Official C12 Clone - Build and Support Thread

[JessJackson]

And The Reds

 

[JessJackson]

And The Reds

Those readings seem quite high.

Your secondary would present a load of well over 600 ohms to the mic pre, that should normally be around 200 ohms.
Primary would be well over 30K. Doesn't seem right.

What frequency does your meter use for DCR?

Do you have the specs for that transformer?

Regards,
Mark

Thats what I was thinking.

Its a Haufe, it came out of a Telefunken USA C12. Its sold to Telefunken as historically correct T/14 wound at the same specification as the vintage Haufe's.

If you divide the numbers, the step down ratio seems to come out the same though.

I believe the greens are the 50ohm wires which you usually tie together in c12 circuit.

 

[micaddict]

Nice sample again, Mark. Keep them coming. 

As much as I like dry percussive sounds, at heart I guess I'm a tone guy. So I have some extra love for ride cymbals. Nice combinations of attack and sustaining, bell tones. Sizzle and crash can be added to taste. I'm no drummer so I hope this makes sense. With a ride alone you can paint many colors and to capture them all, the mic better be good. Sort of like the key test, come to think of it, but more versatile.
Here's an introduction, for those interested:
http://www.youtube.com/watch?v=W-iBfuKvMZo

 

[3nity]

Mark Congrats on the building of that room!!
I see its not finished yet but man it looks and sounds sweet.
It has some kind of vibe dude!
How i long to finally set my things up here, but its gonna be for next year!

Good luck!

 

[chunger]

Let's get some nice custom headbaskets on those mics!  The factory begins volume production on Monday.

 

[HellfireStudios]

Let's get some nice custom headbaskets on those mics!  The factory begins volume production on Monday.

How do I pre-order?

 

[chunger]

Let's get some nice custom headbaskets on those mics!  The factory begins volume production on Monday.

How do I pre-order?

As of right now, I'm not taking pre-order.  If lots of people insist, I may change my mind, but due to the long lead times, last time I did reservations for microphones, it was a lot of legwork tracking everyone's requests, and many people who reserved items did not follow through with purchasing.  I refuse to take money until I have product in hand or at minimum I know for sure I still have time to refund the paypal charges if something goes horribly wrong.

I had to order 500 units for the first run.  There is absolutely no way I will sell that many in any reasonable timeframe which means they should be in stock for quite some time when they arrive.

 

[KMB-AUDIO]

Hi guys,

I received my two kits on Friday! Starting on the power supplies tonight.

I've read through this thread and am curious about the 0 Ohm "resistor".  What is the difference between using this jumper and bare wire?

 

[JessJackson]

Strange things this end,

Just finished the build.

Mic Connected:

Bias and Heater are spot on (although heater adj is VERY sensitive)

Im getting 160v on b+... B+ Adj doesn't seem to be doing much but lowering by the decimal. I am able to get it down to about 158v

Out the wall I have 121v, After the PS Xformer Im getting 225v and 10.3v

Any Thoughts?

 

[Matador]

Strange things this end,

Just finished the build.

Mic Connected:

Bias and Heater are spot on (although heater adj is VERY sensitive)

Im getting 160v on b+... B+ Adj doesn't seem to be doing much but lowering by the decimal. I am able to get it down to about 158v

Out the wall I have 121v, After the PS Xformer Im getting 225v and 10.3v

Any Thoughts?

Is this with the mike connected?  What tube are you using?

 

[Matador]

Hi guys,

I received my two kits on Friday! Starting on the power supplies tonight.

I've read through this thread and am curious about the 0 Ohm "resistor".  What is the difference between using this jumper and bare wire?

No difference:  it's just cleaner and looks better.   For the first two prototypes, I used a short section of solder wick directly across the two SMD pins (which is all a zero ohm resistor is:  essentially a piece of wire).

 

[JessJackson]

Strange things this end,

Just finished the build.

Mic Connected:

Bias and Heater are spot on (although heater adj is VERY sensitive)

Im getting 160v on b+... B+ Adj doesn't seem to be doing much but lowering by the decimal. I am able to get it down to about 158v

Out the wall I have 121v, After the PS Xformer Im getting 225v and 10.3v

Any Thoughts?

Is this with the mike connected?  What tube are you using?

Yes with mic connected...

Without is 195v B+

Using stock tube... i have other GE 5 star nos tubes but I don't want to damage them.

 

[KMB-AUDIO]

Finished one power supply last night and all seems well.

Just wanted to give people a heads up using TNC ACM-1200 mics that their power supply may be a little different than the one that Chunger has picture of here (see attached photo).

On mine, the PCB was  a full rectangle with the transformer attached to the PCB, so I had to drill some holes in the enclosure to mount it.  Additionally, the secondary taps are reversed, so I had to extend one of them to reach the new PCB.

 

[Matador]

Yes with mic connected...

Without is 195v B+

Using stock tube... i have other GE 5 star nos tubes but I don't want to damage them.

The stock 12AX7 pulls less current than a 6072A under the same bias conditions:  this can be seen on the tube plate curves.  If you want to run the mike with that tube, the series pass resistors (91K) need to be increased.  Lowering the grid bias down to -0.2V also helps the tube draw more current.

The 180K resistor from B+ to ground right at the 7-pin XLR output jack is the best test to do for getting things right before a real 6072A goes in.

 

[JessJackson]

Yes with mic connected...

Without is 195v B+

Using stock tube... i have other GE 5 star nos tubes but I don't want to damage them.

The stock 12AX7 pulls less current than a 6072A under the same bias conditions:  this can be seen on the tube plate curves.  If you want to run the mike with that tube, the series pass resistors (91K) need to be increased.  Lowering the grid bias down to -0.2V also helps the tube draw more current.

The 180K resistor from B+ to ground right at the 7-pin XLR output jack is the best test to do for getting things right before a real 6072A goes in.

Thanks Matador,

So I threw a 180k resistor across and B+ was able to reach 114v with Adj pot fully gained.

I then threw my 5 Star GE tube in there and we're back to 144v with Adj pot fully down. The Adj pot only seems to be effecting by decimals, adjusting maybe 2 volts max.

This is with stock capsule, awaiting Tim's capsule... I could try a capsule from my vintage C12 but wouldn't really feel comfortable at this stage.

b+ = 144v
Grid = -0.656v
Plate = 72.9v
Heater = 6.30
Bias = - 1.00

 

[Matador]

The capsule plays no part in the tube current and switching it won't matter.

It looks like the variance is much higher on these tubes than the data sheets imply:  can you increase the bias voltage up to -0.5 volts (as measured at the PSU, not right at the tube grid) and see if you can observe B+ lower down to 120V?

 

[JessJackson]

The capsule plays no part in the tube current and switching it won't matter.

It looks like the variance is much higher on these tubes than the data sheets imply:  can you increase the bias voltage up to -0.5 volts (as measured at the PSU, not right at the tube grid) and see if you can observe B+ lower down to 120V?

So my 180k resistor turned out to be a 165k... I replaced it with a 180k and am now measuring 117.2 at highest adj

With Bias at - 0.5 I am getting 141.2v

I'll try another 5 star GE and I have a EEC 81 i can try also.

 

[chunger]

I may be stating the obvious, but are all of the trimmer pot values verified and installed in the correct positions?  Seems odd that the B+ would only have a few volts of adjustment range regardless of where the final voltage lands . . . and that the bias adjustment would be very touchy as that was quite a gradual change on my sample build per turn of the pot.

 

[JessJackson]

I may be stating the obvious, but are all of the trimmer pot values verified and installed in the correct positions?  Seems odd that the B+ would only have a few volts of adjustment range regardless of where the final voltage lands . . . and that the bias adjustment would be very touchy as that was quite a gradual change on my sample build per turn of the pot.

omg.. i'm a dickhead for this but I thought all Adj pots were the same value.. simple mistake..

In Bias I have installed W502
In B+ I have installed W202
In Heater I have installed W104

Is there an easy way to remove these components because I'm having real difficulties desoldering the three legs at the same time.

Cheers

 

[KMB-AUDIO]

I may be stating the obvious, but are all of the trimmer pot values verified and installed in the correct positions?  Seems odd that the B+ would only have a few volts of adjustment range regardless of where the final voltage lands . . . and that the bias adjustment would be very touchy as that was quite a gradual change on my sample build per turn of the pot.

omg.. i'm a dickhead for this but I thought all Adj pots were the same value.. simple mistake..

In Bias I have installed W502
In B+ I have installed W202
In Heater I have installed W104

Is there an easy way to remove these components because I'm having real difficulties desoldering the three legs at the same time.

Cheers

Get some solder wick my friend! or a de-soldering gun...makes these chores so much easier.