Noisy c414 eb p48

[Whoops]

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!

yes Dont buy capacitors for a good microphone from a local store.
Buy from a good brand from Farnel or Mouser

 

[ricardo]

If you want change every electolytic for tantal, just buy some reputable manufacturer like Roederstein etc.

DON'T USE TANTALUMS.  THEY ARE EVIL FOR LOW NOISE APPLICATIONS.

Today, there are low leakage Aluminium electrolytics which can replace evil Tants in all important paths.  About the only thing Tants are good for is decoupling digital circuits and even there, there are better modern Aluminium equivalents.

.. and this is apart from the failure & reliability issues with Tants that are well documented elsewhere.

Of course if you feel Tants add that extra frisson that makes your girlfriend, wife, mother etc sound like Linda Rondstadt, just ignore everything I say 

 

[ln76d]

Oh man - ricardo - by electrolytic i had in mind tantalum electrolytic, this circuit originaly use tants - i didn't had any issues after recapping tants when used higher voltage ratings. Microphone is used very often.
With most important - output cap - i changed it for film cap.

 

[gbruler]

Ok so we have finally found the problem. C12 (22n) was causing all the noise. When replacing it with a new capacitor it introduced this noise (Which I've mentioned on my last post):
https://drive.google.com/file/d/0ByyLGJW4qi4eV2ZBQjZxQXM5Ujg/view?usp=sharing
I should mention that it's a very high gain, and we probably won't notice the noise on things like drums or strummed guitar, but it is annoying so I should probably replace the capacitor with one that is suitable for microphonic use, would love your help with that (if you could find me a link of a specific cap it would be awesome, as I'm not the tech and I get lost very fast browsing for the right thing)

Thank you very much for all you help!

 

[ln76d]

http://uk.farnell.com/multicomp/mcrr50223x7rk0100/cap-cer-x7r-22nf-100v-rad/dp/1216433

Hard to find C0G/NP0 with these value and THT.

X7R is sufficient.

Change all three 22nF in the circuit!
Check all ground connections of it.

Here you have update document for RF protection for the first run of EB/P48.
http://www.oocities.org/siliconvalley/peaks/5212/p48_2.pdf

Check do you have all ground connections mentioned.

 

[ostudio]

any pictures from inside mic please?

 

[gbruler]

Hey thanks!
I'm not too sure what is the difference between C0G/NP0 to X7R but I've found those on Mouser:

http://www.mouser.co.il/Passive-Components/Capacitors/Ceramic-Capacitors/MLCCs-Multilayer-Ceramic-Capacitors/Multilayer-Ceramic-Capacitors-MLCC-Leaded/_/N-bkrdj?P=1z0wpseZ1z0z7l5Z1z0x6d8Z1yx4atuZ1yxboka&Keyword=Multilayer+Ceramic+Capacitor&FS=True

Will any of those be good? The store you gave me don't do deliveries to my country so I had to look in Mouser anyway..
Thanks!

btw I'll get some photos when we'll have some time to open the mic up

 

[ln76d]

http://www.mouser.co.il/ProductDetail/Kemet/C330C223K1G5TA/?qs=sGAEpiMZZMt3KoXD5rJ2N0ob%252b6zuDzkKjyemIpZhJP4%3d

These are Über-fine!

Difference is in dielectric.
C0G/NP0 dielectric is one of the best which you can buy.