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Help! Bad Tube Mic hum
Old 12th August 2005
  #1
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Help! Bad Tube Mic hum

I just purchased a very nice U47 flavored mic and I am getting a noticable hum at about 200 hz....loud enough to make it unusable........i had the mic tech look at it and everything sounded fine in his studio....when I plug it back in back in my studio the hum is still there big time.........I have tried ungrounding the plug......Moving the mic out of my home studio.......tried different outlets.......have shut off all appliances throughout the house and I am still getting the hum............All my other mics do not hum only this one...........Is it possible I have dirty power running throughtout the house and studio.......I do have the basic Furman voltage regulators and power condtioners throuout my studio ..........Is there anything I could buy that would possibly clean up my power.....something that I could plug into one of my wall sockets and the plug the Tube mic into that. device.....I love the sound of this mic but this hum is unaceptable......ANY HELP IS GREATLY APPRECATED !!!!

Thanks
Old 12th August 2005
  #2


Are you using +48v phantom power?

200Hz is not typical of AC noise in the states.



-tINY

Old 12th August 2005
  #3
Gear Maniac
 
Mrs. Fairman's Avatar
 

Quote:
Originally Posted by ron florentine
I just purchased a very nice U47 flavored mic and I am getting a noticable hum at about 200 hz....loud enough to make it unusable........i had the mic tech look at it and everything sounded fine in his studio....when I plug it back in back in my studio the hum is still there big time.........I have tried ungrounding the plug......Moving the mic out of my home studio.......tried different outlets.......have shut off all appliances throughout the house and I am still getting the hum............All my other mics do not hum only this one...........Is it possible I have dirty power running throughtout the house and studio.......I do have the basic Furman voltage regulators and power condtioners throuout my studio ..........Is there anything I could buy that would possibly clean up my power.....something that I could plug into one of my wall sockets and the plug the Tube mic into that. device.....I love the sound of this mic but this hum is unaceptable......ANY HELP IS GREATLY APPRECATED !!!!

Thanks

Send please a picture with Hz of measurement. 200 Hz not possible.
50/60 or many, many lower... the harmonic waves 100/120 cycles per second.

Send please a picture of microphone.
Ein picture of the opened PSU and microphone.


... PSU.. Elko defectively?
Old 12th August 2005
  #4
Lives for gear
 

It might not be 200 hz....it is a low hum....possibly I am hearing the harmonics on top of the main fundamantal buzz......I matched it between B flat and B natual on my guitar........I am not a tech guy so be easy on me.........I just needed some info on something I could purchase or try before i return the mic that would elimanate the hum promblem.Thank You!
Old 15th August 2005
  #5
Gear Head
 
Marty Shields.'s Avatar
 

If you have annother mike that uses the remote power from your pre or desk, see if that hums, if it does the phantom power from your supply is dirty, and you may need a new cap or 2, if this isn't the case, try changing the lead on the noisy mic and see if that works, Marty.
Old 29th November 2016
  #6
Here for the gear
 

I got the same problem bro can it be the fans off of the pc?
Old 29th November 2016
  #7
Gear Addict
 
Dan Popp's Avatar
This sounds very similar to a problem I had with a transformer mic. Try turning the mic in different directions. If the hum varies by position, it's possible that it's acting as an antenna, picking up electromagnetic interference.

Your other mics that don't exhibit the problem - are they tranformer coupled, or TLM-type?
Old 30th November 2016
  #8
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try a different mic pre. modern mic preamps, especially the ones integrated into interfaces are mid -z (around 2.5K) and would be out of tolerance with a microphone 200 ohm and less out z

the "10x rule" is actually an impedance tolerance. the more away from the actual impedance more noise is measured and audible.
Old 30th November 2016
  #9
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nosebleedaudio's Avatar
 

Sorry but DrTechno is wrong.
Just look at the specs for the Pre @ 200 Ohms...
The lower the MIC impedance the lower the noise from the Pre..
The "So called" 10X times rule is for minimum LOADING of the Mic...
The fact is some Mics are very happy with 5 to 6 times Load Impedance (Mic pre Input Imp.)..

Last edited by nosebleedaudio; 30th November 2016 at 03:30 PM..
Old 30th November 2016
  #10
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whatever, change the mic pre.

Its out of the tolerance range.
Old 30th November 2016
  #11
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anything 600 ohms or less should be revised to be more compatible with modern equipment.

there is no reason for 200 ohm output on those mics. nothing magical happens and the step down is a weak link to begin with in those designs.
Old 30th November 2016
  #12
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now if interface people would wise up, and put an impedance buffer (like what the cloudlifter circuit is) that can be switched out then things could be more compatible, but its only putting a bandage on the situation because of the bad design in the microphone.

btw the cloudlifter cost less than $5 to build. so integrading <$5/channel shouldn’t be a big deal for the interface guys.
Old 30th November 2016
  #13
Lives for gear
I dunno an extra $5 a channel is huge for those manufactures. They'll squabble over a few pennies never mind upwards of $40 on an 8 channel interface for an issue that will only affect a few users (and noticed by only a few of those few affected).
Old 30th November 2016
  #14
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Quote:
Originally Posted by enginefire View Post
I dunno an extra $5 a channel is huge for those manufactures. They'll squabble over a few pennies never mind upwards of $40 on an 8 channel interface for an issue that will only affect a few users (and noticed by only a few of those few affected).
you might be right considering most of them shave off a few cents when they use coupling caps 1/4 of the size that supposed to be in ADCs. But of course, that is where Black lion made most of their money these past few decades exploiting this.
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