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Matched pair of tubes, but different glow in each.

A friend of mine just recently got some tubes for his amp, and he noticed that when he turned the amp on, one of the tubes "glows" more than the other one. The sound is the same in both speakers, but he would just like to know what causes this ?
I dont believe that the tubes he purchased were new, but were a matched pair.
riley804

Showing 2 responses by riley804

riley804 OP
1,224 posts
 
Fatparrot and the others that have responded to this, thank you for your information on this.

I will forward this information to him and let him determine what color the "glow" is in the tubes. I will post his answer tomorrow when I have more information to give.

Thanks again,
riley804 OP
1,224 posts
 
I have got a response from my friend and here is what he says :

"The tubes are RCA 6SN7GTB
The amp is a Sun Audio SV-2a3.
The amp is self biasing.
There is mica holding the plates top and bottom. There are two points on top of the top mica and two points on the bottom of the bottom mica that light up, one tube is brighter, it is more orange/yellow and the dull tube is more orange/red in color.
I switched the tubes and the same one stays bright, the sound is balanced and good either way"

Let me know if this is enough information, or do we need more.

Thanks again.
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