Official C12 Clone - Build and Support Thread

[Pohjamonni]

Hi!

Any word on Tim Campbell?? I haven't been able to reach him via email.

I've been on his list for two capsules since may 14th and at that time he told that capsules will be ready in 10-12 weeks. I know that Tim is extremely busy but it has been almost 20 weeks now and I'm afraid that my order is lost or something... I also have checked my spam folder regularly.

Thanks for the great project. I have a pair of mics ready and working, only missing those capsules.

-Pohjamonni

 

[kcatthedog]

"Wow. On the blueprint of the pcb for the power supply, there is an R4 resistor where, on my pcb, and in the pictures, that's where the B+ adjust trim pot goes. Confusing. I would not have put the trim pot there except that it's that way it is on my pcb, with the dotted line around the B+ adjust and all."

Is there an inconsistency in our directions  ?

 

[scott_humphrey]

Hi!

Any word on Tim Campbell?? I haven't been able to reach him

I recently requested two additional capsules by email, but haven't yet received a confirmation email....

I'm fortunate to have a TC capsule in this C12-style mic and it sounds great. I ordered it in 2010 before the gold rush.

 

[Matador]

Wow. On the blueprint of the pcb for the power supply, there is an R4 resistor where, on my pcb, and in the pictures, that's where the B+ adjust trim pot goes. Confusing. I would not have put the trim pot there except that it's that way it is on my pcb, with the dotted line around the B+ adjust and all.
So, is my power supply ok? Still not getting the trim pot in the B+/R4/whatever to adjust the voltage.

I'm not sure how to answer this:  R4 is the trim pot. 

 

[Melodeath00]

Hi!

Any word on Tim Campbell?? I haven't been able to reach him via email.

I've been on his list for two capsules since may 14th and at that time he told that capsules will be ready in 10-12 weeks. I know that Tim is extremely busy but it has been almost 20 weeks now and I'm afraid that my order is lost or something... I also have checked my spam folder regularly.

Thanks for the great project. I have a pair of mics ready and working, only missing those capsules.

-Pohjamonni

Just to give you some consolation, I am in the same boat as you. I was put on the list on May 14, as well, with a 10-12 week lead time. After 13 weeks I asked for an update, and Tim estimated another 4 weeks. It's been 6 or 7 weeks since then, I believe. Luckily I'm not in a rush, but I'd love to start building my C12. I haven't gotten another update from Tim. I hope the backlog of capsules can be alleviated soon. It must be overwhelming for Tim haha

 

[kcatthedog]

a technician i spoke with yesterday called the trimmers, variable resisters : perhaps that explains this misunderstanding ?

 

[Pip]

a technician i spoke with yesterday called the trimmers, variable resisters : perhaps that explains this misunderstanding ?

They are one and the same. If you look back in the thread and follow Chungers awesome build thread there is little chance to get lost. The most common mistake is putting the wrong trimmer in the wrong place as they all look the same yet all three are different values.

 

[Reverend]

Wow. On the blueprint of the pcb for the power supply, there is an R4 resistor where, on my pcb, and in the pictures, that's where the B+ adjust trim pot goes. Confusing. I would not have put the trim pot there except that it's that way it is on my pcb, with the dotted line around the B+ adjust and all.
So, is my power supply ok? Still not getting the trim pot in the B+/R4/whatever to adjust the voltage.

I'm not sure how to answer this:  R4 is the trim pot.

Ok. What I did was measure by putting the red lead of the DMM on the metal screw on top of the trim pot/R4, and of course the black on ground, and I get straight zeros.
My main problem now is that the B+ trim pot has never adjusted the voltage. I have a new trim pot or R4 that I got from Mouser. Should I install it and see what happens? Thanks.

 

[Matador]

Measuring the screw won't tell you anything useful:  it isn't part of the circuit (unless the pot is busted).

As I asked before, please tell me the markings on the top of R4.  I'm guessing you just have the wrong value (which has happened on a few other occasions in this thread).  Measuring B+ is as good as measuring the voltage across the pot though.

Let's go back to basics:  how exactly are you measuring B+?  How did you connect the 180K resistor and connect it to the PSU?

 

[chunger]

Ok. What I did was measure by putting the red lead of the DMM on the metal screw on top of the trim pot/R4, and of course the black on ground, and I get straight zeros.
My main problem now is that the B+ trim pot has never adjusted the voltage. I have a new trim pot or R4 that I got from Mouser. Should I install it and see what happens? Thanks.

To measure B+, use your DMM on the 5 point terminal block at P6 and P5.

 

[Reverend]

Ok. What I did was measure by putting the red lead of the DMM on the metal screw on top of the trim pot/R4, and of course the black on ground, and I get straight zeros.
My main problem now is that the B+ trim pot has never adjusted the voltage. I have a new trim pot or R4 that I got from Mouser. Should I install it and see what happens? Thanks.

To measure B+, use your DMM on the 5 point terminal block at P6 and P5.

OK. That makes sense. I was thinking "check the voltage at the junction" or something crazy, I don't know. Anyway it measures 187V. Thanks again.

 

[Pohjamonni]

Hi!

Any word on Tim Campbell?? I haven't been able to reach him via email.

I've been on his list for two capsules since may 14th and at that time he told that capsules will be ready in 10-12 weeks. I know that Tim is extremely busy but it has been almost 20 weeks now and I'm afraid that my order is lost or something... I also have checked my spam folder regularly.

Thanks for the great project. I have a pair of mics ready and working, only missing those capsules.

-Pohjamonni

Just to give you some consolation, I am in the same boat as you. I was put on the list on May 14, as well, with a 10-12 week lead time. After 13 weeks I asked for an update, and Tim estimated another 4 weeks. It's been 6 or 7 weeks since then, I believe. Luckily I'm not in a rush, but I'd love to start building my C12. I haven't gotten another update from Tim. I hope the backlog of capsules can be alleviated soon. It must be overwhelming for Tim haha

Hi!

Thanks. That was kind of an information I was expecting/hoping to hear. Maybe they will be ready soon.

-Pohjamonni

 

[Reverend]

Measuring the screw won't tell you anything useful:  it isn't part of the circuit (unless the pot is busted).

As I asked before, please tell me the markings on the top of R4.  I'm guessing you just have the wrong value (which has happened on a few other occasions in this thread).  Measuring B+ is as good as measuring the voltage across the pot though.

Let's go back to basics:  how exactly are you measuring B+?  How did you connect the 180K resistor and connect it to the PSU?

I connected the 180K resistor by putting it in the #5 and #6 pin holes in the cable.
OK. I had the trimmer pots in all the wrong places. I'm a dumba**. I'll desolder them and put them right and start this whole process again as per Chunger's build instructions and see what I get. I'm hoping that this solves my problems with my this build or at least with the psu. If you think that I should replace those trimmers with new ones, let me know - in the meantime I'll try to re-use the trimmer pot resistors. Back to work. I hope not to bug you much more, but I may have some ground issues with the mic.  I'll get to that later. Thanks again.

 

[brewbacca]

I decided to try the micandmod mk-12 capsule since I also wasn't able to get a response from Tim. I finished up the mod on one of my two mics and it seems to be working. How am I supposed to know what voltage should be going through B+, heater, bias etc with a different capsule? I looked for some information on it, but didn't see anything that stood out.

 

[Matador]

I decided to try the micandmod mk-12 capsule since I also wasn't able to get a response from Tim. I finished up the mod on one of my two mics and it seems to be working. How am I supposed to know what voltage should be going through B+, heater, bias etc with a different capsule? I looked for some information on it, but didn't see anything that stood out.

Changing the capsule should not effect any of the voltages.  If it worked with one capsule it should be the same with any other.

 

[brewbacca]

Ok, cool. I tried setting it up for B+ 120V, but my B+ is jumping around a bit and I can't quite get it up to 120V. Without the mic it's around ~210V but with the mic it's around ~100V. The highest I can get it is around 114V before the trim pot maxes (minimums?) out. Is that an issue? (It sounded pretty good to me). I double checked and my trim pots are all in the correct places.

Thanks! (Also, thanks for putting this project out there! It's been fun to work on)

 

[kcatthedog]

your state to connect the two red leads from the tranny to the positive and negative pins on the input to the microphone.

I thought the tranny gives AC voltage therefore, start is the common or neutral  and the finish is the high lead voltage?

or does it not matter which red lead is soldered to the positive and which to the negative ?

thx.

 

[Matador]

your state to connect the two red leads from the tranny to the positive and negative pins on the input to the microphone.

I thought the tranny gives AC voltage therefore, start is the common or neutral  and the finish is the high lead voltage?

or does it not matter which red lead is soldered to the positive and which to the negative ?

thx.

The primary connects to the output cap and ground.  The secondary connects to the XLR jack pins 5 and 6.

And no, it doesn't matter which of the primary leads goes to the output cap (assuming that your red wires are the primary).  If you check earlier in the thread, the primary will have a much higher DC resistance than the secondary so that's a good way to check.

If you are building a matched pair, it's probably best to match the phases between the two (so that a positive going sound pressure when the mike capsules are close) so that they can be easily summed together without phase issues.

 

[kcatthedog]

thank you,

my understanding is the blue thicker leads are the primary and the thinner red wires are the secondary

I understand this is a standard transformer protocal

I have built an ms kit before and am really appreciating the thread and support.


kcat

 

[Matador]

thank you,

my understanding is the blue thicker leads are the primary and the thinner red wires are the secondary

I understand this is a standard transformer protocal

I have built an ms kit before and am really appreciating the thread and support.


kcat

I would caution about making any such assumptions:  if you read the U87 thread, many users got stuck because the wires were the opposite color as the spec sheet indicated.

I would suggest you measure the transformer to be sure, otherwise you'll have all sorts of problems.