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Happy New Year!


OPR

  AKG C-12 point to point boards for Apex 460 Alctron HT-11A, ShuaiYin,SYT-1200 !!

                          $120.00 a set!

http://groupdiy.com/index.php?topic=53970.0
I would recommend at this stage to use
The Matador/Chunger PSU if you can't workout  how to
mod the Apex unit, as It's probably the safest way... :)

Email your interest or support to :openplanrecording@hotmail.com



Suggested parts list




C 12_      75-V730P105X9250 Film Capacitors 1uF(original mic Is .5uf) 250volts 10% Axia    qty=1

R 11, R 16 588-MOX-200003005JE 30M Thick Film Resistor,                                         qty=x2

R 17        71-RN60D-F-100K Metal Film Resistor - 100Kohms 1%                                 qty=1

R 15,R14    588-MOX-300002506FE 250M Thick Film Resistor, 1%                               qty=2

R 12,R 13   71-RN60D-F-499K Metal Film Resistor - 499Kohms 1% 100ppm                qty=2

c 11,C 16   JustRadios.com / ETC 5000pF, 630V Polystyrene Film Axial                        qty=2

C-13        JustRadios.com / ETC 1000pF, 630V Polystyrene Film Axial                           qty=1




C12 circuit




C12 physical layout and schematic assumes Psu 120v -1v Bias at pin 4

http://openplanrecording.files.wordpress.com/2013/06/akg-c12-schematic.pdf




Ok Lets Build it!!













Ok Now make your self a template with for the mounting screws. The spacing from top to bottom is as follows
 6mm 51mm 76mm and 115mm...
Use a 2 mm bit for metal and drill very slowly so as not to overheat and blunt the the bit!!!




Now don't drill through just yet we are just marking the metal at this point!!




Ok you can put the drill all the way through now...
what I haven't shown here is that you'll need to counter sink the outside of the holes on the mounting rails
in order that the screw sits flush with the rail otherwise you'll have difficulty sliding the body on. What i do is use a battery drill with a Philips tip and push it into the hole while drilling, much like carpenters do when working with wood..
 









Be very gentle installing the boards!! Don't force it and to be safe it's good idea to use precision
screwdrivers as these little guys wont allow you to over tighten the screw and risk cracking the boards!!








The best way to install the bottom transformer board is to start all of the screws and work you way around evenly and gradually tightening.





























Use distilled water to cool and clean solder joints(NO IPA!)


















































































« Last Edit: November 01, 2016, 04:59:16 PM by OPR »
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/


micaddict

Re: Official C12 pont to point on Acrylic build and support thread
« Reply #1 on: October 31, 2013, 06:21:25 AM »
I'm not so much into the "likes business" (guess I'm getting too old to keep up with all that stuff), but I must say I kinda like this.  :P

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #2 on: October 31, 2013, 06:24:44 AM »
I like that you like it Micaddict!  8)
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

ciscan.81

Re: Official C12 point to point on Acrylic build and support thread
« Reply #3 on: November 13, 2013, 10:09:11 PM »
Hi

I'm in the early stages of researching a C12 build based on the HT-11A donor...

I've been taking a look at your mics for sale on your wordpress site.

What capsules and tubes specifically do you use for these builds?

I've been trying to get in touch with Tim Campbell to order one of his famous CT12's but I gather he has a huge backlog of orders he is wading through.

I've also been looking into NOS GE 6072A tubes, which are apparently getting harder to find (also more expensive as a result!).

Anyway, nice work on the P2P kits, they look the business. They're certainly on my list of possible routes to take.

Many thanks.

-Wayne


OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #4 on: November 13, 2013, 10:21:41 PM »
Hi Wayne,
I'm using Electroharmonix tubes in my build just make sure you pay the extra to ensure low noise operation! The capsule I'm using are the Chinese 6um type like Advanced audio use but I've made some modifications to the back plate that make them sound flatter and a little closer to the originals but they still don't have that huge proximity of the CK12. I also have a pair of Tims capsules in my personal C12 set that are amazing hopefully he will resume supplying to the community soon!
« Last Edit: November 13, 2013, 10:34:05 PM by OPR »
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

OPR

It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

Re: Official C12 point to point on Acrylic build and support thread
« Reply #6 on: December 26, 2013, 06:27:48 PM »
Interesting... Available?

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #7 on: December 26, 2013, 06:33:14 PM »
Yes they are still available! ;)
shoot me an email if your interested.
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

Re: Official C12 point to point on Acrylic build and support thread
« Reply #8 on: January 08, 2014, 12:07:14 AM »
Hi OPR, I notice you leave Pin 5 of the tube floating. This is the unused heater side, and left floating in the AKG schematic, right? If so, why do you ground Pin 9, or is it ok to leave that floating too? I don't know what they did in the original C12.

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #9 on: January 09, 2014, 05:20:07 PM »
Quote
This is the unused heater side, and left floating in the AKG schematic, right?

Yes.
Pin nine is a center tap common to both heaters, but since were only using one side of the tube I've opted to ground pin nine. I don't think it would matter if it was floating or not,  but grounding removes it from the equation. Just in case ;)
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/


Re: Official C12 point to point on Acrylic build and support thread
« Reply #10 on: April 06, 2014, 11:50:17 AM »
Hello Everybody,
a month ago i decided to build this project and i saw this topic and i bought those boards.
it looked very complicated, hard but i like challenges.
the service was amazing from the beginning, OPR have sent me those boards and I've got it soo quick (considering they are from the other side of the globe).
i had some of problems during the process and each time a guy named Mark from OPR helped me as much as he can and even offered a help with searching. this guy is f*** awesome!

thanks a lot it was a wonderful building!


 
« Last Edit: April 06, 2014, 03:03:23 PM by omribgr »

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #11 on: April 08, 2014, 11:42:00 PM »
Thanks for the kind words Omri!!
Enjoy the Mic!! ;)
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #12 on: May 16, 2014, 12:32:25 AM »
Nice Build by Sergio Armes 8)
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

Re: Official C12 point to point on Acrylic build and support thread
« Reply #13 on: July 04, 2014, 12:41:31 PM »
The time has come for me to start your point to point build.
I have a noobie question about the capacitor voltages.

Your BOM has voltages that are different (and opposite) from the C12 schematic.
How much does it matter if I use a 1000pf @ 630V or a 1000pf @ 250V?


Thanks for your help with this.

Re: Official C12 point to point on Acrylic build and support thread
« Reply #14 on: July 04, 2014, 01:10:45 PM »
It's all temperature related, AFAIK. Higher voltages give you more temperature tolerance, thus affecting positively cap operation. So use high voltage ratings when possible. The usual limitation is size.  Higher voltage caps are usually bigger than lower voltage ones,  so designers usually make compromises based on available space and cost. Someone please correct me if wrong.

OPR

Re: Official C12 point to point on acrylic build and support thread
« Reply #15 on: July 05, 2014, 08:44:00 AM »
Hi Anthony,
I'm not sure what you mean by opposite ?...
The B+ supplies 120v so anything above that will work but you can use higher voltage caps or wattage resistors as long if they fit,and theoretically they should have lower noise also which is why the caps in the Hi z sections caps are rated at 630v when in reality they wouldn't see anywhere near this much voltage.
Hope this helps.
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

Re: Official C12 point to point on Acrylic build and support thread
« Reply #16 on: July 05, 2014, 11:17:23 AM »
Is it impossible to swap tubes after completing this build without desoldering some of the caps?

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #17 on: July 05, 2014, 08:55:09 PM »
Quote
Is it impossible to swap tubes after completing this build without desoldering some of the caps?
Now that would be silly!  ;D See the pic below notice the open area where the tube can be swapped  just as in the original C12 ;)

It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

OPR

Re: Official C12 point to point on Acrylic build and support thread
« Reply #18 on: October 27, 2014, 10:59:45 PM »

Just sharing a shot of Brian Fox's take on our C12 Build with the  Acrylic Boards and Tim Campbell capsule. 8)
It's What's Inside That Matters!

Open Plan Recording

openplanrecording@hotmail.com

http://www.openplanrecording.com/

Re: Official C12 point to point on Acrylic build and support thread
« Reply #19 on: October 27, 2014, 11:46:25 PM »
That looks fantastic. One day, I'd like to rebuild my current C12 point to point, or maybe build another C12 so I have a pair (one p2p, another PCB).

Do you know, does your kit fit the AMI C12 body, or is that a thinner body? I thought it was thinner, but the latest picture I saw online it looked quite similar size-wise.