New RCA tubes - duds? [resolved]

[pofofo]

Hi,

I bought some new tubes from https://vacuumtubesinc.com/index.php/6fj7.html to have a couple of spares, just in case. I got a pair of RCA tubes. I popped in the tubes and after letting them heat up for about 1-1,5 hours played some music.

The right driver made sound, but the left one was dead. When I adjusted the volume, the left driver just made pretty loud scratching noises (with or without music playing), but no music., no matter how loud I turned the pot. The tubes where also much whiter than my GE stock tubes. I popped in the stock GE tubes, and everything works as it should.

Did I just get some duds, or does the tubes need more burn in time? Any ideas?

My S.E.X:
- Works fine with the GE tubes it came with from Bottlehead
- Wired for 4 ohms
- C4S mod
- Modded with resistors to make a little less power, as seen here:
https://forum.bottlehead.com/index.php?topic=13832.0
- Before I did the resistor mod, I checked the voltages and it where good.
- Connected to Raspberry Pi and Schiit Modi 3


Thanks for the help.

[Paul Birkeland]

It's very unlikely to get two duds like that.  I think in all of the random 6FJ7s I've bought over the last seven or so years, I've gotten two total duds.  What I do run into all the time is corrosion on the pins, and just cleaning them is very likely going to bring these back into operating condition (the ones we sent you may have behaved like this when I first tested them and required some cleaning).  Your local auto parts store will have a red abrasive pad for general auto body work, and you can press the pins into this pad and pull them out a few times and you'll likely find yourself back in business.

[pofofo]

It's very unlikely to get two duds like that.  I think in all of the random 6FJ7s I've bought over the last seven or so years, I've gotten two total duds.  What I do run into all the time is corrosion on the pins, and just cleaning them is very likely going to bring these back into operating condition (the ones we sent you may have behaved like this when I first tested them and required some cleaning).  Your local auto parts store will have a red abrasive pad for general auto body work, and you can press the pins into this pad and pull them out a few times and you'll likely find yourself back in business.

Did just what you said and Im back in business allright, thanks Paul!