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?





it is a Audio Note Kit, not the Audio Note UK.  However, there is a bit of a history.  What I learn is that the circuit of this monoblocks is initially designed by Andy Grove who is a prime engineer at Audio Note UK.  


Not going to happen on my end, so your decision is all on you from here on.

You remind me of a recently new "member" who posted that my abbreviation of Audiogon as A’Gon was "pretentious".



i would say I like them.  I sold my X5 before I bought this amp.  I am using them to drive a pair of JBL 4341 now.  I only have 3 power amps to compare: a custom built 300B by Otomon Lab from Japan using Luxman mq-300 schematics, the ANK, and Coincident 211 Dragon.  I then sold the Otomon Lab.  The ANK sound as good as the Coincident yet different.  The ANK are faster, a bit lighter, better mid range, and a bit more holographic.  The Coincident also sound very good.  It is a 211 push-pull delivering 75W per channel.  It produce a lot more power but also sound very lively and holographic.  I had a McIntosh MC 275 IV before.  It is a KT-77 push-pull, and it sounds boring and flat, which leave me an impression that is the characteristic of a push-pull amp.  It is not the case for the Coincident.  On my Harbeth 40.1, it will be clear it needs the Coincident 211.  But for my JBL, both sounds great.  

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Just want to provide an update. I tried adding the diodes but then one of the Sylvania 5931 (which is a rugged 5U4G) dies. I had one of these died died before adding the diodes. And they didn’t arch, but just died with no sound. I think it is not conclusive if the diodes works or not because the tube and symptom are different. But I am concerned and took out the diodes.

then I bought 3 pairs of 5U4GB, 2 pairs of TungSol and 1 pair of Westinghouse. So far so good. I will keep observing. Maybe the amps are just more demanding on the tubes, and some of the old tubes I tried are just bad.