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[mikeman]

Oliver Archut wrote on Wed, 12 May 2010 12:25

Later AKG CK12 used the gold evaporation method, but those ones do not fall in the domain of great sounding.

Oliver,
Could you elaborate on when AKG began installing the later CK12's employing the gold evaporation method? And in which models?

Thank you,
Mike Longhurst

[robft]

I would assume that this C-12 is of the "reduction" gold capsule type as it is one of the earlier ones- it has the pattern selector knob that looks like one on a Lionel train transformer- huge.

When I first bought the mic, perhaps 20 years ago, it sounded great, but occasionally the capsule would cut out if held sideways (as opposed to hanging straight down) and it received a little vibration. I noticed when looking at the capsule, you could see gold that was rubbed off the capsule.

But it sounded so good as it was, I didn't want to do anything about it. Then one day, I went to fire it up, and it was totally dead, no sound. My first thought was that it was the capsule. I'd rather have it NOT be the capsule as I don't want anything that would seriously affect the sound of the mic as it sounded when it worked.

I suppose something could have happened to the power supply as well, or even the wiring in the cable too. At least this could be repaired without having to alter the capsule. I don't want to change anything in the capsule if I don't have to.

I had Stephen Paul Audio work on a couple of my old Neumann mics many years ago, but I was not sure what their current situation is as I've read different stories.

Being in the Midwest US, I'd have to ship it somewhere, but it's a matter of what I can check here and when I have to ship it off somewhere.

So first, I'll check continuity of all wires in the cable. If that checks out, I guess I'll have to ship it out to have the power supply and mic components checked - hopefully its not the capsule.

Who's the best for servicing old AKG tube mics? Is there anything you can think of that I can check here with a multimeter?

[Klaus Heyne]

For your own physical safety and that of other DIYers I will not allow trouble shooting tips for high-voltage equipment, well-meaning as they may be, to be posted here.

Troubleshooting dead mics, especially tube mics efficiently requires an experienced hand.

If you are familiar with tube mic electronics, i.e. high voltage, high impedance equipment, (the capsule's acoustic/mechanical functions are most definitely not the problem here) you will know how to trouble shoot system components in a logical sequence.

If not, give some of the starving professional techs a chance! (no, I am currently not available) and let us all know what the problem ended up being!

Best of luck,

[compasspnt]

Whoever you send it to (James Gangwer, SPA, etc.), be sure to specifically tell them NOT to touch the capsule unless absolutely necessary, and only with your explicit approval.

[miics]

Klaus is right, don't play with it if your not with it skill wise as these mics can definitly give you a nasty if you are NOT sure of what you are doing.

cheers

[ryan streber]

This may be a really dumb idea, and I ask Klaus to delete if I'm totally off-base on this.  But, did you (OP) check to see if the tube is firmly seated? A couple years ago, I had a VM1 "die" on me, and I thought I had to send it out for repair.  Luckily I decided to open it up to check for obvious problems, and sure enough the tube had slightly slipped out of its socket and just needed to be reseated.  Since you mentioned that it used to cut out when it was held sideways, maybe it (or something else) was loose and has now become disconnected or lost contact. Just a thought...

No sincere idea is a dumb idea. Great suggestion! K.H.

[7Hz]

If interested to reskin the capsule , welcome to contact me, we can upgrade with our Golden Drop sputtering method also , if needed. And check the components functionality also.

[Tony Merrill]

Rob, we are indeed still in business. Website should show in my signature.

I would take issue with the statement that there is noone who can rediaphragm these and give them the "magic" that was heard in the "original" configuration. And yes, there is a spread, and they can sound wonderful and they can sound awful. I serviced a 251 not long ago which had never been opened - one of the worst sounding 251s I (and several others) have heard. When I opened the head, I confirmed that the capsule was untouched and in "good" condition. With the owner's blessing, I was able to retune the capsule to sound "magical" once again (by more than just my account,) using the original diaphragms.

I would like to reiterate and attempt to COMPLETELY dispel the notion that SPA would EVER do anything to a capsule without the owner's consent. This is a false legend, and I'm really sick of it. Forget it, and tell all your friends to, as well.

[compasspnt]

I would like to know more about "upgrading with the Golden Drop sputtering method."

[J.J. Blair]

Tony, I'm assuming, since you said you made it sound better, using the original diaphragms, that you simply tuned the delay network?

[miics]

compasspnt wrote on Thu, 10 June 2010 04:23

I would like to know more about "upgrading with the Golden Drop sputtering method."

hmm yeah me too.  

[Tim Campbell]

"The Golden Drop sputtering method" refers to sputtering the membrane in an interconnecting lace like pattern instead of a solid coating.

JZ seem to think this has advantages.

I personally haven't noticed any improvements on capsules that have lost gold in random patterns.

[Oliver Archut]

I never tried JZ version of it, but I have tried some experimental versions of that that supposedly were done by the IRT in the 70s.
The general idea is to compensate the frequency responds by changing the static suck, the idea was dropped because the effect is to little to make a big impact, but AKG did something into the same basic direction late 70s early 80s, hotprinting membranes with a pattern that would actually do correct the frequencies issues.

Best regards,