Official AMI-TAB Funkenwerk-C12-Alternative-Kit

[poctop]

I'm going to end this post by saying, don't bother with this DIY kit.
I've had more headaches with all the misinformation and incomplete packaging than any other DIY kit I've worked on.

It's just not worth it.

Thank you everyone for your help and support.

Have you been using the PCB or the point to point version,
Just curious,
Let me know if you have a chance,
Best,
dAN,

 

[aaquilato]

[/quote]

Have you been using the PCB or the point to point version,
Just curious,
Let me know if you have a chance,
Best,
dAN,
[/quote]

I was using the breadboard PCB version. What ptp version are you referring to?
The kit I received had so many missing pieces, wrong pieces, incomplete pieces, incorrect schematics, etc...

Very disappointed in AMI for such a shoddy job.
I will not be doing business with them again.

 

[poctop]

Have you been using the PCB or the point to point version,
Just curious,
Let me know if you have a chance,
Best,
dAN,
[/quote]

I was using the breadboard PCB version. What ptp version are you referring to?
The kit I received had so many missing pieces, wrong pieces, incomplete pieces, incorrect schematics, etc...

Very disappointed in AMI for such a shoddy job.
I will not be doing business with them again.
[/quote]

I did the pcb for Oliver a While ago for this particular project for his hybrid schematic,
the ptp version is the exact same as breadboard version hence i am not a big Fan of ptp 
some of the DIY member built it with the PCB and enjoyed their build.
but this do not account for the error and wrong parts sent tough so i understand your frustration.
Best,
Dan,

 

[poctop]

Another Project that i have been waiting for ages,  Complete,

AMI D-C12

 

[aaquilato]

Well after what seems to have been a lifetime, with the help of a friend, I finally have this AMI C12 finished.
Thanks to poctop for his new pcb boards!!
Thank you Tim Campbell for your incredible capsule!! It is absolutely marvelous.

Thank you everyone for your help with my noobie questions.

 

[Melodeath00]

Let's hear it! Did you go with the AMI alternative circuit, or the exact C12 circuit?

 

[poctop]

Well after what seems to have been a lifetime, with the help of a friend, I finally have this AMI C12 finished.
Thanks to poctop for his new pcb boards!!
Thank you Tim Campbell for your incredible capsule!! It is absolutely marvelous.

Thank you everyone for your help with my noobie questions.

Glad you made it ,
you are welcome,
Best,

 

[aaquilato]

Let's hear it! Did you go with the AMI alternative circuit, or the exact C12 circuit?

Hi Melodeath00.
I went with the AMI alternative circuit as that's what poctop's pcb's were laid out for.
I really don't know how much different it is as I am a real noobie at this.
How much different is the AMI circuit? I used Oliver's transformer and NOS GE 12AU7 tube.
It's in the burn in stage at the moment but it's sounds very, very nice right now.
I'll post a file or two after it settles in.

I have an Apex 460 that I plan on using OPR's point to point acrylic boards with.
That build uses the exact C12 circuit AFAIK. I have a Beesneez capsule set aside for that build with a Cinemag transformer. I will probably use a 7025a tube to stay close to the original spec.
I have the carbon resistors and some PIO caps as well.
And I'll use Chunger's PSU mod. That's the plan at least. Hopefully it won't take over a year to complete this one.

 

[dougch]

Is the AMI C-12 kit body closer to the original size of the C-12? Is Dan's board (OA C12) made to fit the AMI kit?

 

[poctop]

Dan's board (OA C12) made to fit the AMI kit?

Yes
Best,
DAn,

 

[dudeitsree]

Hopefully someone can help me, I ended up getting over my head on this AMI C12 kit as I am very green at this sort of thing.  I am working off of the same schematics that are posted above, where I'm confused is connecting to the tube socket.  I see where from C3 and R4 go to the plate, but which plate?  Does it need to go to both?  Also, the connections to the Cathode and the heater, I think I need to connect one side of the heater to the 0v as well as the cathode and the other heater to the -6v going to pin 4 of the PSU.  Also which grid do I use?  Both?  Like I said.  I am green, and really have no business doing this but they have my money and I am pretty deep, but I am learning!   

 

[Banzai]

Follow the original schematic for the tube: one half is connected, the other grounded

Then add in R3/R9/R1 from the AMI schematic for your grid voltage

 

[dudeitsree]

Follow the original schematic for the tube: one half is connected, the other grounded

Then add in R3/R9/R1 from the AMI schematic for your grid voltage

Awesome, thank you for the reply!  Looks like this is saying to use the center tap for the heaters, but AMI said not to use the center tap, so I'm a tad confused about that. 

 

[Banzai]

Connect -6V to pin 9, and ground heater pins 4+5 (you can also leave pin 5 disconnected)

Or connect -6V to heater pin 4, and ground pins 9+5. Doesn't really matter.

 

[dudeitsree]

Thanks for the clarification, I wired it as stated above.  I powered the mic on and the tube doesn't work.  At the tube socket, I have 130v at the plate,  0 at the grid and only 1.5 for the heater.  From the PSU I have the same readings except 66v on the heater.  So I think the PSU isn't healthy, it was pre built (the more expensive USA built one).

 

[dudeitsree]

Dennis at AMI gave me a call and helped me out, he was very helpful.  The build is correct but the PSU needs to be swapped due to a small mod that was supposed to done before it was sent (to make the heater voltage negative instead of positive).  Other than that I believe the build was a success, and AMI supported me well. 

 

[Tubemooley]

Reviving this old thread. I am getting ready to build a C12 following Oliver's Alternate Schematic.
Who can help me confirm the capsule connections?
a. Front diaphragm connected to GND.
b. Rear diaphragm receives remote pattern voltage from R2.
Are the two backplates wired together or isolated? I think they're wired together.
c. The bias voltage goes to both backplates from R5.
d. Pull the signal off both backplates, go thru C1 1000pF and input to the grid.
Little help? Thanks.

 

[doqmemory]

Are the two backplates wired together or isolated? I think they're wired together.

Yes, backplates wired together is what the schematic shows.