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[mike zietsman]

I thought I would post about a topic that comes up fairly often and with which I have had some recent experiences.

Out of the mics that I have had access to the akg c414 has always been one of my preferred mics for my own vocals - I have one of those voices that deals terribly with a u87 (but keep one around because it works 'respectably' on so many voices. )

I have had three versions of the c414 which I have used extensively - namely the buls, the eb p48 and the silver eb with the brass ring ck12 (with the brass ringed ck12 being the most recent acquisition).

The two versions that I have owned the longest always worked very well but I have always had several constant issues to do with their sound.

The three main issues that I have had with them are:

1: Almost universally I found myself having to apply quite heavy cuts in the 120 - 230hz region to compensate for a very obvious resonance there that would otherwise act to blur a lot of higher frequencies and make voices sound obviously muddy.

2: Sibilance (when present) was often 'smeary' and difficult to isolate as it would occur at several harmonics making harshness a problem - it almost seams counterintuitive but this harshness often made it difficult to bring 'airiness' and 'detail' into voices. You would almost expect a harsh mic to have detail but I often found myself thinking that vocals sounded harsh and lacking detail.

3: I found the midrange difficult to sculpt.

Upon using the eb with the brass capsule I noticed an immediate difference for the better in almost all regards.

The 120 - 230ish resonance was completely gone in my room. The midrange was more forward and when I have dealt with sibiliance it has been much easier to deal with and more musical (there is also a great deal more air around the top end that doesn't interfere with anything or sound harsh).

I know that this isn't news to a lot of people on this board but I just thought i would share my experience. I didn't think that the sound difference between two mics in a series could be so drastic. The buls and the ebp48 (barring the level difference) were near identical in sound (and at a quality level that I would rank as being a step or two lower than the u87) whereas the OG silver eb was another level of microphone and one I am glad that I purchased!

This forum was also a great resource in establishing the condition of the capsule (using Klaus's  Figure of 8 technique with the grill removed and power applied I couldn't get the diaphragm to suck to the backplate at all for longer than a millisecond). I feel it is only fair to share my experiences in return.

Thank you to everyone who shares their knowledge. I hope this is useful to someone!

[klaus]

As an owner familiar with three different C414 models, performing an additional test would be fun and quite revealing:
would the original CK12 (brass) capsule make a difference in sound if you were to temporarily transplant it to one of the other two mics?

My guess (i.e. MY experience): you would get about 70% of the EB's sound with the original CK12 capsule placed in the more recent models. The remaining 30% being the electronics/transformer of the P48/BULS.

[mike zietsman]

I considered trying just that but decided to leave well enough alone. After using the mics together for a while I decided I was getting everything I liked about a 414 with way less that I didn't out of the silver eb and sold the other two (I generally do mono vocal recordings). I think mic auditions are vital for learning and trying out new mics, plus the gearhead in me really enjoys them - but after a while I have to force myself to make/record some music! The process certainly made me very eager to hear more mics that used the original brass ringed capsule.

Doing the shootout over a bit of a longer period also taught me a lot about the differences in in real world use and how they aren't just academic at all. Seemingly small differences at the initial recording stage lead to much more tangible differences at the mixing stage. (ie. I found the difference in quality of the microphone to become more significant throughout the process of mixing).

[Peller]

Klaus, could I beg you to share some of your experience regarding membrane tension in these capsules? I have two 414EBs with CK12s. One is fine, while the other is suffering from some tension loss, and can get sucked onto the backplate, especially in fig-8. Is there anything that can be done for it other than a re-skin?

[klaus]

In my experience, a significant amount of original AKG CK12, made from 1953 through 1976, suffer from gradual or complete loss of diaphragm tension. The reduced tension often seems unrelated to use or abuse.

Tension loss may be due to several factors:

* the CK12 diaphragm is rather large and unsupported  in its center, unlike similar-sized Neumann capsules with center lead-out screw

* stand-off nipples mounted into backplates, which prevent electrostatic collapse on most Neumann capsules, are not present on CK12

*Styroflex membrane material seems to be more prone to fatigue than polyester/Mylar/PE

Remedies are, in order of my preference:

1. reverse the capsule, and hope that the diaphragm tension on the rear side is still ok. Then forfit patterns other than cardioid for that mic

2. Replace defective  diaphragm with healthy original CK12 diaphragm from same era

3. Replace entire CK12 with healthy CK12 (both AKG products, of course!)

4. Send capsule to Tim Campbell in Denmark, and have him replace both diaphragms

[Peller]

Thank you Klaus,

That is absolutely the clearest statement on the topic I've ever read!

In your experience, how much of an impact does the gradual tension loss have on sound quality, S/N ratio and so on in the early stages, before it becomes significant enough to cause collapse?

[Nob Turner]

a friend asked me last night what the result might be of putting a brass ck12 in a 414B-ULS. is the circuitry significantly different, such that it wouldn't sound similar to an original 414EB?

[klaus]

Coincidentally, I received an email inquiry from Germany with the same question two days ago, to which I responded (in part):

"in these mics, the capsule contributes about 70% (as if one could assign a number to sensual impressions!) to their overall sound. Installing an original CK12 from the 1970s will therefore have a noticeable impact, but the remaining sound-shaping components of the transplant patient will either augment that new experience or partially negate it. The level of either can only be assessed by the listener's astuteness."

An original CK12 "brass" (as if they weren't all delivered with brass surround!) is an expensive proposition these days, so it may be questionable to invest more than the mic was worth in the first place.

[Jim Williams]

Many of the older EB capsules have been removed and used in other mics. One fellow in California a decade ago bought all he could find and placed them into those AKG "The Tube" mics he bought used for about $500. The remainders are privatly held or are suffering from age and use. It's sort of rare to find clean good condition "c-12" capsules these days. New aftermarket solutions may be the best scenerio.

[Pasarski]

FYI: AKG has started to offer re-skinning of brass CK12's. I got this Information from Mr. Michael Amon of AKG Vienna/Austria who is the technician doing the re-skinning.

[klaus]

Thanks for the info. I will chat with Michael, and report back.

[klaus]

Update:
Corresponded with Michael Amon, and he confirms: he personally re-diaphragms CK12 (old style, with diaphragm screws) with current crop of AKG polyester skins.

I will report back, once I have the information as to shipping and payment logistics (re-diaphragming price per side: €150, or €300 for the whole capsule), and, most importantly: quality of work.

I probably will send him and Tim Campbell each an ELA M 251 capsule, and then compare the outcome.

[Tim Campbell]

Since we're mentioning prices here mine are listed on my webpage. 1100 danish kroner (147.50 euro) for 1 membrane, 1500 danish kroner (201.50 euro)  for both. Shipping is 100 danish kroner (14.00 euro)by Fedex.

[klaus]

Appreciated! And an exception I've made on this forum, because of the extreme rarity of the service, and the high demand for it.

[mike zietsman]

Does anybody know if motorboating (low frequency self oscillation) is ever associated with tension loss in the ck12 capsules in the akg c414eb models?

I replaced all of the tantalum capacitors on mine which made it much better but not perfect?

What are the signs of a ck12 capsule on the way out?

Thanks,
Mike