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Solution to Humming Noise From New 6SN7 Tubes

post #1 of 6
11/11/11 at 2:06pm
Thread Starter 

I am one of those who had humming noise with 6SN7 new tubes on Darkvoice 336SE headphone amp. After reading many threads including suggestions for Mod I had hard time to believe Darkvoice would design and manufacture any amp that would not work well with driver tube (6SN7).  I didn't feel like modifying the amp even it's simple to do.  I preferred finding a solution that not requiring modification because I believed that any modification to the amp is going to change the design intend of the product and it could also lead to sound signature change or else.

I contacted Darkvoice and they provided me with a simple suggestion:  Aging the new tube.

 

By following their instruction my 6SN7 tubes are now quiet and sounding really sweet.

The aging process time varies depending on how loud the humming noise you have on individual tube.  One of my 6SN7 took 120 continued burn-in hours to get rid of the humming noise completely. Below is what I suggest you to try before doing any mod to your amp:

 

  1. There are total of two stock tubes in Darkvoice 336SE Headphone AMP (back tube: 6N5P  |  front tube: 6N8P).
  2. Remove back tube-6N5P( leave the socket empty).
  3. Keep 6SN7 tube (the new tube that has humming noise) in its socket.
  4. Turn on the Headphone AMP and leave it on continuously for 48 hours (for burn-in the new 6SN7 tube).
  5. After 48 hours put the back tube 6N5P back to its socket and listen to it.
  6. Continue burn-in process If humming noise is still persist, until it's gone.

 


Edited by ksan - 11/11/11 at 2:09pm
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post #2 of 6
11/12/11 at 12:47am
Quote:
Originally Posted by ksan View Post

I am one of those who had humming noise with 6SN7 new tubes on Darkvoice 336SE .....................

 

I contacted Darkvoice and they provided me with a simple suggestion:  Aging the new tube.

..........


Most of the time, vacuum tubes which have been kept unused in storage have to undergo "tube conditioning".

Residual gases have a way of accumulating inside the unused tube.

These gases have to be "burnt off" over 24hrs before your vacuum tube can settle in.

 

There is a very well written article about tube conditioning at the following link:-

 

http://www.kk5dr.com/Tubes.html

 

I consider this article to be a classic on burn-in w.r.t. vacuum tubes.

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post #3 of 6
11/13/11 at 8:25am
Quote:
Originally Posted by Lord Soth View Post


Most of the time, vacuum tubes which have been kept unused in storage have to undergo "tube conditioning".

Residual gases have a way of accumulating inside the unused tube.

These gases have to be "burnt off" over 24hrs before your vacuum tube can settle in.

 

There is a very well written article about tube conditioning at the following link:-

 

http://www.kk5dr.com/Tubes.html

 

I consider this article to be a classic on burn-in w.r.t. vacuum tubes.


That's a great link, but in scanning it I didn't see any mention of tube getters (maybe power grid tubes are different).  Every audio tube was designed and built with getters in the tube for the very reason mentioned - something was needed to "burn off" gas infiltration.  As noted here and elsewhere with NOS tubes that have sat on the shelves for 40-50 years, it takes time to burn off the accumulated gases inside the tube.
 

 

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post #4 of 6
11/13/11 at 9:20am

Another shortcut I've found is to use a high impedance headphones, only sensitive phones (300 and under) produce any audible humming noise.

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post #5 of 6
11/13/11 at 9:30pm
Thread Starter 
Quote:
Originally Posted by Lord Soth View Post


Most of the time, vacuum tubes which have been kept unused in storage have to undergo "tube conditioning".

Residual gases have a way of accumulating inside the unused tube.

These gases have to be "burnt off" over 24hrs before your vacuum tube can settle in.

 

There is a very well written article about tube conditioning at the following link:-

 

http://www.kk5dr.com/Tubes.html

 

I consider this article to be a classic on burn-in w.r.t. vacuum tubes.

 

Thanks Lord Soth, the article is very educational material and it helps a lot.



 

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post #6 of 6
11/14/11 at 2:19pm

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Edited by Grado77 - 5/18/12 at 3:03am
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