[FEELER] C12 Clone Project

[micaddict]

It's the year of the MIC.

Funny, I was thinking the same thing.

Oh, did I say I'm in?

 

[funkymonksf]

I've been dying for someone to do this!!' I'm totally in!

 

[Rob Flinn]

Can you post some dimensions for the pcb's that are fitting in the mic.  i.e what diameter body will they fit into ?  WOuld it fir into something 38mm in diameter ?

 

[Matador]

Can you post some dimensions for the pcb's that are fitting in the mic.  i.e what diameter body will they fit into ?  WOuld it fir into something 38mm in diameter ?

Does this help?

 

[dissonantstring]

interested and voted.  thank you matador and chunger!

 

[Matador]

Small update:  the PCB panel has been submitted and I should have the prototype panels in my hands late next week.

I also put in my parts orders:  one with TubeDepot for the PCB mount sockets (and a few extra 6072A tubes), one with JustRadio's for the output caps and styrene caps used in the mike (the 1000pF capsule coupling cap and 5000pF used in the polarization filter).  I ordered an assortment of output caps ranging from 0.47uF to 2uF, in polypropylene, polyester, and other formulations.  This cap is a standard place for experimentation so I got a few sizes/types to try.

Here is the preliminary Mouser BOM that I based my order from.  This list doesn't yet include C12 as I don't have a recommendation for it yet.

I will also see if I can get my hands on some AMI T14 transformers so we can compare against the Cinemags.

 

[Biasrocks]

For a CK12 capsule, I would recommend Tim Campbells. Not the cheapest but barring an original CK12 it's by far the best sounding option.

http://www.timcampbell.dk/index2b.htm

Mark

 

[ilmarik]

Year of the Mic! Have to make some money..

BTW, I think resistors R7&R8 are bit too high.

 

[Matador]

Year of the Mic! Have to make some money..

BTW, I think resistors R7&R8 are bit too high.

Yes that was an incorrect cut and paste:  corrected and thanks for pointing it out. 

I think they will end up more in the 1-3 ohm range.

And yes, the Tim Campbell C12 will be the preferred choice, and we will also try some other less expensive choices as well.

 

[usekgb]

Ic old definitely use a pair of pcb's and bodies.

 

[chunger]

Hey. . . had DIY on the brain today and have been making a little bit of headway on the modified HT-11A headbasket design.  I was also lucky that AES is in town this weekend, so I had a chance to speak with Oliver Archut from Tab Funkenwerk at length regarding T-14 transformers and he is amicable to sourcing these to me for this project.  He suggested 3 variants of his T-14 for me to try and gave some insight into optimizing to Tim Campbell's CT12 capsule.

Oliver knows this capsule well and recommends a custom winding on the T-14 to optimize for the bass and treble footprint of Tim's CT12.  I need to have a conversation with Tim at some point in the near future to see if he is willing to source capsules at quantity appropriate to the interest here.

At this point, I'm thinking to go qty. 20 on transformers and qty. 10 on capsules judging from the interest on the poll.  We should have a test microphone up and running within the next 2 weeks to test in studio and tweak on the circuit.

 

[Jim50hertz]

I'm in for two.  I have tnc 1200s already so don't need bodies but am interested in an improved headbasket.  If you can get quantity pricing for Tim's capsules and Oliver's optimised T14 variant that would be fantastic!

 

[chunger]

I'm in for two.  I have tnc 1200s already so don't need bodies but am interested in an improved headbasket.  If you can get quantity pricing for Tim's capsules and Oliver's optimised T14 variant that would be fantastic!

I don't suspect I will be able to get any better pricing on Tim Campbell's capsules.  He has an 8 week backlog last I spoke to him and I don't particularly get the sense he wants to scale up production on a device this time-consuming to build and sensitive to the minutest of details.  Plus, the price he charges for the quality of the product is extremely reasonable.  What i can do is see if I can get hands on 10 pieces so they can be bundled together with the rest of the kit.  This will likely just simplify the purchasing and logistics for everyone including Tim, but not gain much other advantage.

But, you never know.

 

[tonycamp]

Hey Chunger, JMO but, i would consider leaving sourcing the capsule to the project builders. You're probably opening yourself up to potential pandoras box of liability issues on a costly little piece. There are tons of options on the capsule, and everyone here knows of them. No reason for a middle man here, yours and matadors bringing this project to us is more than appreciated and will be in high demand. No need to employ the "no good deed goes unpunished" rule

Again JMO
thanx for all your work in the DIY community, I very much appreciate it

Tony

 

[3nity]

This sounds like the perfect mic project for me.
Already have the 460 mic....just need pcb and tube...
Thanks

 

[bkbirge]

I'd be in for a pair of kitchen sink bundles or whatever bundle has the most parts I don't have to source elsewhere, except the capsule.

 

[desol]

Might be interested in one turnkey pack depending how pricing turns out. I like that you are collaborating with Oliver on specific 'optimizing' of the transformer for the capsule. He knows his stuff. What tube is being used for this?

 

[Enchilada]

Might be interested in one turnkey pack depending how pricing turns out. I like that you are collaborating with Oliver on specific 'optimizing' of the transformer for the capsule. He knows his stuff. What tube is being used for this?

Being a C12 clone one would assume a 6072a.

 

[desol]

Ah...for some reason i was assuming it was some long extinct, ridiculously expensive rare glass thingy. I suppose not!

 

[chunger]

Ah...for some reason i was assuming it was some long extinct, ridiculously expensive rare glass thingy. I suppose not!

What tube is being used for this?

It is not a long extinct ridiculously expensive glassy thing just yet, but it is headed that direction.  I'm sourcing NOS GE6072a tubes from Christian Whitmore and they are not cheap, but it is highly unwise to buy this tube now on Ebay or from untrusted sources.  The current supplies are VERY picked over and quiet, non-microphonic copies are less than 1 out of 10 from batches that has not been previously rejected.  He tests on the best quality modern test equipment, burns the tubes in for 100 hours to ensure stability and listens to each mic-bound tube to make sure it sounds right.

Matador has purchased some new production Electro Harmonix tubes, and I'm also testing NOS Siemens and Mullard 12AT7 tubes also selected and tested by Christian Whitmore.  These are sonically a little different from the GE, but also popular for the C12 mic.  We're going to test and optimize to the capsule so various electronic component specs as well as tube choices will be tested in studio and tweaked on.

It's my aim to have the turn-key package be pretty uncompromising in terms of component choice, so it will be whatever solution sounds the best to the testers (opinions vary).  In the likely case that we arrive at multiple highest-quality configurations, we'll be able to make a few choices based on cost, but if the most-expensive option ends up rising above the other options sonically, I want to offer "best-of-breed" configuration.

Lower-cost solutions I'm sure can be put together by partial package or bare PCB purchase options.