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Tube mic static noise problem Multi-Channel Preamps
Old 12th June 2017
  #1
Gear Head
 

Tube mic static noise problem

Hi,

I just acquired a Manley Reference Cardioid tube mic, bought it from a friend.

When I tested it in my studio, there's a noticeable background noise (hum, static?), I posted a sample of it here. (more noticeable if listened through headphones)

I compared it to my other mics (AKG C414 TL-II, Neumann TLM103), but the others are clean.

My signal chain is Manley Mic -> Avedis MA5 Preamp -> Lynx Aurora

Other preamps used are API 3124 and Vintech X73i.

Tried to swap preamp, mic cable, plugged the power supply to another electric socket, checked the ground, but no luck. The noise is still there.

Could it be the tube?

Or should I use something like Furman/Samson Power Conditioner to get rid of the noise?

Or any suggestion that would help, will be appreciated.

Thanks in advance,
Ari
Attached Files

MANLEY MP3 TEST.mp3 (255.9 KB, 1890 views)


Last edited by bolehnggak; 12th June 2017 at 11:07 AM..
Old 13th June 2017
  #2
Lives for gear
 
teleharmonium's Avatar
 

Quote:
Originally Posted by bolehnggak View Post
Hi,

I just acquired a Manley Reference Cardioid tube mic, bought it from a friend.

When I tested it in my studio, there's a noticeable background noise (hum, static?), I posted a sample of it here. (more noticeable if listened through headphones)

I compared it to my other mics (AKG C414 TL-II, Neumann TLM103), but the others are clean.

My signal chain is Manley Mic -> Avedis MA5 Preamp -> Lynx Aurora

Other preamps used are API 3124 and Vintech X73i.

Tried to swap preamp, mic cable, plugged the power supply to another electric socket, checked the ground, but no luck. The noise is still there.

Could it be the tube?

Or should I use something like Furman/Samson Power Conditioner to get rid of the noise?

Or any suggestion that would help, will be appreciated.

Thanks in advance,
Ari
I would suggest troubleshooting possible causes in the order of simplest and cheapest. It could be the tube, but that doesn't necessarily mean it's bad; sometimes a tube isn't well seated in the socket, or has some buildup on the pins. So to start with you can pull it out, check the pins, and if they look dark or uneven you can carefully clean them.

The best way to do this is with the type of ProGold that is rated for very high temperature, and a tube pin straightener or a spare socket; you would spray or wipe the pins and then insert them (straight up and down) a few times.

Those supplies aren't expensive, but if you don't have much tube gear and want a quick answer you can also carefully clean the pins with a clean nail file or fine steel wool (away from the rest of the mic and your other equipment).

If that doesn't work, next I would put the mic in a sealed box with silica gel packets for a couple of days. Humidity can be a problem for the capsules. After that, I would try swapping the tube.

That's all I can think of for the non technical stuff; from there I would take it to a pro to check the electronics and capsule in the mic and the power supply.
Old 14th June 2017
  #3
Gear Head
 

Thanks for the answer teleharmonium, will try to check the tube. I got the mic from a friend, two days before I tested the mic. Back at his place, the mic had no problem, that's why I bought it. We don't live in the same city, so to have the mic tested back at his place would be quite a hassle. My best bet is to try to fix the mic here.

Thanks again,
Ari
Old 14th June 2017
  #4
Lives for gear
 
HandCrafted Lab's Avatar
 

May be, you need just for some warm up time......day, or few days, being powered up, to recover some internal tube normal conditions.
This also can happen after long time with no mic usage.

Other case - tube can be old and need to be refreshed, lifespan end.
Old 17th June 2017
  #5
Gear Head
 

Thanks for the answer, HandCrafted Lab.

Could be, since the mic was rarely used by the previous owner.

I tried the mic again yesterday, now is up in my room instead of the studio.
The mic was humming, but then i touch the grille, and the hum was kinda faded away.. and then it was no hum.. for a few minutes.

Then the hum came back, then I touch the grille again, then it happened again, the hum faded, gone. but this time, seems that it was gone for good, I even did an acoustic guitar track with the mic, which performed beautifully. It was clear, until I finished recording and using the mic.

Could it be the thing that you said, longer warm up time?

What I'm confused is that, if it's the ground problem, then when I touched the grille, shouldn't it immediately stop humming, and the moment that I stop touching the mic, it would be hum again. Right?
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