Official C12 Clone - Build and Support Thread

[chunger]

Re-read the build documentation at the beginning of this thread.  The BOM changes are explained there in detail.

Could someone please help me out; maybe Chunger, Matador or Dave.

I just received (2) C12 part kits from Chung {also with 251 options]; and have boards from Dave. But I don't seem to have several of the PS resistors that I see listed in the Official C12 BOM and, instead, have other odd value resistors; and instead of (4) 100uf caps there are (2) 100uf and (2) 47uf caps.

Is it possible that I'm looking at some early replaced version of the PS? I don't think I am because the parts in the BOM seem to match the parts in the schematics.

I don't have:
R1,R2 = 90.9k
R6 = 470k
R9 - 392 ohm
R10 = 1k

instead I have [and I do not think these are the microphone parts as they are in separate bags]:
Some of these values may be from meter readings and not necessarily the color codes.
(2) 400k
(2) 33k
(2) 68k
(2) 220 ohm
(1) 499k

Otherwise I have the (2) 1meg and the 4.7 ohm resistors.

I noticed that Dave's PCB uses 75k for R1,R2 where Matador's has 90.1k
And Dave's R4 uses a 250k trim after that, whereas Matador's uses a 100k.
I didn't look any further for any other differences because the other parts I first listed seem way off from what they should be.

Am I somehow making a mistake.

 

[HHH]

Re-read the build documentation at the beginning of this thread.  The BOM changes are explained there in detail.

That was easy enough. Thanks.

 

[granger.frederic]

the biggest issue IS the PCB...

it's time to explain with simple words...

the HiZ section is PCB mounted in this case , and if you look carefully in CANTILEVER.

when you put a mic in front of a loud source, like a human voice or a fender amp .... the pcb in the HiZ VIBRATES and generates a huge distortion and sound coloration.

in a mic, only a slight vibration in the HiZ section  produces a massive parasitic sound , that's why all the high end classics mics are  designed  to  reduce internal resonances, and without PCB in the HiZ section (See U87, U67, U47,ELAM, C12...........)

It's a little better if the PCB is thick , heavy , firmly screwed or damped... and varnished (for moisture long term contamination)

It's too bad to use some marvelous capsules like Tim Cambell or Eric's ones, with such a design

Teflon pins are an improvement but  it's not enough.The only solution is to redesign the Hiz section...

The LowZ section can be PCB mounted however.

building high end mics is ART and LUTHERIE.

i hope it will help...
Cheers

 

[Patrick from Davis]

You say the only solution is to redesign the Hi Z section, but can you tell me what data you have that supports this with respect to this mic?  It seems that two builds are required and then frequency sweeps to see the differences.  Before we start arguing something that theoretically is possible, but may be practically insignificant, shouldn't we check?  At least before a complete redesign?  Without data to support these assertions about this build, I have a difficult time making definitive statements about it without having some questions to their validity.  Going so far as to say the only solution is a complete redesign seems a bit overly dramatic to me.

The other issue is, now, in order to squash this, Matador and Chunger would have to spend a day setting up, measuring, analyzing, and presenting their findings.  That seems like a lot of time if it turns out to be practically insignificant.
Patrick

 

[Category 5]

Frederic, from a spectator's point of view here it's hard to believe you're just trying to be helpful (I may be wrong). I can understand your concern over moisture where PCB and hi-impedance mix but I am satisfied that has been pretty much addressed here.  It's a bummer to have to clean the boards so well, but after doing that, careful storage is all that's required to enjoy these mics for a long time. 

Now you are talking about parasitic resonance of the pcb.  If that's really a problem you're concerned about then the design of the donor mics should be an even more significant one.  Not to stop there, the capsule mount is probably an issue here too.  Then again, in such case an inexpensive shock mount and mic stand might cause a significant resonance too.

Not trying to be a pest if you're intentions are genuinely to help here, but these mics have proven themselves in real world situations already, and the improvements in the revision will translate into even better long term reliability. 

There are other options like point-to-point which will satisfy your desire to float everything like the originals.  So far nobody has provided any quantative evidence that there is a benefit that outweighs the ease of assembly Matador and Chunger are obviously attempting to preserve here.

It's great to have passionate enthusiasts here.  It's what makes GDIY legendary, but at some point it ceases to be helpful and comes across as a battle of who knows more.  Let's see how the new revision performs, and we can all offer our opinions about how future revisions could be better, without simply saying "you need to start over dude".

 

[Matador]

Thanks Cat 5, that is far more diplomatic than I could have managed.  ;D

Discussing PCB component resonance in a tube mike is quite interesting:  like debating the change in gas mileage on a vehicle traveling down the freeway with a bug on the windshield, which is disturbing the airflow over the car....

Hard ground the grid on this design with a jumper wire.  All HIZ portions of the circuit/capsule are completely bypassed, and will not play any part whatsoever in the sound coming out.  Now plug it in, and rap on the side of the mike body with your knuckles.  You will hear a loud thump.  In fact, this is my preferred microphonics test that can be done in circuit!  Fact is, the tube elements will impart far more resonance to the output that inch-long components hard mounted to a PCB assembly, because their combined mass is far less.  I can shift components around all day long and never change this.  Every tube mike will do this, even the originals.

So to make a long story slightly shorter:  I remain unconvinced this is even an issue in practice.  I think it's fine to drive down the freeway with the bug on the windshield, even if it reduces my gas mileage by 10-9%.

 

[granger.frederic]

don't be so nervous guys

i just say that there's room for significant improvements

i need you to realize how it has been probably hard for techs like tim campbell to achieve a near perfect clone of the CK12.

it's  just too bad to put a high end capsule in a  standard chinese mic body and with a cantilevered HiZ PCB

if the goal is to clone the performances of a real C12, i think it's a little bit more complicated ( and luckily...)

look again at all the high end classic mics , and you'll see that the HiZ sections are very carefully designed

If the goal is to make low cost mics , then i suggest you to mount low cost capsules like microphone parts...

you won't put a V12 in a soapbox ...

 

[kidvybes]

...I'm sorry, maybe I'm missing something...where can I purchase one of Mr. Granger's DIY mic kits?...anyone?

 

[granger.frederic]

with pleasure !

if you want one PM me!

(but the price is higher as i I manufacture with the account drips)

 

[kidvybes]

with pleasure !

if you want one PM me!

...I'm interested in DIY (this is a DIY forum I believe)...feel free to PM me with the cost of your complete kit (with a list of the components included), the available body styles, capsules, tubes, transformers, shockmount, etc...or you can provide the link to your web-store...and also please provide the link for the your build thread as well...thanks in advance!

 

[granger.frederic]

i only build finalized mics (i can send you pictures with pleasure) but if you want to DIY then you'd better go to : http://groupdiy.com/index.php?topic=59010.0

(a guy who has understood what i mean)

you can use also a FLEA body (excellent stuff, i personally use it)

 

[kidvybes]

if you want to DIY then you'd better go to : http://groupdiy.com/index.php?topic=59010.0

(a guy who has understood what i mean)

...yep!...that's what I thought...

 

[granger.frederic]

Oh i see...

i really missed the time when civilized people were talking each other about great ideas ....

now the web is plenty of ......

that's the way it goes

 

[kidvybes]

Oh i see...

i really missed the time when civilized people were talking each other about great ideas ....

now the web is plenty of ......

that's the way it goes

Not really...you talk about how much work Tim Campbell has put in...how about all the time, money, and effort (not to mention frustration with manufacturing foul-ups) that Chunger and Matador have invested into this (highly successful) project...and the consistent ongoing support and interest in improving what has already proven itself to be a very viable product...

Check yourself bro...you wouldn't want to appear "arrogant" would you?...("don't be so nervous guys"?...really?)...have a Blessed evening!

 

[granger.frederic]

Pfff !
calm down !

before posting you'd better look at this : https://www.youtube.com/watch?v=p2H5YVfZVFw

for my part everything has been said....

it's time to move on...

 

[granger.frederic]

Oh, thanks Tim !

One more detail: for those who want to measure what i'm talking about , it's very easy !

1: put a 80pf capacitor instead of the capsule and a low microphonic 5 star GE 6072A tube , or better a Jfet (temporary...)
2: put the mic with that type of PCB in front of your favorite Fender  or Marshall Amp
3:set the volume at 5
4lay hendricks/little wind only  8)
5:record the PCB's vibrations
6:cry (i'm kidding...only for this part...because it will record that as well...)

Cheers
Fred

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!

 

[Matador]

That's actually a brilliant idea!

Please perform this experiment on your Matachung C12 build and post the results back to everyone on the thread!

 

[granger.frederic]

Send me a sample if you're too lazy to DIY
I'll send it back to you ASAP!
brilliant isn't it ?

 

[Matador]

You mean you don't own one, and haven't built one?

 

[Category 5]

Oh, thanks Tim !

One more detail: for those who want to measure what i'm talking about , it's very easy !

1: put a 80pf capacitor instead of the capsule and a low microphonic 5 star GE 6072A tube , or better a Jfet (temporary...)
2: put the mic with that type of PCB in front of your favorite Fender  or Marshall Amp
3:set the volume at 5
4lay hendricks/little wind only  8)
5:record the PCB's vibrations
6:cry (i'm kidding...only for this part...because it will record that as well...)

Cheers
Fred

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!

This experiment probably won't yield anything valuable since the polystyrene caps are several times more microphonics than anything else in the circuit besides the tube.  They'd contribute enough microphonics in most cases to mask what you're talking about.  (Even in a ptp version).

I did enjoy the cat video though.  Very cute.