[chesebert]

This is the stock pair of tubes that came with the DV 332. When I first turn the amp on it was nice and warm (sound wise)..now the amp developed some really nasty high notes in the 4-5Khz range ..oh so lovely teeth sounds just gushing out of every album of mine. I pulled the tubes and took a pic. Has these tubes gone to tube heaven?

 

[Rise To The Top]

U wanna fix the title to this? I have no experience with tubes, but the improper title caught my eye.

 

[chesebert]

yes I did notice a grammar mistake. fixed now..thanks.

 

[Roam]

Would you happen to know approximately how many hours are on those tubes?

The dark area on the glass would point towards one of two things given what you've noted in the sound. The tube could just be plain worn out after a long life. Or, the tube could be prematurely pooched from suffering full-power oscillations due to something wrong with the amp, it's possible the internal wiring got nudged or there's a questionable solder joint inside.

 

[chesebert]

Quote:

Originally Posted by Roam /img/forum/go_quote.gif Would you happen to know approximately how many hours are on those tubes? The dark area on the glass would point towards one of two things given what you've noted in the sound. The tube could just be plain worn out after a long life. Or, the tube could be prematurely pooched from suffering full-power oscillations due to something wrong with the amp, it's possible the internal wiring got nudged or there's a questionable solder joint inside.

I had about 200 hours on there IIRC. So are these tubes bad? I hardly touched the amp..what could have happened?

Couple Options:
1. buy a new set of tubes and see if it works better
2. open up the amp (is it even safe?) and see if anything is wrong (how would I even test the amp? I have 0 knowledge on valves)?

I like option 1 better, but if its throwing good tube against bad amp then it may not be such a good idea.

 

[cclragnarok]

You can get quality replacement tubes for the 332 for pretty cheap, so I would replace the tubes first.

 

[chesebert]

I just called the manufacturer (god..it pays to speak Chinese), he said these dark spots are normal after 200hrs of continuous operation. Is he right?

 

[asebastian0]

My 6c336 tend to turn dark in certain areas within a few minutes but sound fine. Have had some 6922 do a similar thing but at the top. Replace them, hopefully that fixes the problem! [Also some of my tubes never do this] Either way, if it looks like a worn out tube and sounds like a worn out tube, its probably a worn out tube.

 

[jamato8]

You can't tell if a tube is bad by the color on the glass. If the getter has turned white the tube has lost vacuum but darkened areas don't mean anything except some electrons have flowed. If the sound has gone bad then most likely the tube/s are bad and need to be replaced no matter how many hours are on them. It is always possible something else has gone bad but the first bet would be the tube unless a resistor is heading south.

 

[chesebert]

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif You can't tell if a tube is bad by the color on the glass. If the getter has turned white the tube has lost vacuum but darkened areas don't mean anything except some electrons have flowed. If the sound has gone bad then most likely the tube/s are bad and need to be replaced no matter how many hours are on them. It is always possible something else has gone bad but the first bet would be the tube unless a resistor is heading south.

seems like the answer from Dark Voice. well..I will just have to avoid vocals until I get my replacement tubes