Official C12 Clone - Build and Support Thread

[Tim Campbell]

Perhaps Oliver Archut wasn't clear when he told me that their capsule was made by Feilo. I know some of the engineers at Gefell who worked with them.

Pricewise , I meant that someone here would pay (not wholesale prices that someone buying 1 capsule wouldn't receive) 145 dollars more than my capsule would cost them ( the 251 is 500 dollars, my capsule is 355). These capsules are not chambered but simply  edge terminated, K67 backplates with membranes. Building a CK12 is much more labor intensive, that's why T-USA and Josephson charge 1500 dollars for their CK12's.

I am sure these capsules sound terrific, maybe as good as mine and I would encourage anyone to buy them.

As far as the sound of my capsule, Bill Schnee and Toby Foster after a long comparison between their C12's and a pair of FLEA F12's with my capsules concluded I currently make the best CK12 capsule in the world (Toby Foster worked with T-USA developing theirs).

 

[strangeandbouncy]

Guys and Gals,



  It's really very simple. If you want a Capsule that sounds as close as is humanly possible to the original CK12 from AKG, buy a Campbell Transmitter Capsule for a ridiculously small amount of money. I mean ridiculously cheap. They are hand made and tuned by Tim HIMSELF. Personally, I have heard a wide variation of CK12s in different mics (ELAM251, AKG C12, AKG C24, AKG 412, AKG C12a, AKG414eb(?), and they vary greatly in my experience. Tim can make them all the same, or Tim can even match his to an existing capsule! His capsule is "the same" in my book!

  Don't f@@k around with Chinese so-called CK12 capsules. Apart form the fact that they are capsules, they have very little in common with the real deal. I am sure that some of them do sound fairly good, but they are NOT the same thing, and they are made on an assembly line by assembly line workers. Tim is not an assembly line, rather a very skilled and dedicated sound engineer who has been using these puppies all his working life. HE MAKES THEM HIMSELF.


  If you have to wait for one. Wait. It is well and truly worth the wait.


  AndyP



ps I am in no way affiliated with Tim. I do, however, use a home-brewed C12-ish mic on a daily basis. It makes me very very happy. Oh, and my clients!

pps - did I say "HE MAKES THEM HIMSELF"? - perhaps I should repeat myself again . . . .

 

[Matador]

I didn't get a lot of time with the prototype with Tim's CT12, but from what I could tell it sounded fantastic.

What I've noticed with the edge-terminate 67 type capsules:  they really need the electronic de-emphasis to sound natural and balanced.  The edge termination doesn't really change this character:  I assume it must be related to the backplate drilling, diaphragm tension, etc (I'm no expert by any means).

The C12 circuit is, for all intents and purposes, "full range", meaning the gain doesn't start dropping off until the output transformer inductance starts to dominate the frequency response.  I think this happens out past 40K, so for audio the circuit is essentially "flat" (I'm hand waving here, but it illustrates my point nonetheless) in the audio regions of interest.

For those trying these capsules, the ELA 251 plate cap is a good band-aid for taming this peaking response:  values in the 470pF to 1,000pF range are a good starting point. 

Tim's capsule sounds perfect without this cap, but you can dial in a very usable sound with this cap.

 

[KMB-AUDIO]

It's really very simple. If you want a Capsule that sounds as close as is humanly possible to the original CK12 from AKG, buy a Campbell Transmitter Capsule for a ridiculously small amount of money. I mean ridiculously cheap. They are hand made and tuned by Tim HIMSELF.

<snip>
pps - did I say "HE MAKES THEM HIMSELF"? - perhaps I should repeat myself again . . . .

I have heard nothing but the highest praises for his capsule, that's why I don't mind waiting! I hope nobody is giving Tim a hard time about his lead time.  You gotta wait for quality!

When I first started looking into buying a capsule from Tim, I had no idea on the price and figured I was going to have to pay double what he is asking for his.  I was pleasantly surprised to find out that they were only 355 for a hand-made, hand-tuned capsule that is the real deal.

I never intended to keep the RK12 in the mics at all, they were bought so I could get the mic built and functioning until the CT12s arrived.  I have a couple other mics that I want to put the RK12 into to to see how they sound in other circuity.  Who knows, I may just build two more "C12s" with these caps.

 

[Ericbazaar]

Hi Matador,

i will replace R1 and R2 for the 6201 Tube.

These tubes are higher mu so a few circuit tweaks will be in order:  mostly lowering R17 down to make the gain about the same as compared to a 12AY7/6072A.

Can you be more specific. R17 can remain in the circuit, or should another resistor to be installed? Which values has the new resistor?
Or better asked, it is better to replace the Electro Harmonix 6072a Tube against a GE Five Star 6201? Is there a sonic advantage?

Thanks

 

[Matador]

I think R17 should be lowered to about 47K.  With -1V bias, idle current looks to be about 1.25mA with a 6201.  R1 and R2 being 100K should still be fine and give adjustment room around the 120V point.  Plate should be sitting at about 60V at idle (same as 6072).

I'm not sure about how the sonics will be different:  the main reason to switch to a 6201 is availability of high quality tubes at this date.  The 6201 has more robust internal construction than the 6072, so it might be quieter (all other things being equal).  With a lower R17, output impedance will be lowered which should make the amp slightly "faster" (for lack of a better term).

I have some parts in transit to me and I'll build a version with this tube.  I'll post my exact tweaks if you don't want to experiment (or be a guinea pig) in this case.

 

[kidvybes]

Perhaps Oliver Archut wasn't clear when he told me that their capsule was made by Feilo. I know some of the engineers at Gefell who worked with them.

...if Oliver says so then the information I received may have been more recently revised...I previously demo'ed serial #10 of the UM17 in August 2011, while the UM25 production was still being finalized, and was informed by my contact at Blackspade in Switzerland that their capsule source was indeed ShuaiYin...(I just reviewed the original correspondence and it clearly states ShuaiuYin was the source for both the original K17 and CK25 capsules)...

...I acquired my GK12d capsule as part of a gear trade, as it was originally intended to be used as an upgrade on a Avantone CV12 by the original owner...if I intended to spend anywhere near the cost of this capsule, I too would opt for your capsule...I only offered up the info as another option...

...my comments were in no way meant to imply that the ADK capsule is a true C12 reproduction, they are clearly an "interpretation" based on K67 backplates...while not an accurate C12 reproduction, I do believe it is a high-quality capsule...no one, certainly not I, questions the integrity of your CT12 capsule...the mic I am currently testing is being evaluated purely based on it's performance and usefulness as a vocal microphone for a particular artist, not it's accuracy as a "C12 clone"...

 

[hyde maintenance]

I'm going to be doing some testing and can post the results if desired.

Desired.

Considering I too haven't heard back on the CT12 I'm trying to order, I'm very interested in hearing those comparisons as well.
I'm thinking about using the double layer headbasket for a variety of reasons, so I wonder if I'd be compromising a few of the reputed strengths of the CT12 anyhow?

Out of curiosity, what are those reasons?

Nothing too mind blowing unfortunately. Basically I'd like to play around with a few variables (including tube type, transformer and output cap) to see if anything strikes my fancy. Also on the practical side, I'd like a bit more capsule protection from dust, spit etc than I would get over the single layer basket.
And if I don't like it I can always pull the thin mesh out.

Glad to hear all is well with Tim Campbell, and hope to hear back from him soon.

 

[gary o]

Well its nice to have more and more capsules for DIY clones or otherwise, the big problem is unless you buy them all to try you just dont know which is best for you & you end up reading other users discriptions of the sound they hear, not good

On a technical note I have been wondering how K67capsules are made to sound like other capsules  ....  the ADK for instance, Blue seem to make capsules that sell for a lot of money like this, I myself have a Violet VD67 capsule £500 K67 style meant to sound like the U67 mic its sound good but wouldnt know what real U67 sounds like tho.... but have been wondering how they tune these & can we tune cheap K67 capsule to sound better...... for what its worth I love the sound of my VD67 but also love sound of Tims capsule tho again I dont have a real C12 to compare but I do think Tims its great value..... also for what its worth I have ADK cheap Vienna thats meant to sound like a C12 & it doesnt sound bad at all......

All the best

 

[chunger]

Nothing too mind blowing unfortunately. Basically I'd like to play around with a few variables (including tube type, transformer and output cap) to see if anything strikes my fancy. Also on the practical side, I'd like a bit more capsule protection from dust, spit etc than I would get over the single layer basket.
And if I don't like it I can always pull the thin mesh out.

Glad to hear all is well with Tim Campbell, and hope to hear back from him soon.

The single layer headbasket looks sexy and shows off the capsule, but I have in mind to put the dual layer headbasket on and try.  If the dual layer influences the sonics in a positive way or I'm neutral as to which one I like better, I will keep the 2 layer on there for the added protection.  Plus, I'm hoping these headbaskets are at a price-point where people can use it as another sonic variable to try quickly.

As I understand, it is very hard to predict what changes in the meshing will do to the sound without just throwing different configurations on the mic and trying them out.  There are a lot of complex acoustic interactions that happen in that small space.  With the new shipment of microphones, I'm happy to be able to offer a few different meshing options to try.

 

[JessJackson]

Thanks Tim, yeah your right its been about 5 weeks, felt like longer lol

since the topic went in that direction i'll say that I have a re skinned vintage ck12 by tele usa capsule in my vintage c12 and i'm not overly impressed with the re-skin job... not smooth on the top.

Best,

J

 

[Ericbazaar]

For those trying these capsules, the ELA 251 plate cap is a good band-aid for taming this peaking response:  values in the 470pF to 1,000pF range are a good starting point. 

Hi Again,

I have a question regarding the exchange of the capacitors. It interests me very much, I want to keep my options open, adjust the microphone from the sound. Are you talking about the replacement of the capacitors C10 and C11? Here in Germany, there are NOS 1nF 630V Polystyrene capacitors of "East German RFT", or Sovcor pure glass capacitor 1nF 300V. I have also discovered Output MCAP condensators of German "Mundorf". I would like to experiment a little! I know it is a C12 clone, but I want a great sounding tube microphone, if it sounds like an original C12 is not important to me.

 

[Gilgamesh]

I added in the plate cap to a 460 mod and it definitely gave a darker more vintage tone but seemed to rob the mic of some of its class as well. I'm planning on gutting it and doing a 251 proper when that kit becomes available.

I used a 220pf cap, I thought the cap in the original 251s varied a bit but was generally between 100pf - 300pf??

 

[gary o]

Gilgamesh do you mean cap between plate & ground on 1961 schematic for ELA251 its a 100pf.......
did I read the ELA was a redesigned C12 for broadcast use kind of nobbling the C12 by rolling off bass b& top ...... 

Im currently experimenting with several tube mics to learn & to decide which to build to use for vocals so far I tried ELA250 with 6072 & 5840, Mk47,M49C (5840) MGM Church mic, & a TB1 (like a ELA C12 crossbread i guess) I hated the sound of the ELA compared to others I guess now it was the low 30M grid resistor which I guess make sense if not meant for recording vocals....

Im gonna have play with this here C12 circuit

 

[Category 5]

Any restrictions on what type of solder to use on this?  I normally use 63/37 but got some lead free solder I'm itching to try too.  Also, is the included 7 pin cable good enough or is that something that should be replaced?

Finally, I plan to test with an JAN AT7 and the stock Alctron capsule.  Is this good enough to trim the voltages, etc?  I wouldn't even think about starting out with Tim's capsule.  Also, since there is a big lead time on Tim's Capsules I think I will use the microphone-parts K12.  Anyone else have experience with this capsule?

BTW  extra thanks to Matador and Chunger who put together a project here that borders on legendary.  The boards look just incredible populated.  it's almost a shame to cover them up!

 

[mwrichardson]

Hi Chunger

I sent you an email directly to your store asking to reserve or pre pay an order of four of the 251 dual mesh head baskets. Did you get that? Do I need to order here? I would be happy to pay the extra to be on the advanced air shipment order.

I also sent Tim Campbell an email ordering 2 capsules. No reply yet. I know I have to get on a waiting list. Tim, if you see this please add me to the order list. I know you get alot of emails and I do not want to add to that.

Thanks guys

Mark Richardson

 

[Matador]

Any restrictions on what type of solder to use on this?  I normally use 63/37 but got some lead free solder I'm itching to try too.  Also, is the included 7 pin cable good enough or is that something that should be replaced?

Finally, I plan to test with an JAN AT7 and the stock Alctron capsule.  Is this good enough to trim the voltages, etc?  I wouldn't even think about starting out with Tim's capsule.  Also, since there is a big lead time on Tim's Capsules I think I will use the microphone-parts K12.  Anyone else have experience with this capsule?

BTW  extra thanks to Matador and Chunger who put together a project here that borders on legendary.  The boards look just incredible populated.  it's almost a shame to cover them up!

Any solder is fine, so long as you have the tools to deal with it.  The electrons won't care!  8)

The 12AT7 pulls more current than the 6072A, but it should still trim out fine.  Is that the tube type you'll stick with?

 

[KMB-AUDIO]

Any restrictions on what type of solder to use on this?  I normally use 63/37 but got some lead free solder I'm itching to try too. 

Before you use that lead free, try it out on something other than your mic first.  It has a different "feel" when soldering that I am not used to yet.  I still have spools of 63/37 to use up though

 

[Category 5]

Any restrictions on what type of solder to use on this?  I normally use 63/37 but got some lead free solder I'm itching to try too.  Also, is the included 7 pin cable good enough or is that something that should be replaced?

Finally, I plan to test with an JAN AT7 and the stock Alctron capsule.  Is this good enough to trim the voltages, etc?  I wouldn't even think about starting out with Tim's capsule.  Also, since there is a big lead time on Tim's Capsules I think I will use the microphone-parts K12.  Anyone else have experience with this capsule?

BTW  extra thanks to Matador and Chunger who put together a project here that borders on legendary.  The boards look just incredible populated.  it's almost a shame to cover them up!

Any solder is fine, so long as you have the tools to deal with it.  The electrons won't care!  8)

The 12AT7 pulls more current than the 6072A, but it should still trim out fine.  Is that the tube type you'll stick with?

No.  I will settle with the recommended GE 6072A.  I want to get as close to original as possible.

Gonna use 63/37 then.  It melts like butter and cools like polished silver.  Scared to go lead free just yet because I just know I'm gonna overheat components getting used to it.

 

[Pip]

Any restrictions on what type of solder to use on this?  I normally use 63/37 but got some lead free solder I'm itching to try too.  Also, is the included 7 pin cable good enough or is that something that should be replaced?

Finally, I plan to test with an JAN AT7 and the stock Alctron capsule.  Is this good enough to trim the voltages, etc?  I wouldn't even think about starting out with Tim's capsule.  Also, since there is a big lead time on Tim's Capsules I think I will use the microphone-parts K12.  Anyone else have experience with this capsule?

BTW  extra thanks to Matador and Chunger who put together a project here that borders on legendary.  The boards look just incredible populated.  it's almost a shame to cover them up!

I use 4% silver solder. A specific brand but do a search their out there. Not because of the sound characteristics or anything so readily debatable (so please don't not here anyway). It is because silver oxide (AgO not Ag2O) conducts as well as silver. Nothing more nothing less.