[hackstu]

Bought two gec 6080s off langrex a month back, very happy with sound but after a week or so one went noisy on startup.

The question I'm asking is I don't really know whether to replace the noisy tube as the noise is gone within 7-10 minutes after startup, then there is no more noise after that, also the noise on startup is quite different to what I've experienced in the past, not your traditional huming/popping sound more like a steam train 'chuffing' sound.

Help!

 

[tomb]

One thing to rule out, but you didn't mention it - swap the tubes in the channels and see if the issue follows the tube. It could be the amplifier's circuit in that channel that's acting up.

Assuming it's definitely the tube, it could be any number of things inside the structure of the tube going on. If you have a tube tester, try testing it to see its condition and whether there's a leak or short. If that checks out (assuming you have the tester), try cleaning the pins and perhaps bending them slightly to ensure maximum contact with the tube socket. It could be that the tube heater has developed a somewhat dodgy connection somewhere and during warm up gets a bit noisy. This could be because the current draw is much higher until things heat up and stabilize.

Just some guesses that you can check out ... Bottom line, if you find nothing - quit worrying about it and enjoy the amp after that 7-10 minutes goes by.

 

[hackstu]

Received a replacement today, that seemed to solve the issue, for now anyway.

 

[hackstu]

Well it didn't, because the replacement tube went crackly after an hour and a half, BUT I did try the original tube again in the other socket, and with a strong finger flick to the chassis/amp on startup it was a lot better. So it seems on reflection I have possibly both dirty and slightly loose sockets, yikes.