Official C12 Clone - Build and Support Thread

[chunger]

Also, what cable are you using?  Under "normal" operating conditions, the import chinese cable if soldered correctly at the factory works fine, but i have heard in noisy enviromnents, premium cable like the Gotham might be of benefit. ..  but this is internet conjecture.

 

[Tim Campbell]

I've seen these bumps on Neumann capsules so it's not exclusive to the Chinese or any particular 3rd party builders.  (Tim I have only seen one of your capsules and neither diaphragm shows debris underneath)  I don't want to slight or sully any product, that's not my intent, but only to maybe pose a question as to what is acceptable for debris under a condenser capsule? ?

Debris can show up inside capsules sometimes over time or if they have been opened but should never be present in a new capsule. CK12's are harder to clean because of the chamber. Many old AKG's have slight amounts of debris that has worked loose over 30 years or so.

I try to be extremely clean with my capsules. They are put through from 5 to 8 ultrasonic baths before final assemble and are inspected for debris when packaging them.

 

[Category 5]

This advice risks people ruining their body-kits and wasting an enormous amount of time: there's zero mechanical benefit in re-tapping perfectly good threads.

Just use stainless steel screws in metric M2 to improve structural strength. They are just as easily available in the US as your standard imperial sizings.

My SOP these days (as I've pointed out previously in the thread) is to re-tap the internal hardware from M2 to 2-56 or 4-40 stainless steel hardware.  In the 7 or 8 prototypes I've built, I've never had any EMI issues, and I wonder if that was because the new hardware held the internal pieces together much tighter.

I agree with this.  I've replaced every screw on every body I've worked on with quality ss screws and the structural integrity was significantly improved. 

 

[Banzai]

If you have that many then you're applying way too much torque; you don't need a breaker bar to tighten an M2 screw! 

Change to a suitably small screwdriver, and the threads will hold up no problem. If there are some that don't, the sage advice is to only re-tap those, or put a bolt on the back of the screws instead. But, nothing beats using correct torque in the first place (not just for this, but DIY in general).

As a sidenote, the threads on the connector housing for the side-rails can be irregular in depth and starting position. If anyone's ordering, buy 4x 8mm long screws for this part. Even if your current T11 kit uses shorter length screws, the longer ones are guaranteed to work on your future kits as well.

The key phrase being "perfectly good":  I had more than a few that just spun forever.

The 5 stages of Bolt Tightening

[list type=decimal]
[*]Loose
[*]Tight
[*]Tighter
[*]Really Tight
[*]Loose
[/list]

 

[Matador]

If you have that many then you're applying way too much torque; you don't need a breaker bar to tighten an M2 screw! 

True this, however they shipped from the factory this way, so I can't take credit in this case.  If nothing else, it behooves everyone to check all of them and repair any that are 'pre-torqued' in this fashion.

I see McMaster Carr carries stainless M2's - can anyone recommend a good length to order?  I'll add some of these to my next order.

 

[Banzai]

M2x5 will work for every screw on some kits, and for others you'll need 4pcs. M2x8 for the connector housing. Get both sizes, and you're covered.

It's also a good idea to tighten:

– Ground lug bolt PSU
– Transformer bolts PSU
– Connector XLR inserts PSU (set-screws)
– Cable connector housings (all set-screws)

All of these ship loose from the factory.

I see McMaster Carr carries stainless M2's - can anyone recommend a good length to order?  I'll add some of these to my next order.

 

[digitall2000]

hi
i want to go back to redesigning the high impedance section (no not really)
but i would like to know about using turret board (what is used for say
guitars amp point to point) for point to point on the high impedance section
instead of polycarbonate (EL M 250-251),  as far as impedance per square
inch or whatever the imp. priorities are.  because i find the clear
polycarbonate hard to work with.  i have built 2 of these kits and love them.
also i have read this whole post. 
thank you,
lance

 

[OPR]

I believe both the 251 and c12, U47, etc used Acrylic for the hi z section which is a completely different material to poly-carbonate.
Guitar amps generally use Phenolic Boards.
Hope this helps 

 

[granger.frederic]

To succinctly resume my beliefs , one last time, about the 10 MegaOhms to x GigaOhms range HiZ sections :

the weak point in low end mics is often the HIZ sections and body metalwork (internal resonances).This can introduce sound colorations, microphonic issues and lower max SPL capability.

- electrical insulation : ideally the HiZ should be hermetically encapsulated to become moisture resistant, because the HiZ resistors, the Stiroflex caps and the PCB could absorb moisture with time (check the surface microporosity) and then  could change their high impedance value .Acrylic sealed chamber/point to point is a good answer, Teflon /Pcb is the cheapest. All parts and flux should be perfectly cleaned with isopropyl alcohol (we should always use gloves) .The distances between the HiZ components should be as short as possible. A well built high end capsule, should be , on the other hand,  lastingly moisture resistant if properly used, but must be cleaned as well,  if needed.

-mechanical insulation/internal resonances reduction: the vibration behavior must be well designed by various damping systems.
the tube must be well damped , as well as all the HiZ parts, including capsule, resistors,caps and HiZ wires.All the HiZ parts must be mechanically decoupled from the body and mounted on non resonant material (acrylic for example).Encapsulation helps a lot of course.The body/headbasket resonances should be reduced at best as well (powder coating,non parallel sides...).
The low end body assemblies are often unstable (unscrewing with time) and resonant.Varnish could fix the unscrewing issue for an indefinite period of time.

all the high end classic mics have that kind of crucial optimizations...

hope it will help ...

 

[vinylwall]

...
Anyways I'm selling my c12 in the black market if anyone wants to pick one up for much less than what is in it for parts.
...

Hi MicDaddy.

Your inbox is full.  I haven't received any tracking info.  Has the mic shipped?

Thanks.
Jimi Ray

 

[vinylwall]

Here's a vocal test done with my first build of Matador's C12.  Lead vocal is done on the C12 and backing vocals are done with Dany's D-EF47 mic.

"I'll Be Around":

https://dl.dropboxusercontent.com/u/47755719/JaneyB-Motown/07-I%27ll%20Be%20Around%20%28RS4-150406%29.mp3

 

[HHH]

Nice. What capsule did you use?

 

[vinylwall]

Nice. What capsule did you use?

Thanks.  Eric Heiserman HK12 capsule and a NOS GE 6072 5Star tube.

 

[JessJackson]

I used matador c12 on this joint.

https://www.youtube.com/watch?v=KJ-mfwEHAvI

 

[Category 5]

I used matador c12 on this joint.

https://www.youtube.com/watch?v=KJ-mfwEHAvI

Sounds very nice Jess.  Was this Tim's capsule?  Any other details on what amp/processing you used?  This mic suits the vocalist well.

Did you use Matador's PSU or one of your originals?  i remember a while back you had mentioned there were some audible differences.

 

[Millerjay]

Hey guys,

Does anyone know of another place to get a C12 single layer mic grill besides studio 939? I ordered one from them 3 weeks ago and I can't get anyone to respond to my emails.

 

[saxmonster]

Hey guys,

Does anyone know of another place to get a C12 single layer mic grill besides studio 939? I ordered one from them 3 weeks ago and I can't get anyone to respond to my emails.

Give Chunger some more time, he will get them out to you.  He is very busy and behind on his orders.  Its worth the wait.

-Scott

 

[chunger]

Hi millerj,

Your order is currently #4 in the shipping queue And should be going out mid-late this week.  The backlog is still high right now until completion of the ela m251 prototype. 

Hey guys,

Does anyone know of another place to get a C12 single layer mic grill besides studio 939? I ordered one from them 3 weeks ago and I can't get anyone to respond to my emails.

Hey guys,

Does anyone know of another place to get a C12 single layer mic grill besides studio 939? I ordered one from them 3 weeks ago and I can't get anyone to respond to my emails.

 

[MPCNYC]

Hi…built a couple of C12 using the PCB. The first I used the BOM for the PS a listed in the PDF. B+ voltages are fine, I could get 120v easily under load.

I'm building a 2nd mic and using the cap and resistor changes mentioned to make the PS the latest revision. For some reason I can't get the PS lower than 132v when under load, trimmer is set to the lowest possible value.  The other power supply gets the B+ where it should be with either mic I've built.  The 6072 tubes were matched, so the settings with the original PS are pretty much identical.

What do the latest changes in the BOM for the PS address? Any thoughts on what I can do to correct this high B+ issue?

 

[Matador]

To be specific, this was lowering R1 and R2 down to 68K?