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Weird ground noise issue with AKG c414 b-xls mics I just got
Old 26th January 2019
  #1
Here for the gear
 

Weird ground noise issue with AKG c414 b-xls mics I just got

Just got a matched pair of C414 B-XLS mics. I record using a Tascam 488 mkii (8 track cassette recorder). For some reason, these AKGs are making a low humming sound only when used with the Tascam.

When I plug the AKGs into my interface and record digitally to my DAW, no humming. If I take that same signal and plug it into the Tascam - humming. If I touch any metal on the mic or cables or the tascam the humming stops or abates.

Now before you conclude the issue is with the Tascam - when I take down the AKGs and plug in my old ADK mics, no humming. There is something about these AKGs that are causing some weird ground issue with the Tascam. I've been recording with this Tascam for 5 years, been using all kinds of different mics - condensers and dynamics both, and I've never had this issue. Has anyone heard of this happening, or have any clue what is going on? Thanks.
Old 1st June 2019
  #2
Gear Nut
 

Quote:
Originally Posted by tmross View Post
Just got a matched pair of C414 B-XLS mics. I record using a Tascam 488 mkii (8 track cassette recorder). For some reason, these AKGs are making a low humming sound only when used with the Tascam.

When I plug the AKGs into my interface and record digitally to my DAW, no humming. If I take that same signal and plug it into the Tascam - humming. If I touch any metal on the mic or cables or the tascam the humming stops or abates.

Now before you conclude the issue is with the Tascam - when I take down the AKGs and plug in my old ADK mics, no humming. There is something about these AKGs that are causing some weird ground issue with the Tascam. I've been recording with this Tascam for 5 years, been using all kinds of different mics - condensers and dynamics both, and I've never had this issue. Has anyone heard of this happening, or have any clue what is going on? Thanks.

Hi tmross, did you fixed it?

I'm having the same problem with that particular mic. Have to do some tests but here's something I'm going to try.

https://wijproductions.com/2016/12/0...-problems/amp/

Best regards
Old 1st June 2019
  #3
Here for the gear
 

I wasn't able to fix it, no. I contacted AKG tech support, they said there were no known issues between the 414 xls and tascams. But since you're having this problem too I think they ought to reconsider this! Tbh I think the circuit in that mic is just way too complicated for its own good, and is probably the root of the incompatibility with older tape machines. The LED light/memory switch system is just impractical and annoying. And who on earth needs 5 different polar patterns. Anyway I sold my pair of XLS's right after AKG told me there were no known issues. I got a shure KSM32 instead and have also been using my ADK Vienna's issue-free. The ADKs sound better than the AKGs anyway. If you like the AKGs I suggest selling the XLS and getting the B-ULS which was the previous model and is just way more simple in design.
Old 1st June 2019
  #4
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nosebleedaudio's Avatar
 

The Tascam is NOT grounded, I would connect a ground wire to the chassis and some other gear that IS grounded..
Old 1st June 2019
  #5
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I'd also ensure that whatever you're using to provide phantom power is really putting out 48v. 414s can act funny without full voltage.
Old 1st June 2019
  #6
Gear Nut
 

Thanks I'll try into another preamplifier.
Old 1st June 2019
  #7
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MarkF48's Avatar
This is the key phrase..... "If I touch any metal on the mic or cables or the tascam the humming stops or abates."

I had this happen as well with a mic (not an AKG) into a USB powered Tascam interface. The USB power in the computer was not grounded well or at all. Touching the mic or cables reduced the hum. As a band-aid fix I grounded the Tascam interface to another piece of gear that was AC grounded using a 1/4" patch cable to create a ground connection. The patch cable did nothing other than give the Tascam a ground and was easy to do.
Old 2nd June 2019
  #8
Quote:
Originally Posted by tmross View Post
I wasn't able to fix it, no. I contacted AKG tech support, they said there were no known issues between the 414 xls and tascams. But since you're having this problem too I think they ought to reconsider this! Tbh I think the circuit in that mic is just way too complicated for its own good, and is probably the root of the incompatibility with older tape machines. The LED light/memory switch system is just impractical and annoying. And who on earth needs 5 different polar patterns. Anyway I sold my pair of XLS's right after AKG told me there were no known issues. I got a shure KSM32 instead and have also been using my ADK Vienna's issue-free. The ADKs sound better than the AKGs anyway. If you like the AKGs I suggest selling the XLS and getting the B-ULS which was the previous model and is just way more simple in design.
I have a fairly similar issue with my AKG C451E's. I sometimes use the preamps of this old Yamaha EM200 desk when putting the 451's on drum OH's as they sound smoother this way. I'm having the hum issue as well. I run external phantom power for this and my fix was to put the phantom in a different power outlet. We have two power outlets in the wall, one providing for the audio stuff and another for the oven, coffee machine and similar. Strangely enough it stops humming feeding through the "non music" outlet.

Could be worth a shot to get a stereo phantom power and try this and then try a different outlet than the Tascam if the hum persists. If the power ain't grounded wear rubber shoes.
Old 5th June 2019
  #9
Gear Nut
 

Quote:
Originally Posted by MarkF48 View Post
This is the key phrase..... "If I touch any metal on the mic or cables or the tascam the humming stops or abates."

I had this happen as well with a mic (not an AKG) into a USB powered Tascam interface. The USB power in the computer was not grounded well or at all. Touching the mic or cables reduced the hum. As a band-aid fix I grounded the Tascam interface to another piece of gear that was AC grounded using a 1/4" patch cable to create a ground connection. The patch cable did nothing other than give the Tascam a ground and was easy to do.
Hi MarkF48, in my case when my hand starts to get close to the mic, the hum goes up from notorious to absurd.

I have a 414 XLII B and a XLII and only the first one is doing the hum.

Both connected to the uphoria umc 404hd.

I did try in different setup (change interfaces) and it seems that is just the combination of the XLII B and the behringer.

Thanks
Old 6th June 2019
  #10
Gear Addict
 
Rentzen's Avatar
I have the same issue with one of my c414 xls mics (the other good one I sold - this one I can't sell because of this issue). Ground hum. Faraday cage thing. I tried taking the mike apart to fix it but didn't but couldn't out how to get rid of the hum. It is very annoying!!!
Old 6th June 2019
  #11
Gear Nut
 

Quote:
Originally Posted by Rentzen View Post
I have the same issue with one of my c414 xls mics (the other good one I sold - this one I can't sell because of this issue). Ground hum. Faraday cage thing. I tried taking the mike apart to fix it but didn't but couldn't out how to get rid of the hum. It is very annoying!!!
Hi Rentzen what gear are you using with it?

I had 50hz hum in the 414 B XLS II in conjuction with the behringer uphoria umc404hd.
The mic only would make the noise in this interface.

I did ask for help in the Music tribe forum and in a couple of posts the gentlemen assisting me got it quickly.

It turns out that this particular mic and interface would not get rid of the ground which was causing the noise, because they are not connected to something with ground isolation.

The solution was simply to conect an active monitor to the output of the umc and since the speaker has ground conection it will go away trough its power cable.

Anyway, I hope to help here as they helped me.

Best regards
Old 6th June 2019
  #12
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Rentzen's Avatar
Quote:
Originally Posted by Borja View Post
Hi Rentzen what gear are you using with it?

I had 50hz hum in the 414 B XLS II in conjuction with the behringer uphoria umc404hd.
The mic only would make the noise in this interface.

I did ask for help in the Music tribe forum and in a couple of posts the gentlemen assisting me got it quickly.

It turns out that this particular mic and interface would not get rid of the ground which was causing the noise, because they are not connected to something with ground isolation.

The solution was simply to conect an active monitor to the output of the umc and since the speaker has ground conection it will go away trough its power cable.

Anyway, I hope to help here as they helped me.

Best regards
Thanks for the reply!

I am using the mic with a RME UCX and my monitors are Focals CMS65.

It is a long time since I've been using the c414 - I only took it out to repair it and sell it, so I haven't tried it with other pre-amps for example to see if that would help (I own a Line Audio pre-amp and a Universal Audio 2108).

I do know that the hum disappears if I gently press the mesh / screen (or what it is called).
This suggests to me that it is some kind of soldering that has gone loose as I have read in the link above, from an earlier post, that the mesh works as this faraday cage - maybe I am completely off :-)

I will try and do some more research and all help is very much appreciated
Old 6th June 2019
  #13
Gear Nut
 

Quote:
Originally Posted by Rentzen View Post
Thanks for the reply!

I am using the mic with a RME UCX and my monitors are Focals CMS65.

It is a long time since I've been using the c414 - I only took it out to repair it and sell it, so I haven't tried it with other pre-amps for example to see if that would help (I own a Line Audio pre-amp and a Universal Audio 2108).

I do know that the hum disappears if I gently press the mesh / screen (or what it is called).
This suggests to me that it is some kind of soldering that has gone loose as I have read in the link above, from an earlier post, that the mesh works as this faraday cage - maybe I am completely off :-)

I will try and do some more research and all help is very much appreciated
Yes. In my case when I pressed the grill the hum went away.
And it seems that you're using an usb interface as well as me.
I would try to connect the mic in another interface to see if its the RME or the mic or a combination of both.
Old 6th June 2019
  #14
Gear Addict
 
Rentzen's Avatar
Quote:
Originally Posted by Borja View Post
Yes. In my case when I pressed the grill the hum went away.
And it seems that you're using an usb interface as well as me.
I would try to connect the mic in another interface to see if its the RME or the mic or a combination of both.
I'll check it and report back!
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