G7 noise troubleshooting session. [Solved]

[haima]

Perhaps this is a silly question, but how much gain are you applying?

There will always be some noise of course - perhaps you are just amplifying it too much throughout the whole listening chain and it seems more noisy than it would be in realistic use?

Just something to check...

 

[pasarski]

Sorry I missed that. Good idea to put the capsule back and test. Noise might be acceptable, depending what you're gonna record with it.

 

[Tergo247]

I had the gain set pretty hot; hot enough for the noise to register on the level LEDs of my pre so I could tell easily if it became quieter over the burn in. And it did. I'm hopeful fellas. I'll get a chance this afternoon to get the capsule back in.

 

[Tergo247]

I have the capsule in. I need to crank the pre all the way to the max to get a suitable level just speaking into the mic, and the noise makes what little level I get unusable. Another problem that I've always had is the polarization switching has never worked. The switch does nothing whatsoever. I get the loud pop everyone complains about, but no change in pattern whatsoever. Unrelated issue or clue?

 

[haima]

Have another capsule to try?

 

[Tergo247]

I don't unfortunately. I'm going to hit all the solder joints in the PSU and see if that helps. I can double check my connections more easily if I take it all apart too... I'm thinking if there's a flux ridden ground it could be causing my issues.

 

[haima]

AFAIK it's a good idea to keep all the high impedance stuff very clean of flux and moisture - perhaps try a good flux remover or iso-alcohol and cotton tips/buds.

It's always possible there is something wrong with your capsule - if it's putting out really low level then the mic might seem noisy.

 

[Tergo247]

That was the realization I was coming around to. If I set the pre where I normally have it for condenser mics, the noise is all but imperceptible. Can't tell you how much I want to blow another 300-500 on this project :/ I guess Peluso does capsule refurbishing (that's what I'm using). Maybe I'll see what's up with that. 

 

[haima]

You could ask him to at least TEST the capsule - then you'll know if it's to blame. Perhaps the problem lies elsewhere.  :

 

[haima]

Or get a capsule out of a super cheap condenser to compare? Isn't there Chinese condensers for like $50 now?

 

[Tergo247]

Point taken. I did get an MXL something or other free the other day. Maybe I'll rip that apart... in the meantime I desoldered, defluxed, and resoldered all the joints between the capsule and the 1 gig resistors with no effect. I was sure that would help, they were pretty dirty... That's it for me for today. Thanks a lot for your time Haima.

 

[haima]

Good luck!

 

[Tergo247]

I think I may have it... on the schematic there are a few components marked with an * for an optional feedback circuit. On the PCB there are more components marked with a * than the schematic. Closer examination of the PCB layout states that a * simply means that that particular component should be mounted on the PCB side. Knowing nothing about building microphones, I omitted everything with a *, assuming they were all fb components when in fact, they may be coupling caps! Could it be... thoughts?

 

[pasarski]

Yes you have it. You should only omit 2k2 pot and 100MF cap. You seem to be missing some very important components. No wonder it isn't working properly.. Good luck!

 

[Tergo247]

Haha!! That was totally it! That's why my polar pattern select never worked and my signal level sucked. It sounds great, I can't wait to try it out. I think I'll make a new post that condenses all the problems I had along with pics and sound bytes in the next week. Thanks again everyone! I owe you all my G7!!

 

[haima]

wow! AWESOME. i love simple fixes like that.

Alls well that ends well!  ;D