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Is rectifier tube arcing a problem?

I did some research and couldn’t find a definite answer.  I have an amp that I tried 6 different pairs of 5U4G and 5U4GB. 3 pairs has arcing (RCA 5U4G, TungSol, Svetlana 5C3S) and 3 pairs don’t (RCA 5U4G with hanging filament, EH 5U4GB, Sylvania 5931).  I took the amp to a technician and he checked everything, he can’t find anything wrong.  The problem is, I like the sound of the TungSol and Svetlana which both have arcing.  The technician said it is ok to keep using them, but honestly I am not too comfortable.  But I like their sound.  Is it really ok to keep using the arcing tubes?  Will it damage the amp?

 

 

gte357s
gte357s OP
281 posts
 

BTW, it seems the arcing can developed over time.  Both the Svetlana 5C3S started arcing after several weeks.  Both the RCA arc right the way.  I just got the TungSol.  One of them started arcing after a couple hrs of use.  The other one doesn’t arc (yet).  
 

I also read I should wait 2 or 3 mins before restarting the amp.  I swap cables and restart in less than a min.  Can this be a reason of causing the arcing?  Once the tube starts to arc, it arc every time afterwards.  

immatthewj
1,039 posts
 

My first tube amp was a Cary SLA 70 which used a pair of CV729s/5R4GYs/CV378s and I remember when one of them started doing something weird (this was almost 30 years ago, but maybe it arced or glowed or flashed, I don’t remember precisely) and when I called Cray (this was when Cray offered much better customer service than they do now) I was told that it wasn’t anything to be afraid of, but that the tube was probably on its way out & I should probably keep one on hand.

Since that time, I did have a couple of rectifier tubes fail with a flash or an arc on startup, and that would blow the AC power fuse, but no other damage.

I am not an electrician or a tech so this is not advice, only my experience with a somewhat similar situation.

pesky_wabbit's avatar
pesky_wabbit
1,183 posts
 

Can this be a reason of causing the arcing? 

No.

as long as your amp is fused correctly you shouldn‘t suffer catastrophic consequences due to rectifier failure. The fact that they are arcing does tend to suggest that they are on the way out. Sounds like the Tung Sol you bought was a dud. All assuming your tech is competent.

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