Noisy c414 eb p48

Thank you ver much guys for all the comments!
I'll go with Tim's advice and not touch the capsule, we'll do the PCB cleaning on the weekend and will let you know if it solved the problem, I really hope it does.

I'll ask again because no one answered the first time, using a CK12 capsule to mic a bass or guitar cabinet is not a good idea, is it true for the k47\M7 capsule too?
Thanks

sorry but i don't speculate at all , i just try to explain your capsule destruction !

to resume it was a chemical reaction with diluted isopropanol or other alcohol
however, i never seen a chemical reaction with diluted isopropanol and gold/mylar/brass/good quality plastic on 100 cleaning

BUT Gefell M7 were using PVC for their M7 ! (like Neumann)

i would not use a solvant on PVC membranes for stiffing/crackling/dilution issues

I mean that you speculate about how someone could possibly make something not about the effect
I agree - with chemical reaction - i wrote that in the first place.
Now i would also not use for PVC any solvant - but i wanted to try - this capsule also needed a reskin (second side was unglued) and overall condition was poor.  I wouldn't risk on a good capsule - and that's why i don't recommend this to the people which have no experience. Water always will be safer.
Overall i can say, that for now i have no need to use any solvant.
Last year i cleaned at least 30 capsules - all looks good, all works good.

gbruler said:

I'll ask again because no one answered the first time, using a CK12 capsule to mic a bass or guitar cabinet is not a good idea, is it true for the k47\M7 capsule too?
Thanks

Click to expand...

No it's not.
All depends on many factors even for CK12. With different polarisation voltage the capsule will work little bit different for example - different diaphragms stiffness.
Do you have original capsule for this microphone?
So called "Teflon CK12" if are in good condition can handle really loud sources without problem.

ln76d said:

I mean that you speculate about how someone could possibly make something not about the effect
I agree - with chemical reaction - i wrote that in the first place.
Now i would also not use for PVC any solvant - but i wanted to try - this capsule also needed a reskin (second side was unglued) and overall condition was poor.  I wouldn't risk on a good capsule - and that's why i don't recommend this to the people which have no experience. Water always will be safer.
Overall i can say, that for now i have no need to use any solvant.
Last year i cleaned at least 30 capsules - all looks good, all works good.

Click to expand...

hmm , true but is it fair enough to say that only water for moderately dirty capsules (dust) and diluted solvant for highly dirty capsules (grease), and no solvant for PVC ?

Yes it is.  And i don't had this completely in mind  to don't agree with that.
I said before that i agree with your method and each one have it own methods -  but when i don't need (even for really yucky bastards) solvant am not using it at all - this is simple thing to check - using only water first and when there is no good effect then are always other possibilities to finish the work in the other way.

good, thanks
but i do it differently
i clean capsules not for visually aspects but only when insulation is lost (sonic reasons), and that kind of contamination imposes me a solvant in 90% of the cases
if you have found a method to dilute the fats and oils with only temperate water, please tell us because i haven't found one.
however, if it's your job i can understand you will keep it for you

gbruler don't use any mic on a bass cabinet that's expensive and not designed to handle those kind of spl's.
Dynamic mics like those designed for bass drums are great in that application. If you want the top end of a condenser mic move it farther back and just sum it with the dynamic.

granger.frederic said:

good, thanks
but i do it differently
i clean capsules not for visually aspects but only when insulation is lost (sonic reasons), and that kind of contamination imposes me a solvant in 90% of the cases
if you have found a method to dilute the fats and oils with only temperate water, please tell us because i haven't found one.
however, if it's your job i can understand you will keep it for you

Click to expand...

Of course am cleaning for sonic aspects ;D
When the capsule works fine and looks not so fresh am not cleaning it for better look
If something isn't broken - don't fix it
Let say that my clients dont eat fat fries or drink oil before vocal recording so i had no problem with fat or oil.
If we count fingerprints (many people have sticky hands) - i had no problem with clean it with the water.
If i will have mentioned problem and i will have to use something different than water or isopropyl with water i will let you know guys. Am not from those which want to take all the secrets to the grave

Tim Campbell said:

gbruler don't use any mic on a bass cabinet that's expensive and not designed to handle those kind of spl's.
Dynamic mics like those designed for bass drums are great in that application. If you want the top end of a condenser mic move it farther back and just sum it with the dynamic.

Click to expand...

I was thinkiing that this is obvious
If not - yes i agree with Tim. Also condenser microphones in close applications with bass guitar doesn't sound good in my opinion.
So even if it can handle high spl and will not die after one verse - one chorus - i would use LDC  microphone at least one meter from the cab to take fuller whole cabinet spectrum with some add of the room and mix  it with some decent dynamic microphone like D12 family, MD421, RE20 and others.

Duplicate post.

Am not from those which want to take all the secrets to the grave

Click to expand...

Too many of those and you wouldn't have a DIY forum, methinks.  :

Of course am cleaning for sonic aspects ;D
When the capsule works fine and looks not so fresh am not cleaning it for better look
If something isn't broken - don't fix it
Let say that my clients dont eat fat fries or drink oil before vocal recording so i had no problem with fat or oil.
If we count fingerprints (many people have sticky hands) - i had no problem with clean it with the water.
If i will have mentioned problem and i will have to use something different than water or isopropyl with water i will let you know guys. Am not from those which want to take all the secrets to the grave

[/quote]

i fact the process of contamination comes mainly from the saliva , fog , blast waves and various other things that are coming out of the singer's mouth ... :-\

in fact it comes also with time only, as the air contains some micro-particles of fat amongst other things, and static condenser capsules , by definition , are static and have a poor tendency to attract those particles...

we're talking about old,used and dirty capsules, thus there is necessarily grease/fat/oil on those capsules

you can add nicotine/human cells/micro-organisms... etc...

i doubt you can clean all that stuff with only distilled water , otherwise i would not eat with your cutlery (i'm kidding)

I could write - you wanna bet? - but i'll not
It's a splitting a hairs.
I love to debate but this topic isn't worth that many posts.
I don't like ping-pong topics or pissing contests
Believe, not believe. Don't care.
Last time - you have your methods i have mine other people probably have their own.
Do we have to prove anything to each other?
When i will get some interesting specimen i will specially make for you video or at least put some pictures.
I think that from my side is the time to say stop

It's quite relevant , on the contrary
A capsule can be considered as a consumable in a vocal use ...
After years of recordings , these can be restored to (near) original specs with a good cleaning
An accurate method can be efficient , and a bad can be  more or less unefficient to devastating
Distilled water is the simplest solvent and is enough for the lowest contaminations (my opinion...)
you can still use for the highly contaminated capsules , or you can realize that distilled water is not enough efficient on very dirty capsules , and use another solvent.
choice is yours !
regards
Fred

I've cleaned a lot of AKG and Neumann Capsules.

Only use Distilled water and a really soft brush. If you have to use the brush use really light circular movements.
Never had any problem, and never damaged the gold outer layer using this method.

I would never, ever use alcohol or any other solvent in a capsule even if it's diluted.
It can be dangerous and quite aggressive to the capsule materials, also Distilled Water works really good on it's own.

Neumann says the same thing also:



Neumann tech doc on cleaning the capsules:
www.neumann.com/download.php?download=info0028.PDF

more info:
https://www.brownsound.net/cleaning-a-u87-capsule/

Hey, a little update, we have tried to clean the PCB, the switches and basically anything you guys have suggested (except for the capsule of course), and nothing has changed. Our next step will be to replace the capacitors, even though we did that a year ago. Any recommendation on specific capacitors you've had good experience with or suggestion of more things to look at are very welcome!
Thank you

You should post pictures of the capsule.

Could it be a transistor failure?

Try replacing the capsule with capacitors again and see if the noise is still present while operating all switches.
Sometimes it is necessary to clean the switches 2 or 3 times.
Since the mic has been repaired could it be a cold solder joint?

If it's the capsule email me and I'll tell you how best to mail it to me.

gbruler said:

Hey, a little update, we have tried to clean the PCB, the switches and basically anything you guys have suggested (except for the capsule of course), and nothing has changed. Our next step will be to replace the capacitors, even though we did that a year ago. Any recommendation on specific capacitors you've had good experience with or suggestion of more things to look at are very welcome!
Thank you

Click to expand...

Check is your circuit updated for RF protection.
http://www.oocities.org/siliconvalley/peaks/5212/p48_2.pdf

For capacitors:  C7 have tendency to failure and there's a really good  improvement with changing C11 (which also have tendency to failure).
I used 6.8uF/63V tantal for C7 but it can be also aluminium elctrolytic.
For C11 i used 3.3uF Evox rifa MMK (MKT) - you will have to make a little more space to fit it but it is possible and really worth.

Hey guys!
We have finally had some time to deal with the microphone again and I'm happy to say that I think that it's not the capsule that causes the noise.  We have managed to get rid of the weird noise, my dad replaced some capacitors and he says that he is not sure which one caused the problem, but it has to be C13, C14, C12, C11 or C17. Well, we are still not finished, as now there is a weird noise around 3k and the signal to noise is not that great. You can really hear the noise when you switch to cardioid, it takes  a couple of seconds to get stable. Also, the EQ analyzer shows a constant rumble under 50hz, I couldn't really hear it with my ears though.
Here is a short clip on Cardioid position, I'm holding the mic with my hand, about 5 inches away.

https://drive.google.com/file/d/0ByyLGJW4qi4ecHdjVlNsRF9KWXM/view?usp=sharing

Our guess is that the mic might be working well now, but the capacitors we have bought are not suitable for a microphone (my dad just bought them from a local store), so if you guys think that's the case, I would really appreciate it if you could give us recommendation for better capacitors which we can order online.
Thank you very much!

Switching noise, which disapear after few sec. is normal behavior in this microphone.
If you want change every electolytic for tantal, just buy some reputable manufacturer like Roederstein etc.
Buy caps with higher voltage ratings than original.
For C11 you have my recommendation above - worth.