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[halocline]

Hello,

I recently purchased a pair of older AKG 414 B-ULS. I had used this pair of mics on two previous recording projects (classical music) and I really liked them, so eventually I bought them. I sent them to an authorized AKG repairman to get them checked out. He claims that one of the capsules is dirty, and both should be replaced at a cost of $400 each. I'm concerned that this would really change the character of the mics. I asked him about cleaning the capsules and he said that it can't be done. However, just reading a bit on this forum, it seems that at least some capsules can be cleaned. Would it be possible to get my capsules cleaned?

He also mentioned that the current AKG capsules, at least the ones that he has, are identical to the original capsules in my mics and that changing them would not make them sound like new 414s (i.e XLS) which I do not like nearly as much for my application. I'm a little skeptical about this, but I really don't know.

When I used them before, I did not notice any appreciable difference between the mics, but they were rented out in the period of time between when I used them for my project and and later when I bought them. I did not critically listen to them when I bought them, because I was already very familiar with them, and I'm certain I could return them at any time. I just sent them off to get them checked for any problems.

Thanks for any advice!

[radardoug]

Yes, capsules can be cleaned, but only if they are not too dirty! Sounds a bit odd I know. The AKG design does not suffer from contamination as badly as the Neumann capsules. It really depends how dirty they are. Had you used the microphones recently, and were you happy with them? Do they have any noise floor problems?

[klaus]

To add to and also correct some notions about condenser mic capsule cleaning:

ALL capsules if exposed to dust and other airborne contaminants will eventually need to be cleaned. However, the audible or electrical effect of that contamination will vary from capsule type to capsule type.

AKG's CK12 types- from oldest to current- will potentially dirty up just as much as Neumann capsule types. But the total breakdown and loss of capacitance will happen sooner on some Neumann types, due to the proximity of the two normally highly insulated conductive surfaces, and the arrangement of electrical connection.

Your 'Teflon' CK12 is just as cleanable as any other AKG, Neumann, or whatever other brand of gold-sputtered capsules you may have laying around. The repair person is incorrect in that regard (if he actually said so in the first place). In professional hands, a high-quality condenser capsule that is contaminated can be returned to factory specs in most cases without any detrimental audible effects, and often substantial savings over purchasing a replacement capsule.
Maybe the repair person just did not feel comfortable enough in his technique.

Finally, regarding capsule replacement and its sonic consequences: A replacement capsule, even one that is identical in design to the original it replaces will sound audibly different (unless you are not very observant or don't care about subtleties.)  So it is always a good idea to try capsule restoration first and replacement last- especially when the sound of the original capsule was particularly pleasing.

[halocline]

Thank you for this information. The last time I used the mics was in November. At that time I noticed no problems. They might have been a little noisier than the much newer XLII pair that I compared them to, but I far preferred the character of the sound of the older mics. There was a really big difference. I'll try to find someone else to clean these capsules. Is it appropriate to ask for recommendations on this forum?

Thank you again, I am a novice recording engineer but a very experienced classical musician with a pretty detailed perception of sound, at least for my instrument.

[klaus]

Yes, it is totally appropriate to inquire about services on this forum (I am taking myself out of competition, of course):
This is always a reliable source for information on such matters.

The only taboo: pricing and value discussions, because unscrupulous individuals have repeatedly exploited the forum's authority by trying to add a stamp of approval to their often outlandish pricing with claims like: "as can be verified by the prices mentioned on Klaus Heyne's Mic Lab" (see details in 'Ground Rules').

[Jim Williams]

Besides common contaminents found on capsule surfaces, AKG 414 B-ULS models were packed sealed in a plastic bag. They also had the wind screen over the mic inside that bag. The cloth that covered it sheads fibers. Every new AKG 414 B-ULS came contaminated from the factory with hundreds of these tiny fibers all over the capsule.

When new they are easily whisked away, but once the oils glue them down they can be very difficult to remove. I brought that up to them over 15 years ago, but they don't care and never stopped doing that with the B-ULS and TL models.

[halocline]

Here are photos of each of the capsules. Although its not as dramatic on the photos, one is much dirtier than the other. The first one has lots of spots (dried spit?) while the 2nd looks more like a mirror, except dusty. At least I hope the image gets attached!

[halocline]

Here's the second, much cleaner looking one.

[klaus]

These surfaces need to be cleaned.  The sooner the better.
The lint on the diaphragms is, as  Jim Williams, mentioned, sticking and not leaving again voluntarily.  That indicates that there is now a sticky surface  which promotes permanent attachment of additional airborne particles. 

[Will Russell]

I hope Klaus doesn't mine me "putting him into the competition" by saying that I had him clean the capsules on my 2 414B-ULSs and that came back sounding wonderful.

[zakco]

In your first post you said:

He also mentioned that the current AKG capsules, at least the ones that he has, are identical to the original capsules in my mics and that changing them would not make them sound like new 414s (i.e XLS) which I do not like nearly as much for my application. I'm a little skeptical about this, but I really don't know.

In your second post you said:

They might have been a little noisier than the much newer XLII pair that I compared them to, but I far preferred the character of the sound of the older mics.

Not to nitpick, but could you clarify which newer model you actually did a true A/B test with? The reason I ask, is that the two variations are really quite different. In theory, your B-ULS should be much closer soundwise to the XLS than the XLII which would be closer to the TLII of the past...

Comparing the differences in capsule sound between the B-ULS and the XLII would, IMO, not be much of a worthwhile exercise as the electronic circuits (to my knowledge) are different enough to make any capsule judgment difficult. In other words, are you hearing the capsules or the electronic circuits?

Klaus, if I'm off base here, or these comments are inappropriate for this forum, please accept my apologies and feel free to edit or delete as you see fit...

Zak Cohen

[halocline]

You are correct that I was comparing the B-ULS to the XLII, not the XLS which supposedly has the flatter response as does the B-ULS. It was hardly a comprehensive or scientific test, I just had two pairs, tried them both, liked the sound of the B-ULS mics much better. My point is that I don't really want the character of the mics to change, except I guess we would all like quieter and more complete musical detail. I would imagine that capsule replacement would change character. Although I'm more or less a beginner with regards to evaluating microphones, I'm starting to see that they are more like acoustic instruments than electronic devices. As such, I imagine they're all somewhat individualistic.

Interestingly, I got the mics back and connected them to a good preamp (grace), put on some headphones and crumpled a bit of paper and jungled a set of keys in front of each mic. They did sound different. Then I turned the headphones around and some of the difference stayed in the same ear...I guess the lesson of the day was that my ears are not identical.