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My mic gives 50hz noise ...
Old 28th January 2007
  #1
Gear Head
 

My mic gives 50hz noise ...

Hello,

I've got a pair of T-bone SC-100II which are the same as the apex 185 http://www.apexelectronics.com/index.php?tmp=4&id=79

When I plug them to my gold mike preamp a lowend noise like AC 50Hz comes.
If I touch one of them, the hum stops!

If I plug other electrostatics mike in this preamp, the sound is ok. If I plug only one of the apex 185, the noise appears.

I tried ground lifting the preamp but it doesn't change nothing at all. I check the cables, they are ok.

I record acoustic nylon string guitars so the level is really low. I discovered the low-end noise this way.

Do you know how to remove this hum noise because these mics in themself are quite nice for the price?

Thank you in advance for your advice.

Best regards

Damien
Old 29th January 2007
  #2
Gear Head
 

Do you think a Behringer micro HD400 could help between the preamp and the soundcard inputs?
it's a kind of transfo that balance the signal to remove hum.
http://www.zzounds.com/item--BEHHD400
Old 29th January 2007
  #3
BVB
Gear Maniac
 

Hi ,

You can check if the body of your mic is grounded or not.
Take an ohm multimeter and measure between the body and pin 1 of the mic.
You should read 0 ohm.

Greets
Paul
Old 14th May 2014
  #4
Here for the gear
 

Quote:
Originally Posted by BVB View Post
Hi ,

You can check if the body of your mic is grounded or not.
Take an ohm multimeter and measure between the body and pin 1 of the mic.
You should read 0 ohm.

Greets
Paul
I have the same problem. I am using MXL770 condenser mic with a Yamaha ML10 mixer and TASCAM DP-008 portable digital studio. I tried your suggestion, the ohm meter read zero. I have tried changing out 4 different xlr cords, some were worse than others, but they all had the same hum. I've even tried using just the digital record, and just the mixer, no difference. The mic has a -10dB pre-attenuation switch and a 6 dB/octave @ 150Hz high pass switch. I have tried with both switches on and/or off. It is a brand new mic, could there be a factory defect? Any suggestions?

AZCrooner
Old 14th May 2014
  #5
Lives for gear
 
Ike Zimbel's Avatar
 

Hi,
Mics usually hum like that because the capsule is not properly shielded. If you are reading 0 ohms between the mic body and Pin-1 of the XLR, try the same test to the screen over the capsule. If it reads anything much above 0, it may not be making proper contact with the rest of the mic body. Try gently tightening any screws or rings that hold the mic together.
Best,
Ike
Old 14th May 2014
  #6
Lives for gear
 

As a test try:
a] A different brand of mic pre-amp.
b] A different building.
Old 14th May 2014
  #7
Here for the gear
 

hi, (since Apex 180 and MXL 603 appear to be similar (and being slightly familiar with 603S)--I'm speculating a bit here, so just FWIW) since hum reduces when the mic body is touched, this would suggest it isn't grounded. Therefore (as Ike Zimbel suggests above but with a bit more specificity) you might try removing the mic housing (the main long "tube" portion which unscrews from the top capsule end portion), look for two small screws at the output XLR end, and (definitely if they are loose) carefully tighten the screws to ensure that the ends break through the PCB "resist" (green coating) and they contact circuit ground on the PCB. Be very judicious with the amount of force since you don't want to strip these screws.
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