interesting to find out that Tim edge-threads the secondary
backplate that threads into the primary backplate which is mounted into
the insulated backplate mounting ring ; just like the original CK-12 capsule.

I'm very familiar with the CK-12 capsule; based on my evolving experience,
when I dismantled my first of many which had been damaged in the early
1970's.  I was very curious to see, learn and understand the inner workings.

Soon after, I contacted AKG with the help of a dear old friend (Manfred
Krauter) who as a teenager working consecutive springs seasons at AKG
in the early 60's as an apprentice machinist which was part of his technical
school training. As It turned out, Manfred had contacts over at AKG.

I explained to Manfred what I hough I would need for an CK-12 Capsule
restoration.  So! Manfred wrote a letter to AKG and a week or so later,
Manfred received a call all from from an old friend from AKG, informing
him that for a nominal fee (shipping that is) he would mail out a Care
package.

Three weeks go by and the care package arrives at Manfred's place
As soon a as I open the way larger box than I had expected, I was totally
floored by the contents within the box.

The contents included:

Well over two dozen prepared diaphragms that were obviously tensioned
and mounted to a thin flat square frame that were individually enclosed in
protective container-like packet.

A spiral bound CK-12 assembly persons instruction binder

A diagram with instructions pertaining to the construction of a rather simple
to build multi-station assembly Jig for assembling the CK-12 capsule.

Now! The Mother Load, " I think my My Heart stopped for ten seconds.

Every Part; Yes! every part needed to assemble at least a dozen plus capsules.
Yah!  The brass mounting rings, Insulated mounting rings with primary & secondary
backplates, spacing rings, screws and whatever else that wonderful AKG friend of
Manfred had sent.

Of course this was to be a one shot deal at the time, which I'm very grateful for.
But enough about me.

I do feel that there's somewhat of a concern over tim Campbell's CT12, to which
I have mentioned the capsule being shrouded in mystery. His webpage lacking
in info, No detailed specs etc!.  About the only thing I know is the capsule costs
2,000 Kroner or $365 U.S. Also it's said that Tim uses a CNC to mill some of the
components; for that to me still puts the price into question. There are questions
that I would most like to Know. How about you?. So! please chime in to help
advance this thread.

CHEERS…ZANDRU...

 

[Tim Campbell]

Zandru,
I have no idea what you are implying by your first ever post on this forum. I have been a member of this group for more than 10 yrs. Many of the members here know me personally. I don't post using an alias and all my personal information is easily accessible. If you search this forum you'll find many contributions from me about all aspects of capsule manufacture going back 10 years.
I first offered my CT12 capsule for sale here more than 6 years ago. Probably close to 2000 of my capsules are in use out in the world at large.
This is a build thread for Chunger's mic not a capsule thread and so I'm not sure how hijacking this thread to discuss me or inconsequential details of my capsules serves that end especially given the current limited availability of my capsule for this project. Your time might be better served investigating a capsule you could actually use in this build since my OEM customers currently consume almost all of my output leaving very few of my capsules for sale to private customers.
Ultimately if you have any doubts about my capsules please buy someone elses or use one of your original AKG's.
Currently Josephson, MBHO, Korby, Beyerdynamic, Lawson, Telefunken, Beesneez, Tskguy and even AKG manufacture versions of this capsule that are readily available for sale and can be used in this build.

 

[Phrazemaster]

I'm not sure that requiring a manufacturer to divulge all the details of their manufacturing process is fair. The art of capsule creation is indeed one "shrouded in mystery" and very few capsule makers share their secrets. It is a business, after all. I very much doubt if Stradivarius went around telling everyone what varnish he used or how he created his signature sound.

For example, if you visit Neumann's own site, you'll find that although they do devote a page to a general description of their capsule making process - http://www.neumann.com/?lang=en&id=about_us_history_part_7, they in fact do not discuss intimate details such as hole placement, patterning, how to machine the backplates, etc. Nor would one expect them to.

In addition, Tim never claimed to create "original C12 capsules" - how could he? He is not AKG. It is always clear from the beginning that, as close to the originals as they may be,  these are "clones" or "recreations" or "C12-like." And judging by the number of high-end customers he has, they are particularly excellent. As DIY guys/gals we have to recognize the limitations of the forms we are creating. Some parts are just not available, or are simply out of reach. Like a VF14 tube for a U47 clone - or an actual C12 capsule for a C12 clone. But that's the fun of it all, DIY - not buying original everything and sticking it together. For that, we could all just save up and buy an original. There's something thrilling about creating something ourselves that makes it all worthwhile, and the fact that our microphones are not the "actual" microphone we are cloning is obvious from the get-go.

I must agree with Tim, Zandru, the post sounds inflammatory. If you are sharing because you want to sell your hoard, please post in the black market. But singling out Tim seems wrong. I did not hear you denigrating any of the other C12 capsule manufacturers in Tim's list, who most likely have left the details of their capsules "shrouded in mystery" too, and if you visit their website the best you will come up with is their capsules are "faithful recreations" and not much else in the way of technical details.

Having said all that, it's great you have a hoard of C12 capsules. But nobody ever expects a recreated capsule to be micron-perfect to the originals. This is, after all, DIY.

Thanks, Tim, for making your capsules available to this DIY community. I understand you are so swamped you have a 10-week wait time. This only speaks to the quality of your work. Thank-you.

Cheers,

Mike

 

[zandru]

chunger… If You please,  I hope It's ok by you…fellow Group Diy'er & cohort may need relief from emotional distraught…
I'm not trying to step on your toes…

Tim,

It seems that you have no Idea what I'm implying on my first ever post on this forum. You have gone to some length referencing yourself (which is most applicable).
However my post deals with a fervent interest in building the C-12 clone in which I came to embrace chunger's easy to understand assembly instructions that has
caused me to proceed with the project. My post is in no way an attempt to (as you claim) Hijack chunger's thread".

Tim, You and your CT12 are by no means inconsequential within chunger's "official C12 Clone-Build and Support Thread". The CT12 is in fact of considerable
relevance and if you sense that you were disrespected in any way by me , you have been mistaken. I myself have also referenced myself to some length in my
first post but certainly not as a ploy to sell anything as referred to by you; and definitely did not attempt to draw any attention away from any possible revenue
that might blow your way from this thread.

chunger, I admire your build, assembly explination, simplicity and that Tim Campbell's CT12 custom designed & practically hand built capsule was your chose for the build.
This is why I would like to know more about the CT12…. Cheers  to all…  (My so-called alias) …Zandru… I will post My profile ASAP…For those persons who demand
transparency and full dislcosure...

 

[Tim Campbell]

Zandru,
I made no reference to you selling anything. You're mixing me up with Phrazemaster.
My capsule is in very short supply and so no longer the primary one for this build. I believe it's unlikely that my CT12 will be the capsule you use in your construction. There are at least 10 or 12 other capsules that would work well in this mic but their mechanical construction has nothing directly to do with assembling this kit. A discussion of capsule construction would indeed hijack this thread from the intended purpose of helping DIYers assemble this mic.

"I do feel that there's somewhat of a concern over tim Campbell's CT12, to which
I have mentioned the capsule being shrouded in mystery. His webpage lacking
in info, No detailed specs etc!.  About the only thing I know is the capsule costs
2,000 Kroner or $365 U.S. Also it's said that Tim uses a CNC to mill some of the
components; for that to me still puts the price into question."

Why would you feel concern over this? What could you question about the price?
Ben Sneesby's capsule currently costs $370 US, Tskyguy plans on selling his at $350 US , MBHO's capsule is only slightly more expensive, AKG's current capsule is just over $200,
Telefunken and Josephson's capsule cost about $1500 US. I have no idea about prices for the other manufacturers. Only Telefunken of all these manufacturers post any details about their capsule construction. This doesn't seemed to have caused much concern to their many users.

On a lighter note you wrote," There are questions
that I would most like to Know. " believe me I'm a guy who knows a lot of questions.

Welcome to the forum and good luck with your build.

 

[Pip]

Do it yourself!

 

[jplebre]

@Tim, sent you an email, but I'm guessing you are not doing one off capsules for forum members anymore?

 

[ArnoldLayne]

Hi Matador,
I'm still having problems with my mic.. I fixed the polarity issues by bridging FB and FC, but I noticed some pops and sometimes loud, windy sounds.
I thoroughly scrubbed the area on the PCB around the teflon standoffs (will take some pictures tomorrow).  Should I clip off the extra leads ?

There is also a big hum which goes away once I put the mic inside its metal tube.

 

[chunger]

Hi zandru,

I am a bit perplexed at the reason for your original post.  I am quite glad you have a stash of original akg c12 capsules and variouas parts and internal assembly procedure documents.  If you are interested in helping to refine the available capsules for this build, please feel free to either post knowledge and documentation on forum or forward the info along to any number of capsule builders here to help refine their clone capsule specs.  That should alleviate some of the mystery you seem concerned about.

As for Tim's capsules, he is a long-standing contributor to the diy community and the construction, consistency, and sonic performance of his capsules speak for themselves.  Top tier is the only possible conclusion in all regards.

I do hope that his efforts to scale up production are successful and these can once again be readily available for diy.

if you are interested in loaning original capsule parts to me I would be happy to generate photos and precise drawings of all critical dimensions so the general knowledge base can be broadened.

 

[Matador]

Hi Matador,
I'm still having problems with my mic.. I fixed the polarity issues by bridging FB and FC, but I noticed some pops and sometimes loud, windy sounds.
I thoroughly scrubbed the area on the PCB around the teflon standoffs (will take some pictures tomorrow).  Should I clip off the extra leads ?

There is also a big hum which goes away once I put the mic inside its metal tube.

The hum is expected.  The outer tube shields everything inside.

Pops sound like caps leaking DC.  I would try to lift out one side of both C10 and C11 (both are filters so the mike will work without them, albeit at perhaps some higher hum) to see if it changes/goes away.

Board leakage from solder flux sounds like sizzling to my ears.

 

[Spencerleehorton]

HI Guys,

my C12 sounds great just wanted to adjust it a little as its a tad thin on the bottom end, or rather a little bright on the top.
where should i implement changes in the circuit to adjust this?
Im using a RK-12 from microphone parts as the capsule and a Sowter 9610 transformer.

regards

Spence.

 

[jplebre]

the original C12's I used do feel rather airy and bright on the top end. Not overly, just nice - like icing on a cake.
(oh dear! the lingo I'm adopting these days).

They did not have the mid range energy and body as some neumanns.

does it feel like it's excessively unbalanced? I don't know the capsule.
Which cap did you use?

 

[ArnoldLayne]

Pops sound like caps leaking DC.  I would try to lift out one side of both C10 and C11 (both are filters so the mike will work without them, albeit at perhaps some higher hum) to see if it changes/goes away.

Bingo ! Pops and "windy" noises are now gone. S/N seems lower now, but I guess this is expected.
So, should I replace C10 and C11 ? If so, will 160V/4700pF styros work instead ?

Thanks a lot for your help